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Annotation of GNUtools/cc/fold-const.c, revision 1.1

1.1     ! root        1: /* Fold a constant sub-tree into a single node for C-compiler
        !             2:    Copyright (C) 1987, 1988, 1992, 1993 Free Software Foundation, Inc.
        !             3: 
        !             4: This file is part of GNU CC.
        !             5: 
        !             6: GNU CC is free software; you can redistribute it and/or modify
        !             7: it under the terms of the GNU General Public License as published by
        !             8: the Free Software Foundation; either version 2, or (at your option)
        !             9: any later version.
        !            10: 
        !            11: GNU CC is distributed in the hope that it will be useful,
        !            12: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            14: GNU General Public License for more details.
        !            15: 
        !            16: You should have received a copy of the GNU General Public License
        !            17: along with GNU CC; see the file COPYING.  If not, write to
        !            18: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
        !            19: 
        !            20: /*@@ Fix lossage on folding division of big integers.  */
        !            21: 
        !            22: /*@@ This file should be rewritten to use an arbitrary precision
        !            23:   @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
        !            24:   @@ Perhaps the routines could also be used for bc/dc, and made a lib.
        !            25:   @@ The routines that translate from the ap rep should
        !            26:   @@ warn if precision et. al. is lost.
        !            27:   @@ This would also make life easier when this technology is used
        !            28:   @@ for cross-compilers.  */
        !            29: 
        !            30: 
        !            31: /* The entry points in this file are fold, size_int and size_binop.
        !            32: 
        !            33:    fold takes a tree as argument and returns a simplified tree.
        !            34: 
        !            35:    size_binop takes a tree code for an arithmetic operation
        !            36:    and two operands that are trees, and produces a tree for the
        !            37:    result, assuming the type comes from `sizetype'.
        !            38: 
        !            39:    size_int takes an integer value, and creates a tree constant
        !            40:    with type from `sizetype'.  */
        !            41:    
        !            42: #include <stdio.h>
        !            43: #include <setjmp.h>
        !            44: #include "config.h"
        !            45: #include "flags.h"
        !            46: #include "tree.h"
        !            47: 
        !            48: /* Handle floating overflow for `const_binop'.  */
        !            49: static jmp_buf float_error;
        !            50: 
        !            51: static void encode     PROTO((short *, HOST_WIDE_INT, HOST_WIDE_INT));
        !            52: static void decode     PROTO((short *, HOST_WIDE_INT *, HOST_WIDE_INT *));
        !            53: static int div_and_round_double PROTO((enum tree_code, int, HOST_WIDE_INT,
        !            54:                                       HOST_WIDE_INT, HOST_WIDE_INT,
        !            55:                                       HOST_WIDE_INT, HOST_WIDE_INT *,
        !            56:                                       HOST_WIDE_INT *, HOST_WIDE_INT *,
        !            57:                                       HOST_WIDE_INT *));
        !            58: static int split_tree  PROTO((tree, enum tree_code, tree *, tree *, int *));
        !            59: static tree const_binop PROTO((enum tree_code, tree, tree, int));
        !            60: static tree fold_convert PROTO((tree, tree));
        !            61: static enum tree_code invert_tree_comparison PROTO((enum tree_code));
        !            62: static enum tree_code swap_tree_comparison PROTO((enum tree_code));
        !            63: static int operand_equal_for_comparison_p PROTO((tree, tree, tree));
        !            64: static int twoval_comparison_p PROTO((tree, tree *, tree *, int *));
        !            65: static tree eval_subst PROTO((tree, tree, tree, tree, tree));
        !            66: static tree omit_one_operand PROTO((tree, tree, tree));
        !            67: static tree distribute_bit_expr PROTO((enum tree_code, tree, tree, tree));
        !            68: static tree make_bit_field_ref PROTO((tree, tree, int, int, int));
        !            69: static tree optimize_bit_field_compare PROTO((enum tree_code, tree,
        !            70:                                              tree, tree));
        !            71: static tree decode_field_reference PROTO((tree, int *, int *,
        !            72:                                          enum machine_mode *, int *,
        !            73:                                          int *, tree *));
        !            74: static int all_ones_mask_p PROTO((tree, int));
        !            75: static int simple_operand_p PROTO((tree));
        !            76: static tree range_test PROTO((enum tree_code, tree, enum tree_code,
        !            77:                               enum tree_code, tree, tree, tree));
        !            78: static tree fold_truthop PROTO((enum tree_code, tree, tree, tree));
        !            79: 
        !            80: #ifndef BRANCH_COST
        !            81: #define BRANCH_COST 1
        !            82: #endif
        !            83: 
        !            84: /* Yield nonzero if a signed left shift of A by B bits overflows.  */
        !            85: #define left_shift_overflows(a, b)  ((a)  !=  ((a) << (b)) >> (b))
        !            86: 
        !            87: /* Suppose A1 + B1 = SUM1, using 2's complement arithmetic ignoring overflow.
        !            88:    Suppose A, B and SUM have the same respective signs as A1, B1, and SUM1.
        !            89:    Then this yields nonzero if overflow occurred during the addition.
        !            90:    Overflow occurs if A and B have the same sign, but A and SUM differ in sign.
        !            91:    Use `^' to test whether signs differ, and `< 0' to isolate the sign.  */
        !            92: #define overflow_sum_sign(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
        !            93: 
        !            94: /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
        !            95:    We do that by representing the two-word integer as MAX_SHORTS shorts,
        !            96:    with only 8 bits stored in each short, as a positive number.  */
        !            97: 
        !            98: /* Unpack a two-word integer into MAX_SHORTS shorts.
        !            99:    LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
        !           100:    SHORTS points to the array of shorts.  */
        !           101: 
        !           102: static void
        !           103: encode (shorts, low, hi)
        !           104:      short *shorts;
        !           105:      HOST_WIDE_INT low, hi;
        !           106: {
        !           107:   register int i;
        !           108: 
        !           109:   for (i = 0; i < MAX_SHORTS / 2; i++)
        !           110:     {
        !           111:       shorts[i] = (low >> (i * 8)) & 0xff;
        !           112:       shorts[i + MAX_SHORTS / 2] = (hi >> (i * 8) & 0xff);
        !           113:     }
        !           114: }
        !           115: 
        !           116: /* Pack an array of MAX_SHORTS shorts into a two-word integer.
        !           117:    SHORTS points to the array of shorts.
        !           118:    The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces.  */
        !           119: 
        !           120: static void
        !           121: decode (shorts, low, hi)
        !           122:      short *shorts;
        !           123:      HOST_WIDE_INT *low, *hi;
        !           124: {
        !           125:   register int i;
        !           126:   HOST_WIDE_INT lv = 0, hv = 0;
        !           127: 
        !           128:   for (i = 0; i < MAX_SHORTS / 2; i++)
        !           129:     {
        !           130:       lv |= (HOST_WIDE_INT) shorts[i] << (i * 8);
        !           131:       hv |= (HOST_WIDE_INT) shorts[i + MAX_SHORTS / 2] << (i * 8);
        !           132:     }
        !           133: 
        !           134:   *low = lv, *hi = hv;
        !           135: }
        !           136: 
        !           137: /* Make the integer constant T valid for its type
        !           138:    by setting to 0 or 1 all the bits in the constant
        !           139:    that don't belong in the type.
        !           140:    Yield 1 if a signed overflow occurs, 0 otherwise.
        !           141:    If OVERFLOW is nonzero, a signed overflow has already occurred
        !           142:    in calculating T, so propagate it.  */
        !           143: 
        !           144: int
        !           145: force_fit_type (t, overflow)
        !           146:      tree t;
        !           147:      int overflow;
        !           148: {
        !           149:   HOST_WIDE_INT low, high;
        !           150:   register int prec;
        !           151: 
        !           152:   if (TREE_CODE (t) != INTEGER_CST)
        !           153:     return overflow;
        !           154: 
        !           155:   low = TREE_INT_CST_LOW (t);
        !           156:   high = TREE_INT_CST_HIGH (t);
        !           157: 
        !           158:   if (TREE_CODE (TREE_TYPE (t)) == POINTER_TYPE)
        !           159:     prec = POINTER_SIZE;
        !           160:   else
        !           161:     prec = TYPE_PRECISION (TREE_TYPE (t));
        !           162: 
        !           163:   /* First clear all bits that are beyond the type's precision.  */
        !           164: 
        !           165:   if (prec == 2 * HOST_BITS_PER_WIDE_INT)
        !           166:     ;
        !           167:   else if (prec > HOST_BITS_PER_WIDE_INT)
        !           168:     {
        !           169:       TREE_INT_CST_HIGH (t)
        !           170:        &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
        !           171:     }
        !           172:   else
        !           173:     {
        !           174:       TREE_INT_CST_HIGH (t) = 0;
        !           175:       if (prec < HOST_BITS_PER_WIDE_INT)
        !           176:        TREE_INT_CST_LOW (t) &= ~((HOST_WIDE_INT) (-1) << prec);
        !           177:     }
        !           178: 
        !           179:   /* Unsigned types do not suffer sign extension or overflow.  */
        !           180:   if (TREE_UNSIGNED (TREE_TYPE (t)))
        !           181:     return 0;
        !           182: 
        !           183:   /* If the value's sign bit is set, extend the sign.  */
        !           184:   if (prec != 2 * HOST_BITS_PER_WIDE_INT
        !           185:       && (prec > HOST_BITS_PER_WIDE_INT
        !           186:          ? (TREE_INT_CST_HIGH (t)
        !           187:             & ((HOST_WIDE_INT) 1 << (prec - HOST_BITS_PER_WIDE_INT - 1)))
        !           188:          : TREE_INT_CST_LOW (t) & ((HOST_WIDE_INT) 1 << (prec - 1))))
        !           189:     {
        !           190:       /* Value is negative:
        !           191:         set to 1 all the bits that are outside this type's precision.  */
        !           192:       if (prec > HOST_BITS_PER_WIDE_INT)
        !           193:        {
        !           194:          TREE_INT_CST_HIGH (t)
        !           195:            |= ((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
        !           196:        }
        !           197:       else
        !           198:        {
        !           199:          TREE_INT_CST_HIGH (t) = -1;
        !           200:          if (prec < HOST_BITS_PER_WIDE_INT)
        !           201:            TREE_INT_CST_LOW (t) |= ((HOST_WIDE_INT) (-1) << prec);
        !           202:        }
        !           203:     }
        !           204: 
        !           205:   /* Yield nonzero if signed overflow occurred.  */
        !           206:   return
        !           207:     ((overflow | (low ^ TREE_INT_CST_LOW (t)) | (high ^ TREE_INT_CST_HIGH (t)))
        !           208:      != 0);
        !           209: }
        !           210: 
        !           211: /* Add two doubleword integers with doubleword result.
        !           212:    Each argument is given as two `HOST_WIDE_INT' pieces.
        !           213:    One argument is L1 and H1; the other, L2 and H2.
        !           214:    The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV.
        !           215:    We use the 8-shorts representation internally.  */
        !           216: 
        !           217: int
        !           218: add_double (l1, h1, l2, h2, lv, hv)
        !           219:      HOST_WIDE_INT l1, h1, l2, h2;
        !           220:      HOST_WIDE_INT *lv, *hv;
        !           221: {
        !           222:   short arg1[MAX_SHORTS];
        !           223:   short arg2[MAX_SHORTS];
        !           224:   register int carry = 0;
        !           225:   register int i;
        !           226: 
        !           227:   encode (arg1, l1, h1);
        !           228:   encode (arg2, l2, h2);
        !           229: 
        !           230:   for (i = 0; i < MAX_SHORTS; i++)
        !           231:     {
        !           232:       carry += arg1[i] + arg2[i];
        !           233:       arg1[i] = carry & 0xff;
        !           234:       carry >>= 8;
        !           235:     }
        !           236: 
        !           237:   decode (arg1, lv, hv);
        !           238:   return overflow_sum_sign (h1, h2, *hv);
        !           239: }
        !           240: 
        !           241: /* Negate a doubleword integer with doubleword result.
        !           242:    Return nonzero if the operation overflows, assuming it's signed.
        !           243:    The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
        !           244:    The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV.
        !           245:    We use the 8-shorts representation internally.  */
        !           246: 
        !           247: int
        !           248: neg_double (l1, h1, lv, hv)
        !           249:      HOST_WIDE_INT l1, h1;
        !           250:      HOST_WIDE_INT *lv, *hv;
        !           251: {
        !           252:   if (l1 == 0)
        !           253:     {
        !           254:       *lv = 0;
        !           255:       *hv = - h1;
        !           256:       return (*hv & h1) < 0;
        !           257:     }
        !           258:   else
        !           259:     {
        !           260:       *lv = - l1;
        !           261:       *hv = ~ h1;
        !           262:       return 0;
        !           263:     }
        !           264: }
        !           265: 
        !           266: /* Multiply two doubleword integers with doubleword result.
        !           267:    Return nonzero if the operation overflows, assuming it's signed.
        !           268:    Each argument is given as two `HOST_WIDE_INT' pieces.
        !           269:    One argument is L1 and H1; the other, L2 and H2.
        !           270:    The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV.
        !           271:    We use the 8-shorts representation internally.  */
        !           272: 
        !           273: int
        !           274: mul_double (l1, h1, l2, h2, lv, hv)
        !           275:      HOST_WIDE_INT l1, h1, l2, h2;
        !           276:      HOST_WIDE_INT *lv, *hv;
        !           277: {
        !           278:   short arg1[MAX_SHORTS];
        !           279:   short arg2[MAX_SHORTS];
        !           280:   short prod[MAX_SHORTS * 2];
        !           281:   register int carry = 0;
        !           282:   register int i, j, k;
        !           283:   HOST_WIDE_INT toplow, tophigh, neglow, neghigh;
        !           284: 
        !           285:   /* These cases are used extensively, arising from pointer combinations.  */
        !           286:   if (h2 == 0)
        !           287:     {
        !           288:       if (l2 == 2)
        !           289:        {
        !           290:          int overflow = left_shift_overflows (h1, 1);
        !           291:          unsigned HOST_WIDE_INT temp = l1 + l1;
        !           292:          *hv = (h1 << 1) + (temp < l1);
        !           293:          *lv = temp;
        !           294:          return overflow;
        !           295:        }
        !           296:       if (l2 == 4)
        !           297:        {
        !           298:          int overflow = left_shift_overflows (h1, 2);
        !           299:          unsigned HOST_WIDE_INT temp = l1 + l1;
        !           300:          h1 = (h1 << 2) + ((temp < l1) << 1);
        !           301:          l1 = temp;
        !           302:          temp += temp;
        !           303:          h1 += (temp < l1);
        !           304:          *lv = temp;
        !           305:          *hv = h1;
        !           306:          return overflow;
        !           307:        }
        !           308:       if (l2 == 8)
        !           309:        {
        !           310:          int overflow = left_shift_overflows (h1, 3);
        !           311:          unsigned HOST_WIDE_INT temp = l1 + l1;
        !           312:          h1 = (h1 << 3) + ((temp < l1) << 2);
        !           313:          l1 = temp;
        !           314:          temp += temp;
        !           315:          h1 += (temp < l1) << 1;
        !           316:          l1 = temp;
        !           317:          temp += temp;
        !           318:          h1 += (temp < l1);
        !           319:          *lv = temp;
        !           320:          *hv = h1;
        !           321:          return overflow;
        !           322:        }
        !           323:     }
        !           324: 
        !           325:   encode (arg1, l1, h1);
        !           326:   encode (arg2, l2, h2);
        !           327: 
        !           328:   bzero (prod, sizeof prod);
        !           329: 
        !           330:   for (i = 0; i < MAX_SHORTS; i++)
        !           331:     for (j = 0; j < MAX_SHORTS; j++)
        !           332:       {
        !           333:        k = i + j;
        !           334:        carry = arg1[i] * arg2[j];
        !           335:        while (carry)
        !           336:          {
        !           337:            carry += prod[k];
        !           338:            prod[k] = carry & 0xff;
        !           339:            carry >>= 8;
        !           340:            k++;
        !           341:          }
        !           342:       }
        !           343: 
        !           344:   decode (prod, lv, hv);       /* This ignores
        !           345:                                   prod[MAX_SHORTS] -> prod[MAX_SHORTS*2-1] */
        !           346: 
        !           347:   /* Check for overflow by calculating the top half of the answer in full;
        !           348:      it should agree with the low half's sign bit.  */
        !           349:   decode (prod+MAX_SHORTS, &toplow, &tophigh);
        !           350:   if (h1 < 0)
        !           351:     {
        !           352:       neg_double (l2, h2, &neglow, &neghigh);
        !           353:       add_double (neglow, neghigh, toplow, tophigh, &toplow, &tophigh);
        !           354:     }
        !           355:   if (h2 < 0)
        !           356:     {
        !           357:       neg_double (l1, h1, &neglow, &neghigh);
        !           358:       add_double (neglow, neghigh, toplow, tophigh, &toplow, &tophigh);
        !           359:     }
        !           360:   return (*hv < 0 ? ~(toplow & tophigh) : toplow | tophigh) != 0;
        !           361: }
        !           362: 
        !           363: /* Shift the doubleword integer in L1, H1 left by COUNT places
        !           364:    keeping only PREC bits of result.
        !           365:    Shift right if COUNT is negative.
        !           366:    ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
        !           367:    Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV.  */
        !           368: 
        !           369: void
        !           370: lshift_double (l1, h1, count, prec, lv, hv, arith)
        !           371:      HOST_WIDE_INT l1, h1, count;
        !           372:      int prec;
        !           373:      HOST_WIDE_INT *lv, *hv;
        !           374:      int arith;
        !           375: {
        !           376:   short arg1[MAX_SHORTS];
        !           377:   register int i;
        !           378:   register int carry;
        !           379: 
        !           380:   if (count < 0)
        !           381:     {
        !           382:       rshift_double (l1, h1, - count, prec, lv, hv, arith);
        !           383:       return;
        !           384:     }
        !           385: 
        !           386:   encode (arg1, l1, h1);
        !           387: 
        !           388:   if (count > prec)
        !           389:     count = prec;
        !           390: 
        !           391:   while (count > 0)
        !           392:     {
        !           393:       carry = 0;
        !           394:       for (i = 0; i < MAX_SHORTS; i++)
        !           395:        {
        !           396:          carry += arg1[i] << 1;
        !           397:          arg1[i] = carry & 0xff;
        !           398:          carry >>= 8;
        !           399:        }
        !           400:       count--;
        !           401:     }
        !           402: 
        !           403:   decode (arg1, lv, hv);
        !           404: }
        !           405: 
        !           406: /* Shift the doubleword integer in L1, H1 right by COUNT places
        !           407:    keeping only PREC bits of result.  COUNT must be positive.
        !           408:    ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
        !           409:    Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV.  */
        !           410: 
        !           411: void
        !           412: rshift_double (l1, h1, count, prec, lv, hv, arith)
        !           413:      HOST_WIDE_INT l1, h1, count;
        !           414:      int prec;
        !           415:      HOST_WIDE_INT *lv, *hv;
        !           416:      int arith;
        !           417: {
        !           418:   short arg1[MAX_SHORTS];
        !           419:   register int i;
        !           420:   register int carry;
        !           421: 
        !           422:   encode (arg1, l1, h1);
        !           423: 
        !           424:   if (count > prec)
        !           425:     count = prec;
        !           426: 
        !           427:   while (count > 0)
        !           428:     {
        !           429:       carry = arith && arg1[7] >> 7; 
        !           430:       for (i = MAX_SHORTS - 1; i >= 0; i--)
        !           431:        {
        !           432:          carry <<= 8;
        !           433:          carry += arg1[i];
        !           434:          arg1[i] = (carry >> 1) & 0xff;
        !           435:        }
        !           436:       count--;
        !           437:     }
        !           438: 
        !           439:   decode (arg1, lv, hv);
        !           440: }
        !           441: 
        !           442: /* Rotate the doubldword integer in L1, H1 left by COUNT places
        !           443:    keeping only PREC bits of result.
        !           444:    Rotate right if COUNT is negative.
        !           445:    Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV.  */
        !           446: 
        !           447: void
        !           448: lrotate_double (l1, h1, count, prec, lv, hv)
        !           449:      HOST_WIDE_INT l1, h1, count;
        !           450:      int prec;
        !           451:      HOST_WIDE_INT *lv, *hv;
        !           452: {
        !           453:   short arg1[MAX_SHORTS];
        !           454:   register int i;
        !           455:   register int carry;
        !           456: 
        !           457:   if (count < 0)
        !           458:     {
        !           459:       rrotate_double (l1, h1, - count, prec, lv, hv);
        !           460:       return;
        !           461:     }
        !           462: 
        !           463:   encode (arg1, l1, h1);
        !           464: 
        !           465:   if (count > prec)
        !           466:     count = prec;
        !           467: 
        !           468:   carry = arg1[MAX_SHORTS - 1] >> 7;
        !           469:   while (count > 0)
        !           470:     {
        !           471:       for (i = 0; i < MAX_SHORTS; i++)
        !           472:        {
        !           473:          carry += arg1[i] << 1;
        !           474:          arg1[i] = carry & 0xff;
        !           475:          carry >>= 8;
        !           476:        }
        !           477:       count--;
        !           478:     }
        !           479: 
        !           480:   decode (arg1, lv, hv);
        !           481: }
        !           482: 
        !           483: /* Rotate the doubleword integer in L1, H1 left by COUNT places
        !           484:    keeping only PREC bits of result.  COUNT must be positive.
        !           485:    Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV.  */
        !           486: 
        !           487: void
        !           488: rrotate_double (l1, h1, count, prec, lv, hv)
        !           489:      HOST_WIDE_INT l1, h1, count;
        !           490:      int prec;
        !           491:      HOST_WIDE_INT *lv, *hv;
        !           492: {
        !           493:   short arg1[MAX_SHORTS];
        !           494:   register int i;
        !           495:   register int carry;
        !           496: 
        !           497:   encode (arg1, l1, h1);
        !           498: 
        !           499:   if (count > prec)
        !           500:     count = prec;
        !           501: 
        !           502:   carry = arg1[0] & 1;
        !           503:   while (count > 0)
        !           504:     {
        !           505:       for (i = MAX_SHORTS - 1; i >= 0; i--)
        !           506:        {
        !           507:          carry <<= 8;
        !           508:          carry += arg1[i];
        !           509:          arg1[i] = (carry >> 1) & 0xff;
        !           510:        }
        !           511:       count--;
        !           512:     }
        !           513: 
        !           514:   decode (arg1, lv, hv);
        !           515: }
        !           516: 
        !           517: /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
        !           518:    for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
        !           519:    CODE is a tree code for a kind of division, one of
        !           520:    TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
        !           521:    or EXACT_DIV_EXPR
        !           522:    It controls how the quotient is rounded to a integer.
        !           523:    Return nonzero if the operation overflows.
        !           524:    UNS nonzero says do unsigned division.  */
        !           525: 
        !           526: static int
        !           527: div_and_round_double (code, uns,
        !           528:                      lnum_orig, hnum_orig, lden_orig, hden_orig,
        !           529:                      lquo, hquo, lrem, hrem)
        !           530:      enum tree_code code;
        !           531:      int uns;
        !           532:      HOST_WIDE_INT lnum_orig, hnum_orig; /* num == numerator == dividend */
        !           533:      HOST_WIDE_INT lden_orig, hden_orig; /* den == denominator == divisor */
        !           534:      HOST_WIDE_INT *lquo, *hquo, *lrem, *hrem;
        !           535: {
        !           536:   int quo_neg = 0;
        !           537:   short num[MAX_SHORTS + 1];   /* extra element for scaling.  */
        !           538:   short den[MAX_SHORTS], quo[MAX_SHORTS];
        !           539:   register int i, j, work;
        !           540:   register int carry = 0;
        !           541:   HOST_WIDE_INT lnum = lnum_orig;
        !           542:   HOST_WIDE_INT hnum = hnum_orig;
        !           543:   HOST_WIDE_INT lden = lden_orig;
        !           544:   HOST_WIDE_INT hden = hden_orig;
        !           545:   int overflow = 0;
        !           546: 
        !           547:   if ((hden == 0) && (lden == 0))
        !           548:     abort ();
        !           549: 
        !           550:   /* calculate quotient sign and convert operands to unsigned.  */
        !           551:   if (!uns) 
        !           552:     {
        !           553:       if (hnum < 0)
        !           554:        {
        !           555:          quo_neg = ~ quo_neg;
        !           556:          /* (minimum integer) / (-1) is the only overflow case.  */
        !           557:          if (neg_double (lnum, hnum, &lnum, &hnum) && (lden & hden) == -1)
        !           558:            overflow = 1;
        !           559:        }
        !           560:       if (hden < 0) 
        !           561:        {
        !           562:          quo_neg = ~ quo_neg;
        !           563:          neg_double (lden, hden, &lden, &hden);
        !           564:        }
        !           565:     }
        !           566: 
        !           567:   if (hnum == 0 && hden == 0)
        !           568:     {                          /* single precision */
        !           569:       *hquo = *hrem = 0;
        !           570:       /* This unsigned division rounds toward zero.  */
        !           571:       *lquo = lnum / (unsigned HOST_WIDE_INT) lden;
        !           572:       goto finish_up;
        !           573:     }
        !           574: 
        !           575:   if (hnum == 0)
        !           576:     {                          /* trivial case: dividend < divisor */
        !           577:       /* hden != 0 already checked.  */
        !           578:       *hquo = *lquo = 0;
        !           579:       *hrem = hnum;
        !           580:       *lrem = lnum;
        !           581:       goto finish_up;
        !           582:     }
        !           583: 
        !           584:   bzero (quo, sizeof quo);
        !           585: 
        !           586:   bzero (num, sizeof num);     /* to zero 9th element */
        !           587:   bzero (den, sizeof den);
        !           588: 
        !           589:   encode (num, lnum, hnum); 
        !           590:   encode (den, lden, hden);
        !           591: 
        !           592:   /* This code requires more than just hden == 0.
        !           593:      We also have to require that we don't need more than three bytes
        !           594:      to hold CARRY.  If we ever did need four bytes to hold it, we
        !           595:      would lose part of it when computing WORK on the next round.  */
        !           596:   if (hden == 0 && (((unsigned HOST_WIDE_INT) lden << 8) >> 8) == lden)
        !           597:     {                          /* simpler algorithm */
        !           598:       /* hnum != 0 already checked.  */
        !           599:       for (i = MAX_SHORTS - 1; i >= 0; i--)
        !           600:        {
        !           601:          work = num[i] + (carry << 8);
        !           602:          quo[i] = work / (unsigned HOST_WIDE_INT) lden;
        !           603:          carry = work % (unsigned HOST_WIDE_INT) lden;
        !           604:        }
        !           605:     }
        !           606:   else {                       /* full double precision,
        !           607:                                   with thanks to Don Knuth's
        !           608:                                   "Seminumerical Algorithms".  */
        !           609: #define BASE 256
        !           610:     int quo_est, scale, num_hi_sig, den_hi_sig, quo_hi_sig;
        !           611: 
        !           612:     /* Find the highest non-zero divisor digit.  */
        !           613:     for (i = MAX_SHORTS - 1; ; i--)
        !           614:       if (den[i] != 0) {
        !           615:        den_hi_sig = i;
        !           616:        break;
        !           617:       }
        !           618:     for (i = MAX_SHORTS - 1; ; i--)
        !           619:       if (num[i] != 0) {
        !           620:        num_hi_sig = i;
        !           621:        break;
        !           622:       }
        !           623:     quo_hi_sig = num_hi_sig - den_hi_sig + 1;
        !           624: 
        !           625:     /* Insure that the first digit of the divisor is at least BASE/2.
        !           626:        This is required by the quotient digit estimation algorithm.  */
        !           627: 
        !           628:     scale = BASE / (den[den_hi_sig] + 1);
        !           629:     if (scale > 1) {           /* scale divisor and dividend */
        !           630:       carry = 0;
        !           631:       for (i = 0; i <= MAX_SHORTS - 1; i++) {
        !           632:        work = (num[i] * scale) + carry;
        !           633:        num[i] = work & 0xff;
        !           634:        carry = work >> 8;
        !           635:        if (num[i] != 0) num_hi_sig = i;
        !           636:       }
        !           637:       carry = 0;
        !           638:       for (i = 0; i <= MAX_SHORTS - 1; i++) {
        !           639:        work = (den[i] * scale) + carry;
        !           640:        den[i] = work & 0xff;
        !           641:        carry = work >> 8;
        !           642:        if (den[i] != 0) den_hi_sig = i;
        !           643:       }
        !           644:     }
        !           645: 
        !           646:     /* Main loop */
        !           647:     for (i = quo_hi_sig; i > 0; i--) {
        !           648:       /* guess the next quotient digit, quo_est, by dividing the first
        !           649:         two remaining dividend digits by the high order quotient digit.
        !           650:         quo_est is never low and is at most 2 high.  */
        !           651: 
        !           652:       int num_hi;              /* index of highest remaining dividend digit */
        !           653: 
        !           654:       num_hi = i + den_hi_sig;
        !           655: 
        !           656:       work = (num[num_hi] * BASE) + (num_hi > 0 ? num[num_hi - 1] : 0);
        !           657:       if (num[num_hi] != den[den_hi_sig]) {
        !           658:        quo_est = work / den[den_hi_sig];
        !           659:       }
        !           660:       else {
        !           661:        quo_est = BASE - 1;
        !           662:       }
        !           663: 
        !           664:       /* refine quo_est so it's usually correct, and at most one high.   */
        !           665:       while ((den[den_hi_sig - 1] * quo_est)
        !           666:             > (((work - (quo_est * den[den_hi_sig])) * BASE)
        !           667:                 + ((num_hi - 1) > 0 ? num[num_hi - 2] : 0)))
        !           668:        quo_est--;
        !           669: 
        !           670:       /* Try QUO_EST as the quotient digit, by multiplying the
        !           671:          divisor by QUO_EST and subtracting from the remaining dividend.
        !           672:         Keep in mind that QUO_EST is the I - 1st digit.  */
        !           673: 
        !           674:       carry = 0;
        !           675: 
        !           676:       for (j = 0; j <= den_hi_sig; j++)
        !           677:        {
        !           678:          int digit;
        !           679: 
        !           680:          work = num[i + j - 1] - (quo_est * den[j]) + carry;
        !           681:          digit = work & 0xff;
        !           682:          carry = work >> 8;
        !           683:          if (digit < 0)
        !           684:            {
        !           685:              digit += BASE;
        !           686:              carry--;
        !           687:            }
        !           688:          num[i + j - 1] = digit;
        !           689:        }
        !           690: 
        !           691:       /* if quo_est was high by one, then num[i] went negative and
        !           692:         we need to correct things.  */
        !           693: 
        !           694:       if (num[num_hi] < 0)
        !           695:        {
        !           696:          quo_est--;
        !           697:          carry = 0;            /* add divisor back in */
        !           698:          for (j = 0; j <= den_hi_sig; j++)
        !           699:            {
        !           700:              work = num[i + j - 1] + den[j] + carry;
        !           701:              if (work > BASE)
        !           702:                {
        !           703:                  work -= BASE;
        !           704:                  carry = 1;
        !           705:                }
        !           706:              else
        !           707:                {
        !           708:                  carry = 0;
        !           709:                }
        !           710:              num[i + j - 1] = work;
        !           711:            }
        !           712:          num [num_hi] += carry;
        !           713:        }
        !           714: 
        !           715:       /* store the quotient digit.  */
        !           716:       quo[i - 1] = quo_est;
        !           717:     }
        !           718:   }
        !           719: 
        !           720:   decode (quo, lquo, hquo);
        !           721: 
        !           722:  finish_up:
        !           723:   /* if result is negative, make it so.  */
        !           724:   if (quo_neg)
        !           725:     neg_double (*lquo, *hquo, lquo, hquo);
        !           726: 
        !           727:   /* compute trial remainder:  rem = num - (quo * den)  */
        !           728:   mul_double (*lquo, *hquo, lden_orig, hden_orig, lrem, hrem);
        !           729:   neg_double (*lrem, *hrem, lrem, hrem);
        !           730:   add_double (lnum_orig, hnum_orig, *lrem, *hrem, lrem, hrem);
        !           731: 
        !           732:   switch (code)
        !           733:     {
        !           734:     case TRUNC_DIV_EXPR:
        !           735:     case TRUNC_MOD_EXPR:       /* round toward zero */
        !           736:     case EXACT_DIV_EXPR:       /* for this one, it shouldn't matter */
        !           737:       return overflow;
        !           738: 
        !           739:     case FLOOR_DIV_EXPR:
        !           740:     case FLOOR_MOD_EXPR:       /* round toward negative infinity */
        !           741:       if (quo_neg && (*lrem != 0 || *hrem != 0))   /* ratio < 0 && rem != 0 */
        !           742:        {
        !           743:          /* quo = quo - 1;  */
        !           744:          add_double (*lquo, *hquo, (HOST_WIDE_INT) -1, (HOST_WIDE_INT)  -1,
        !           745:                      lquo, hquo);
        !           746:        }
        !           747:       else return overflow;
        !           748:       break;
        !           749: 
        !           750:     case CEIL_DIV_EXPR:
        !           751:     case CEIL_MOD_EXPR:                /* round toward positive infinity */
        !           752:       if (!quo_neg && (*lrem != 0 || *hrem != 0))  /* ratio > 0 && rem != 0 */
        !           753:        {
        !           754:          add_double (*lquo, *hquo, (HOST_WIDE_INT) 1, (HOST_WIDE_INT) 0,
        !           755:                      lquo, hquo);
        !           756:        }
        !           757:       else return overflow;
        !           758:       break;
        !           759:     
        !           760:     case ROUND_DIV_EXPR:
        !           761:     case ROUND_MOD_EXPR:       /* round to closest integer */
        !           762:       {
        !           763:        HOST_WIDE_INT labs_rem = *lrem, habs_rem = *hrem;
        !           764:        HOST_WIDE_INT labs_den = lden, habs_den = hden, ltwice, htwice;
        !           765: 
        !           766:        /* get absolute values */
        !           767:        if (*hrem < 0) neg_double (*lrem, *hrem, &labs_rem, &habs_rem);
        !           768:        if (hden < 0) neg_double (lden, hden, &labs_den, &habs_den);
        !           769: 
        !           770:        /* if (2 * abs (lrem) >= abs (lden)) */
        !           771:        mul_double ((HOST_WIDE_INT) 2, (HOST_WIDE_INT) 0,
        !           772:                    labs_rem, habs_rem, &ltwice, &htwice);
        !           773:        if (((unsigned HOST_WIDE_INT) habs_den
        !           774:             < (unsigned HOST_WIDE_INT) htwice)
        !           775:            || (((unsigned HOST_WIDE_INT) habs_den
        !           776:                 == (unsigned HOST_WIDE_INT) htwice)
        !           777:                && ((HOST_WIDE_INT unsigned) labs_den
        !           778:                    < (unsigned HOST_WIDE_INT) ltwice)))
        !           779:          {
        !           780:            if (*hquo < 0)
        !           781:              /* quo = quo - 1;  */
        !           782:              add_double (*lquo, *hquo,
        !           783:                          (HOST_WIDE_INT) -1, (HOST_WIDE_INT) -1, lquo, hquo);
        !           784:            else
        !           785:              /* quo = quo + 1; */
        !           786:              add_double (*lquo, *hquo, (HOST_WIDE_INT) 1, (HOST_WIDE_INT) 0,
        !           787:                          lquo, hquo);
        !           788:          }
        !           789:        else return overflow;
        !           790:       }
        !           791:       break;
        !           792: 
        !           793:     default:
        !           794:       abort ();
        !           795:     }
        !           796: 
        !           797:   /* compute true remainder:  rem = num - (quo * den)  */
        !           798:   mul_double (*lquo, *hquo, lden_orig, hden_orig, lrem, hrem);
        !           799:   neg_double (*lrem, *hrem, lrem, hrem);
        !           800:   add_double (lnum_orig, hnum_orig, *lrem, *hrem, lrem, hrem);
        !           801:   return overflow;
        !           802: }
        !           803: 
        !           804: #ifndef REAL_ARITHMETIC
        !           805: /* Effectively truncate a real value to represent
        !           806:    the nearest possible value in a narrower mode.
        !           807:    The result is actually represented in the same data type as the argument,
        !           808:    but its value is usually different.  */
        !           809: 
        !           810: REAL_VALUE_TYPE
        !           811: real_value_truncate (mode, arg)
        !           812:      enum machine_mode mode;
        !           813:      REAL_VALUE_TYPE arg;
        !           814: {
        !           815: #ifdef __STDC__
        !           816:   /* Make sure the value is actually stored in memory before we turn off
        !           817:      the handler.  */
        !           818:   volatile
        !           819: #endif
        !           820:     REAL_VALUE_TYPE value;
        !           821:   jmp_buf handler, old_handler;
        !           822:   int handled;
        !           823: 
        !           824:   if (setjmp (handler))
        !           825:     {
        !           826:       error ("floating overflow");
        !           827:       return dconst0;
        !           828:     }
        !           829:   handled = push_float_handler (handler, old_handler);
        !           830:   value = REAL_VALUE_TRUNCATE (mode, arg);
        !           831:   pop_float_handler (handled, old_handler);
        !           832:   return value;
        !           833: }
        !           834: 
        !           835: #if TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
        !           836: 
        !           837: /* Check for infinity in an IEEE double precision number.  */
        !           838: 
        !           839: int
        !           840: target_isinf (x)
        !           841:      REAL_VALUE_TYPE x;
        !           842: {
        !           843:   /* The IEEE 64-bit double format.  */
        !           844:   union {
        !           845:     REAL_VALUE_TYPE d;
        !           846:     struct {
        !           847:       unsigned sign      :  1;
        !           848:       unsigned exponent  : 11;
        !           849:       unsigned mantissa1 : 20;
        !           850:       unsigned mantissa2;
        !           851:     } little_endian;
        !           852:     struct {
        !           853:       unsigned mantissa2;
        !           854:       unsigned mantissa1 : 20;
        !           855:       unsigned exponent  : 11;
        !           856:       unsigned sign      :  1;
        !           857:     } big_endian;    
        !           858:   } u;
        !           859: 
        !           860:   u.d = dconstm1;
        !           861:   if (u.big_endian.sign == 1)
        !           862:     {
        !           863:       u.d = x;
        !           864:       return (u.big_endian.exponent == 2047
        !           865:              && u.big_endian.mantissa1 == 0
        !           866:              && u.big_endian.mantissa2 == 0);
        !           867:     }
        !           868:   else
        !           869:     {
        !           870:       u.d = x;
        !           871:       return (u.little_endian.exponent == 2047
        !           872:              && u.little_endian.mantissa1 == 0
        !           873:              && u.little_endian.mantissa2 == 0);
        !           874:     }
        !           875: }
        !           876: 
        !           877: /* Check whether an IEEE double precision number is a NaN.  */
        !           878: 
        !           879: int
        !           880: target_isnan (x)
        !           881:      REAL_VALUE_TYPE x;
        !           882: {
        !           883:   /* The IEEE 64-bit double format.  */
        !           884:   union {
        !           885:     REAL_VALUE_TYPE d;
        !           886:     struct {
        !           887:       unsigned sign      :  1;
        !           888:       unsigned exponent  : 11;
        !           889:       unsigned mantissa1 : 20;
        !           890:       unsigned mantissa2;
        !           891:     } little_endian;
        !           892:     struct {
        !           893:       unsigned mantissa2;
        !           894:       unsigned mantissa1 : 20;
        !           895:       unsigned exponent  : 11;
        !           896:       unsigned sign      :  1;
        !           897:     } big_endian;    
        !           898:   } u;
        !           899: 
        !           900:   u.d = dconstm1;
        !           901:   if (u.big_endian.sign == 1)
        !           902:     {
        !           903:       u.d = x;
        !           904:       return (u.big_endian.exponent == 2047
        !           905:              && (u.big_endian.mantissa1 != 0
        !           906:                  || u.big_endian.mantissa2 != 0));
        !           907:     }
        !           908:   else
        !           909:     {
        !           910:       u.d = x;
        !           911:       return (u.little_endian.exponent == 2047
        !           912:              && (u.little_endian.mantissa1 != 0
        !           913:                  || u.little_endian.mantissa2 != 0));
        !           914:     }
        !           915: }
        !           916: 
        !           917: /* Check for a negative IEEE double precision number.  */
        !           918: 
        !           919: int
        !           920: target_negative (x)
        !           921:      REAL_VALUE_TYPE x;
        !           922: {
        !           923:   /* The IEEE 64-bit double format.  */
        !           924:   union {
        !           925:     REAL_VALUE_TYPE d;
        !           926:     struct {
        !           927:       unsigned sign      :  1;
        !           928:       unsigned exponent  : 11;
        !           929:       unsigned mantissa1 : 20;
        !           930:       unsigned mantissa2;
        !           931:     } little_endian;
        !           932:     struct {
        !           933:       unsigned mantissa2;
        !           934:       unsigned mantissa1 : 20;
        !           935:       unsigned exponent  : 11;
        !           936:       unsigned sign      :  1;
        !           937:     } big_endian;    
        !           938:   } u;
        !           939: 
        !           940:   u.d = dconstm1;
        !           941:   if (u.big_endian.sign == 1)
        !           942:     {
        !           943:       u.d = x;
        !           944:       return u.big_endian.sign;
        !           945:     }
        !           946:   else
        !           947:     {
        !           948:       u.d = x;
        !           949:       return u.little_endian.sign;
        !           950:     }
        !           951: }
        !           952: #else /* Target not IEEE */
        !           953: 
        !           954: /* Let's assume other float formats don't have infinity.
        !           955:    (This can be overridden by redefining REAL_VALUE_ISINF.)  */
        !           956: 
        !           957: target_isinf (x)
        !           958:      REAL_VALUE_TYPE x;
        !           959: {
        !           960:   return 0;
        !           961: }
        !           962: 
        !           963: /* Let's assume other float formats don't have NaNs.
        !           964:    (This can be overridden by redefining REAL_VALUE_ISNAN.)  */
        !           965: 
        !           966: target_isnan (x)
        !           967:      REAL_VALUE_TYPE x;
        !           968: {
        !           969:   return 0;
        !           970: }
        !           971: 
        !           972: /* Let's assume other float formats don't have minus zero.
        !           973:    (This can be overridden by redefining REAL_VALUE_NEGATIVE.)  */
        !           974: 
        !           975: target_negative (x)
        !           976:      REAL_VALUE_TYPE x;
        !           977: {
        !           978:   return x < 0;
        !           979: }
        !           980: #endif /* Target not IEEE */
        !           981: #endif /* no REAL_ARITHMETIC */
        !           982: 
        !           983: /* Split a tree IN into a constant and a variable part
        !           984:    that could be combined with CODE to make IN.
        !           985:    CODE must be a commutative arithmetic operation.
        !           986:    Store the constant part into *CONP and the variable in &VARP.
        !           987:    Return 1 if this was done; zero means the tree IN did not decompose
        !           988:    this way.
        !           989: 
        !           990:    If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR.
        !           991:    Therefore, we must tell the caller whether the variable part
        !           992:    was subtracted.  We do this by storing 1 or -1 into *VARSIGNP.
        !           993:    The value stored is the coefficient for the variable term.
        !           994:    The constant term we return should always be added;
        !           995:    we negate it if necessary.  */
        !           996: 
        !           997: static int
        !           998: split_tree (in, code, varp, conp, varsignp)
        !           999:      tree in;
        !          1000:      enum tree_code code;
        !          1001:      tree *varp, *conp;
        !          1002:      int *varsignp;
        !          1003: {
        !          1004:   register tree outtype = TREE_TYPE (in);
        !          1005:   *varp = 0;
        !          1006:   *conp = 0;
        !          1007: 
        !          1008:   /* Strip any conversions that don't change the machine mode.  */
        !          1009:   while ((TREE_CODE (in) == NOP_EXPR
        !          1010:          || TREE_CODE (in) == CONVERT_EXPR)
        !          1011:         && (TYPE_MODE (TREE_TYPE (in))
        !          1012:             == TYPE_MODE (TREE_TYPE (TREE_OPERAND (in, 0)))))
        !          1013:     in = TREE_OPERAND (in, 0);
        !          1014: 
        !          1015:   if (TREE_CODE (in) == code
        !          1016:       || (! FLOAT_TYPE_P (TREE_TYPE (in))
        !          1017:          /* We can associate addition and subtraction together
        !          1018:             (even though the C standard doesn't say so)
        !          1019:             for integers because the value is not affected.
        !          1020:             For reals, the value might be affected, so we can't.  */
        !          1021:          && ((code == PLUS_EXPR && TREE_CODE (in) == MINUS_EXPR)
        !          1022:              || (code == MINUS_EXPR && TREE_CODE (in) == PLUS_EXPR))))
        !          1023:     {
        !          1024:       enum tree_code code = TREE_CODE (TREE_OPERAND (in, 0));
        !          1025:       if (code == INTEGER_CST)
        !          1026:        {
        !          1027:          *conp = TREE_OPERAND (in, 0);
        !          1028:          *varp = TREE_OPERAND (in, 1);
        !          1029:          if (TYPE_MODE (TREE_TYPE (*varp)) != TYPE_MODE (outtype)
        !          1030:              && TREE_TYPE (*varp) != outtype)
        !          1031:            *varp = convert (outtype, *varp);
        !          1032:          *varsignp = (TREE_CODE (in) == MINUS_EXPR) ? -1 : 1;
        !          1033:          return 1;
        !          1034:        }
        !          1035:       if (TREE_CONSTANT (TREE_OPERAND (in, 1)))
        !          1036:        {
        !          1037:          *conp = TREE_OPERAND (in, 1);
        !          1038:          *varp = TREE_OPERAND (in, 0);
        !          1039:          *varsignp = 1;
        !          1040:          if (TYPE_MODE (TREE_TYPE (*varp)) != TYPE_MODE (outtype)
        !          1041:              && TREE_TYPE (*varp) != outtype)
        !          1042:            *varp = convert (outtype, *varp);
        !          1043:          if (TREE_CODE (in) == MINUS_EXPR)
        !          1044:            {
        !          1045:              /* If operation is subtraction and constant is second,
        !          1046:                 must negate it to get an additive constant.
        !          1047:                 And this cannot be done unless it is a manifest constant.
        !          1048:                 It could also be the address of a static variable.
        !          1049:                 We cannot negate that, so give up.  */
        !          1050:              if (TREE_CODE (*conp) == INTEGER_CST)
        !          1051:                /* Subtracting from integer_zero_node loses for long long.  */
        !          1052:                *conp = fold (build1 (NEGATE_EXPR, TREE_TYPE (*conp), *conp));
        !          1053:              else
        !          1054:                return 0;
        !          1055:            }
        !          1056:          return 1;
        !          1057:        }
        !          1058:       if (TREE_CONSTANT (TREE_OPERAND (in, 0)))
        !          1059:        {
        !          1060:          *conp = TREE_OPERAND (in, 0);
        !          1061:          *varp = TREE_OPERAND (in, 1);
        !          1062:          if (TYPE_MODE (TREE_TYPE (*varp)) != TYPE_MODE (outtype)
        !          1063:              && TREE_TYPE (*varp) != outtype)
        !          1064:            *varp = convert (outtype, *varp);
        !          1065:          *varsignp = (TREE_CODE (in) == MINUS_EXPR) ? -1 : 1;
        !          1066:          return 1;
        !          1067:        }
        !          1068:     }
        !          1069:   return 0;
        !          1070: }
        !          1071: 
        !          1072: /* Combine two constants NUM and ARG2 under operation CODE
        !          1073:    to produce a new constant.
        !          1074:    We assume ARG1 and ARG2 have the same data type,
        !          1075:    or at least are the same kind of constant and the same machine mode.
        !          1076: 
        !          1077:    If NOTRUNC is nonzero, do not truncate the result to fit the data type.  */
        !          1078: 
        !          1079: static tree
        !          1080: const_binop (code, arg1, arg2, notrunc)
        !          1081:      enum tree_code code;
        !          1082:      register tree arg1, arg2;
        !          1083:      int notrunc;
        !          1084: {
        !          1085:   if (TREE_CODE (arg1) == INTEGER_CST)
        !          1086:     {
        !          1087:       register HOST_WIDE_INT int1l = TREE_INT_CST_LOW (arg1);
        !          1088:       register HOST_WIDE_INT int1h = TREE_INT_CST_HIGH (arg1);
        !          1089:       HOST_WIDE_INT int2l = TREE_INT_CST_LOW (arg2);
        !          1090:       HOST_WIDE_INT int2h = TREE_INT_CST_HIGH (arg2);
        !          1091:       HOST_WIDE_INT low, hi;
        !          1092:       HOST_WIDE_INT garbagel, garbageh;
        !          1093:       register tree t;
        !          1094:       int uns = TREE_UNSIGNED (TREE_TYPE (arg1));
        !          1095:       int overflow = 0;
        !          1096: 
        !          1097:       switch (code)
        !          1098:        {
        !          1099:        case BIT_IOR_EXPR:
        !          1100:          t = build_int_2 (int1l | int2l, int1h | int2h);
        !          1101:          break;
        !          1102: 
        !          1103:        case BIT_XOR_EXPR:
        !          1104:          t = build_int_2 (int1l ^ int2l, int1h ^ int2h);
        !          1105:          break;
        !          1106: 
        !          1107:        case BIT_AND_EXPR:
        !          1108:          t = build_int_2 (int1l & int2l, int1h & int2h);
        !          1109:          break;
        !          1110: 
        !          1111:        case BIT_ANDTC_EXPR:
        !          1112:          t = build_int_2 (int1l & ~int2l, int1h & ~int2h);
        !          1113:          break;
        !          1114: 
        !          1115:        case RSHIFT_EXPR:
        !          1116:          int2l = - int2l;
        !          1117:        case LSHIFT_EXPR:
        !          1118:          /* It's unclear from the C standard whether shifts can overflow.
        !          1119:             The following code ignores overflow; perhaps a C standard
        !          1120:             interpretation ruling is needed.  */
        !          1121:          lshift_double (int1l, int1h, int2l,
        !          1122:                         TYPE_PRECISION (TREE_TYPE (arg1)),
        !          1123:                         &low, &hi,
        !          1124:                         !uns);
        !          1125:          t = build_int_2 (low, hi);
        !          1126:          TREE_TYPE (t) = TREE_TYPE (arg1);
        !          1127:          if (!notrunc)
        !          1128:            force_fit_type (t, 0);
        !          1129:          TREE_OVERFLOW (t) = TREE_OVERFLOW (arg1) | TREE_OVERFLOW (arg2);
        !          1130:          TREE_CONSTANT_OVERFLOW (t)
        !          1131:            = TREE_CONSTANT_OVERFLOW (arg1) | TREE_CONSTANT_OVERFLOW (arg2);
        !          1132:          return t;
        !          1133: 
        !          1134:        case RROTATE_EXPR:
        !          1135:          int2l = - int2l;
        !          1136:        case LROTATE_EXPR:
        !          1137:          lrotate_double (int1l, int1h, int2l,
        !          1138:                          TYPE_PRECISION (TREE_TYPE (arg1)),
        !          1139:                          &low, &hi);
        !          1140:          t = build_int_2 (low, hi);
        !          1141:          break;
        !          1142: 
        !          1143:        case PLUS_EXPR:
        !          1144:          if (int1h == 0)
        !          1145:            {
        !          1146:              int2l += int1l;
        !          1147:              if ((unsigned HOST_WIDE_INT) int2l < int1l)
        !          1148:                {
        !          1149:                  hi = int2h++;
        !          1150:                  overflow = int2h < hi;
        !          1151:                }
        !          1152:              t = build_int_2 (int2l, int2h);
        !          1153:              break;
        !          1154:            }
        !          1155:          if (int2h == 0)
        !          1156:            {
        !          1157:              int1l += int2l;
        !          1158:              if ((unsigned HOST_WIDE_INT) int1l < int2l)
        !          1159:                {
        !          1160:                  hi = int1h++;
        !          1161:                  overflow = int1h < hi;
        !          1162:                }
        !          1163:              t = build_int_2 (int1l, int1h);
        !          1164:              break;
        !          1165:            }
        !          1166:          overflow = add_double (int1l, int1h, int2l, int2h, &low, &hi);
        !          1167:          t = build_int_2 (low, hi);
        !          1168:          break;
        !          1169: 
        !          1170:        case MINUS_EXPR:
        !          1171:          if (int2h == 0 && int2l == 0)
        !          1172:            {
        !          1173:              t = build_int_2 (int1l, int1h);
        !          1174:              break;
        !          1175:            }
        !          1176:          neg_double (int2l, int2h, &low, &hi);
        !          1177:          add_double (int1l, int1h, low, hi, &low, &hi);
        !          1178:          overflow = overflow_sum_sign (hi, int2h, int1h);
        !          1179:          t = build_int_2 (low, hi);
        !          1180:          break;
        !          1181: 
        !          1182:        case MULT_EXPR:
        !          1183:          /* Optimize simple cases.  */
        !          1184:          if (int1h == 0)
        !          1185:            {
        !          1186:              unsigned HOST_WIDE_INT temp;
        !          1187: 
        !          1188:              switch (int1l)
        !          1189:                {
        !          1190:                case 0:
        !          1191:                  t = build_int_2 (0, 0);
        !          1192:                  goto got_it;
        !          1193:                case 1:
        !          1194:                  t = build_int_2 (int2l, int2h);
        !          1195:                  goto got_it;
        !          1196:                case 2:
        !          1197:                  overflow = left_shift_overflows (int2h, 1);
        !          1198:                  temp = int2l + int2l;
        !          1199:                  int2h = (int2h << 1) + (temp < int2l);
        !          1200:                  t = build_int_2 (temp, int2h);
        !          1201:                  goto got_it;
        !          1202: #if 0 /* This code can lose carries.  */
        !          1203:                case 3:
        !          1204:                  temp = int2l + int2l + int2l;
        !          1205:                  int2h = int2h * 3 + (temp < int2l);
        !          1206:                  t = build_int_2 (temp, int2h);
        !          1207:                  goto got_it;
        !          1208: #endif
        !          1209:                case 4:
        !          1210:                  overflow = left_shift_overflows (int2h, 2);
        !          1211:                  temp = int2l + int2l;
        !          1212:                  int2h = (int2h << 2) + ((temp < int2l) << 1);
        !          1213:                  int2l = temp;
        !          1214:                  temp += temp;
        !          1215:                  int2h += (temp < int2l);
        !          1216:                  t = build_int_2 (temp, int2h);
        !          1217:                  goto got_it;
        !          1218:                case 8:
        !          1219:                  overflow = left_shift_overflows (int2h, 3);
        !          1220:                  temp = int2l + int2l;
        !          1221:                  int2h = (int2h << 3) + ((temp < int2l) << 2);
        !          1222:                  int2l = temp;
        !          1223:                  temp += temp;
        !          1224:                  int2h += (temp < int2l) << 1;
        !          1225:                  int2l = temp;
        !          1226:                  temp += temp;
        !          1227:                  int2h += (temp < int2l);
        !          1228:                  t = build_int_2 (temp, int2h);
        !          1229:                  goto got_it;
        !          1230:                default:
        !          1231:                  break;
        !          1232:                }
        !          1233:            }
        !          1234: 
        !          1235:          if (int2h == 0)
        !          1236:            {
        !          1237:              if (int2l == 0)
        !          1238:                {
        !          1239:                  t = build_int_2 (0, 0);
        !          1240:                  break;
        !          1241:                }
        !          1242:              if (int2l == 1)
        !          1243:                {
        !          1244:                  t = build_int_2 (int1l, int1h);
        !          1245:                  break;
        !          1246:                }
        !          1247:            }
        !          1248: 
        !          1249:          overflow = mul_double (int1l, int1h, int2l, int2h, &low, &hi);
        !          1250:          t = build_int_2 (low, hi);
        !          1251:          break;
        !          1252: 
        !          1253:        case TRUNC_DIV_EXPR:
        !          1254:        case FLOOR_DIV_EXPR: case CEIL_DIV_EXPR:
        !          1255:        case EXACT_DIV_EXPR:
        !          1256:          /* This is a shortcut for a common special case.
        !          1257:             It reduces the number of tree nodes generated
        !          1258:             and saves time.  */
        !          1259:          if (int2h == 0 && int2l > 0
        !          1260:              && TREE_TYPE (arg1) == sizetype
        !          1261:              && int1h == 0 && int1l >= 0)
        !          1262:            {
        !          1263:              if (code == CEIL_DIV_EXPR)
        !          1264:                int1l += int2l-1;
        !          1265:              return size_int (int1l / int2l);
        !          1266:            }
        !          1267:        case ROUND_DIV_EXPR: 
        !          1268:          if (int2h == 0 && int2l == 1)
        !          1269:            {
        !          1270:              t = build_int_2 (int1l, int1h);
        !          1271:              break;
        !          1272:            }
        !          1273:          if (int1l == int2l && int1h == int2h)
        !          1274:            {
        !          1275:              if ((int1l | int1h) == 0)
        !          1276:                abort ();
        !          1277:              t = build_int_2 (1, 0);
        !          1278:              break;
        !          1279:            }
        !          1280:          overflow = div_and_round_double (code, uns,
        !          1281:                                           int1l, int1h, int2l, int2h,
        !          1282:                                           &low, &hi, &garbagel, &garbageh);
        !          1283:          t = build_int_2 (low, hi);
        !          1284:          break;
        !          1285: 
        !          1286:        case TRUNC_MOD_EXPR: case ROUND_MOD_EXPR: 
        !          1287:        case FLOOR_MOD_EXPR: case CEIL_MOD_EXPR:
        !          1288:          overflow = div_and_round_double (code, uns,
        !          1289:                                           int1l, int1h, int2l, int2h,
        !          1290:                                           &garbagel, &garbageh, &low, &hi);
        !          1291:          t = build_int_2 (low, hi);
        !          1292:          break;
        !          1293: 
        !          1294:        case MIN_EXPR:
        !          1295:        case MAX_EXPR:
        !          1296:          if (uns)
        !          1297:            {
        !          1298:              low = (((unsigned HOST_WIDE_INT) int1h
        !          1299:                      < (unsigned HOST_WIDE_INT) int2h)
        !          1300:                     || (((unsigned HOST_WIDE_INT) int1h
        !          1301:                          == (unsigned HOST_WIDE_INT) int2h)
        !          1302:                         && ((unsigned HOST_WIDE_INT) int1l
        !          1303:                             < (unsigned HOST_WIDE_INT) int2l)));
        !          1304:            }
        !          1305:          else
        !          1306:            {
        !          1307:              low = ((int1h < int2h)
        !          1308:                     || ((int1h == int2h)
        !          1309:                         && ((unsigned HOST_WIDE_INT) int1l
        !          1310:                             < (unsigned HOST_WIDE_INT) int2l)));
        !          1311:            }
        !          1312:          if (low == (code == MIN_EXPR))
        !          1313:            t = build_int_2 (int1l, int1h);
        !          1314:          else
        !          1315:            t = build_int_2 (int2l, int2h);
        !          1316:          break;
        !          1317: 
        !          1318:        default:
        !          1319:          abort ();
        !          1320:        }
        !          1321:     got_it:
        !          1322:       TREE_TYPE (t) = TREE_TYPE (arg1);
        !          1323:       TREE_OVERFLOW (t)
        !          1324:        = ((notrunc ? !uns && overflow : force_fit_type (t, overflow))
        !          1325:           | TREE_OVERFLOW (arg1)
        !          1326:           | TREE_OVERFLOW (arg2));
        !          1327:       TREE_CONSTANT_OVERFLOW (t) = (TREE_OVERFLOW (t)
        !          1328:                                    | TREE_CONSTANT_OVERFLOW (arg1)
        !          1329:                                    | TREE_CONSTANT_OVERFLOW (arg2));
        !          1330:       return t;
        !          1331:     }
        !          1332: #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
        !          1333:   if (TREE_CODE (arg1) == REAL_CST)
        !          1334:     {
        !          1335:       REAL_VALUE_TYPE d1;
        !          1336:       REAL_VALUE_TYPE d2;
        !          1337:       REAL_VALUE_TYPE value;
        !          1338:       tree t;
        !          1339: 
        !          1340:       d1 = TREE_REAL_CST (arg1);
        !          1341:       d2 = TREE_REAL_CST (arg2);
        !          1342:       if (setjmp (float_error))
        !          1343:        {
        !          1344:          pedwarn ("floating overflow in constant expression");
        !          1345:          return build (code, TREE_TYPE (arg1), arg1, arg2);
        !          1346:        }
        !          1347:       set_float_handler (float_error);
        !          1348: 
        !          1349: #ifdef REAL_ARITHMETIC
        !          1350:       REAL_ARITHMETIC (value, code, d1, d2);
        !          1351: #else
        !          1352:       switch (code)
        !          1353:        {
        !          1354:        case PLUS_EXPR:
        !          1355:          value = d1 + d2;
        !          1356:          break;
        !          1357: 
        !          1358:        case MINUS_EXPR:
        !          1359:          value = d1 - d2;
        !          1360:          break;
        !          1361: 
        !          1362:        case MULT_EXPR:
        !          1363:          value = d1 * d2;
        !          1364:          break;
        !          1365: 
        !          1366:        case RDIV_EXPR:
        !          1367: #ifndef REAL_INFINITY
        !          1368:          if (d2 == 0)
        !          1369:            abort ();
        !          1370: #endif
        !          1371: 
        !          1372:          value = d1 / d2;
        !          1373:          break;
        !          1374: 
        !          1375:        case MIN_EXPR:
        !          1376:          value = MIN (d1, d2);
        !          1377:          break;
        !          1378: 
        !          1379:        case MAX_EXPR:
        !          1380:          value = MAX (d1, d2);
        !          1381:          break;
        !          1382: 
        !          1383:        default:
        !          1384:          abort ();
        !          1385:        }
        !          1386: #endif /* no REAL_ARITHMETIC */
        !          1387:       t = build_real (TREE_TYPE (arg1),
        !          1388:                      real_value_truncate (TYPE_MODE (TREE_TYPE (arg1)), value));
        !          1389:       set_float_handler (NULL_PTR);
        !          1390:       return t;
        !          1391:     }
        !          1392: #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
        !          1393:   if (TREE_CODE (arg1) == COMPLEX_CST)
        !          1394:     {
        !          1395:       register tree r1 = TREE_REALPART (arg1);
        !          1396:       register tree i1 = TREE_IMAGPART (arg1);
        !          1397:       register tree r2 = TREE_REALPART (arg2);
        !          1398:       register tree i2 = TREE_IMAGPART (arg2);
        !          1399:       register tree t;
        !          1400: 
        !          1401:       switch (code)
        !          1402:        {
        !          1403:        case PLUS_EXPR:
        !          1404:          t = build_complex (const_binop (PLUS_EXPR, r1, r2, notrunc),
        !          1405:                             const_binop (PLUS_EXPR, i1, i2, notrunc));
        !          1406:          break;
        !          1407: 
        !          1408:        case MINUS_EXPR:
        !          1409:          t = build_complex (const_binop (MINUS_EXPR, r1, r2, notrunc),
        !          1410:                             const_binop (MINUS_EXPR, i1, i2, notrunc));
        !          1411:          break;
        !          1412: 
        !          1413:        case MULT_EXPR:
        !          1414:          t = build_complex (const_binop (MINUS_EXPR,
        !          1415:                                          const_binop (MULT_EXPR,
        !          1416:                                                       r1, r2, notrunc),
        !          1417:                                          const_binop (MULT_EXPR,
        !          1418:                                                       i1, i2, notrunc),
        !          1419:                                          notrunc),
        !          1420:                             const_binop (PLUS_EXPR,
        !          1421:                                          const_binop (MULT_EXPR,
        !          1422:                                                       r1, i2, notrunc),
        !          1423:                                          const_binop (MULT_EXPR,
        !          1424:                                                       i1, r2, notrunc),
        !          1425:                                          notrunc));
        !          1426:          break;
        !          1427: 
        !          1428:        case RDIV_EXPR:
        !          1429:          {
        !          1430:            register tree magsquared
        !          1431:              = const_binop (PLUS_EXPR,
        !          1432:                             const_binop (MULT_EXPR, r2, r2, notrunc),
        !          1433:                             const_binop (MULT_EXPR, i2, i2, notrunc),
        !          1434:                             notrunc);
        !          1435:            t = build_complex (const_binop (RDIV_EXPR,
        !          1436:                                            const_binop (PLUS_EXPR,
        !          1437:                                                         const_binop (MULT_EXPR, r1, r2, notrunc),
        !          1438:                                                         const_binop (MULT_EXPR, i1, i2, notrunc),
        !          1439:                                                         notrunc),
        !          1440:                                            magsquared, notrunc),
        !          1441:                               const_binop (RDIV_EXPR,
        !          1442:                                            const_binop (MINUS_EXPR,
        !          1443:                                                         const_binop (MULT_EXPR, i1, r2, notrunc),
        !          1444:                                                         const_binop (MULT_EXPR, r1, i2, notrunc),
        !          1445:                                                         notrunc),
        !          1446:                                            magsquared, notrunc));
        !          1447:          }
        !          1448:          break;
        !          1449: 
        !          1450:        default:
        !          1451:          abort ();
        !          1452:        }
        !          1453:       TREE_TYPE (t) = TREE_TYPE (arg1);
        !          1454:       return t;
        !          1455:     }
        !          1456:   return 0;
        !          1457: }
        !          1458: 
        !          1459: /* Return an INTEGER_CST with value V and type from `sizetype'.  */
        !          1460: 
        !          1461: tree
        !          1462: size_int (number)
        !          1463:      unsigned int number;
        !          1464: {
        !          1465:   register tree t;
        !          1466:   /* Type-size nodes already made for small sizes.  */
        !          1467:   static tree size_table[2*HOST_BITS_PER_WIDE_INT + 1];
        !          1468: 
        !          1469:   if (number < 2*HOST_BITS_PER_WIDE_INT + 1
        !          1470:       && size_table[number] != 0)
        !          1471:     return size_table[number];
        !          1472:   if (number < 2*HOST_BITS_PER_WIDE_INT + 1)
        !          1473:     {
        !          1474:       push_obstacks_nochange ();
        !          1475:       /* Make this a permanent node.  */
        !          1476:       end_temporary_allocation ();
        !          1477:       t = build_int_2 (number, 0);
        !          1478:       TREE_TYPE (t) = sizetype;
        !          1479:       size_table[number] = t;
        !          1480:       pop_obstacks ();
        !          1481:     }
        !          1482:   else
        !          1483:     {
        !          1484:       t = build_int_2 (number, 0);
        !          1485:       TREE_TYPE (t) = sizetype;
        !          1486:     }
        !          1487:   return t;
        !          1488: }
        !          1489: 
        !          1490: /* Combine operands OP1 and OP2 with arithmetic operation CODE.
        !          1491:    CODE is a tree code.  Data type is taken from `sizetype',
        !          1492:    If the operands are constant, so is the result.  */
        !          1493: 
        !          1494: tree
        !          1495: size_binop (code, arg0, arg1)
        !          1496:      enum tree_code code;
        !          1497:      tree arg0, arg1;
        !          1498: {
        !          1499:   /* Handle the special case of two integer constants faster.  */
        !          1500:   if (TREE_CODE (arg0) == INTEGER_CST && TREE_CODE (arg1) == INTEGER_CST)
        !          1501:     {
        !          1502:       /* And some specific cases even faster than that.  */
        !          1503:       if (code == PLUS_EXPR
        !          1504:          && TREE_INT_CST_LOW (arg0) == 0
        !          1505:          && TREE_INT_CST_HIGH (arg0) == 0)
        !          1506:        return arg1;
        !          1507:       if (code == MINUS_EXPR
        !          1508:          && TREE_INT_CST_LOW (arg1) == 0
        !          1509:          && TREE_INT_CST_HIGH (arg1) == 0)
        !          1510:        return arg0;
        !          1511:       if (code == MULT_EXPR
        !          1512:          && TREE_INT_CST_LOW (arg0) == 1
        !          1513:          && TREE_INT_CST_HIGH (arg0) == 0)
        !          1514:        return arg1;
        !          1515:       /* Handle general case of two integer constants.  */
        !          1516:       return const_binop (code, arg0, arg1, 1);
        !          1517:     }
        !          1518: 
        !          1519:   if (arg0 == error_mark_node || arg1 == error_mark_node)
        !          1520:     return error_mark_node;
        !          1521: 
        !          1522:   return fold (build (code, sizetype, arg0, arg1));
        !          1523: }
        !          1524: 
        !          1525: /* Given T, a tree representing type conversion of ARG1, a constant,
        !          1526:    return a constant tree representing the result of conversion.  */
        !          1527: 
        !          1528: static tree
        !          1529: fold_convert (t, arg1)
        !          1530:      register tree t;
        !          1531:      register tree arg1;
        !          1532: {
        !          1533:   register tree type = TREE_TYPE (t);
        !          1534: 
        !          1535:   if (TREE_CODE (type) == POINTER_TYPE || INTEGRAL_TYPE_P (type))
        !          1536:     {
        !          1537:       if (TREE_CODE (arg1) == INTEGER_CST)
        !          1538:        {
        !          1539:          /* Given an integer constant, make new constant with new type,
        !          1540:             appropriately sign-extended or truncated.  */
        !          1541:          t = build_int_2 (TREE_INT_CST_LOW (arg1),
        !          1542:                           TREE_INT_CST_HIGH (arg1));
        !          1543:          TREE_TYPE (t) = type;
        !          1544:          /* Indicate an overflow if (1) ARG1 already overflowed,
        !          1545:             or (2) force_fit_type indicates an overflow.
        !          1546:             Tell force_fit_type that an overflow has already occurred
        !          1547:             if ARG1 is a too-large unsigned value and T is signed.  */
        !          1548:          TREE_OVERFLOW (t)
        !          1549:            = (TREE_OVERFLOW (arg1)
        !          1550:               | force_fit_type (t,
        !          1551:                                 (TREE_INT_CST_HIGH (arg1) < 0
        !          1552:                                  & (TREE_UNSIGNED (type)
        !          1553:                                     < TREE_UNSIGNED (TREE_TYPE (arg1))))));
        !          1554:          TREE_CONSTANT_OVERFLOW (t)
        !          1555:            = TREE_OVERFLOW (t) | TREE_CONSTANT_OVERFLOW (arg1);
        !          1556:        }
        !          1557: #if !defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
        !          1558:       else if (TREE_CODE (arg1) == REAL_CST)
        !          1559:        {
        !          1560:          REAL_VALUE_TYPE l, x, u;
        !          1561: 
        !          1562:          l = real_value_from_int_cst (TYPE_MIN_VALUE (type));
        !          1563:          x = TREE_REAL_CST (arg1);
        !          1564:          u = real_value_from_int_cst (TYPE_MAX_VALUE (type));
        !          1565: 
        !          1566:          /* See if X will be in range after truncation towards 0.
        !          1567:             To compensate for truncation, move the bounds away from 0,
        !          1568:             but reject if X exactly equals the adjusted bounds.  */
        !          1569: #ifdef REAL_ARITHMETIC
        !          1570:          REAL_ARITHMETIC (l, MINUS_EXPR, l, dconst1);
        !          1571:          REAL_ARITHMETIC (u, PLUS_EXPR, u, dconst1);
        !          1572: #else
        !          1573:          l--;
        !          1574:          u++;
        !          1575: #endif
        !          1576:          if (! (REAL_VALUES_LESS (l, x) && REAL_VALUES_LESS (x, u)))
        !          1577:            {
        !          1578:              pedwarn ("real constant out of range for integer conversion");
        !          1579:              return t;
        !          1580:            }
        !          1581: #ifndef REAL_ARITHMETIC
        !          1582:          {
        !          1583:            REAL_VALUE_TYPE d;
        !          1584:            HOST_WIDE_INT low, high;
        !          1585:            HOST_WIDE_INT half_word
        !          1586:              = (HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2);
        !          1587: 
        !          1588:            d = TREE_REAL_CST (arg1);
        !          1589:            if (d < 0)
        !          1590:              d = -d;
        !          1591: 
        !          1592:            high = (HOST_WIDE_INT) (d / half_word / half_word);
        !          1593:            d -= (REAL_VALUE_TYPE) high * half_word * half_word;
        !          1594:            if (d >= (REAL_VALUE_TYPE) half_word * half_word / 2)
        !          1595:              {
        !          1596:                low = d - (REAL_VALUE_TYPE) half_word * half_word / 2;
        !          1597:                low |= (HOST_WIDE_INT) -1 << (HOST_BITS_PER_WIDE_INT - 1);
        !          1598:              }
        !          1599:            else
        !          1600:              low = (HOST_WIDE_INT) d;
        !          1601:            if (TREE_REAL_CST (arg1) < 0)
        !          1602:              neg_double (low, high, &low, &high);
        !          1603:            t = build_int_2 (low, high);
        !          1604:          }
        !          1605: #else
        !          1606:          {
        !          1607:            HOST_WIDE_INT low, high;
        !          1608:            REAL_VALUE_TO_INT (&low, &high, (TREE_REAL_CST (arg1)));
        !          1609:            t = build_int_2 (low, high);
        !          1610:          }
        !          1611: #endif
        !          1612:          TREE_TYPE (t) = type;
        !          1613:          force_fit_type (t, 0);
        !          1614:        }
        !          1615: #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
        !          1616:       TREE_TYPE (t) = type;
        !          1617:     }
        !          1618:   else if (TREE_CODE (type) == REAL_TYPE)
        !          1619:     {
        !          1620: #if !defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
        !          1621:       if (TREE_CODE (arg1) == INTEGER_CST)
        !          1622:        return build_real_from_int_cst (type, arg1);
        !          1623: #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
        !          1624:       if (TREE_CODE (arg1) == REAL_CST)
        !          1625:        {
        !          1626:          if (setjmp (float_error))
        !          1627:            {
        !          1628:              pedwarn ("floating overflow in constant expression");
        !          1629:              return t;
        !          1630:            }
        !          1631:          set_float_handler (float_error);
        !          1632: 
        !          1633:          t = build_real (type, real_value_truncate (TYPE_MODE (type),
        !          1634:                                                     TREE_REAL_CST (arg1)));
        !          1635:          set_float_handler (NULL_PTR);
        !          1636:          return t;
        !          1637:        }
        !          1638:     }
        !          1639:   TREE_CONSTANT (t) = 1;
        !          1640:   return t;
        !          1641: }
        !          1642: 
        !          1643: /* Return an expr equal to X but certainly not valid as an lvalue.
        !          1644:    Also make sure it is not valid as an null pointer constant.  */
        !          1645: 
        !          1646: tree
        !          1647: non_lvalue (x)
        !          1648:      tree x;
        !          1649: {
        !          1650:   tree result;
        !          1651: 
        !          1652:   /* These things are certainly not lvalues.  */
        !          1653:   if (TREE_CODE (x) == NON_LVALUE_EXPR
        !          1654:       || TREE_CODE (x) == INTEGER_CST
        !          1655:       || TREE_CODE (x) == REAL_CST
        !          1656:       || TREE_CODE (x) == STRING_CST
        !          1657:       || TREE_CODE (x) == ADDR_EXPR)
        !          1658:     {
        !          1659:       if (TREE_CODE (x) == INTEGER_CST && integer_zerop (x))
        !          1660:        {
        !          1661:          /* Use NOP_EXPR instead of NON_LVALUE_EXPR
        !          1662:             so convert_for_assignment won't strip it.
        !          1663:             This is so this 0 won't be treated as a null pointer constant.  */
        !          1664:          result = build1 (NOP_EXPR, TREE_TYPE (x), x);
        !          1665:          TREE_CONSTANT (result) = TREE_CONSTANT (x);
        !          1666:          return result;
        !          1667:        }
        !          1668:       return x;
        !          1669:     }
        !          1670: 
        !          1671:   result = build1 (NON_LVALUE_EXPR, TREE_TYPE (x), x);
        !          1672:   TREE_CONSTANT (result) = TREE_CONSTANT (x);
        !          1673:   return result;
        !          1674: }
        !          1675: 
        !          1676: /* When pedantic, return an expr equal to X but certainly not valid as a
        !          1677:    pedantic lvalue.  Otherwise, return X.  */
        !          1678: 
        !          1679: tree
        !          1680: pedantic_non_lvalue (x)
        !          1681:      tree x;
        !          1682: {
        !          1683:   if (pedantic)
        !          1684:     return non_lvalue (x);
        !          1685:   else
        !          1686:     return x;
        !          1687: }
        !          1688: 
        !          1689: /* Given a tree comparison code, return the code that is the logical inverse
        !          1690:    of the given code.  It is not safe to do this for floating-point
        !          1691:    comparisons, except for NE_EXPR and EQ_EXPR.  */
        !          1692: 
        !          1693: static enum tree_code
        !          1694: invert_tree_comparison (code)
        !          1695:      enum tree_code code;
        !          1696: {
        !          1697:   switch (code)
        !          1698:     {
        !          1699:     case EQ_EXPR:
        !          1700:       return NE_EXPR;
        !          1701:     case NE_EXPR:
        !          1702:       return EQ_EXPR;
        !          1703:     case GT_EXPR:
        !          1704:       return LE_EXPR;
        !          1705:     case GE_EXPR:
        !          1706:       return LT_EXPR;
        !          1707:     case LT_EXPR:
        !          1708:       return GE_EXPR;
        !          1709:     case LE_EXPR:
        !          1710:       return GT_EXPR;
        !          1711:     default:
        !          1712:       abort ();
        !          1713:     }
        !          1714: }
        !          1715: 
        !          1716: /* Similar, but return the comparison that results if the operands are
        !          1717:    swapped.  This is safe for floating-point.  */
        !          1718: 
        !          1719: static enum tree_code
        !          1720: swap_tree_comparison (code)
        !          1721:      enum tree_code code;
        !          1722: {
        !          1723:   switch (code)
        !          1724:     {
        !          1725:     case EQ_EXPR:
        !          1726:     case NE_EXPR:
        !          1727:       return code;
        !          1728:     case GT_EXPR:
        !          1729:       return LT_EXPR;
        !          1730:     case GE_EXPR:
        !          1731:       return LE_EXPR;
        !          1732:     case LT_EXPR:
        !          1733:       return GT_EXPR;
        !          1734:     case LE_EXPR:
        !          1735:       return GE_EXPR;
        !          1736:     default:
        !          1737:       abort ();
        !          1738:     }
        !          1739: }
        !          1740: 
        !          1741: /* Return nonzero if two operands are necessarily equal.
        !          1742:    If ONLY_CONST is non-zero, only return non-zero for constants.
        !          1743:    This function tests whether the operands are indistinguishable;
        !          1744:    it does not test whether they are equal using C's == operation.
        !          1745:    The distinction is important for IEEE floating point, because
        !          1746:    (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
        !          1747:    (2) two NaNs may be indistinguishable, but NaN!=NaN.  */
        !          1748: 
        !          1749: int
        !          1750: operand_equal_p (arg0, arg1, only_const)
        !          1751:      tree arg0, arg1;
        !          1752:      int only_const;
        !          1753: {
        !          1754:   /* If both types don't have the same signedness, then we can't consider
        !          1755:      them equal.  We must check this before the STRIP_NOPS calls
        !          1756:      because they may change the signedness of the arguments.  */
        !          1757:   if (TREE_UNSIGNED (TREE_TYPE (arg0)) != TREE_UNSIGNED (TREE_TYPE (arg1)))
        !          1758:     return 0;
        !          1759: 
        !          1760:   STRIP_NOPS (arg0);
        !          1761:   STRIP_NOPS (arg1);
        !          1762: 
        !          1763:   /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
        !          1764:      We don't care about side effects in that case because the SAVE_EXPR
        !          1765:      takes care of that for us.  */
        !          1766:   if (TREE_CODE (arg0) == SAVE_EXPR && arg0 == arg1)
        !          1767:     return ! only_const;
        !          1768: 
        !          1769:   if (TREE_SIDE_EFFECTS (arg0) || TREE_SIDE_EFFECTS (arg1))
        !          1770:     return 0;
        !          1771: 
        !          1772:   if (TREE_CODE (arg0) == TREE_CODE (arg1)
        !          1773:       && TREE_CODE (arg0) == ADDR_EXPR
        !          1774:       && TREE_OPERAND (arg0, 0) == TREE_OPERAND (arg1, 0))
        !          1775:     return 1;
        !          1776: 
        !          1777:   if (TREE_CODE (arg0) == TREE_CODE (arg1)
        !          1778:       && TREE_CODE (arg0) == INTEGER_CST
        !          1779:       && TREE_INT_CST_LOW (arg0) == TREE_INT_CST_LOW (arg1)
        !          1780:       && TREE_INT_CST_HIGH (arg0) == TREE_INT_CST_HIGH (arg1))
        !          1781:     return 1;
        !          1782: 
        !          1783:   /* Detect when real constants are equal.  */
        !          1784:   if (TREE_CODE (arg0) == TREE_CODE (arg1)
        !          1785:       && TREE_CODE (arg0) == REAL_CST)
        !          1786:     return !bcmp (&TREE_REAL_CST (arg0), &TREE_REAL_CST (arg1),
        !          1787:                  sizeof (REAL_VALUE_TYPE));
        !          1788: 
        !          1789:   if (only_const)
        !          1790:     return 0;
        !          1791: 
        !          1792:   if (arg0 == arg1)
        !          1793:     return 1;
        !          1794: 
        !          1795:   if (TREE_CODE (arg0) != TREE_CODE (arg1))
        !          1796:     return 0;
        !          1797:   /* This is needed for conversions and for COMPONENT_REF.
        !          1798:      Might as well play it safe and always test this.  */
        !          1799:   if (TYPE_MODE (TREE_TYPE (arg0)) != TYPE_MODE (TREE_TYPE (arg1)))
        !          1800:     return 0;
        !          1801: 
        !          1802:   switch (TREE_CODE_CLASS (TREE_CODE (arg0)))
        !          1803:     {
        !          1804:     case '1':
        !          1805:       /* Two conversions are equal only if signedness and modes match.  */
        !          1806:       if ((TREE_CODE (arg0) == NOP_EXPR || TREE_CODE (arg0) == CONVERT_EXPR)
        !          1807:          && (TREE_UNSIGNED (TREE_TYPE (arg0))
        !          1808:              != TREE_UNSIGNED (TREE_TYPE (arg1))))
        !          1809:        return 0;
        !          1810: 
        !          1811:       return operand_equal_p (TREE_OPERAND (arg0, 0),
        !          1812:                              TREE_OPERAND (arg1, 0), 0);
        !          1813: 
        !          1814:     case '<':
        !          1815:     case '2':
        !          1816:       return (operand_equal_p (TREE_OPERAND (arg0, 0),
        !          1817:                               TREE_OPERAND (arg1, 0), 0)
        !          1818:              && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          1819:                                  TREE_OPERAND (arg1, 1), 0));
        !          1820: 
        !          1821:     case 'r':
        !          1822:       switch (TREE_CODE (arg0))
        !          1823:        {
        !          1824:        case INDIRECT_REF:
        !          1825:          return operand_equal_p (TREE_OPERAND (arg0, 0),
        !          1826:                                  TREE_OPERAND (arg1, 0), 0);
        !          1827: 
        !          1828:        case COMPONENT_REF:
        !          1829:        case ARRAY_REF:
        !          1830:          return (operand_equal_p (TREE_OPERAND (arg0, 0),
        !          1831:                                   TREE_OPERAND (arg1, 0), 0)
        !          1832:                  && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          1833:                                      TREE_OPERAND (arg1, 1), 0));
        !          1834: 
        !          1835:        case BIT_FIELD_REF:
        !          1836:          return (operand_equal_p (TREE_OPERAND (arg0, 0),
        !          1837:                                   TREE_OPERAND (arg1, 0), 0)
        !          1838:                  && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          1839:                                      TREE_OPERAND (arg1, 1), 0)
        !          1840:                  && operand_equal_p (TREE_OPERAND (arg0, 2),
        !          1841:                                      TREE_OPERAND (arg1, 2), 0));
        !          1842:        }
        !          1843:       break;
        !          1844:     }
        !          1845: 
        !          1846:   return 0;
        !          1847: }
        !          1848: 
        !          1849: /* Similar to operand_equal_p, but see if ARG0 might have been made by
        !          1850:    shorten_compare from ARG1 when ARG1 was being compared with OTHER. 
        !          1851: 
        !          1852:    When in doubt, return 0.  */
        !          1853: 
        !          1854: static int 
        !          1855: operand_equal_for_comparison_p (arg0, arg1, other)
        !          1856:      tree arg0, arg1;
        !          1857:      tree other;
        !          1858: {
        !          1859:   int unsignedp1, unsignedpo;
        !          1860:   tree primarg1, primother;
        !          1861:   int correct_width;
        !          1862: 
        !          1863:   if (operand_equal_p (arg0, arg1, 0))
        !          1864:     return 1;
        !          1865: 
        !          1866:   if (! INTEGRAL_TYPE_P (TREE_TYPE (arg0)))
        !          1867:     return 0;
        !          1868: 
        !          1869:   /* Duplicate what shorten_compare does to ARG1 and see if that gives the
        !          1870:      actual comparison operand, ARG0.
        !          1871: 
        !          1872:      First throw away any conversions to wider types
        !          1873:      already present in the operands.  */
        !          1874: 
        !          1875:   primarg1 = get_narrower (arg1, &unsignedp1);
        !          1876:   primother = get_narrower (other, &unsignedpo);
        !          1877: 
        !          1878:   correct_width = TYPE_PRECISION (TREE_TYPE (arg1));
        !          1879:   if (unsignedp1 == unsignedpo
        !          1880:       && TYPE_PRECISION (TREE_TYPE (primarg1)) < correct_width
        !          1881:       && TYPE_PRECISION (TREE_TYPE (primother)) < correct_width)
        !          1882:     {
        !          1883:       tree type = TREE_TYPE (arg0);
        !          1884: 
        !          1885:       /* Make sure shorter operand is extended the right way
        !          1886:         to match the longer operand.  */
        !          1887:       primarg1 = convert (signed_or_unsigned_type (unsignedp1,
        !          1888:                                                  TREE_TYPE (primarg1)),
        !          1889:                         primarg1);
        !          1890: 
        !          1891:       if (operand_equal_p (arg0, convert (type, primarg1), 0))
        !          1892:        return 1;
        !          1893:     }
        !          1894: 
        !          1895:   return 0;
        !          1896: }
        !          1897: 
        !          1898: /* See if ARG is an expression that is either a comparison or is performing
        !          1899:    arithmetic on comparisons.  The comparisons must only be comparing
        !          1900:    two different values, which will be stored in *CVAL1 and *CVAL2; if
        !          1901:    they are non-zero it means that some operands have already been found.
        !          1902:    No variables may be used anywhere else in the expression except in the
        !          1903:    comparisons.  If SAVE_P is true it means we removed a SAVE_EXPR around
        !          1904:    the expression and save_expr needs to be called with CVAL1 and CVAL2.
        !          1905: 
        !          1906:    If this is true, return 1.  Otherwise, return zero.  */
        !          1907: 
        !          1908: static int
        !          1909: twoval_comparison_p (arg, cval1, cval2, save_p)
        !          1910:      tree arg;
        !          1911:      tree *cval1, *cval2;
        !          1912:      int *save_p;
        !          1913: {
        !          1914:   enum tree_code code = TREE_CODE (arg);
        !          1915:   char class = TREE_CODE_CLASS (code);
        !          1916: 
        !          1917:   /* We can handle some of the 'e' cases here.  */
        !          1918:   if (class == 'e' && code == TRUTH_NOT_EXPR)
        !          1919:     class = '1';
        !          1920:   else if (class == 'e'
        !          1921:           && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR
        !          1922:               || code == COMPOUND_EXPR))
        !          1923:     class = '2';
        !          1924: 
        !          1925:   /* ??? Disable this since the SAVE_EXPR might already be in use outside
        !          1926:      the expression.  There may be no way to make this work, but it needs
        !          1927:      to be looked at again for 2.6.  */
        !          1928: #if 0
        !          1929:   else if (class == 'e' && code == SAVE_EXPR && SAVE_EXPR_RTL (arg) == 0)
        !          1930:     {
        !          1931:       /* If we've already found a CVAL1 or CVAL2, this expression is
        !          1932:         two complex to handle.  */
        !          1933:       if (*cval1 || *cval2)
        !          1934:        return 0;
        !          1935: 
        !          1936:       class = '1';
        !          1937:       *save_p = 1;
        !          1938:     }
        !          1939: #endif
        !          1940: 
        !          1941:   switch (class)
        !          1942:     {
        !          1943:     case '1':
        !          1944:       return twoval_comparison_p (TREE_OPERAND (arg, 0), cval1, cval2, save_p);
        !          1945: 
        !          1946:     case '2':
        !          1947:       return (twoval_comparison_p (TREE_OPERAND (arg, 0), cval1, cval2, save_p)
        !          1948:              && twoval_comparison_p (TREE_OPERAND (arg, 1),
        !          1949:                                      cval1, cval2, save_p));
        !          1950: 
        !          1951:     case 'c':
        !          1952:       return 1;
        !          1953: 
        !          1954:     case 'e':
        !          1955:       if (code == COND_EXPR)
        !          1956:        return (twoval_comparison_p (TREE_OPERAND (arg, 0),
        !          1957:                                     cval1, cval2, save_p)
        !          1958:                && twoval_comparison_p (TREE_OPERAND (arg, 1),
        !          1959:                                        cval1, cval2, save_p)
        !          1960:                && twoval_comparison_p (TREE_OPERAND (arg, 2),
        !          1961:                                        cval1, cval2, save_p));
        !          1962:       return 0;
        !          1963:          
        !          1964:     case '<':
        !          1965:       /* First see if we can handle the first operand, then the second.  For
        !          1966:         the second operand, we know *CVAL1 can't be zero.  It must be that
        !          1967:         one side of the comparison is each of the values; test for the
        !          1968:         case where this isn't true by failing if the two operands
        !          1969:         are the same.  */
        !          1970: 
        !          1971:       if (operand_equal_p (TREE_OPERAND (arg, 0),
        !          1972:                           TREE_OPERAND (arg, 1), 0))
        !          1973:        return 0;
        !          1974: 
        !          1975:       if (*cval1 == 0)
        !          1976:        *cval1 = TREE_OPERAND (arg, 0);
        !          1977:       else if (operand_equal_p (*cval1, TREE_OPERAND (arg, 0), 0))
        !          1978:        ;
        !          1979:       else if (*cval2 == 0)
        !          1980:        *cval2 = TREE_OPERAND (arg, 0);
        !          1981:       else if (operand_equal_p (*cval2, TREE_OPERAND (arg, 0), 0))
        !          1982:        ;
        !          1983:       else
        !          1984:        return 0;
        !          1985: 
        !          1986:       if (operand_equal_p (*cval1, TREE_OPERAND (arg, 1), 0))
        !          1987:        ;
        !          1988:       else if (*cval2 == 0)
        !          1989:        *cval2 = TREE_OPERAND (arg, 1);
        !          1990:       else if (operand_equal_p (*cval2, TREE_OPERAND (arg, 1), 0))
        !          1991:        ;
        !          1992:       else
        !          1993:        return 0;
        !          1994: 
        !          1995:       return 1;
        !          1996:     }
        !          1997: 
        !          1998:   return 0;
        !          1999: }
        !          2000: 
        !          2001: /* ARG is a tree that is known to contain just arithmetic operations and
        !          2002:    comparisons.  Evaluate the operations in the tree substituting NEW0 for
        !          2003:    any occurrence of OLD0 as an operand of a comparison and likewise for
        !          2004:    NEW1 and OLD1.  */
        !          2005: 
        !          2006: static tree
        !          2007: eval_subst (arg, old0, new0, old1, new1)
        !          2008:      tree arg;
        !          2009:      tree old0, new0, old1, new1;
        !          2010: {
        !          2011:   tree type = TREE_TYPE (arg);
        !          2012:   enum tree_code code = TREE_CODE (arg);
        !          2013:   char class = TREE_CODE_CLASS (code);
        !          2014: 
        !          2015:   /* We can handle some of the 'e' cases here.  */
        !          2016:   if (class == 'e' && code == TRUTH_NOT_EXPR)
        !          2017:     class = '1';
        !          2018:   else if (class == 'e'
        !          2019:           && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR))
        !          2020:     class = '2';
        !          2021: 
        !          2022:   switch (class)
        !          2023:     {
        !          2024:     case '1':
        !          2025:       return fold (build1 (code, type,
        !          2026:                           eval_subst (TREE_OPERAND (arg, 0),
        !          2027:                                       old0, new0, old1, new1)));
        !          2028: 
        !          2029:     case '2':
        !          2030:       return fold (build (code, type,
        !          2031:                          eval_subst (TREE_OPERAND (arg, 0),
        !          2032:                                      old0, new0, old1, new1),
        !          2033:                          eval_subst (TREE_OPERAND (arg, 1),
        !          2034:                                      old0, new0, old1, new1)));
        !          2035: 
        !          2036:     case 'e':
        !          2037:       switch (code)
        !          2038:        {
        !          2039:        case SAVE_EXPR:
        !          2040:          return eval_subst (TREE_OPERAND (arg, 0), old0, new0, old1, new1);
        !          2041: 
        !          2042:        case COMPOUND_EXPR:
        !          2043:          return eval_subst (TREE_OPERAND (arg, 1), old0, new0, old1, new1);
        !          2044: 
        !          2045:        case COND_EXPR:
        !          2046:          return fold (build (code, type,
        !          2047:                              eval_subst (TREE_OPERAND (arg, 0),
        !          2048:                                          old0, new0, old1, new1),
        !          2049:                              eval_subst (TREE_OPERAND (arg, 1),
        !          2050:                                          old0, new0, old1, new1),
        !          2051:                              eval_subst (TREE_OPERAND (arg, 2),
        !          2052:                                          old0, new0, old1, new1)));
        !          2053:        }
        !          2054: 
        !          2055:     case '<':
        !          2056:       {
        !          2057:        tree arg0 = TREE_OPERAND (arg, 0);
        !          2058:        tree arg1 = TREE_OPERAND (arg, 1);
        !          2059: 
        !          2060:        /* We need to check both for exact equality and tree equality.  The
        !          2061:           former will be true if the operand has a side-effect.  In that
        !          2062:           case, we know the operand occurred exactly once.  */
        !          2063: 
        !          2064:        if (arg0 == old0 || operand_equal_p (arg0, old0, 0))
        !          2065:          arg0 = new0;
        !          2066:        else if (arg0 == old1 || operand_equal_p (arg0, old1, 0))
        !          2067:          arg0 = new1;
        !          2068: 
        !          2069:        if (arg1 == old0 || operand_equal_p (arg1, old0, 0))
        !          2070:          arg1 = new0;
        !          2071:        else if (arg1 == old1 || operand_equal_p (arg1, old1, 0))
        !          2072:          arg1 = new1;
        !          2073: 
        !          2074:        return fold (build (code, type, arg0, arg1));
        !          2075:       }
        !          2076:     }
        !          2077: 
        !          2078:   return arg;
        !          2079: }
        !          2080: 
        !          2081: /* Return a tree for the case when the result of an expression is RESULT
        !          2082:    converted to TYPE and OMITTED was previously an operand of the expression
        !          2083:    but is now not needed (e.g., we folded OMITTED * 0).
        !          2084: 
        !          2085:    If OMITTED has side effects, we must evaluate it.  Otherwise, just do
        !          2086:    the conversion of RESULT to TYPE.  */
        !          2087: 
        !          2088: static tree
        !          2089: omit_one_operand (type, result, omitted)
        !          2090:      tree type, result, omitted;
        !          2091: {
        !          2092:   tree t = convert (type, result);
        !          2093: 
        !          2094:   if (TREE_SIDE_EFFECTS (omitted))
        !          2095:     return build (COMPOUND_EXPR, type, omitted, t);
        !          2096: 
        !          2097:   return non_lvalue (t);
        !          2098: }
        !          2099: 
        !          2100: /* Return a simplified tree node for the truth-negation of ARG.  This
        !          2101:    never alters ARG itself.  We assume that ARG is an operation that
        !          2102:    returns a truth value (0 or 1).  */
        !          2103: 
        !          2104: tree
        !          2105: invert_truthvalue (arg)
        !          2106:      tree arg;
        !          2107: {
        !          2108:   tree type = TREE_TYPE (arg);
        !          2109:   enum tree_code code = TREE_CODE (arg);
        !          2110: 
        !          2111:   if (code == ERROR_MARK)
        !          2112:     return arg;
        !          2113: 
        !          2114:   /* If this is a comparison, we can simply invert it, except for
        !          2115:      floating-point non-equality comparisons, in which case we just
        !          2116:      enclose a TRUTH_NOT_EXPR around what we have.  */
        !          2117: 
        !          2118:   if (TREE_CODE_CLASS (code) == '<')
        !          2119:     {
        !          2120:       if (FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (arg, 0)))
        !          2121:          && code != NE_EXPR && code != EQ_EXPR)
        !          2122:        return build1 (TRUTH_NOT_EXPR, type, arg);
        !          2123:       else
        !          2124:        return build (invert_tree_comparison (code), type,
        !          2125:                      TREE_OPERAND (arg, 0), TREE_OPERAND (arg, 1));
        !          2126:     }
        !          2127: 
        !          2128:   switch (code)
        !          2129:     {
        !          2130:     case INTEGER_CST:
        !          2131:       return convert (type, build_int_2 (TREE_INT_CST_LOW (arg) == 0
        !          2132:                                         && TREE_INT_CST_HIGH (arg) == 0, 0));
        !          2133: 
        !          2134:     case TRUTH_AND_EXPR:
        !          2135:       return build (TRUTH_OR_EXPR, type,
        !          2136:                    invert_truthvalue (TREE_OPERAND (arg, 0)),
        !          2137:                    invert_truthvalue (TREE_OPERAND (arg, 1)));
        !          2138: 
        !          2139:     case TRUTH_OR_EXPR:
        !          2140:       return build (TRUTH_AND_EXPR, type,
        !          2141:                    invert_truthvalue (TREE_OPERAND (arg, 0)),
        !          2142:                    invert_truthvalue (TREE_OPERAND (arg, 1)));
        !          2143: 
        !          2144:     case TRUTH_XOR_EXPR:
        !          2145:       /* Here we can invert either operand.  We invert the first operand
        !          2146:         unless the second operand is a TRUTH_NOT_EXPR in which case our
        !          2147:         result is the XOR of the first operand with the inside of the
        !          2148:         negation of the second operand.  */
        !          2149: 
        !          2150:       if (TREE_CODE (TREE_OPERAND (arg, 1)) == TRUTH_NOT_EXPR)
        !          2151:        return build (TRUTH_XOR_EXPR, type, TREE_OPERAND (arg, 0),
        !          2152:                      TREE_OPERAND (TREE_OPERAND (arg, 1), 0));
        !          2153:       else
        !          2154:        return build (TRUTH_XOR_EXPR, type,
        !          2155:                      invert_truthvalue (TREE_OPERAND (arg, 0)),
        !          2156:                      TREE_OPERAND (arg, 1));
        !          2157: 
        !          2158:     case TRUTH_ANDIF_EXPR:
        !          2159:       return build (TRUTH_ORIF_EXPR, type,
        !          2160:                    invert_truthvalue (TREE_OPERAND (arg, 0)),
        !          2161:                    invert_truthvalue (TREE_OPERAND (arg, 1)));
        !          2162: 
        !          2163:     case TRUTH_ORIF_EXPR:
        !          2164:       return build (TRUTH_ANDIF_EXPR, type,
        !          2165:                    invert_truthvalue (TREE_OPERAND (arg, 0)),
        !          2166:                    invert_truthvalue (TREE_OPERAND (arg, 1)));
        !          2167: 
        !          2168:     case TRUTH_NOT_EXPR:
        !          2169:       return TREE_OPERAND (arg, 0);
        !          2170: 
        !          2171:     case COND_EXPR:
        !          2172:       return build (COND_EXPR, type, TREE_OPERAND (arg, 0),
        !          2173:                    invert_truthvalue (TREE_OPERAND (arg, 1)),
        !          2174:                    invert_truthvalue (TREE_OPERAND (arg, 2)));
        !          2175: 
        !          2176:     case COMPOUND_EXPR:
        !          2177:       return build (COMPOUND_EXPR, type, TREE_OPERAND (arg, 0),
        !          2178:                    invert_truthvalue (TREE_OPERAND (arg, 1)));
        !          2179: 
        !          2180:     case NON_LVALUE_EXPR:
        !          2181:       return invert_truthvalue (TREE_OPERAND (arg, 0));
        !          2182: 
        !          2183:     case NOP_EXPR:
        !          2184:     case CONVERT_EXPR:
        !          2185:     case FLOAT_EXPR:
        !          2186:       return build1 (TREE_CODE (arg), type,
        !          2187:                     invert_truthvalue (TREE_OPERAND (arg, 0)));
        !          2188: 
        !          2189:     case BIT_AND_EXPR:
        !          2190:       if (!integer_onep (TREE_OPERAND (arg, 1)))
        !          2191:        break;
        !          2192:       return build (EQ_EXPR, type, arg, convert (type, integer_zero_node));
        !          2193: 
        !          2194:     case SAVE_EXPR:
        !          2195:       return build1 (TRUTH_NOT_EXPR, type, arg);
        !          2196:     }
        !          2197:   if (TREE_CODE (TREE_TYPE (arg)) != BOOLEAN_TYPE)
        !          2198:     abort ();
        !          2199:   return build1 (TRUTH_NOT_EXPR, type, arg);
        !          2200: }
        !          2201: 
        !          2202: /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
        !          2203:    operands are another bit-wise operation with a common input.  If so,
        !          2204:    distribute the bit operations to save an operation and possibly two if
        !          2205:    constants are involved.  For example, convert
        !          2206:        (A | B) & (A | C) into A | (B & C)
        !          2207:    Further simplification will occur if B and C are constants.
        !          2208: 
        !          2209:    If this optimization cannot be done, 0 will be returned.  */
        !          2210: 
        !          2211: static tree
        !          2212: distribute_bit_expr (code, type, arg0, arg1)
        !          2213:      enum tree_code code;
        !          2214:      tree type;
        !          2215:      tree arg0, arg1;
        !          2216: {
        !          2217:   tree common;
        !          2218:   tree left, right;
        !          2219: 
        !          2220:   if (TREE_CODE (arg0) != TREE_CODE (arg1)
        !          2221:       || TREE_CODE (arg0) == code
        !          2222:       || (TREE_CODE (arg0) != BIT_AND_EXPR
        !          2223:          && TREE_CODE (arg0) != BIT_IOR_EXPR))
        !          2224:     return 0;
        !          2225: 
        !          2226:   if (operand_equal_p (TREE_OPERAND (arg0, 0), TREE_OPERAND (arg1, 0), 0))
        !          2227:     {
        !          2228:       common = TREE_OPERAND (arg0, 0);
        !          2229:       left = TREE_OPERAND (arg0, 1);
        !          2230:       right = TREE_OPERAND (arg1, 1);
        !          2231:     }
        !          2232:   else if (operand_equal_p (TREE_OPERAND (arg0, 0), TREE_OPERAND (arg1, 1), 0))
        !          2233:     {
        !          2234:       common = TREE_OPERAND (arg0, 0);
        !          2235:       left = TREE_OPERAND (arg0, 1);
        !          2236:       right = TREE_OPERAND (arg1, 0);
        !          2237:     }
        !          2238:   else if (operand_equal_p (TREE_OPERAND (arg0, 1), TREE_OPERAND (arg1, 0), 0))
        !          2239:     {
        !          2240:       common = TREE_OPERAND (arg0, 1);
        !          2241:       left = TREE_OPERAND (arg0, 0);
        !          2242:       right = TREE_OPERAND (arg1, 1);
        !          2243:     }
        !          2244:   else if (operand_equal_p (TREE_OPERAND (arg0, 1), TREE_OPERAND (arg1, 1), 0))
        !          2245:     {
        !          2246:       common = TREE_OPERAND (arg0, 1);
        !          2247:       left = TREE_OPERAND (arg0, 0);
        !          2248:       right = TREE_OPERAND (arg1, 0);
        !          2249:     }
        !          2250:   else
        !          2251:     return 0;
        !          2252: 
        !          2253:   return fold (build (TREE_CODE (arg0), type, common,
        !          2254:                      fold (build (code, type, left, right))));
        !          2255: }
        !          2256: 
        !          2257: /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
        !          2258:    starting at BITPOS.  The field is unsigned if UNSIGNEDP is non-zero.  */
        !          2259: 
        !          2260: static tree
        !          2261: make_bit_field_ref (inner, type, bitsize, bitpos, unsignedp)
        !          2262:      tree inner;
        !          2263:      tree type;
        !          2264:      int bitsize, bitpos;
        !          2265:      int unsignedp;
        !          2266: {
        !          2267:   tree result = build (BIT_FIELD_REF, type, inner,
        !          2268:                       size_int (bitsize), size_int (bitpos));
        !          2269: 
        !          2270:   TREE_UNSIGNED (result) = unsignedp;
        !          2271: 
        !          2272:   return result;
        !          2273: }
        !          2274: 
        !          2275: /* Optimize a bit-field compare.
        !          2276: 
        !          2277:    There are two cases:  First is a compare against a constant and the
        !          2278:    second is a comparison of two items where the fields are at the same
        !          2279:    bit position relative to the start of a chunk (byte, halfword, word)
        !          2280:    large enough to contain it.  In these cases we can avoid the shift
        !          2281:    implicit in bitfield extractions.
        !          2282: 
        !          2283:    For constants, we emit a compare of the shifted constant with the
        !          2284:    BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
        !          2285:    compared.  For two fields at the same position, we do the ANDs with the
        !          2286:    similar mask and compare the result of the ANDs.
        !          2287: 
        !          2288:    CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
        !          2289:    COMPARE_TYPE is the type of the comparison, and LHS and RHS
        !          2290:    are the left and right operands of the comparison, respectively.
        !          2291: 
        !          2292:    If the optimization described above can be done, we return the resulting
        !          2293:    tree.  Otherwise we return zero.  */
        !          2294: 
        !          2295: static tree
        !          2296: optimize_bit_field_compare (code, compare_type, lhs, rhs)
        !          2297:      enum tree_code code;
        !          2298:      tree compare_type;
        !          2299:      tree lhs, rhs;
        !          2300: {
        !          2301:   int lbitpos, lbitsize, rbitpos, rbitsize;
        !          2302:   int lnbitpos, lnbitsize, rnbitpos, rnbitsize;
        !          2303:   tree type = TREE_TYPE (lhs);
        !          2304:   tree signed_type, unsigned_type;
        !          2305:   int const_p = TREE_CODE (rhs) == INTEGER_CST;
        !          2306:   enum machine_mode lmode, rmode, lnmode, rnmode;
        !          2307:   int lunsignedp, runsignedp;
        !          2308:   int lvolatilep = 0, rvolatilep = 0;
        !          2309:   tree linner, rinner;
        !          2310:   tree mask;
        !          2311:   tree offset;
        !          2312: 
        !          2313:   /* Get all the information about the extractions being done.  If the bit size
        !          2314:      if the same as the size of the underlying object, we aren't doing an
        !          2315:      extraction at all and so can do nothing.  */
        !          2316:   linner = get_inner_reference (lhs, &lbitsize, &lbitpos, &offset, &lmode,
        !          2317:                                &lunsignedp, &lvolatilep);
        !          2318:   if (linner == lhs || lbitsize == GET_MODE_BITSIZE (lmode) || lbitsize < 0
        !          2319:       || offset != 0)
        !          2320:     return 0;
        !          2321: 
        !          2322:  if (!const_p)
        !          2323:    {
        !          2324:      /* If this is not a constant, we can only do something if bit positions,
        !          2325:        sizes, and signedness are the same.   */
        !          2326:      rinner = get_inner_reference (rhs, &rbitsize, &rbitpos, &offset,
        !          2327:                                   &rmode, &runsignedp, &rvolatilep);
        !          2328: 
        !          2329:      if (rinner == rhs || lbitpos != rbitpos || lbitsize != rbitsize
        !          2330:         || lunsignedp != runsignedp || offset != 0)
        !          2331:        return 0;
        !          2332:    }
        !          2333: 
        !          2334:   /* See if we can find a mode to refer to this field.  We should be able to,
        !          2335:      but fail if we can't.  */
        !          2336:   lnmode = get_best_mode (lbitsize, lbitpos,
        !          2337:                          TYPE_ALIGN (TREE_TYPE (linner)), word_mode,
        !          2338:                          lvolatilep);
        !          2339:   if (lnmode == VOIDmode)
        !          2340:     return 0;
        !          2341: 
        !          2342:   /* Set signed and unsigned types of the precision of this mode for the
        !          2343:      shifts below.  */
        !          2344:   signed_type = type_for_mode (lnmode, 0);
        !          2345:   unsigned_type = type_for_mode (lnmode, 1);
        !          2346: 
        !          2347:   if (! const_p)
        !          2348:     {
        !          2349:       rnmode = get_best_mode (rbitsize, rbitpos, 
        !          2350:                              TYPE_ALIGN (TREE_TYPE (rinner)), word_mode,
        !          2351:                              rvolatilep);
        !          2352:       if (rnmode == VOIDmode)
        !          2353:        return 0;
        !          2354:     }
        !          2355:     
        !          2356:   /* Compute the bit position and size for the new reference and our offset
        !          2357:      within it. If the new reference is the same size as the original, we
        !          2358:      won't optimize anything, so return zero.  */
        !          2359:   lnbitsize = GET_MODE_BITSIZE (lnmode);
        !          2360:   lnbitpos = lbitpos & ~ (lnbitsize - 1);
        !          2361:   lbitpos -= lnbitpos;
        !          2362:   if (lnbitsize == lbitsize)
        !          2363:     return 0;
        !          2364: 
        !          2365:   if (! const_p)
        !          2366:     {
        !          2367:       rnbitsize = GET_MODE_BITSIZE (rnmode);
        !          2368:       rnbitpos = rbitpos & ~ (rnbitsize - 1);
        !          2369:       rbitpos -= rnbitpos;
        !          2370:       if (rnbitsize == rbitsize)
        !          2371:        return 0;
        !          2372:     }
        !          2373: 
        !          2374: #if BYTES_BIG_ENDIAN
        !          2375:   lbitpos = lnbitsize - lbitsize - lbitpos;
        !          2376: #endif
        !          2377: 
        !          2378:   /* Make the mask to be used against the extracted field.  */
        !          2379:   mask = build_int_2 (~0, ~0);
        !          2380:   TREE_TYPE (mask) = unsigned_type;
        !          2381:   force_fit_type (mask, 0);
        !          2382:   mask = convert (unsigned_type, mask);
        !          2383:   mask = const_binop (LSHIFT_EXPR, mask, size_int (lnbitsize - lbitsize), 0);
        !          2384:   mask = const_binop (RSHIFT_EXPR, mask,
        !          2385:                      size_int (lnbitsize - lbitsize - lbitpos), 0);
        !          2386: 
        !          2387:   if (! const_p)
        !          2388:     /* If not comparing with constant, just rework the comparison
        !          2389:        and return.  */
        !          2390:     return build (code, compare_type,
        !          2391:                  build (BIT_AND_EXPR, unsigned_type,
        !          2392:                         make_bit_field_ref (linner, unsigned_type,
        !          2393:                                             lnbitsize, lnbitpos, 1),
        !          2394:                         mask),
        !          2395:                  build (BIT_AND_EXPR, unsigned_type,
        !          2396:                         make_bit_field_ref (rinner, unsigned_type,
        !          2397:                                             rnbitsize, rnbitpos, 1),
        !          2398:                         mask));
        !          2399: 
        !          2400:   /* Otherwise, we are handling the constant case. See if the constant is too
        !          2401:      big for the field.  Warn and return a tree of for 0 (false) if so.  We do
        !          2402:      this not only for its own sake, but to avoid having to test for this
        !          2403:      error case below.  If we didn't, we might generate wrong code.
        !          2404: 
        !          2405:      For unsigned fields, the constant shifted right by the field length should
        !          2406:      be all zero.  For signed fields, the high-order bits should agree with 
        !          2407:      the sign bit.  */
        !          2408: 
        !          2409:   if (lunsignedp)
        !          2410:     {
        !          2411:       if (! integer_zerop (const_binop (RSHIFT_EXPR,
        !          2412:                                        convert (unsigned_type, rhs),
        !          2413:                                        size_int (lbitsize), 0)))
        !          2414:        {
        !          2415:          warning ("comparison is always %s due to width of bitfield",
        !          2416:                   code == NE_EXPR ? "one" : "zero");
        !          2417:          return convert (compare_type,
        !          2418:                          (code == NE_EXPR
        !          2419:                           ? integer_one_node : integer_zero_node));
        !          2420:        }
        !          2421:     }
        !          2422:   else
        !          2423:     {
        !          2424:       tree tem = const_binop (RSHIFT_EXPR, convert (signed_type, rhs),
        !          2425:                              size_int (lbitsize - 1), 0);
        !          2426:       if (! integer_zerop (tem) && ! integer_all_onesp (tem))
        !          2427:        {
        !          2428:          warning ("comparison is always %s due to width of bitfield",
        !          2429:                   code == NE_EXPR ? "one" : "zero");
        !          2430:          return convert (compare_type,
        !          2431:                          (code == NE_EXPR
        !          2432:                           ? integer_one_node : integer_zero_node));
        !          2433:        }
        !          2434:     }
        !          2435: 
        !          2436:   /* Single-bit compares should always be against zero.  */
        !          2437:   if (lbitsize == 1 && ! integer_zerop (rhs))
        !          2438:     {
        !          2439:       code = code == EQ_EXPR ? NE_EXPR : EQ_EXPR;
        !          2440:       rhs = convert (type, integer_zero_node);
        !          2441:     }
        !          2442: 
        !          2443:   /* Make a new bitfield reference, shift the constant over the
        !          2444:      appropriate number of bits and mask it with the computed mask
        !          2445:      (in case this was a signed field).  If we changed it, make a new one.  */
        !          2446:   lhs = make_bit_field_ref (linner, unsigned_type, lnbitsize, lnbitpos, 1);
        !          2447:   if (lvolatilep)
        !          2448:     {
        !          2449:       TREE_SIDE_EFFECTS (lhs) = 1;
        !          2450:       TREE_THIS_VOLATILE (lhs) = 1;
        !          2451:     }
        !          2452: 
        !          2453:   rhs = fold (const_binop (BIT_AND_EXPR,
        !          2454:                           const_binop (LSHIFT_EXPR,
        !          2455:                                        convert (unsigned_type, rhs),
        !          2456:                                        size_int (lbitpos), 0),
        !          2457:                           mask, 0));
        !          2458: 
        !          2459:   return build (code, compare_type,
        !          2460:                build (BIT_AND_EXPR, unsigned_type, lhs, mask),
        !          2461:                rhs);
        !          2462: }
        !          2463: 
        !          2464: /* Subroutine for fold_truthop: decode a field reference.
        !          2465: 
        !          2466:    If EXP is a comparison reference, we return the innermost reference.
        !          2467: 
        !          2468:    *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
        !          2469:    set to the starting bit number.
        !          2470: 
        !          2471:    If the innermost field can be completely contained in a mode-sized
        !          2472:    unit, *PMODE is set to that mode.  Otherwise, it is set to VOIDmode.
        !          2473: 
        !          2474:    *PVOLATILEP is set to 1 if the any expression encountered is volatile;
        !          2475:    otherwise it is not changed.
        !          2476: 
        !          2477:    *PUNSIGNEDP is set to the signedness of the field.
        !          2478: 
        !          2479:    *PMASK is set to the mask used.  This is either contained in a
        !          2480:    BIT_AND_EXPR or derived from the width of the field.
        !          2481: 
        !          2482:    Return 0 if this is not a component reference or is one that we can't
        !          2483:    do anything with.  */
        !          2484: 
        !          2485: static tree
        !          2486: decode_field_reference (exp, pbitsize, pbitpos, pmode, punsignedp,
        !          2487:                        pvolatilep, pmask)
        !          2488:      tree exp;
        !          2489:      int *pbitsize, *pbitpos;
        !          2490:      enum machine_mode *pmode;
        !          2491:      int *punsignedp, *pvolatilep;
        !          2492:      tree *pmask;
        !          2493: {
        !          2494:   tree mask = 0;
        !          2495:   tree inner;
        !          2496:   tree offset;
        !          2497: 
        !          2498:   /* All the optimizations using this function assume integer fields.  
        !          2499:      There are problems with FP fields since the type_for_size call
        !          2500:      below can fail for, e.g., XFmode.  */
        !          2501:   if (! INTEGRAL_TYPE_P (TREE_TYPE (exp)))
        !          2502:     return 0;
        !          2503: 
        !          2504:   STRIP_NOPS (exp);
        !          2505: 
        !          2506:   if (TREE_CODE (exp) == BIT_AND_EXPR)
        !          2507:     {
        !          2508:       mask = TREE_OPERAND (exp, 1);
        !          2509:       exp = TREE_OPERAND (exp, 0);
        !          2510:       STRIP_NOPS (exp); STRIP_NOPS (mask);
        !          2511:       if (TREE_CODE (mask) != INTEGER_CST)
        !          2512:        return 0;
        !          2513:     }
        !          2514: 
        !          2515:   if (TREE_CODE (exp) != COMPONENT_REF && TREE_CODE (exp) != ARRAY_REF
        !          2516:       && TREE_CODE (exp) != BIT_FIELD_REF)
        !          2517:     return 0;
        !          2518: 
        !          2519:   inner = get_inner_reference (exp, pbitsize, pbitpos, &offset, pmode,
        !          2520:                               punsignedp, pvolatilep);
        !          2521:   if (inner == exp || *pbitsize < 0 || offset != 0)
        !          2522:     return 0;
        !          2523:   
        !          2524:   if (mask == 0)
        !          2525:     {
        !          2526:       tree unsigned_type = type_for_size (*pbitsize, 1);
        !          2527:       int precision = TYPE_PRECISION (unsigned_type);
        !          2528: 
        !          2529:       mask = build_int_2 (~0, ~0);
        !          2530:       TREE_TYPE (mask) = unsigned_type;
        !          2531:       force_fit_type (mask, 0);
        !          2532:       mask = const_binop (LSHIFT_EXPR, mask, size_int (precision - *pbitsize), 0);
        !          2533:       mask = const_binop (RSHIFT_EXPR, mask, size_int (precision - *pbitsize), 0);
        !          2534:     }
        !          2535: 
        !          2536:   *pmask = mask;
        !          2537:   return inner;
        !          2538: }
        !          2539: 
        !          2540: /* Return non-zero if MASK represents a mask of SIZE ones in the low-order
        !          2541:    bit positions.  */
        !          2542: 
        !          2543: static int
        !          2544: all_ones_mask_p (mask, size)
        !          2545:      tree mask;
        !          2546:      int size;
        !          2547: {
        !          2548:   tree type = TREE_TYPE (mask);
        !          2549:   int precision = TYPE_PRECISION (type);
        !          2550:   tree tmask;
        !          2551: 
        !          2552:   tmask = build_int_2 (~0, ~0);
        !          2553:   TREE_TYPE (tmask) = signed_type (type);
        !          2554:   force_fit_type (tmask, 0);
        !          2555:   return
        !          2556:     operand_equal_p (mask, 
        !          2557:                     const_binop (RSHIFT_EXPR,
        !          2558:                                  const_binop (LSHIFT_EXPR, tmask,
        !          2559:                                               size_int (precision - size), 0),
        !          2560:                                  size_int (precision - size), 0),
        !          2561:                     0);
        !          2562: }
        !          2563: 
        !          2564: /* Subroutine for fold_truthop: determine if an operand is simple enough
        !          2565:    to be evaluated unconditionally.  */
        !          2566: 
        !          2567: static int 
        !          2568: simple_operand_p (exp)
        !          2569:      tree exp;
        !          2570: {
        !          2571:   /* Strip any conversions that don't change the machine mode.  */
        !          2572:   while ((TREE_CODE (exp) == NOP_EXPR
        !          2573:          || TREE_CODE (exp) == CONVERT_EXPR)
        !          2574:         && (TYPE_MODE (TREE_TYPE (exp))
        !          2575:             == TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)))))
        !          2576:     exp = TREE_OPERAND (exp, 0);
        !          2577: 
        !          2578:   return (TREE_CODE_CLASS (TREE_CODE (exp)) == 'c'
        !          2579:          || (TREE_CODE_CLASS (TREE_CODE (exp)) == 'd'
        !          2580:              && ! TREE_ADDRESSABLE (exp)
        !          2581:              && ! TREE_THIS_VOLATILE (exp)
        !          2582:              && ! DECL_NONLOCAL (exp)
        !          2583:              /* Don't regard global variables as simple.  They may be
        !          2584:                 allocated in ways unknown to the compiler (shared memory,
        !          2585:                 #pragma weak, etc).  */
        !          2586:              && ! TREE_PUBLIC (exp)
        !          2587:              && ! DECL_EXTERNAL (exp)
        !          2588:              /* Loading a static variable is unduly expensive, but global
        !          2589:                 registers aren't expensive.  */
        !          2590:              && (! TREE_STATIC (exp) || DECL_REGISTER (exp))));
        !          2591: }
        !          2592: 
        !          2593: /* Subroutine for fold_truthop: try to optimize a range test.
        !          2594: 
        !          2595:    For example, "i >= 2 && i =< 9" can be done as "(unsigned) (i - 2) <= 7".
        !          2596: 
        !          2597:    JCODE is the logical combination of the two terms.  It is TRUTH_AND_EXPR
        !          2598:    (representing TRUTH_ANDIF_EXPR and TRUTH_AND_EXPR) or TRUTH_OR_EXPR
        !          2599:    (representing TRUTH_ORIF_EXPR and TRUTH_OR_EXPR).  TYPE is the type of
        !          2600:    the result.
        !          2601: 
        !          2602:    VAR is the value being tested.  LO_CODE and HI_CODE are the comparison
        !          2603:    operators comparing VAR to LO_CST and HI_CST.  LO_CST is known to be no
        !          2604:    larger than HI_CST (they may be equal).
        !          2605: 
        !          2606:    We return the simplified tree or 0 if no optimization is possible.  */
        !          2607: 
        !          2608: static tree
        !          2609: range_test (jcode, type, lo_code, hi_code, var, lo_cst, hi_cst)
        !          2610:      enum tree_code jcode, lo_code, hi_code;
        !          2611:      tree type, var, lo_cst, hi_cst;
        !          2612: {
        !          2613:   tree utype;
        !          2614:   enum tree_code rcode;
        !          2615: 
        !          2616:   /* See if this is a range test and normalize the constant terms.  */
        !          2617: 
        !          2618:   if (jcode == TRUTH_AND_EXPR)
        !          2619:     {
        !          2620:       switch (lo_code)
        !          2621:        {
        !          2622:        case NE_EXPR:
        !          2623:          /* See if we have VAR != CST && VAR != CST+1.  */
        !          2624:          if (! (hi_code == NE_EXPR
        !          2625:                 && TREE_INT_CST_LOW (hi_cst) - TREE_INT_CST_LOW (lo_cst) == 1
        !          2626:                 && tree_int_cst_equal (integer_one_node,
        !          2627:                                        const_binop (MINUS_EXPR,
        !          2628:                                                     hi_cst, lo_cst, 0))))
        !          2629:            return 0;
        !          2630: 
        !          2631:          rcode = GT_EXPR;
        !          2632:          break;
        !          2633: 
        !          2634:        case GT_EXPR:
        !          2635:        case GE_EXPR:
        !          2636:          if (hi_code == LT_EXPR)
        !          2637:            hi_cst = const_binop (MINUS_EXPR, hi_cst, integer_one_node, 0);
        !          2638:          else if (hi_code != LE_EXPR)
        !          2639:            return 0;
        !          2640: 
        !          2641:          if (lo_code == GT_EXPR)
        !          2642:            lo_cst = const_binop (PLUS_EXPR, lo_cst, integer_one_node, 0);
        !          2643: 
        !          2644:          /* We now have VAR >= LO_CST && VAR <= HI_CST.  */
        !          2645:          rcode = LE_EXPR;
        !          2646:          break;
        !          2647: 
        !          2648:        default:
        !          2649:          return 0;
        !          2650:        }
        !          2651:     }
        !          2652:   else
        !          2653:     {
        !          2654:       switch (lo_code)
        !          2655:        {
        !          2656:        case EQ_EXPR:
        !          2657:          /* See if we have VAR == CST || VAR == CST+1.  */
        !          2658:          if (! (hi_code == EQ_EXPR
        !          2659:                 && TREE_INT_CST_LOW (hi_cst) - TREE_INT_CST_LOW (lo_cst) == 1
        !          2660:                 && tree_int_cst_equal (integer_one_node,
        !          2661:                                        const_binop (MINUS_EXPR,
        !          2662:                                                     hi_cst, lo_cst, 0))))
        !          2663:            return 0;
        !          2664: 
        !          2665:          rcode = LE_EXPR;
        !          2666:          break;
        !          2667: 
        !          2668:        case LE_EXPR:
        !          2669:        case LT_EXPR:
        !          2670:          if (hi_code == GE_EXPR)
        !          2671:            hi_cst = const_binop (MINUS_EXPR, hi_cst, integer_one_node, 0);
        !          2672:          else if (hi_code != GT_EXPR)
        !          2673:            return 0;
        !          2674: 
        !          2675:          if (lo_code == LE_EXPR)
        !          2676:            lo_cst = const_binop (PLUS_EXPR, lo_cst, integer_one_node, 0);
        !          2677: 
        !          2678:          /* We now have VAR < LO_CST || VAR > HI_CST.  */
        !          2679:          rcode = GT_EXPR;
        !          2680:          break;
        !          2681: 
        !          2682:        default:
        !          2683:          return 0;
        !          2684:        }
        !          2685:     }
        !          2686: 
        !          2687:   /* When normalizing, it is possible to both increment the smaller constant
        !          2688:      and decrement the larger constant.  See if they are still ordered.  */
        !          2689:   if (tree_int_cst_lt (hi_cst, lo_cst))
        !          2690:     return 0;
        !          2691: 
        !          2692:   /* Fail if VAR isn't an integer.  */
        !          2693:   utype = TREE_TYPE (var);
        !          2694:   if (! INTEGRAL_TYPE_P (utype))
        !          2695:     return 0;
        !          2696: 
        !          2697:   /* The range test is invalid if subtracting the two constants results
        !          2698:      in overflow.  This can happen in traditional mode.  */
        !          2699:   if (! int_fits_type_p (hi_cst, TREE_TYPE (var))
        !          2700:       || ! int_fits_type_p (lo_cst, TREE_TYPE (var)))
        !          2701:     return 0;
        !          2702: 
        !          2703:   if (! TREE_UNSIGNED (utype))
        !          2704:     {
        !          2705:       utype = unsigned_type (utype);
        !          2706:       var = convert (utype, var);
        !          2707:       lo_cst = convert (utype, lo_cst);
        !          2708:       hi_cst = convert (utype, hi_cst);
        !          2709:     }
        !          2710: 
        !          2711:   return fold (convert (type,
        !          2712:                        build (rcode, utype,
        !          2713:                               build (MINUS_EXPR, utype, var, lo_cst),
        !          2714:                               const_binop (MINUS_EXPR, hi_cst, lo_cst, 0))));
        !          2715: }
        !          2716: 
        !          2717: /* Find ways of folding logical expressions of LHS and RHS:
        !          2718:    Try to merge two comparisons to the same innermost item.
        !          2719:    Look for range tests like "ch >= '0' && ch <= '9'".
        !          2720:    Look for combinations of simple terms on machines with expensive branches
        !          2721:    and evaluate the RHS unconditionally.
        !          2722: 
        !          2723:    For example, if we have p->a == 2 && p->b == 4 and we can make an
        !          2724:    object large enough to span both A and B, we can do this with a comparison
        !          2725:    against the object ANDed with the a mask.
        !          2726: 
        !          2727:    If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
        !          2728:    operations to do this with one comparison.
        !          2729: 
        !          2730:    We check for both normal comparisons and the BIT_AND_EXPRs made this by
        !          2731:    function and the one above.
        !          2732: 
        !          2733:    CODE is the logical operation being done.  It can be TRUTH_ANDIF_EXPR,
        !          2734:    TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
        !          2735: 
        !          2736:    TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
        !          2737:    two operands.
        !          2738: 
        !          2739:    We return the simplified tree or 0 if no optimization is possible.  */
        !          2740: 
        !          2741: static tree
        !          2742: fold_truthop (code, truth_type, lhs, rhs)
        !          2743:      enum tree_code code;
        !          2744:      tree truth_type, lhs, rhs;
        !          2745: {
        !          2746:   /* If this is the "or" of two comparisons, we can do something if we
        !          2747:      the comparisons are NE_EXPR.  If this is the "and", we can do something
        !          2748:      if the comparisons are EQ_EXPR.  I.e., 
        !          2749:        (a->b == 2 && a->c == 4) can become (a->new == NEW).
        !          2750: 
        !          2751:      WANTED_CODE is this operation code.  For single bit fields, we can
        !          2752:      convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
        !          2753:      comparison for one-bit fields.  */
        !          2754: 
        !          2755:   enum tree_code wanted_code;
        !          2756:   enum tree_code lcode, rcode;
        !          2757:   tree ll_arg, lr_arg, rl_arg, rr_arg;
        !          2758:   tree ll_inner, lr_inner, rl_inner, rr_inner;
        !          2759:   int ll_bitsize, ll_bitpos, lr_bitsize, lr_bitpos;
        !          2760:   int rl_bitsize, rl_bitpos, rr_bitsize, rr_bitpos;
        !          2761:   int xll_bitpos, xlr_bitpos, xrl_bitpos, xrr_bitpos;
        !          2762:   int lnbitsize, lnbitpos, rnbitsize, rnbitpos;
        !          2763:   int ll_unsignedp, lr_unsignedp, rl_unsignedp, rr_unsignedp;
        !          2764:   enum machine_mode ll_mode, lr_mode, rl_mode, rr_mode;
        !          2765:   enum machine_mode lnmode, rnmode;
        !          2766:   tree ll_mask, lr_mask, rl_mask, rr_mask;
        !          2767:   tree l_const, r_const;
        !          2768:   tree type, result;
        !          2769:   int first_bit, end_bit;
        !          2770:   int volatilep;
        !          2771: 
        !          2772:   /* Start by getting the comparison codes and seeing if this looks like
        !          2773:      a range test.  Fail if anything is volatile.  If one operand is a
        !          2774:      BIT_AND_EXPR with the constant one, treat it as if it were surrounded
        !          2775:      with a NE_EXPR.  */
        !          2776: 
        !          2777:   if (TREE_SIDE_EFFECTS (lhs)
        !          2778:       || TREE_SIDE_EFFECTS (rhs))
        !          2779:     return 0;
        !          2780: 
        !          2781:   lcode = TREE_CODE (lhs);
        !          2782:   rcode = TREE_CODE (rhs);
        !          2783: 
        !          2784:   if (lcode == BIT_AND_EXPR && integer_onep (TREE_OPERAND (lhs, 1)))
        !          2785:     lcode = NE_EXPR, lhs = build (NE_EXPR, truth_type, lhs, integer_zero_node);
        !          2786: 
        !          2787:   if (rcode == BIT_AND_EXPR && integer_onep (TREE_OPERAND (rhs, 1)))
        !          2788:     rcode = NE_EXPR, rhs = build (NE_EXPR, truth_type, rhs, integer_zero_node);
        !          2789: 
        !          2790:   if (TREE_CODE_CLASS (lcode) != '<'
        !          2791:       || TREE_CODE_CLASS (rcode) != '<')
        !          2792:     return 0;
        !          2793: 
        !          2794:   code = ((code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR)
        !          2795:          ? TRUTH_AND_EXPR : TRUTH_OR_EXPR);
        !          2796: 
        !          2797:   ll_arg = TREE_OPERAND (lhs, 0);
        !          2798:   lr_arg = TREE_OPERAND (lhs, 1);
        !          2799:   rl_arg = TREE_OPERAND (rhs, 0);
        !          2800:   rr_arg = TREE_OPERAND (rhs, 1);
        !          2801:   
        !          2802:   if (TREE_CODE (lr_arg) == INTEGER_CST
        !          2803:       && TREE_CODE (rr_arg) == INTEGER_CST
        !          2804:       && operand_equal_p (ll_arg, rl_arg, 0))
        !          2805:     {
        !          2806:       if (tree_int_cst_lt (lr_arg, rr_arg))
        !          2807:        result = range_test (code, truth_type, lcode, rcode,
        !          2808:                             ll_arg, lr_arg, rr_arg);
        !          2809:       else
        !          2810:        result = range_test (code, truth_type, rcode, lcode,
        !          2811:                             ll_arg, rr_arg, lr_arg);
        !          2812: 
        !          2813:       /* If this isn't a range test, it also isn't a comparison that
        !          2814:         can be merged.  However, it wins to evaluate the RHS unconditionally
        !          2815:         on machines with expensive branches.   */
        !          2816: 
        !          2817:       if (result == 0 && BRANCH_COST >= 2)
        !          2818:        {
        !          2819:          if (TREE_CODE (ll_arg) != VAR_DECL
        !          2820:              && TREE_CODE (ll_arg) != PARM_DECL)
        !          2821:            {
        !          2822:              /* Avoid evaluating the variable part twice.  */
        !          2823:              ll_arg = save_expr (ll_arg);
        !          2824:              lhs = build (lcode, TREE_TYPE (lhs), ll_arg, lr_arg);
        !          2825:              rhs = build (rcode, TREE_TYPE (rhs), ll_arg, rr_arg);
        !          2826:            }
        !          2827:          return build (code, truth_type, lhs, rhs);
        !          2828:        }
        !          2829:       return result;
        !          2830:     }
        !          2831: 
        !          2832:   /* If the RHS can be evaluated unconditionally and its operands are
        !          2833:      simple, it wins to evaluate the RHS unconditionally on machines
        !          2834:      with expensive branches.  In this case, this isn't a comparison
        !          2835:      that can be merged.  */
        !          2836: 
        !          2837:   /* @@ I'm not sure it wins on the m88110 to do this if the comparisons
        !          2838:      are with zero (tmw).  */
        !          2839: 
        !          2840:   if (BRANCH_COST >= 2
        !          2841:       && INTEGRAL_TYPE_P (TREE_TYPE (rhs))
        !          2842:       && simple_operand_p (rl_arg)
        !          2843:       && simple_operand_p (rr_arg))
        !          2844:     return build (code, truth_type, lhs, rhs);
        !          2845: 
        !          2846:   /* See if the comparisons can be merged.  Then get all the parameters for
        !          2847:      each side.  */
        !          2848: 
        !          2849:   if ((lcode != EQ_EXPR && lcode != NE_EXPR)
        !          2850:       || (rcode != EQ_EXPR && rcode != NE_EXPR))
        !          2851:     return 0;
        !          2852: 
        !          2853:   volatilep = 0;
        !          2854:   ll_inner = decode_field_reference (ll_arg,
        !          2855:                                     &ll_bitsize, &ll_bitpos, &ll_mode,
        !          2856:                                     &ll_unsignedp, &volatilep, &ll_mask);
        !          2857:   lr_inner = decode_field_reference (lr_arg,
        !          2858:                                     &lr_bitsize, &lr_bitpos, &lr_mode,
        !          2859:                                     &lr_unsignedp, &volatilep, &lr_mask);
        !          2860:   rl_inner = decode_field_reference (rl_arg,
        !          2861:                                     &rl_bitsize, &rl_bitpos, &rl_mode,
        !          2862:                                     &rl_unsignedp, &volatilep, &rl_mask);
        !          2863:   rr_inner = decode_field_reference (rr_arg,
        !          2864:                                     &rr_bitsize, &rr_bitpos, &rr_mode,
        !          2865:                                     &rr_unsignedp, &volatilep, &rr_mask);
        !          2866: 
        !          2867:   /* It must be true that the inner operation on the lhs of each
        !          2868:      comparison must be the same if we are to be able to do anything.
        !          2869:      Then see if we have constants.  If not, the same must be true for
        !          2870:      the rhs's.  */
        !          2871:   if (volatilep || ll_inner == 0 || rl_inner == 0
        !          2872:       || ! operand_equal_p (ll_inner, rl_inner, 0))
        !          2873:     return 0;
        !          2874: 
        !          2875:   if (TREE_CODE (lr_arg) == INTEGER_CST
        !          2876:       && TREE_CODE (rr_arg) == INTEGER_CST)
        !          2877:     l_const = lr_arg, r_const = rr_arg;
        !          2878:   else if (lr_inner == 0 || rr_inner == 0
        !          2879:           || ! operand_equal_p (lr_inner, rr_inner, 0))
        !          2880:     return 0;
        !          2881:   else
        !          2882:     l_const = r_const = 0;
        !          2883: 
        !          2884:   /* If either comparison code is not correct for our logical operation,
        !          2885:      fail.  However, we can convert a one-bit comparison against zero into
        !          2886:      the opposite comparison against that bit being set in the field.  */
        !          2887: 
        !          2888:   wanted_code = (code == TRUTH_AND_EXPR ? EQ_EXPR : NE_EXPR);
        !          2889:   if (lcode != wanted_code)
        !          2890:     {
        !          2891:       if (l_const && integer_zerop (l_const) && integer_pow2p (ll_mask))
        !          2892:        l_const = ll_mask;
        !          2893:       else
        !          2894:        return 0;
        !          2895:     }
        !          2896: 
        !          2897:   if (rcode != wanted_code)
        !          2898:     {
        !          2899:       if (r_const && integer_zerop (r_const) && integer_pow2p (rl_mask))
        !          2900:        r_const = rl_mask;
        !          2901:       else
        !          2902:        return 0;
        !          2903:     }
        !          2904: 
        !          2905:   /* See if we can find a mode that contains both fields being compared on
        !          2906:      the left.  If we can't, fail.  Otherwise, update all constants and masks
        !          2907:      to be relative to a field of that size.  */
        !          2908:   first_bit = MIN (ll_bitpos, rl_bitpos);
        !          2909:   end_bit = MAX (ll_bitpos + ll_bitsize, rl_bitpos + rl_bitsize);
        !          2910:   lnmode = get_best_mode (end_bit - first_bit, first_bit,
        !          2911:                          TYPE_ALIGN (TREE_TYPE (ll_inner)), word_mode,
        !          2912:                          volatilep);
        !          2913:   if (lnmode == VOIDmode)
        !          2914:     return 0;
        !          2915: 
        !          2916:   lnbitsize = GET_MODE_BITSIZE (lnmode);
        !          2917:   lnbitpos = first_bit & ~ (lnbitsize - 1);
        !          2918:   type = type_for_size (lnbitsize, 1);
        !          2919:   xll_bitpos = ll_bitpos - lnbitpos, xrl_bitpos = rl_bitpos - lnbitpos;
        !          2920: 
        !          2921: #if BYTES_BIG_ENDIAN
        !          2922:   xll_bitpos = lnbitsize - xll_bitpos - ll_bitsize;
        !          2923:   xrl_bitpos = lnbitsize - xrl_bitpos - rl_bitsize;
        !          2924: #endif
        !          2925: 
        !          2926:   ll_mask = const_binop (LSHIFT_EXPR, convert (type, ll_mask),
        !          2927:                         size_int (xll_bitpos), 0);
        !          2928:   rl_mask = const_binop (LSHIFT_EXPR, convert (type, rl_mask),
        !          2929:                         size_int (xrl_bitpos), 0);
        !          2930: 
        !          2931:   /* Make sure the constants are interpreted as unsigned, so we
        !          2932:      don't have sign bits outside the range of their type.  */
        !          2933: 
        !          2934:   if (l_const)
        !          2935:     {
        !          2936:       l_const = convert (unsigned_type (TREE_TYPE (l_const)), l_const);
        !          2937:       l_const = const_binop (LSHIFT_EXPR, convert (type, l_const),
        !          2938:                             size_int (xll_bitpos), 0);
        !          2939:     }
        !          2940:   if (r_const)
        !          2941:     {
        !          2942:       r_const = convert (unsigned_type (TREE_TYPE (r_const)), r_const);
        !          2943:       r_const = const_binop (LSHIFT_EXPR, convert (type, r_const),
        !          2944:                             size_int (xrl_bitpos), 0);
        !          2945:     }
        !          2946: 
        !          2947:   /* If the right sides are not constant, do the same for it.  Also,
        !          2948:      disallow this optimization if a size or signedness mismatch occurs
        !          2949:      between the left and right sides.  */
        !          2950:   if (l_const == 0)
        !          2951:     {
        !          2952:       if (ll_bitsize != lr_bitsize || rl_bitsize != rr_bitsize
        !          2953:          || ll_unsignedp != lr_unsignedp || rl_unsignedp != rr_unsignedp
        !          2954:          /* Make sure the two fields on the right
        !          2955:             correspond to the left without being swapped.  */
        !          2956:          || ll_bitpos - rl_bitpos != lr_bitpos - rr_bitpos)
        !          2957:        return 0;
        !          2958: 
        !          2959:       first_bit = MIN (lr_bitpos, rr_bitpos);
        !          2960:       end_bit = MAX (lr_bitpos + lr_bitsize, rr_bitpos + rr_bitsize);
        !          2961:       rnmode = get_best_mode (end_bit - first_bit, first_bit,
        !          2962:                              TYPE_ALIGN (TREE_TYPE (lr_inner)), word_mode,
        !          2963:                              volatilep);
        !          2964:       if (rnmode == VOIDmode)
        !          2965:        return 0;
        !          2966: 
        !          2967:       rnbitsize = GET_MODE_BITSIZE (rnmode);
        !          2968:       rnbitpos = first_bit & ~ (rnbitsize - 1);
        !          2969:       xlr_bitpos = lr_bitpos - rnbitpos, xrr_bitpos = rr_bitpos - rnbitpos;
        !          2970: 
        !          2971: #if BYTES_BIG_ENDIAN
        !          2972:       xlr_bitpos = rnbitsize - xlr_bitpos - lr_bitsize;
        !          2973:       xrr_bitpos = rnbitsize - xrr_bitpos - rr_bitsize;
        !          2974: #endif
        !          2975: 
        !          2976:       lr_mask = const_binop (LSHIFT_EXPR, convert (type, lr_mask),
        !          2977:                             size_int (xlr_bitpos), 0);
        !          2978:       rr_mask = const_binop (LSHIFT_EXPR, convert (type, rr_mask),
        !          2979:                             size_int (xrr_bitpos), 0);
        !          2980: 
        !          2981:       /* Make a mask that corresponds to both fields being compared.
        !          2982:         Do this for both items being compared.  If the masks agree,
        !          2983:         we can do this by masking both and comparing the masked
        !          2984:         results.  */
        !          2985:       ll_mask = const_binop (BIT_IOR_EXPR, ll_mask, rl_mask, 0);
        !          2986:       lr_mask = const_binop (BIT_IOR_EXPR, lr_mask, rr_mask, 0);
        !          2987:       if (operand_equal_p (ll_mask, lr_mask, 0) && lnbitsize == rnbitsize)
        !          2988:        {
        !          2989:          lhs = make_bit_field_ref (ll_inner, type, lnbitsize, lnbitpos,
        !          2990:                                    ll_unsignedp || rl_unsignedp);
        !          2991:          rhs = make_bit_field_ref (lr_inner, type, rnbitsize, rnbitpos,
        !          2992:                                    lr_unsignedp || rr_unsignedp);
        !          2993:          if (! all_ones_mask_p (ll_mask, lnbitsize))
        !          2994:            {
        !          2995:              lhs = build (BIT_AND_EXPR, type, lhs, ll_mask);
        !          2996:              rhs = build (BIT_AND_EXPR, type, rhs, ll_mask);
        !          2997:            }
        !          2998:          return build (wanted_code, truth_type, lhs, rhs);
        !          2999:        }
        !          3000: 
        !          3001:       /* There is still another way we can do something:  If both pairs of
        !          3002:         fields being compared are adjacent, we may be able to make a wider
        !          3003:         field containing them both.  */
        !          3004:       if ((ll_bitsize + ll_bitpos == rl_bitpos
        !          3005:           && lr_bitsize + lr_bitpos == rr_bitpos)
        !          3006:          || (ll_bitpos == rl_bitpos + rl_bitsize
        !          3007:              && lr_bitpos == rr_bitpos + rr_bitsize))
        !          3008:        return build (wanted_code, truth_type,
        !          3009:                      make_bit_field_ref (ll_inner, type,
        !          3010:                                          ll_bitsize + rl_bitsize,
        !          3011:                                          MIN (ll_bitpos, rl_bitpos),
        !          3012:                                          ll_unsignedp),
        !          3013:                      make_bit_field_ref (lr_inner, type,
        !          3014:                                          lr_bitsize + rr_bitsize,
        !          3015:                                          MIN (lr_bitpos, rr_bitpos),
        !          3016:                                          lr_unsignedp));
        !          3017: 
        !          3018:       return 0;
        !          3019:     }
        !          3020: 
        !          3021:   /* Handle the case of comparisons with constants.  If there is something in
        !          3022:      common between the masks, those bits of the constants must be the same.
        !          3023:      If not, the condition is always false.  Test for this to avoid generating
        !          3024:      incorrect code below.  */
        !          3025:   result = const_binop (BIT_AND_EXPR, ll_mask, rl_mask, 0);
        !          3026:   if (! integer_zerop (result)
        !          3027:       && simple_cst_equal (const_binop (BIT_AND_EXPR, result, l_const, 0),
        !          3028:                           const_binop (BIT_AND_EXPR, result, r_const, 0)) != 1)
        !          3029:     {
        !          3030:       if (wanted_code == NE_EXPR)
        !          3031:        {
        !          3032:          warning ("`or' of unmatched not-equal tests is always 1");
        !          3033:          return convert (truth_type, integer_one_node);
        !          3034:        }
        !          3035:       else
        !          3036:        {
        !          3037:          warning ("`and' of mutually exclusive equal-tests is always zero");
        !          3038:          return convert (truth_type, integer_zero_node);
        !          3039:        }
        !          3040:     }
        !          3041: 
        !          3042:   /* Construct the expression we will return.  First get the component
        !          3043:      reference we will make.  Unless the mask is all ones the width of
        !          3044:      that field, perform the mask operation.  Then compare with the
        !          3045:      merged constant.  */
        !          3046:   result = make_bit_field_ref (ll_inner, type, lnbitsize, lnbitpos,
        !          3047:                               ll_unsignedp || rl_unsignedp);
        !          3048: 
        !          3049:   ll_mask = const_binop (BIT_IOR_EXPR, ll_mask, rl_mask, 0);
        !          3050:   if (! all_ones_mask_p (ll_mask, lnbitsize))
        !          3051:     result = build (BIT_AND_EXPR, type, result, ll_mask);
        !          3052: 
        !          3053:   return build (wanted_code, truth_type, result,
        !          3054:                const_binop (BIT_IOR_EXPR, l_const, r_const, 0));
        !          3055: }
        !          3056: 
        !          3057: /* Perform constant folding and related simplification of EXPR.
        !          3058:    The related simplifications include x*1 => x, x*0 => 0, etc.,
        !          3059:    and application of the associative law.
        !          3060:    NOP_EXPR conversions may be removed freely (as long as we
        !          3061:    are careful not to change the C type of the overall expression)
        !          3062:    We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
        !          3063:    but we can constant-fold them if they have constant operands.  */
        !          3064: 
        !          3065: tree
        !          3066: fold (expr) 
        !          3067:      tree expr;
        !          3068: {
        !          3069:   register tree t = expr;
        !          3070:   tree t1 = NULL_TREE;
        !          3071:   tree tem;
        !          3072:   tree type = TREE_TYPE (expr);
        !          3073:   register tree arg0, arg1;
        !          3074:   register enum tree_code code = TREE_CODE (t);
        !          3075:   register int kind;
        !          3076:   int invert;
        !          3077: 
        !          3078:   /* WINS will be nonzero when the switch is done
        !          3079:      if all operands are constant.  */
        !          3080: 
        !          3081:   int wins = 1;
        !          3082: 
        !          3083:   /* Don't try to process an RTL_EXPR since its operands aren't trees.  */
        !          3084:   if (code == RTL_EXPR)
        !          3085:     return t;
        !          3086: 
        !          3087:   /* Return right away if already constant.  */
        !          3088:   if (TREE_CONSTANT (t))
        !          3089:     {
        !          3090:       if (code == CONST_DECL)
        !          3091:        return DECL_INITIAL (t);
        !          3092:       return t;
        !          3093:     }
        !          3094:   
        !          3095:   kind = TREE_CODE_CLASS (code);
        !          3096:   if (code == NOP_EXPR || code == FLOAT_EXPR || code == CONVERT_EXPR)
        !          3097:     {
        !          3098:       tree subop;
        !          3099: 
        !          3100:       /* Special case for conversion ops that can have fixed point args.  */
        !          3101:       arg0 = TREE_OPERAND (t, 0);
        !          3102: 
        !          3103:       /* Don't use STRIP_NOPS, because signedness of argument type matters.  */
        !          3104:       if (arg0 != 0)
        !          3105:        STRIP_TYPE_NOPS (arg0);
        !          3106: 
        !          3107:       if (arg0 != 0 && TREE_CODE (arg0) == COMPLEX_CST)
        !          3108:        subop = TREE_REALPART (arg0);
        !          3109:       else
        !          3110:        subop = arg0;
        !          3111: 
        !          3112:       if (subop != 0 && TREE_CODE (subop) != INTEGER_CST
        !          3113: #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
        !          3114:          && TREE_CODE (subop) != REAL_CST
        !          3115: #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
        !          3116:          )
        !          3117:        /* Note that TREE_CONSTANT isn't enough:
        !          3118:           static var addresses are constant but we can't
        !          3119:           do arithmetic on them.  */
        !          3120:        wins = 0;
        !          3121:     }
        !          3122:   else if (kind == 'e' || kind == '<'
        !          3123:           || kind == '1' || kind == '2' || kind == 'r')
        !          3124:     {
        !          3125:       register int len = tree_code_length[(int) code];
        !          3126:       register int i;
        !          3127:       for (i = 0; i < len; i++)
        !          3128:        {
        !          3129:          tree op = TREE_OPERAND (t, i);
        !          3130:          tree subop;
        !          3131: 
        !          3132:          if (op == 0)
        !          3133:            continue;           /* Valid for CALL_EXPR, at least.  */
        !          3134: 
        !          3135:          if (kind == '<' || code == RSHIFT_EXPR)
        !          3136:            {
        !          3137:              /* Signedness matters here.  Perhaps we can refine this
        !          3138:                 later.  */
        !          3139:              STRIP_TYPE_NOPS (op);
        !          3140:            }
        !          3141:          else
        !          3142:            {
        !          3143:              /* Strip any conversions that don't change the mode.  */
        !          3144:              STRIP_NOPS (op);
        !          3145:            }
        !          3146:          
        !          3147:          if (TREE_CODE (op) == COMPLEX_CST)
        !          3148:            subop = TREE_REALPART (op);
        !          3149:          else
        !          3150:            subop = op;
        !          3151: 
        !          3152:          if (TREE_CODE (subop) != INTEGER_CST
        !          3153: #if ! defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
        !          3154:              && TREE_CODE (subop) != REAL_CST
        !          3155: #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
        !          3156:              )
        !          3157:            /* Note that TREE_CONSTANT isn't enough:
        !          3158:               static var addresses are constant but we can't
        !          3159:               do arithmetic on them.  */
        !          3160:            wins = 0;
        !          3161: 
        !          3162:          if (i == 0)
        !          3163:            arg0 = op;
        !          3164:          else if (i == 1)
        !          3165:            arg1 = op;
        !          3166:        }
        !          3167:     }
        !          3168: 
        !          3169:   /* If this is a commutative operation, and ARG0 is a constant, move it
        !          3170:      to ARG1 to reduce the number of tests below.  */
        !          3171:   if ((code == PLUS_EXPR || code == MULT_EXPR || code == MIN_EXPR
        !          3172:        || code == MAX_EXPR || code == BIT_IOR_EXPR || code == BIT_XOR_EXPR
        !          3173:        || code == BIT_AND_EXPR)
        !          3174:       && (TREE_CODE (arg0) == INTEGER_CST || TREE_CODE (arg0) == REAL_CST))
        !          3175:     {
        !          3176:       tem = arg0; arg0 = arg1; arg1 = tem;
        !          3177: 
        !          3178:       tem = TREE_OPERAND (t, 0); TREE_OPERAND (t, 0) = TREE_OPERAND (t, 1);
        !          3179:       TREE_OPERAND (t, 1) = tem;
        !          3180:     }
        !          3181: 
        !          3182:   /* Now WINS is set as described above,
        !          3183:      ARG0 is the first operand of EXPR,
        !          3184:      and ARG1 is the second operand (if it has more than one operand).
        !          3185: 
        !          3186:      First check for cases where an arithmetic operation is applied to a
        !          3187:      compound, conditional, or comparison operation.  Push the arithmetic
        !          3188:      operation inside the compound or conditional to see if any folding
        !          3189:      can then be done.  Convert comparison to conditional for this purpose.
        !          3190:      The also optimizes non-constant cases that used to be done in
        !          3191:      expand_expr.
        !          3192: 
        !          3193:      Before we do that, see if this is a BIT_AND_EXPR or a BIT_OR_EXPR,
        !          3194:      one of the operands is a comparison and the other is either a comparison
        !          3195:      or a BIT_AND_EXPR with the constant 1.  In that case, the code below
        !          3196:      would make the expression more complex.  Change it to a
        !          3197:      TRUTH_{AND,OR}_EXPR.  Likewise, convert a similar NE_EXPR to 
        !          3198:      TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR.  */
        !          3199: 
        !          3200:   if ((code == BIT_AND_EXPR || code == BIT_IOR_EXPR
        !          3201:        || code == EQ_EXPR || code == NE_EXPR)
        !          3202:       && ((TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
        !          3203:           && (TREE_CODE_CLASS (TREE_CODE (arg1)) == '<'
        !          3204:               || (TREE_CODE (arg1) == BIT_AND_EXPR
        !          3205:                   && integer_onep (TREE_OPERAND (arg1, 1)))))
        !          3206:          || (TREE_CODE_CLASS (TREE_CODE (arg1)) == '<'
        !          3207:              && (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
        !          3208:                  || (TREE_CODE (arg0) == BIT_AND_EXPR
        !          3209:                      && integer_onep (TREE_OPERAND (arg0, 1)))))))
        !          3210:     {
        !          3211:       t = fold (build (code == BIT_AND_EXPR ? TRUTH_AND_EXPR
        !          3212:                       : code == BIT_IOR_EXPR ? TRUTH_OR_EXPR
        !          3213:                       : TRUTH_XOR_EXPR,
        !          3214:                       type, arg0, arg1));
        !          3215: 
        !          3216:       if (code == EQ_EXPR)
        !          3217:        t = invert_truthvalue (t);
        !          3218: 
        !          3219:       return t;
        !          3220:     }
        !          3221: 
        !          3222:   if (TREE_CODE_CLASS (code) == '1')
        !          3223:     {
        !          3224:       if (TREE_CODE (arg0) == COMPOUND_EXPR)
        !          3225:        return build (COMPOUND_EXPR, type, TREE_OPERAND (arg0, 0),
        !          3226:                      fold (build1 (code, type, TREE_OPERAND (arg0, 1))));
        !          3227:       else if (TREE_CODE (arg0) == COND_EXPR)
        !          3228:        {
        !          3229:          t = fold (build (COND_EXPR, type, TREE_OPERAND (arg0, 0),
        !          3230:                           fold (build1 (code, type, TREE_OPERAND (arg0, 1))),
        !          3231:                           fold (build1 (code, type, TREE_OPERAND (arg0, 2)))));
        !          3232: 
        !          3233:          /* If this was a conversion, and all we did was to move into
        !          3234:             inside the COND_EXPR, bring it back out.  Then return so we
        !          3235:             don't get into an infinite recursion loop taking the conversion
        !          3236:             out and then back in.  */
        !          3237: 
        !          3238:          if ((code == NOP_EXPR || code == CONVERT_EXPR
        !          3239:               || code == NON_LVALUE_EXPR)
        !          3240:              && TREE_CODE (t) == COND_EXPR
        !          3241:              && TREE_CODE (TREE_OPERAND (t, 1)) == code
        !          3242:              && TREE_CODE (TREE_OPERAND (t, 2)) == code
        !          3243:              && (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 1), 0))
        !          3244:                  == TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 2), 0))))
        !          3245:            t = build1 (code, type,
        !          3246:                        build (COND_EXPR,
        !          3247:                               TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 1), 0)),
        !          3248:                               TREE_OPERAND (t, 0),
        !          3249:                               TREE_OPERAND (TREE_OPERAND (t, 1), 0),
        !          3250:                               TREE_OPERAND (TREE_OPERAND (t, 2), 0)));
        !          3251:          return t;
        !          3252:        }
        !          3253:       else if (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<') 
        !          3254:        return fold (build (COND_EXPR, type, arg0,
        !          3255:                            fold (build1 (code, type, integer_one_node)),
        !          3256:                            fold (build1 (code, type, integer_zero_node))));
        !          3257:    }
        !          3258:   else if (TREE_CODE_CLASS (code) == '2'
        !          3259:           || TREE_CODE_CLASS (code) == '<')
        !          3260:     {
        !          3261:       if (TREE_CODE (arg1) == COMPOUND_EXPR)
        !          3262:        return build (COMPOUND_EXPR, type, TREE_OPERAND (arg1, 0),
        !          3263:                      fold (build (code, type,
        !          3264:                                   arg0, TREE_OPERAND (arg1, 1))));
        !          3265:       else if (TREE_CODE (arg1) == COND_EXPR
        !          3266:               || TREE_CODE_CLASS (TREE_CODE (arg1)) == '<')
        !          3267:        {
        !          3268:          tree test, true_value, false_value;
        !          3269: 
        !          3270:          if (TREE_CODE (arg1) == COND_EXPR)
        !          3271:            {
        !          3272:              test = TREE_OPERAND (arg1, 0);
        !          3273:              true_value = TREE_OPERAND (arg1, 1);
        !          3274:              false_value = TREE_OPERAND (arg1, 2);
        !          3275:            }
        !          3276:          else
        !          3277:            {
        !          3278:              test = arg1;
        !          3279:              true_value = integer_one_node;
        !          3280:              false_value = integer_zero_node;
        !          3281:            }
        !          3282: 
        !          3283:          /* If ARG0 is complex we want to make sure we only evaluate
        !          3284:             it once.  Though this is only required if it is volatile, it
        !          3285:             might be more efficient even if it is not.  However, if we
        !          3286:             succeed in folding one part to a constant, we do not need
        !          3287:             to make this SAVE_EXPR.  Since we do this optimization
        !          3288:             primarily to see if we do end up with constant and this
        !          3289:             SAVE_EXPR interfers with later optimizations, suppressing
        !          3290:             it when we can is important.  */
        !          3291: 
        !          3292:          if ((TREE_CODE (arg0) != VAR_DECL && TREE_CODE (arg0) != PARM_DECL)
        !          3293:              || TREE_SIDE_EFFECTS (arg0))
        !          3294:            {
        !          3295:              tree lhs = fold (build (code, type, arg0, true_value));
        !          3296:              tree rhs = fold (build (code, type, arg0, false_value));
        !          3297: 
        !          3298:              if (TREE_CONSTANT (lhs) || TREE_CONSTANT (rhs))
        !          3299:                return fold (build (COND_EXPR, type, test, lhs, rhs));
        !          3300: 
        !          3301:              arg0 = save_expr (arg0);
        !          3302:            }
        !          3303: 
        !          3304:          test = fold (build (COND_EXPR, type, test,
        !          3305:                              fold (build (code, type, arg0, true_value)),
        !          3306:                              fold (build (code, type, arg0, false_value))));
        !          3307:          if (TREE_CODE (arg0) == SAVE_EXPR)
        !          3308:            return build (COMPOUND_EXPR, type,
        !          3309:                          convert (void_type_node, arg0), test);
        !          3310:          else
        !          3311:            return convert (type, test);
        !          3312:        }
        !          3313: 
        !          3314:       else if (TREE_CODE (arg0) == COMPOUND_EXPR)
        !          3315:        return build (COMPOUND_EXPR, type, TREE_OPERAND (arg0, 0),
        !          3316:                      fold (build (code, type, TREE_OPERAND (arg0, 1), arg1)));
        !          3317:       else if (TREE_CODE (arg0) == COND_EXPR
        !          3318:               || TREE_CODE_CLASS (TREE_CODE (arg0)) == '<')
        !          3319:        {
        !          3320:          tree test, true_value, false_value;
        !          3321: 
        !          3322:          if (TREE_CODE (arg0) == COND_EXPR)
        !          3323:            {
        !          3324:              test = TREE_OPERAND (arg0, 0);
        !          3325:              true_value = TREE_OPERAND (arg0, 1);
        !          3326:              false_value = TREE_OPERAND (arg0, 2);
        !          3327:            }
        !          3328:          else
        !          3329:            {
        !          3330:              test = arg0;
        !          3331:              true_value = integer_one_node;
        !          3332:              false_value = integer_zero_node;
        !          3333:            }
        !          3334: 
        !          3335:          if ((TREE_CODE (arg1) != VAR_DECL && TREE_CODE (arg1) != PARM_DECL)
        !          3336:              || TREE_SIDE_EFFECTS (arg1))
        !          3337:            {
        !          3338:              tree lhs = fold (build (code, type, true_value, arg1));
        !          3339:              tree rhs = fold (build (code, type, false_value, arg1));
        !          3340: 
        !          3341:              if (TREE_CONSTANT (lhs) || TREE_CONSTANT (rhs))
        !          3342:                return fold (build (COND_EXPR, type, test, lhs, rhs));
        !          3343: 
        !          3344:              arg1 = save_expr (arg1);
        !          3345:            }
        !          3346: 
        !          3347:          test = fold (build (COND_EXPR, type, test,
        !          3348:                              fold (build (code, type, true_value, arg1)),
        !          3349:                              fold (build (code, type, false_value, arg1))));
        !          3350:          if (TREE_CODE (arg1) == SAVE_EXPR)
        !          3351:            return build (COMPOUND_EXPR, type,
        !          3352:                          convert (void_type_node, arg1), test);
        !          3353:          else
        !          3354:            return convert (type, test);
        !          3355:        }
        !          3356:     }
        !          3357:   else if (TREE_CODE_CLASS (code) == '<'
        !          3358:           && TREE_CODE (arg0) == COMPOUND_EXPR)
        !          3359:     return build (COMPOUND_EXPR, type, TREE_OPERAND (arg0, 0),
        !          3360:                  fold (build (code, type, TREE_OPERAND (arg0, 1), arg1)));
        !          3361:   else if (TREE_CODE_CLASS (code) == '<'
        !          3362:           && TREE_CODE (arg1) == COMPOUND_EXPR)
        !          3363:     return build (COMPOUND_EXPR, type, TREE_OPERAND (arg1, 0),
        !          3364:                  fold (build (code, type, arg0, TREE_OPERAND (arg1, 1))));
        !          3365:          
        !          3366:   switch (code)
        !          3367:     {
        !          3368:     case INTEGER_CST:
        !          3369:     case REAL_CST:
        !          3370:     case STRING_CST:
        !          3371:     case COMPLEX_CST:
        !          3372:     case CONSTRUCTOR:
        !          3373:       return t;
        !          3374: 
        !          3375:     case CONST_DECL:
        !          3376:       return fold (DECL_INITIAL (t));
        !          3377: 
        !          3378:     case NOP_EXPR:
        !          3379:     case FLOAT_EXPR:
        !          3380:     case CONVERT_EXPR:
        !          3381:     case FIX_TRUNC_EXPR:
        !          3382:       /* Other kinds of FIX are not handled properly by fold_convert.  */
        !          3383: 
        !          3384:       /* In addition to the cases of two conversions in a row 
        !          3385:         handled below, if we are converting something to its own
        !          3386:         type via an object of identical or wider precision, neither
        !          3387:         conversion is needed.  */
        !          3388:       if ((TREE_CODE (TREE_OPERAND (t, 0)) == NOP_EXPR
        !          3389:           || TREE_CODE (TREE_OPERAND (t, 0)) == CONVERT_EXPR)
        !          3390:          && TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)) == TREE_TYPE (t)
        !          3391:          && ((INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3392:               && INTEGRAL_TYPE_P (TREE_TYPE (t)))
        !          3393:              || (FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3394:                  && FLOAT_TYPE_P (TREE_TYPE (t))))
        !          3395:          && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3396:              >= TYPE_PRECISION (TREE_TYPE (t))))
        !          3397:        return TREE_OPERAND (TREE_OPERAND (t, 0), 0);
        !          3398: 
        !          3399:       /* Two conversions in a row are not needed unless:
        !          3400:         - the intermediate type is narrower than both initial and final, or
        !          3401:         - the intermediate type and innermost type differ in signedness,
        !          3402:           and the outermost type is wider than the intermediate, or
        !          3403:         - the initial type is a pointer type and the precisions of the
        !          3404:           intermediate and final types differ, or
        !          3405:         - the final type is a pointer type and the precisions of the 
        !          3406:          initial and intermediate types differ.  */
        !          3407:       if ((TREE_CODE (TREE_OPERAND (t, 0)) == NOP_EXPR
        !          3408:           || TREE_CODE (TREE_OPERAND (t, 0)) == CONVERT_EXPR)
        !          3409:          && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3410:              > TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))
        !          3411:              ||
        !          3412:              TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3413:              > TYPE_PRECISION (TREE_TYPE (t)))
        !          3414:          && ! ((TREE_CODE (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))
        !          3415:                 == INTEGER_TYPE)
        !          3416:                && (TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3417:                    == INTEGER_TYPE)
        !          3418:                && (TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3419:                    != TREE_UNSIGNED (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))
        !          3420:                && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3421:                    < TYPE_PRECISION (TREE_TYPE (t))))
        !          3422:          && ((TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3423:               && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3424:                   > TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))))
        !          3425:              ==
        !          3426:              (TREE_UNSIGNED (TREE_TYPE (t))
        !          3427:               && (TYPE_PRECISION (TREE_TYPE (t))
        !          3428:                   > TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0))))))
        !          3429:          && ! ((TREE_CODE (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))
        !          3430:                 == POINTER_TYPE)
        !          3431:                && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0)))
        !          3432:                    != TYPE_PRECISION (TREE_TYPE (t))))
        !          3433:          && ! (TREE_CODE (TREE_TYPE (t)) == POINTER_TYPE
        !          3434:                && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)))
        !          3435:                    != TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (t, 0))))))
        !          3436:        return convert (TREE_TYPE (t), TREE_OPERAND (TREE_OPERAND (t, 0), 0));
        !          3437: 
        !          3438:       if (TREE_CODE (TREE_OPERAND (t, 0)) == MODIFY_EXPR
        !          3439:          && TREE_CONSTANT (TREE_OPERAND (TREE_OPERAND (t, 0), 1))
        !          3440:          /* Detect assigning a bitfield.  */
        !          3441:          && !(TREE_CODE (TREE_OPERAND (TREE_OPERAND (t, 0), 0)) == COMPONENT_REF
        !          3442:               && DECL_BIT_FIELD (TREE_OPERAND (TREE_OPERAND (TREE_OPERAND (t, 0), 0), 1))))
        !          3443:        {
        !          3444:          /* Don't leave an assignment inside a conversion
        !          3445:             unless assigning a bitfield.  */
        !          3446:          tree prev = TREE_OPERAND (t, 0);
        !          3447:          TREE_OPERAND (t, 0) = TREE_OPERAND (prev, 1);
        !          3448:          /* First do the assignment, then return converted constant.  */
        !          3449:          t = build (COMPOUND_EXPR, TREE_TYPE (t), prev, fold (t));
        !          3450:          TREE_USED (t) = 1;
        !          3451:          return t;
        !          3452:        }
        !          3453:       if (!wins)
        !          3454:        {
        !          3455:          TREE_CONSTANT (t) = TREE_CONSTANT (arg0);
        !          3456:          return t;
        !          3457:        }
        !          3458:       return fold_convert (t, arg0);
        !          3459: 
        !          3460: #if 0  /* This loses on &"foo"[0].  */
        !          3461:     case ARRAY_REF:
        !          3462:        {
        !          3463:          int i;
        !          3464: 
        !          3465:          /* Fold an expression like: "foo"[2] */
        !          3466:          if (TREE_CODE (arg0) == STRING_CST
        !          3467:              && TREE_CODE (arg1) == INTEGER_CST
        !          3468:              && !TREE_INT_CST_HIGH (arg1)
        !          3469:              && (i = TREE_INT_CST_LOW (arg1)) < TREE_STRING_LENGTH (arg0))
        !          3470:            {
        !          3471:              t = build_int_2 (TREE_STRING_POINTER (arg0)[i], 0);
        !          3472:              TREE_TYPE (t) = TREE_TYPE (TREE_TYPE (arg0));
        !          3473:              force_fit_type (t, 0);
        !          3474:            }
        !          3475:        }
        !          3476:       return t;
        !          3477: #endif /* 0 */
        !          3478: 
        !          3479:     case RANGE_EXPR:
        !          3480:       TREE_CONSTANT (t) = wins;
        !          3481:       return t;
        !          3482: 
        !          3483:     case NEGATE_EXPR:
        !          3484:       if (wins)
        !          3485:        {
        !          3486:          if (TREE_CODE (arg0) == INTEGER_CST)
        !          3487:            {
        !          3488:              HOST_WIDE_INT low, high;
        !          3489:              int overflow = neg_double (TREE_INT_CST_LOW (arg0),
        !          3490:                                         TREE_INT_CST_HIGH (arg0),
        !          3491:                                         &low, &high);
        !          3492:              t = build_int_2 (low, high);
        !          3493:              TREE_TYPE (t) = type;
        !          3494:              TREE_OVERFLOW (t)
        !          3495:                = (TREE_OVERFLOW (arg0)
        !          3496:                   | force_fit_type (t, overflow));
        !          3497:              TREE_CONSTANT_OVERFLOW (t)
        !          3498:                = TREE_OVERFLOW (t) | TREE_CONSTANT_OVERFLOW (arg0);
        !          3499:            }
        !          3500:          else if (TREE_CODE (arg0) == REAL_CST)
        !          3501:            t = build_real (type, REAL_VALUE_NEGATE (TREE_REAL_CST (arg0)));
        !          3502:          TREE_TYPE (t) = type;
        !          3503:        }
        !          3504:       else if (TREE_CODE (arg0) == NEGATE_EXPR)
        !          3505:        return TREE_OPERAND (arg0, 0);
        !          3506: 
        !          3507:       /* Convert - (a - b) to (b - a) for non-floating-point.  */
        !          3508:       else if (TREE_CODE (arg0) == MINUS_EXPR && ! FLOAT_TYPE_P (type))
        !          3509:        return build (MINUS_EXPR, type, TREE_OPERAND (arg0, 1),
        !          3510:                      TREE_OPERAND (arg0, 0));
        !          3511: 
        !          3512:       return t;
        !          3513: 
        !          3514:     case ABS_EXPR:
        !          3515:       if (wins)
        !          3516:        {
        !          3517:          if (TREE_CODE (arg0) == INTEGER_CST)
        !          3518:            {
        !          3519:              if (! TREE_UNSIGNED (type)
        !          3520:                  && TREE_INT_CST_HIGH (arg0) < 0)
        !          3521:                {
        !          3522:                  HOST_WIDE_INT low, high;
        !          3523:                  int overflow = neg_double (TREE_INT_CST_LOW (arg0),
        !          3524:                                             TREE_INT_CST_HIGH (arg0),
        !          3525:                                             &low, &high);
        !          3526:                  t = build_int_2 (low, high);
        !          3527:                  TREE_TYPE (t) = type;
        !          3528:                  TREE_OVERFLOW (t)
        !          3529:                    = (TREE_OVERFLOW (arg0)
        !          3530:                       | force_fit_type (t, overflow));
        !          3531:                  TREE_CONSTANT_OVERFLOW (t)
        !          3532:                    = TREE_OVERFLOW (t) | TREE_CONSTANT_OVERFLOW (arg0);
        !          3533:                }
        !          3534:            }
        !          3535:          else if (TREE_CODE (arg0) == REAL_CST)
        !          3536:            {
        !          3537:              if (REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg0)))
        !          3538:                t = build_real (type,
        !          3539:                                REAL_VALUE_NEGATE (TREE_REAL_CST (arg0)));
        !          3540:            }
        !          3541:          TREE_TYPE (t) = type;
        !          3542:        }
        !          3543:       else if (TREE_CODE (arg0) == ABS_EXPR || TREE_CODE (arg0) == NEGATE_EXPR)
        !          3544:        return build1 (ABS_EXPR, type, TREE_OPERAND (arg0, 0));
        !          3545:       return t;
        !          3546: 
        !          3547:     case CONJ_EXPR:
        !          3548:       if (TREE_CODE (TREE_TYPE (arg0)) != COMPLEX_TYPE)
        !          3549:        return arg0;
        !          3550:       else if (TREE_CODE (arg0) == COMPLEX_EXPR)
        !          3551:        return build (COMPLEX_EXPR, TREE_TYPE (arg0),
        !          3552:                      TREE_OPERAND (arg0, 0),
        !          3553:                      fold (build1 (NEGATE_EXPR,
        !          3554:                                    TREE_TYPE (TREE_TYPE (arg0)),
        !          3555:                                    TREE_OPERAND (arg0, 1))));
        !          3556:       else if (TREE_CODE (arg0) == COMPLEX_CST)
        !          3557:        return build_complex (TREE_OPERAND (arg0, 0),
        !          3558:                              fold (build1 (NEGATE_EXPR,
        !          3559:                                            TREE_TYPE (TREE_TYPE (arg0)),
        !          3560:                                            TREE_OPERAND (arg0, 1))));
        !          3561:       else if (TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR)
        !          3562:        return fold (build (TREE_CODE (arg0), type,
        !          3563:                            fold (build1 (CONJ_EXPR, type,
        !          3564:                                          TREE_OPERAND (arg0, 0))),
        !          3565:                            fold (build1 (CONJ_EXPR,
        !          3566:                                          type, TREE_OPERAND (arg0, 1)))));
        !          3567:       else if (TREE_CODE (arg0) == CONJ_EXPR)
        !          3568:        return TREE_OPERAND (arg0, 0);
        !          3569:       return t;
        !          3570: 
        !          3571:     case BIT_NOT_EXPR:
        !          3572:       if (wins)
        !          3573:        {
        !          3574:          if (TREE_CODE (arg0) == INTEGER_CST)
        !          3575:            t = build_int_2 (~ TREE_INT_CST_LOW (arg0),
        !          3576:                             ~ TREE_INT_CST_HIGH (arg0));
        !          3577:          TREE_TYPE (t) = type;
        !          3578:          force_fit_type (t, 0);
        !          3579:          TREE_OVERFLOW (t) = TREE_OVERFLOW (arg0);
        !          3580:          TREE_CONSTANT_OVERFLOW (t) = TREE_CONSTANT_OVERFLOW (arg0);
        !          3581:        }
        !          3582:       else if (TREE_CODE (arg0) == BIT_NOT_EXPR)
        !          3583:        return TREE_OPERAND (arg0, 0);
        !          3584:       return t;
        !          3585: 
        !          3586:     case PLUS_EXPR:
        !          3587:       /* A + (-B) -> A - B */
        !          3588:       if (TREE_CODE (arg1) == NEGATE_EXPR)
        !          3589:        return fold (build (MINUS_EXPR, type, arg0, TREE_OPERAND (arg1, 0)));
        !          3590:       else if (! FLOAT_TYPE_P (type))
        !          3591:        {
        !          3592:          if (integer_zerop (arg1))
        !          3593:            return non_lvalue (convert (type, arg0));
        !          3594: 
        !          3595:          /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
        !          3596:             with a constant, and the two constants have no bits in common,
        !          3597:             we should treat this as a BIT_IOR_EXPR since this may produce more
        !          3598:             simplifications.  */
        !          3599:          if (TREE_CODE (arg0) == BIT_AND_EXPR
        !          3600:              && TREE_CODE (arg1) == BIT_AND_EXPR
        !          3601:              && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
        !          3602:              && TREE_CODE (TREE_OPERAND (arg1, 1)) == INTEGER_CST
        !          3603:              && integer_zerop (const_binop (BIT_AND_EXPR,
        !          3604:                                             TREE_OPERAND (arg0, 1),
        !          3605:                                             TREE_OPERAND (arg1, 1), 0)))
        !          3606:            {
        !          3607:              code = BIT_IOR_EXPR;
        !          3608:              goto bit_ior;
        !          3609:            }
        !          3610: 
        !          3611:          /* (A * C) + (B * C) -> (A+B) * C.  Since we are most concerned
        !          3612:             about the case where C is a constant, just try one of the
        !          3613:             four possibilities.  */
        !          3614: 
        !          3615:          if (TREE_CODE (arg0) == MULT_EXPR && TREE_CODE (arg1) == MULT_EXPR
        !          3616:              && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          3617:                                  TREE_OPERAND (arg1, 1), 0))
        !          3618:            return fold (build (MULT_EXPR, type,
        !          3619:                                fold (build (PLUS_EXPR, type,
        !          3620:                                             TREE_OPERAND (arg0, 0),
        !          3621:                                             TREE_OPERAND (arg1, 0))),
        !          3622:                                TREE_OPERAND (arg0, 1)));
        !          3623:        }
        !          3624:       /* In IEEE floating point, x+0 may not equal x.  */
        !          3625:       else if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
        !          3626:               && real_zerop (arg1))
        !          3627:        return non_lvalue (convert (type, arg0));
        !          3628:     associate:
        !          3629:       /* In most languages, can't associate operations on floats
        !          3630:         through parentheses.  Rather than remember where the parentheses
        !          3631:         were, we don't associate floats at all.  It shouldn't matter much.  */
        !          3632:       if (FLOAT_TYPE_P (type))
        !          3633:        goto binary;
        !          3634:       /* The varsign == -1 cases happen only for addition and subtraction.
        !          3635:         It says that the arg that was split was really CON minus VAR.
        !          3636:         The rest of the code applies to all associative operations.  */
        !          3637:       if (!wins)
        !          3638:        {
        !          3639:          tree var, con;
        !          3640:          int varsign;
        !          3641: 
        !          3642:          if (split_tree (arg0, code, &var, &con, &varsign))
        !          3643:            {
        !          3644:              if (varsign == -1)
        !          3645:                {
        !          3646:                  /* EXPR is (CON-VAR) +- ARG1.  */
        !          3647:                  /* If it is + and VAR==ARG1, return just CONST.  */
        !          3648:                  if (code == PLUS_EXPR && operand_equal_p (var, arg1, 0))
        !          3649:                    return convert (TREE_TYPE (t), con);
        !          3650:                    
        !          3651:                  /* If ARG0 is a constant, don't change things around;
        !          3652:                     instead keep all the constant computations together.  */
        !          3653: 
        !          3654:                  if (TREE_CONSTANT (arg0))
        !          3655:                    return t;
        !          3656: 
        !          3657:                  /* Otherwise return (CON +- ARG1) - VAR.  */
        !          3658:                  TREE_SET_CODE (t, MINUS_EXPR);
        !          3659:                  TREE_OPERAND (t, 1) = var;
        !          3660:                  TREE_OPERAND (t, 0)
        !          3661:                    = fold (build (code, TREE_TYPE (t), con, arg1));
        !          3662:                }
        !          3663:              else
        !          3664:                {
        !          3665:                  /* EXPR is (VAR+CON) +- ARG1.  */
        !          3666:                  /* If it is - and VAR==ARG1, return just CONST.  */
        !          3667:                  if (code == MINUS_EXPR && operand_equal_p (var, arg1, 0))
        !          3668:                    return convert (TREE_TYPE (t), con);
        !          3669:                    
        !          3670:                  /* If ARG0 is a constant, don't change things around;
        !          3671:                     instead keep all the constant computations together.  */
        !          3672: 
        !          3673:                  if (TREE_CONSTANT (arg0))
        !          3674:                    return t;
        !          3675: 
        !          3676:                  /* Otherwise return VAR +- (ARG1 +- CON).  */
        !          3677:                  TREE_OPERAND (t, 1) = tem
        !          3678:                    = fold (build (code, TREE_TYPE (t), arg1, con));
        !          3679:                  TREE_OPERAND (t, 0) = var;
        !          3680:                  if (integer_zerop (tem)
        !          3681:                      && (code == PLUS_EXPR || code == MINUS_EXPR))
        !          3682:                    return convert (type, var);
        !          3683:                  /* If we have x +/- (c - d) [c an explicit integer]
        !          3684:                     change it to x -/+ (d - c) since if d is relocatable
        !          3685:                     then the latter can be a single immediate insn
        !          3686:                     and the former cannot.  */
        !          3687:                  if (TREE_CODE (tem) == MINUS_EXPR
        !          3688:                      && TREE_CODE (TREE_OPERAND (tem, 0)) == INTEGER_CST)
        !          3689:                    {
        !          3690:                      tree tem1 = TREE_OPERAND (tem, 1);
        !          3691:                      TREE_OPERAND (tem, 1) = TREE_OPERAND (tem, 0);
        !          3692:                      TREE_OPERAND (tem, 0) = tem1;
        !          3693:                      TREE_SET_CODE (t,
        !          3694:                                     (code == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR));
        !          3695:                    }
        !          3696:                }
        !          3697:              return t;
        !          3698:            }
        !          3699: 
        !          3700:          if (split_tree (arg1, code, &var, &con, &varsign))
        !          3701:            {
        !          3702:              if (TREE_CONSTANT (arg1))
        !          3703:                return t;
        !          3704: 
        !          3705:              if (varsign == -1)
        !          3706:                TREE_SET_CODE (t,
        !          3707:                               (code == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR));
        !          3708: 
        !          3709:              /* EXPR is ARG0 +- (CON +- VAR).  */
        !          3710:              if (TREE_CODE (t) == MINUS_EXPR
        !          3711:                  && operand_equal_p (var, arg0, 0))
        !          3712:                {
        !          3713:                  /* If VAR and ARG0 cancel, return just CON or -CON.  */
        !          3714:                  if (code == PLUS_EXPR)
        !          3715:                    return convert (TREE_TYPE (t), con);
        !          3716:                  return fold (build1 (NEGATE_EXPR, TREE_TYPE (t),
        !          3717:                                       convert (TREE_TYPE (t), con)));
        !          3718:                }
        !          3719: 
        !          3720:              TREE_OPERAND (t, 0)
        !          3721:                = fold (build (code, TREE_TYPE (t), arg0, con));
        !          3722:              TREE_OPERAND (t, 1) = var;
        !          3723:              if (integer_zerop (TREE_OPERAND (t, 0))
        !          3724:                  && TREE_CODE (t) == PLUS_EXPR)
        !          3725:                return convert (TREE_TYPE (t), var);
        !          3726:              return t;
        !          3727:            }
        !          3728:        }
        !          3729:     binary:
        !          3730: #if defined (REAL_IS_NOT_DOUBLE) && ! defined (REAL_ARITHMETIC)
        !          3731:       if (TREE_CODE (arg1) == REAL_CST)
        !          3732:        return t;
        !          3733: #endif /* REAL_IS_NOT_DOUBLE, and no REAL_ARITHMETIC */
        !          3734:       if (wins)
        !          3735:        t1 = const_binop (code, arg0, arg1, 0);
        !          3736:       if (t1 != NULL_TREE)
        !          3737:        {
        !          3738:          /* The return value should always have
        !          3739:             the same type as the original expression.  */
        !          3740:          TREE_TYPE (t1) = TREE_TYPE (t);
        !          3741:          return t1;
        !          3742:        }
        !          3743:       return t;
        !          3744: 
        !          3745:     case MINUS_EXPR:
        !          3746:       if (! FLOAT_TYPE_P (type))
        !          3747:        {
        !          3748:          if (! wins && integer_zerop (arg0))
        !          3749:            return build1 (NEGATE_EXPR, type, arg1);
        !          3750:          if (integer_zerop (arg1))
        !          3751:            return non_lvalue (convert (type, arg0));
        !          3752: 
        !          3753:          /* (A * C) - (B * C) -> (A-B) * C.  Since we are most concerned
        !          3754:             about the case where C is a constant, just try one of the
        !          3755:             four possibilities.  */
        !          3756: 
        !          3757:          if (TREE_CODE (arg0) == MULT_EXPR && TREE_CODE (arg1) == MULT_EXPR
        !          3758:              && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          3759:                                  TREE_OPERAND (arg1, 1), 0))
        !          3760:            return fold (build (MULT_EXPR, type,
        !          3761:                                fold (build (MINUS_EXPR, type,
        !          3762:                                             TREE_OPERAND (arg0, 0),
        !          3763:                                             TREE_OPERAND (arg1, 0))),
        !          3764:                                TREE_OPERAND (arg0, 1)));
        !          3765:        }
        !          3766:       /* Convert A - (-B) to A + B.  */
        !          3767:       else if (TREE_CODE (arg1) == NEGATE_EXPR)
        !          3768:        return fold (build (PLUS_EXPR, type, arg0, TREE_OPERAND (arg1, 0)));
        !          3769:       else if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
        !          3770:        {
        !          3771:          /* Except with IEEE floating point, 0-x equals -x.  */
        !          3772:          if (! wins && real_zerop (arg0))
        !          3773:            return build1 (NEGATE_EXPR, type, arg1);
        !          3774:          /* Except with IEEE floating point, x-0 equals x.  */
        !          3775:          if (real_zerop (arg1))
        !          3776:            return non_lvalue (convert (type, arg0));
        !          3777: 
        !          3778:          /* Fold &x - &x.  This can happen from &x.foo - &x. 
        !          3779:             This is unsafe for certain floats even in non-IEEE formats.
        !          3780:             In IEEE, it is unsafe because it does wrong for NaNs.
        !          3781:             Also note that operand_equal_p is always false if an operand
        !          3782:             is volatile.  */
        !          3783: 
        !          3784:          if (operand_equal_p (arg0, arg1, FLOAT_TYPE_P (type)))
        !          3785:            return convert (type, integer_zero_node);
        !          3786:        }
        !          3787:       goto associate;
        !          3788: 
        !          3789:     case MULT_EXPR:
        !          3790:       if (! FLOAT_TYPE_P (type))
        !          3791:        {
        !          3792:          if (integer_zerop (arg1))
        !          3793:            return omit_one_operand (type, arg1, arg0);
        !          3794:          if (integer_onep (arg1))
        !          3795:            return non_lvalue (convert (type, arg0));
        !          3796: 
        !          3797:          /* (a * (1 << b)) is (a << b)  */
        !          3798:          if (TREE_CODE (arg1) == LSHIFT_EXPR
        !          3799:              && integer_onep (TREE_OPERAND (arg1, 0)))
        !          3800:            return fold (build (LSHIFT_EXPR, type, arg0,
        !          3801:                                TREE_OPERAND (arg1, 1)));
        !          3802:          if (TREE_CODE (arg0) == LSHIFT_EXPR
        !          3803:              && integer_onep (TREE_OPERAND (arg0, 0)))
        !          3804:            return fold (build (LSHIFT_EXPR, type, arg1,
        !          3805:                                TREE_OPERAND (arg0, 1)));
        !          3806:        }
        !          3807:       else
        !          3808:        {
        !          3809:          /* x*0 is 0, except for IEEE floating point.  */
        !          3810:          if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
        !          3811:              && real_zerop (arg1))
        !          3812:            return omit_one_operand (type, arg1, arg0);
        !          3813:          /* In IEEE floating point, x*1 is not equivalent to x for snans.
        !          3814:             However, ANSI says we can drop signals,
        !          3815:             so we can do this anyway.  */
        !          3816:          if (real_onep (arg1))
        !          3817:            return non_lvalue (convert (type, arg0));
        !          3818:          /* x*2 is x+x */
        !          3819:          if (! wins && real_twop (arg1))
        !          3820:            {
        !          3821:              tree arg = save_expr (arg0);
        !          3822:              return build (PLUS_EXPR, type, arg, arg);
        !          3823:            }
        !          3824:        }
        !          3825:       goto associate;
        !          3826: 
        !          3827:     case BIT_IOR_EXPR:
        !          3828:     bit_ior:
        !          3829:       if (integer_all_onesp (arg1))
        !          3830:        return omit_one_operand (type, arg1, arg0);
        !          3831:       if (integer_zerop (arg1))
        !          3832:        return non_lvalue (convert (type, arg0));
        !          3833:       t1 = distribute_bit_expr (code, type, arg0, arg1);
        !          3834:       if (t1 != NULL_TREE)
        !          3835:        return t1;
        !          3836: 
        !          3837:       /* (a << C1) | (a >> C2) if A is unsigned and C1+C2 is the size of A
        !          3838:         is a rotate of A by C1 bits.  */
        !          3839: 
        !          3840:       if ((TREE_CODE (arg0) == RSHIFT_EXPR
        !          3841:           || TREE_CODE (arg0) == LSHIFT_EXPR)
        !          3842:          && (TREE_CODE (arg1) == RSHIFT_EXPR
        !          3843:              || TREE_CODE (arg1) == LSHIFT_EXPR)
        !          3844:          && TREE_CODE (arg0) != TREE_CODE (arg1)
        !          3845:          && operand_equal_p (TREE_OPERAND (arg0, 0), TREE_OPERAND (arg1,0), 0)
        !          3846:          && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (arg0, 0)))
        !          3847:          && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
        !          3848:          && TREE_CODE (TREE_OPERAND (arg1, 1)) == INTEGER_CST
        !          3849:          && TREE_INT_CST_HIGH (TREE_OPERAND (arg0, 1)) == 0
        !          3850:          && TREE_INT_CST_HIGH (TREE_OPERAND (arg1, 1)) == 0
        !          3851:          && ((TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1))
        !          3852:               + TREE_INT_CST_LOW (TREE_OPERAND (arg1, 1)))
        !          3853:              == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0)))))
        !          3854:        return build (LROTATE_EXPR, type, TREE_OPERAND (arg0, 0),
        !          3855:                      TREE_CODE (arg0) == LSHIFT_EXPR
        !          3856:                      ? TREE_OPERAND (arg0, 1) : TREE_OPERAND (arg1, 1));
        !          3857: 
        !          3858:       goto associate;
        !          3859: 
        !          3860:     case BIT_XOR_EXPR:
        !          3861:       if (integer_zerop (arg1))
        !          3862:        return non_lvalue (convert (type, arg0));
        !          3863:       if (integer_all_onesp (arg1))
        !          3864:        return fold (build1 (BIT_NOT_EXPR, type, arg0));
        !          3865:       goto associate;
        !          3866: 
        !          3867:     case BIT_AND_EXPR:
        !          3868:     bit_and:
        !          3869:       if (integer_all_onesp (arg1))
        !          3870:        return non_lvalue (convert (type, arg0));
        !          3871:       if (integer_zerop (arg1))
        !          3872:        return omit_one_operand (type, arg1, arg0);
        !          3873:       t1 = distribute_bit_expr (code, type, arg0, arg1);
        !          3874:       if (t1 != NULL_TREE)
        !          3875:        return t1;
        !          3876:       /* Simplify ((int)c & 0x377) into (int)c, if c is unsigned char.  */
        !          3877:       if (TREE_CODE (arg0) == INTEGER_CST && TREE_CODE (arg1) == NOP_EXPR
        !          3878:          && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (arg1, 0))))
        !          3879:        {
        !          3880:          int prec = TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg1, 0)));
        !          3881:          if (prec < BITS_PER_WORD && prec < HOST_BITS_PER_WIDE_INT
        !          3882:              && (~TREE_INT_CST_LOW (arg0)
        !          3883:                  & (((HOST_WIDE_INT) 1 << prec) - 1)) == 0)
        !          3884:            return build1 (NOP_EXPR, type, TREE_OPERAND (arg1, 0));
        !          3885:        }
        !          3886:       if (TREE_CODE (arg1) == INTEGER_CST && TREE_CODE (arg0) == NOP_EXPR
        !          3887:          && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (arg0, 0))))
        !          3888:        {
        !          3889:          int prec = TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0)));
        !          3890:          if (prec < BITS_PER_WORD && prec < HOST_BITS_PER_WIDE_INT
        !          3891:              && (~TREE_INT_CST_LOW (arg1)
        !          3892:                  & (((HOST_WIDE_INT) 1 << prec) - 1)) == 0)
        !          3893:            return build1 (NOP_EXPR, type, TREE_OPERAND (arg0, 0));
        !          3894:        }
        !          3895:       goto associate;
        !          3896: 
        !          3897:     case BIT_ANDTC_EXPR:
        !          3898:       if (integer_all_onesp (arg0))
        !          3899:        return non_lvalue (convert (type, arg1));
        !          3900:       if (integer_zerop (arg0))
        !          3901:        return omit_one_operand (type, arg0, arg1);
        !          3902:       if (TREE_CODE (arg1) == INTEGER_CST)
        !          3903:        {
        !          3904:          arg1 = fold (build1 (BIT_NOT_EXPR, type, arg1));
        !          3905:          code = BIT_AND_EXPR;
        !          3906:          goto bit_and;
        !          3907:        }
        !          3908:       goto binary;
        !          3909: 
        !          3910:     case TRUNC_DIV_EXPR:
        !          3911:     case ROUND_DIV_EXPR:
        !          3912:     case FLOOR_DIV_EXPR:
        !          3913:     case CEIL_DIV_EXPR:
        !          3914:     case EXACT_DIV_EXPR:
        !          3915:     case RDIV_EXPR:
        !          3916:       if (integer_onep (arg1))
        !          3917:        return non_lvalue (convert (type, arg0));
        !          3918:       if (integer_zerop (arg1))
        !          3919:        return t;
        !          3920: 
        !          3921:       /* Look for ((a * C1) / C3) or (((a * C1) + C2) / C3),
        !          3922:         where C1 % C3 == 0 or C3 % C1 == 0.  We can simplify these
        !          3923:         expressions, which often appear in the offsets or sizes of
        !          3924:         objects with a varying size.  Only deal with positive divisors
        !          3925:         and multiplicands.   If C2 is negative, we must have C2 % C3 == 0.
        !          3926: 
        !          3927:         Look for NOPs and SAVE_EXPRs inside.  */
        !          3928: 
        !          3929:       if (TREE_CODE (arg1) == INTEGER_CST
        !          3930:          && tree_int_cst_lt (integer_zero_node, arg1))
        !          3931:        {
        !          3932:          int have_save_expr = 0;
        !          3933:          tree c2 = integer_zero_node;
        !          3934:          tree xarg0 = arg0;
        !          3935: 
        !          3936:          if (TREE_CODE (xarg0) == SAVE_EXPR)
        !          3937:            have_save_expr = 1, xarg0 = TREE_OPERAND (xarg0, 0);
        !          3938: 
        !          3939:          STRIP_NOPS (xarg0);
        !          3940: 
        !          3941:          if (TREE_CODE (xarg0) == PLUS_EXPR
        !          3942:              && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST)
        !          3943:            c2 = TREE_OPERAND (xarg0, 1), xarg0 = TREE_OPERAND (xarg0, 0);
        !          3944:          else if (TREE_CODE (xarg0) == MINUS_EXPR
        !          3945:                   && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST
        !          3946:                   /* If we are doing this computation unsigned, the negate
        !          3947:                      is incorrect.  */
        !          3948:                   && ! TREE_UNSIGNED (type))
        !          3949:            {
        !          3950:              c2 = fold (build1 (NEGATE_EXPR, type, TREE_OPERAND (xarg0, 1)));
        !          3951:              xarg0 = TREE_OPERAND (xarg0, 0);
        !          3952:            }
        !          3953: 
        !          3954:          if (TREE_CODE (xarg0) == SAVE_EXPR)
        !          3955:            have_save_expr = 1, xarg0 = TREE_OPERAND (xarg0, 0);
        !          3956: 
        !          3957:          STRIP_NOPS (xarg0);
        !          3958: 
        !          3959:          if (TREE_CODE (xarg0) == MULT_EXPR
        !          3960:              && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST
        !          3961:              && tree_int_cst_lt (integer_zero_node, TREE_OPERAND (xarg0, 1))
        !          3962:              && (integer_zerop (const_binop (TRUNC_MOD_EXPR,
        !          3963:                                              TREE_OPERAND (xarg0, 1), arg1, 1))
        !          3964:                  || integer_zerop (const_binop (TRUNC_MOD_EXPR, arg1,
        !          3965:                                                 TREE_OPERAND (xarg0, 1), 1)))
        !          3966:              && (tree_int_cst_lt (integer_zero_node, c2)
        !          3967:                  || integer_zerop (const_binop (TRUNC_MOD_EXPR, c2,
        !          3968:                                                 arg1, 1))))
        !          3969:            {
        !          3970:              tree outer_div = integer_one_node;
        !          3971:              tree c1 = TREE_OPERAND (xarg0, 1);
        !          3972:              tree c3 = arg1;
        !          3973: 
        !          3974:              /* If C3 > C1, set them equal and do a divide by
        !          3975:                 C3/C1 at the end of the operation.  */
        !          3976:              if (tree_int_cst_lt (c1, c3))
        !          3977:                outer_div = const_binop (code, c3, c1, 0), c3 = c1;
        !          3978:                
        !          3979:              /* The result is A * (C1/C3) + (C2/C3).  */
        !          3980:              t = fold (build (PLUS_EXPR, type,
        !          3981:                               fold (build (MULT_EXPR, type,
        !          3982:                                            TREE_OPERAND (xarg0, 0),
        !          3983:                                            const_binop (code, c1, c3, 1))),
        !          3984:                               const_binop (code, c2, c3, 1)));
        !          3985: 
        !          3986:              if (! integer_onep (outer_div))
        !          3987:                t = fold (build (code, type, t, outer_div));
        !          3988: 
        !          3989:              if (have_save_expr)
        !          3990:                t = save_expr (t);
        !          3991: 
        !          3992:              return t;
        !          3993:            }
        !          3994:        }
        !          3995: 
        !          3996: #if !defined (REAL_IS_NOT_DOUBLE) || defined (REAL_ARITHMETIC)
        !          3997: #ifndef REAL_INFINITY
        !          3998:       if (TREE_CODE (arg1) == REAL_CST
        !          3999:          && real_zerop (arg1))
        !          4000:        return t;
        !          4001: #endif
        !          4002: #endif /* not REAL_IS_NOT_DOUBLE, or REAL_ARITHMETIC */
        !          4003: 
        !          4004:       goto binary;
        !          4005: 
        !          4006:     case CEIL_MOD_EXPR:
        !          4007:     case FLOOR_MOD_EXPR:
        !          4008:     case ROUND_MOD_EXPR:
        !          4009:     case TRUNC_MOD_EXPR:
        !          4010:       if (integer_onep (arg1))
        !          4011:        return omit_one_operand (type, integer_zero_node, arg0);
        !          4012:       if (integer_zerop (arg1))
        !          4013:        return t;
        !          4014: 
        !          4015:       /* Look for ((a * C1) % C3) or (((a * C1) + C2) % C3),
        !          4016:         where C1 % C3 == 0.  Handle similarly to the division case,
        !          4017:         but don't bother with SAVE_EXPRs.  */
        !          4018: 
        !          4019:       if (TREE_CODE (arg1) == INTEGER_CST
        !          4020:          && ! integer_zerop (arg1))
        !          4021:        {
        !          4022:          tree c2 = integer_zero_node;
        !          4023:          tree xarg0 = arg0;
        !          4024: 
        !          4025:          if (TREE_CODE (xarg0) == PLUS_EXPR
        !          4026:              && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST)
        !          4027:            c2 = TREE_OPERAND (xarg0, 1), xarg0 = TREE_OPERAND (xarg0, 0);
        !          4028:          else if (TREE_CODE (xarg0) == MINUS_EXPR
        !          4029:                   && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST
        !          4030:                   && ! TREE_UNSIGNED (type))
        !          4031:            {
        !          4032:              c2 = fold (build1 (NEGATE_EXPR, type, TREE_OPERAND (xarg0, 1)));
        !          4033:              xarg0 = TREE_OPERAND (xarg0, 0);
        !          4034:            }
        !          4035: 
        !          4036:          STRIP_NOPS (xarg0);
        !          4037: 
        !          4038:          if (TREE_CODE (xarg0) == MULT_EXPR
        !          4039:              && TREE_CODE (TREE_OPERAND (xarg0, 1)) == INTEGER_CST
        !          4040:              && integer_zerop (const_binop (TRUNC_MOD_EXPR,
        !          4041:                                             TREE_OPERAND (xarg0, 1),
        !          4042:                                             arg1, 1))
        !          4043:              && tree_int_cst_lt (integer_zero_node, c2))
        !          4044:            /* The result is (C2%C3).  */
        !          4045:            return omit_one_operand (type, const_binop (code, c2, arg1, 1),
        !          4046:                                     TREE_OPERAND (xarg0, 0));
        !          4047:        }
        !          4048: 
        !          4049:       goto binary;
        !          4050: 
        !          4051:     case LSHIFT_EXPR:
        !          4052:     case RSHIFT_EXPR:
        !          4053:     case LROTATE_EXPR:
        !          4054:     case RROTATE_EXPR:
        !          4055:       if (integer_zerop (arg1))
        !          4056:        return non_lvalue (convert (type, arg0));
        !          4057:       /* Since negative shift count is not well-defined,
        !          4058:         don't try to compute it in the compiler.  */
        !          4059:       if (tree_int_cst_lt (arg1, integer_zero_node))
        !          4060:        return t;
        !          4061:       goto binary;
        !          4062: 
        !          4063:     case MIN_EXPR:
        !          4064:       if (operand_equal_p (arg0, arg1, 0))
        !          4065:        return arg0;
        !          4066:       if (INTEGRAL_TYPE_P (type)
        !          4067:          && operand_equal_p (arg1, TYPE_MIN_VALUE (type), 1))
        !          4068:        return omit_one_operand (type, arg1, arg0);
        !          4069:       goto associate;
        !          4070: 
        !          4071:     case MAX_EXPR:
        !          4072:       if (operand_equal_p (arg0, arg1, 0))
        !          4073:        return arg0;
        !          4074:       if (INTEGRAL_TYPE_P (type)
        !          4075:          && operand_equal_p (arg1, TYPE_MAX_VALUE (type), 1))
        !          4076:        return omit_one_operand (type, arg1, arg0);
        !          4077:       goto associate;
        !          4078: 
        !          4079:     case TRUTH_NOT_EXPR:
        !          4080:       /* Note that the operand of this must be an int
        !          4081:         and its values must be 0 or 1.
        !          4082:         ("true" is a fixed value perhaps depending on the language,
        !          4083:         but we don't handle values other than 1 correctly yet.)  */
        !          4084:       return invert_truthvalue (arg0);
        !          4085: 
        !          4086:     case TRUTH_ANDIF_EXPR:
        !          4087:       /* Note that the operands of this must be ints
        !          4088:         and their values must be 0 or 1.
        !          4089:         ("true" is a fixed value perhaps depending on the language.)  */
        !          4090:       /* If first arg is constant zero, return it.  */
        !          4091:       if (integer_zerop (arg0))
        !          4092:        return arg0;
        !          4093:     case TRUTH_AND_EXPR:
        !          4094:       /* If either arg is constant true, drop it.  */
        !          4095:       if (TREE_CODE (arg0) == INTEGER_CST && ! integer_zerop (arg0))
        !          4096:        return non_lvalue (arg1);
        !          4097:       if (TREE_CODE (arg1) == INTEGER_CST && ! integer_zerop (arg1))
        !          4098:        return non_lvalue (arg0);
        !          4099:       /* If second arg is constant zero, result is zero, but first arg
        !          4100:         must be evaluated.  */
        !          4101:       if (integer_zerop (arg1))
        !          4102:        return omit_one_operand (type, arg1, arg0);
        !          4103: 
        !          4104:     truth_andor:
        !          4105:       /* Check for the possibility of merging component references.  If our
        !          4106:         lhs is another similar operation, try to merge its rhs with our
        !          4107:         rhs.  Then try to merge our lhs and rhs.  */
        !          4108:       if (optimize)
        !          4109:        {
        !          4110:          if (TREE_CODE (arg0) == code)
        !          4111:            {
        !          4112:              tem = fold_truthop (code, type,
        !          4113:                                  TREE_OPERAND (arg0, 1), arg1);
        !          4114:              if (tem)
        !          4115:                return fold (build (code, type, TREE_OPERAND (arg0, 0), tem));
        !          4116:            }
        !          4117: 
        !          4118:          tem = fold_truthop (code, type, arg0, arg1);
        !          4119:          if (tem)
        !          4120:            return tem;
        !          4121:        }
        !          4122:       return t;
        !          4123: 
        !          4124:     case TRUTH_ORIF_EXPR:
        !          4125:       /* Note that the operands of this must be ints
        !          4126:         and their values must be 0 or true.
        !          4127:         ("true" is a fixed value perhaps depending on the language.)  */
        !          4128:       /* If first arg is constant true, return it.  */
        !          4129:       if (TREE_CODE (arg0) == INTEGER_CST && ! integer_zerop (arg0))
        !          4130:        return arg0;
        !          4131:     case TRUTH_OR_EXPR:
        !          4132:       /* If either arg is constant zero, drop it.  */
        !          4133:       if (TREE_CODE (arg0) == INTEGER_CST && integer_zerop (arg0))
        !          4134:        return non_lvalue (arg1);
        !          4135:       if (TREE_CODE (arg1) == INTEGER_CST && integer_zerop (arg1))
        !          4136:        return non_lvalue (arg0);
        !          4137:       /* If second arg is constant true, result is true, but we must
        !          4138:         evaluate first arg.  */
        !          4139:       if (TREE_CODE (arg1) == INTEGER_CST && ! integer_zerop (arg1))
        !          4140:        return omit_one_operand (type, arg1, arg0);
        !          4141:       goto truth_andor;
        !          4142: 
        !          4143:     case TRUTH_XOR_EXPR:
        !          4144:       /* If either arg is constant zero, drop it.  */
        !          4145:       if (integer_zerop (arg0))
        !          4146:        return non_lvalue (arg1);
        !          4147:       if (integer_zerop (arg1))
        !          4148:        return non_lvalue (arg0);
        !          4149:       /* If either arg is constant true, this is a logical inversion.  */
        !          4150:       if (integer_onep (arg0))
        !          4151:        return non_lvalue (invert_truthvalue (arg1));
        !          4152:       if (integer_onep (arg1))
        !          4153:        return non_lvalue (invert_truthvalue (arg0));
        !          4154:       return t;
        !          4155: 
        !          4156:     case EQ_EXPR:
        !          4157:     case NE_EXPR:
        !          4158:     case LT_EXPR:
        !          4159:     case GT_EXPR:
        !          4160:     case LE_EXPR:
        !          4161:     case GE_EXPR:
        !          4162:       /* If one arg is a constant integer, put it last.  */
        !          4163:       if (TREE_CODE (arg0) == INTEGER_CST
        !          4164:          && TREE_CODE (arg1) != INTEGER_CST)
        !          4165:        {
        !          4166:          TREE_OPERAND (t, 0) = arg1;
        !          4167:          TREE_OPERAND (t, 1) = arg0;
        !          4168:          arg0 = TREE_OPERAND (t, 0);
        !          4169:          arg1 = TREE_OPERAND (t, 1);
        !          4170:          code = swap_tree_comparison (code);
        !          4171:          TREE_SET_CODE (t, code);
        !          4172:        }
        !          4173: 
        !          4174:       /* Convert foo++ == CONST into ++foo == CONST + INCR.
        !          4175:         First, see if one arg is constant; find the constant arg
        !          4176:         and the other one.  */
        !          4177:       {
        !          4178:        tree constop = 0, varop;
        !          4179:        tree *constoploc;
        !          4180: 
        !          4181:        if (TREE_CONSTANT (arg1))
        !          4182:          constoploc = &TREE_OPERAND (t, 1), constop = arg1, varop = arg0;
        !          4183:        if (TREE_CONSTANT (arg0))
        !          4184:          constoploc = &TREE_OPERAND (t, 0), constop = arg0, varop = arg1;
        !          4185: 
        !          4186:        if (constop && TREE_CODE (varop) == POSTINCREMENT_EXPR)
        !          4187:          {
        !          4188:            /* This optimization is invalid for ordered comparisons
        !          4189:               if CONST+INCR overflows or if foo+incr might overflow.
        !          4190:               This optimization is invalid for floating point due to rounding.
        !          4191:               For pointer types we assume overflow doesn't happen.  */
        !          4192:            if (TREE_CODE (TREE_TYPE (varop)) == POINTER_TYPE
        !          4193:                || (! FLOAT_TYPE_P (TREE_TYPE (varop))
        !          4194:                    && (code == EQ_EXPR || code == NE_EXPR)))
        !          4195:              {
        !          4196:                tree newconst
        !          4197:                  = fold (build (PLUS_EXPR, TREE_TYPE (varop),
        !          4198:                                 constop, TREE_OPERAND (varop, 1)));
        !          4199:                TREE_SET_CODE (varop, PREINCREMENT_EXPR);
        !          4200:                *constoploc = newconst;
        !          4201:                return t;
        !          4202:              }
        !          4203:          }
        !          4204:        else if (constop && TREE_CODE (varop) == POSTDECREMENT_EXPR)
        !          4205:          {
        !          4206:            if (TREE_CODE (TREE_TYPE (varop)) == POINTER_TYPE
        !          4207:                || (! FLOAT_TYPE_P (TREE_TYPE (varop))
        !          4208:                    && (code == EQ_EXPR || code == NE_EXPR)))
        !          4209:              {
        !          4210:                tree newconst
        !          4211:                  = fold (build (MINUS_EXPR, TREE_TYPE (varop),
        !          4212:                                 constop, TREE_OPERAND (varop, 1)));
        !          4213:                TREE_SET_CODE (varop, PREDECREMENT_EXPR);
        !          4214:                *constoploc = newconst;
        !          4215:                return t;
        !          4216:              }
        !          4217:          }
        !          4218:       }
        !          4219: 
        !          4220:       /* Change X >= CST to X > (CST - 1) if CST is positive.  */
        !          4221:       if (TREE_CODE (arg1) == INTEGER_CST
        !          4222:          && TREE_CODE (arg0) != INTEGER_CST
        !          4223:          && ! tree_int_cst_lt (arg1, integer_one_node))
        !          4224:        {
        !          4225:          switch (TREE_CODE (t))
        !          4226:            {
        !          4227:            case GE_EXPR:
        !          4228:              code = GT_EXPR;
        !          4229:              TREE_SET_CODE (t, code);
        !          4230:              arg1 = const_binop (MINUS_EXPR, arg1, integer_one_node, 0);
        !          4231:              TREE_OPERAND (t, 1) = arg1;
        !          4232:              break;
        !          4233: 
        !          4234:            case LT_EXPR:
        !          4235:              code = LE_EXPR;
        !          4236:              TREE_SET_CODE (t, code);
        !          4237:              arg1 = const_binop (MINUS_EXPR, arg1, integer_one_node, 0);
        !          4238:              TREE_OPERAND (t, 1) = arg1;
        !          4239:            }
        !          4240:        }
        !          4241: 
        !          4242:       /* If this is an EQ or NE comparison with zero and ARG0 is
        !          4243:         (1 << foo) & bar, convert it to (bar >> foo) & 1.  Both require
        !          4244:         two operations, but the latter can be done in one less insn
        !          4245:         one machine that have only two-operand insns or on which a
        !          4246:         constant cannot be the first operand.  */
        !          4247:       if (integer_zerop (arg1) && (code == EQ_EXPR || code == NE_EXPR)
        !          4248:          && TREE_CODE (arg0) == BIT_AND_EXPR)
        !          4249:        {
        !          4250:          if (TREE_CODE (TREE_OPERAND (arg0, 0)) == LSHIFT_EXPR
        !          4251:              && integer_onep (TREE_OPERAND (TREE_OPERAND (arg0, 0), 0)))
        !          4252:            return
        !          4253:              fold (build (code, type,
        !          4254:                           build (BIT_AND_EXPR, TREE_TYPE (arg0),
        !          4255:                                  build (RSHIFT_EXPR,
        !          4256:                                         TREE_TYPE (TREE_OPERAND (arg0, 0)),
        !          4257:                                         TREE_OPERAND (arg0, 1),
        !          4258:                                         TREE_OPERAND (TREE_OPERAND (arg0, 0), 1)),
        !          4259:                                  convert (TREE_TYPE (arg0),
        !          4260:                                           integer_one_node)),
        !          4261:                           arg1));
        !          4262:          else if (TREE_CODE (TREE_OPERAND (arg0, 1)) == LSHIFT_EXPR
        !          4263:                   && integer_onep (TREE_OPERAND (TREE_OPERAND (arg0, 1), 0)))
        !          4264:            return
        !          4265:              fold (build (code, type,
        !          4266:                           build (BIT_AND_EXPR, TREE_TYPE (arg0),
        !          4267:                                  build (RSHIFT_EXPR,
        !          4268:                                         TREE_TYPE (TREE_OPERAND (arg0, 1)),
        !          4269:                                         TREE_OPERAND (arg0, 0),
        !          4270:                                         TREE_OPERAND (TREE_OPERAND (arg0, 1), 1)),
        !          4271:                                  convert (TREE_TYPE (arg0),
        !          4272:                                           integer_one_node)),
        !          4273:                           arg1));
        !          4274:        }
        !          4275: 
        !          4276:       /* If this is an NE or EQ comparison of zero against the result of a
        !          4277:         signed MOD operation whose second operand is a power of 2, make
        !          4278:         the MOD operation unsigned since it is simpler and equivalent.  */
        !          4279:       if ((code == NE_EXPR || code == EQ_EXPR)
        !          4280:          && integer_zerop (arg1)
        !          4281:          && ! TREE_UNSIGNED (TREE_TYPE (arg0))
        !          4282:          && (TREE_CODE (arg0) == TRUNC_MOD_EXPR
        !          4283:              || TREE_CODE (arg0) == CEIL_MOD_EXPR
        !          4284:              || TREE_CODE (arg0) == FLOOR_MOD_EXPR
        !          4285:              || TREE_CODE (arg0) == ROUND_MOD_EXPR)
        !          4286:          && integer_pow2p (TREE_OPERAND (arg0, 1)))
        !          4287:        {
        !          4288:          tree newtype = unsigned_type (TREE_TYPE (arg0));
        !          4289:          tree newmod = build (TREE_CODE (arg0), newtype,
        !          4290:                               convert (newtype, TREE_OPERAND (arg0, 0)),
        !          4291:                               convert (newtype, TREE_OPERAND (arg0, 1)));
        !          4292: 
        !          4293:          return build (code, type, newmod, convert (newtype, arg1));
        !          4294:        }
        !          4295: 
        !          4296:       /* If this is an NE comparison of zero with an AND of one, remove the
        !          4297:         comparison since the AND will give the correct value.  */
        !          4298:       if (code == NE_EXPR && integer_zerop (arg1)
        !          4299:          && TREE_CODE (arg0) == BIT_AND_EXPR
        !          4300:          && integer_onep (TREE_OPERAND (arg0, 1)))
        !          4301:        return convert (type, arg0);
        !          4302: 
        !          4303:       /* If we have (A & C) == C where C is a power of 2, convert this into
        !          4304:         (A & C) != 0.  Similarly for NE_EXPR.  */
        !          4305:       if ((code == EQ_EXPR || code == NE_EXPR)
        !          4306:          && TREE_CODE (arg0) == BIT_AND_EXPR
        !          4307:          && integer_pow2p (TREE_OPERAND (arg0, 1))
        !          4308:          && operand_equal_p (TREE_OPERAND (arg0, 1), arg1, 0))
        !          4309:        return build (code == EQ_EXPR ? NE_EXPR : EQ_EXPR, type,
        !          4310:                      arg0, integer_zero_node);
        !          4311: 
        !          4312:       /* Simplify comparison of something with itself.  (For IEEE
        !          4313:         floating-point, we can only do some of these simplifications.)  */
        !          4314:       if (operand_equal_p (arg0, arg1, 0))
        !          4315:        {
        !          4316:          switch (code)
        !          4317:            {
        !          4318:            case EQ_EXPR:
        !          4319:            case GE_EXPR:
        !          4320:            case LE_EXPR:
        !          4321:              if (INTEGRAL_TYPE_P (TREE_TYPE (arg0)))
        !          4322:                {
        !          4323:                  t = build_int_2 (1, 0);
        !          4324:                  TREE_TYPE (t) = type;
        !          4325:                  return t;
        !          4326:                }
        !          4327:              code = EQ_EXPR;
        !          4328:              TREE_SET_CODE (t, code);
        !          4329:              break;
        !          4330: 
        !          4331:            case NE_EXPR:
        !          4332:              /* For NE, we can only do this simplification if integer.  */
        !          4333:              if (! INTEGRAL_TYPE_P (TREE_TYPE (arg0)))
        !          4334:                break;
        !          4335:              /* ... fall through ... */
        !          4336:            case GT_EXPR:
        !          4337:            case LT_EXPR:
        !          4338:              t = build_int_2 (0, 0);
        !          4339:              TREE_TYPE (t) = type;
        !          4340:              return t;
        !          4341:            }
        !          4342:        }
        !          4343: 
        !          4344:       /* An unsigned comparison against 0 can be simplified.  */
        !          4345:       if (integer_zerop (arg1)
        !          4346:          && (INTEGRAL_TYPE_P (TREE_TYPE (arg1))
        !          4347:              || TREE_CODE (TREE_TYPE (arg1)) == POINTER_TYPE)
        !          4348:          && TREE_UNSIGNED (TREE_TYPE (arg1)))
        !          4349:        {
        !          4350:          switch (TREE_CODE (t))
        !          4351:            {
        !          4352:            case GT_EXPR:
        !          4353:              code = NE_EXPR;
        !          4354:              TREE_SET_CODE (t, NE_EXPR);
        !          4355:              break;
        !          4356:            case LE_EXPR:
        !          4357:              code = EQ_EXPR;
        !          4358:              TREE_SET_CODE (t, EQ_EXPR);
        !          4359:              break;
        !          4360:            case GE_EXPR:
        !          4361:              return omit_one_operand (type,
        !          4362:                                       convert (type, integer_one_node),
        !          4363:                                       arg0);
        !          4364:            case LT_EXPR:
        !          4365:              return omit_one_operand (type,
        !          4366:                                       convert (type, integer_zero_node),
        !          4367:                                       arg0);
        !          4368:            }
        !          4369:        }
        !          4370: 
        !          4371:       /* If we are comparing an expression that just has comparisons
        !          4372:         of two integer values, arithmetic expressions of those comparisons,
        !          4373:         and constants, we can simplify it.  There are only three cases
        !          4374:         to check: the two values can either be equal, the first can be
        !          4375:         greater, or the second can be greater.  Fold the expression for
        !          4376:         those three values.  Since each value must be 0 or 1, we have
        !          4377:         eight possibilities, each of which corresponds to the constant 0
        !          4378:         or 1 or one of the six possible comparisons.
        !          4379: 
        !          4380:         This handles common cases like (a > b) == 0 but also handles
        !          4381:         expressions like  ((x > y) - (y > x)) > 0, which supposedly
        !          4382:         occur in macroized code.  */
        !          4383: 
        !          4384:       if (TREE_CODE (arg1) == INTEGER_CST && TREE_CODE (arg0) != INTEGER_CST)
        !          4385:        {
        !          4386:          tree cval1 = 0, cval2 = 0;
        !          4387:          int save_p = 0;
        !          4388: 
        !          4389:          if (twoval_comparison_p (arg0, &cval1, &cval2, &save_p)
        !          4390:              /* Don't handle degenerate cases here; they should already
        !          4391:                 have been handled anyway.  */
        !          4392:              && cval1 != 0 && cval2 != 0
        !          4393:              && ! (TREE_CONSTANT (cval1) && TREE_CONSTANT (cval2))
        !          4394:              && TREE_TYPE (cval1) == TREE_TYPE (cval2)
        !          4395:              && INTEGRAL_TYPE_P (TREE_TYPE (cval1))
        !          4396:              && ! operand_equal_p (TYPE_MIN_VALUE (TREE_TYPE (cval1)),
        !          4397:                                    TYPE_MAX_VALUE (TREE_TYPE (cval2)), 0))
        !          4398:            {
        !          4399:              tree maxval = TYPE_MAX_VALUE (TREE_TYPE (cval1));
        !          4400:              tree minval = TYPE_MIN_VALUE (TREE_TYPE (cval1));
        !          4401: 
        !          4402:              /* We can't just pass T to eval_subst in case cval1 or cval2
        !          4403:                 was the same as ARG1.  */
        !          4404: 
        !          4405:              tree high_result
        !          4406:                = fold (build (code, type,
        !          4407:                               eval_subst (arg0, cval1, maxval, cval2, minval),
        !          4408:                               arg1));
        !          4409:              tree equal_result
        !          4410:                = fold (build (code, type,
        !          4411:                               eval_subst (arg0, cval1, maxval, cval2, maxval),
        !          4412:                               arg1));
        !          4413:              tree low_result
        !          4414:                = fold (build (code, type,
        !          4415:                               eval_subst (arg0, cval1, minval, cval2, maxval),
        !          4416:                               arg1));
        !          4417: 
        !          4418:              /* All three of these results should be 0 or 1.  Confirm they
        !          4419:                 are.  Then use those values to select the proper code
        !          4420:                 to use.  */
        !          4421: 
        !          4422:              if ((integer_zerop (high_result)
        !          4423:                   || integer_onep (high_result))
        !          4424:                  && (integer_zerop (equal_result)
        !          4425:                      || integer_onep (equal_result))
        !          4426:                  && (integer_zerop (low_result)
        !          4427:                      || integer_onep (low_result)))
        !          4428:                {
        !          4429:                  /* Make a 3-bit mask with the high-order bit being the
        !          4430:                     value for `>', the next for '=', and the low for '<'.  */
        !          4431:                  switch ((integer_onep (high_result) * 4)
        !          4432:                          + (integer_onep (equal_result) * 2)
        !          4433:                          + integer_onep (low_result))
        !          4434:                    {
        !          4435:                    case 0:
        !          4436:                      /* Always false.  */
        !          4437:                      return omit_one_operand (type, integer_zero_node, arg0);
        !          4438:                    case 1:
        !          4439:                      code = LT_EXPR;
        !          4440:                      break;
        !          4441:                    case 2:
        !          4442:                      code = EQ_EXPR;
        !          4443:                      break;
        !          4444:                    case 3:
        !          4445:                      code = LE_EXPR;
        !          4446:                      break;
        !          4447:                    case 4:
        !          4448:                      code = GT_EXPR;
        !          4449:                      break;
        !          4450:                    case 5:
        !          4451:                      code = NE_EXPR;
        !          4452:                      break;
        !          4453:                    case 6:
        !          4454:                      code = GE_EXPR;
        !          4455:                      break;
        !          4456:                    case 7:
        !          4457:                      /* Always true.  */
        !          4458:                      return omit_one_operand (type, integer_one_node, arg0);
        !          4459:                    }
        !          4460: 
        !          4461:                  t = build (code, type, cval1, cval2);
        !          4462:                  if (save_p)
        !          4463:                    return save_expr (t);
        !          4464:                  else
        !          4465:                    return fold (t);
        !          4466:                }
        !          4467:            }
        !          4468:        }
        !          4469: 
        !          4470:       /* If this is a comparison of a field, we may be able to simplify it.  */
        !          4471:       if ((TREE_CODE (arg0) == COMPONENT_REF
        !          4472:                || TREE_CODE (arg0) == BIT_FIELD_REF)
        !          4473:               && (code == EQ_EXPR || code == NE_EXPR)
        !          4474:               /* Handle the constant case even without -O
        !          4475:                  to make sure the warnings are given.  */
        !          4476:               && (optimize || TREE_CODE (arg1) == INTEGER_CST))
        !          4477:        {
        !          4478:          t1 = optimize_bit_field_compare (code, type, arg0, arg1);
        !          4479:          return t1 ? t1 : t;
        !          4480:        }
        !          4481: 
        !          4482:       /* From here on, the only cases we handle are when the result is
        !          4483:         known to be a constant.
        !          4484: 
        !          4485:         To compute GT, swap the arguments and do LT.
        !          4486:         To compute GE, do LT and invert the result.
        !          4487:         To compute LE, swap the arguments, do LT and invert the result.
        !          4488:         To compute NE, do EQ and invert the result.
        !          4489: 
        !          4490:         Therefore, the code below must handle only EQ and LT.  */
        !          4491: 
        !          4492:       if (code == LE_EXPR || code == GT_EXPR)
        !          4493:        {
        !          4494:          tem = arg0, arg0 = arg1, arg1 = tem;
        !          4495:          code = swap_tree_comparison (code);
        !          4496:        }
        !          4497: 
        !          4498:       /* Note that it is safe to invert for real values here because we
        !          4499:         will check below in the one case that it matters.  */
        !          4500: 
        !          4501:       invert = 0;
        !          4502:       if (code == NE_EXPR || code == GE_EXPR)
        !          4503:        {
        !          4504:          invert = 1;
        !          4505:          code = invert_tree_comparison (code);
        !          4506:        }
        !          4507: 
        !          4508:       /* Compute a result for LT or EQ if args permit;
        !          4509:         otherwise return T.  */
        !          4510:       if (TREE_CODE (arg0) == INTEGER_CST && TREE_CODE (arg1) == INTEGER_CST)
        !          4511:        {
        !          4512:          if (code == EQ_EXPR)
        !          4513:            t1 = build_int_2 ((TREE_INT_CST_LOW (arg0)
        !          4514:                               == TREE_INT_CST_LOW (arg1))
        !          4515:                              && (TREE_INT_CST_HIGH (arg0)
        !          4516:                                  == TREE_INT_CST_HIGH (arg1)),
        !          4517:                              0);
        !          4518:          else
        !          4519:            t1 = build_int_2 ((TREE_UNSIGNED (TREE_TYPE (arg0))
        !          4520:                               ? INT_CST_LT_UNSIGNED (arg0, arg1)
        !          4521:                               : INT_CST_LT (arg0, arg1)),
        !          4522:                              0);
        !          4523:        }
        !          4524: 
        !          4525:       /* Assume a nonexplicit constant cannot equal an explicit one,
        !          4526:         since such code would be undefined anyway.
        !          4527:         Exception: on sysvr4, using #pragma weak,
        !          4528:         a label can come out as 0.  */
        !          4529:       else if (TREE_CODE (arg1) == INTEGER_CST
        !          4530:               && !integer_zerop (arg1)
        !          4531:               && TREE_CONSTANT (arg0)
        !          4532:               && TREE_CODE (arg0) == ADDR_EXPR
        !          4533:               && code == EQ_EXPR)
        !          4534:        t1 = build_int_2 (0, 0);
        !          4535: 
        !          4536:       /* Two real constants can be compared explicitly.  */
        !          4537:       else if (TREE_CODE (arg0) == REAL_CST && TREE_CODE (arg1) == REAL_CST)
        !          4538:        {
        !          4539:          /* If either operand is a NaN, the result is false with two
        !          4540:             exceptions: First, an NE_EXPR is true on NaNs, but that case
        !          4541:             is already handled correctly since we will be inverting the
        !          4542:             result for NE_EXPR.  Second, if we had inverted a LE_EXPR
        !          4543:             or a GE_EXPR into a LT_EXPR, we must return true so that it
        !          4544:             will be inverted into false.  */
        !          4545: 
        !          4546:          if (REAL_VALUE_ISNAN (TREE_REAL_CST (arg0))
        !          4547:              || REAL_VALUE_ISNAN (TREE_REAL_CST (arg1)))
        !          4548:            t1 = build_int_2 (invert && code == LT_EXPR, 0);
        !          4549: 
        !          4550:          else if (code == EQ_EXPR)
        !          4551:            t1 = build_int_2 (REAL_VALUES_EQUAL (TREE_REAL_CST (arg0),
        !          4552:                                                 TREE_REAL_CST (arg1)),
        !          4553:                              0);
        !          4554:          else
        !          4555:            t1 = build_int_2 (REAL_VALUES_LESS (TREE_REAL_CST (arg0),
        !          4556:                                                TREE_REAL_CST (arg1)),
        !          4557:                              0);
        !          4558:        }
        !          4559: 
        !          4560:       if (t1 == NULL_TREE)
        !          4561:        return t;
        !          4562: 
        !          4563:       if (invert)
        !          4564:        TREE_INT_CST_LOW (t1) ^= 1;
        !          4565: 
        !          4566:       TREE_TYPE (t1) = type;
        !          4567:       return t1;
        !          4568: 
        !          4569:     case COND_EXPR:
        !          4570:       /* Pedantic ANSI C says that a conditional expression is never an lvalue,
        !          4571:         so all simple results must be passed through pedantic_non_lvalue.  */
        !          4572:       if (TREE_CODE (arg0) == INTEGER_CST)
        !          4573:        return pedantic_non_lvalue
        !          4574:          (TREE_OPERAND (t, (integer_zerop (arg0) ? 2 : 1)));
        !          4575:       else if (operand_equal_p (arg1, TREE_OPERAND (expr, 2), 0))
        !          4576:        return pedantic_non_lvalue (omit_one_operand (type, arg1, arg0));
        !          4577: 
        !          4578:       /* If the second operand is zero, invert the comparison and swap
        !          4579:         the second and third operands.  Likewise if the second operand
        !          4580:         is constant and the third is not or if the third operand is
        !          4581:         equivalent to the first operand of the comparison.  */
        !          4582: 
        !          4583:       if (integer_zerop (arg1)
        !          4584:          || (TREE_CONSTANT (arg1) && ! TREE_CONSTANT (TREE_OPERAND (t, 2)))
        !          4585:          || (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
        !          4586:              && operand_equal_for_comparison_p (TREE_OPERAND (arg0, 0),
        !          4587:                                                 TREE_OPERAND (t, 2),
        !          4588:                                                 TREE_OPERAND (arg0, 1))))
        !          4589:        {
        !          4590:          /* See if this can be inverted.  If it can't, possibly because
        !          4591:             it was a floating-point inequality comparison, don't do
        !          4592:             anything.  */
        !          4593:          tem = invert_truthvalue (arg0);
        !          4594: 
        !          4595:          if (TREE_CODE (tem) != TRUTH_NOT_EXPR)
        !          4596:            {
        !          4597:              arg0 = TREE_OPERAND (t, 0) = tem;
        !          4598:              TREE_OPERAND (t, 1) = TREE_OPERAND (t, 2);
        !          4599:              TREE_OPERAND (t, 2) = arg1;
        !          4600:              arg1 = TREE_OPERAND (t, 1);
        !          4601:            }
        !          4602:        }
        !          4603: 
        !          4604:       /* If we have A op B ? A : C, we may be able to convert this to a
        !          4605:         simpler expression, depending on the operation and the values
        !          4606:         of B and C.  IEEE floating point prevents this though,
        !          4607:         because A or B might be -0.0 or a NaN.  */
        !          4608: 
        !          4609:       if (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
        !          4610:          && (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
        !          4611:              || ! FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0))))
        !          4612:          && operand_equal_for_comparison_p (TREE_OPERAND (arg0, 0),
        !          4613:                                             arg1, TREE_OPERAND (arg0, 1)))
        !          4614:        {
        !          4615:          tree arg2 = TREE_OPERAND (t, 2);
        !          4616:          enum tree_code comp_code = TREE_CODE (arg0);
        !          4617: 
        !          4618:          /* If we have A op 0 ? A : -A, this is A, -A, abs (A), or abs (-A),
        !          4619:             depending on the comparison operation.  */
        !          4620:          if (integer_zerop (TREE_OPERAND (arg0, 1))
        !          4621:              && TREE_CODE (arg2) == NEGATE_EXPR
        !          4622:              && operand_equal_p (TREE_OPERAND (arg2, 0), arg1, 0))
        !          4623:            switch (comp_code)
        !          4624:              {
        !          4625:              case EQ_EXPR:
        !          4626:                return pedantic_non_lvalue
        !          4627:                  (fold (build1 (NEGATE_EXPR, type, arg1)));
        !          4628:              case NE_EXPR:
        !          4629:                return pedantic_non_lvalue (convert (type, arg1));
        !          4630:              case GE_EXPR:
        !          4631:              case GT_EXPR:
        !          4632:                return pedantic_non_lvalue
        !          4633:                  (fold (build1 (ABS_EXPR, type, arg1)));
        !          4634:              case LE_EXPR:
        !          4635:              case LT_EXPR:
        !          4636:                return pedantic_non_lvalue
        !          4637:                  (fold (build1 (NEGATE_EXPR, type,
        !          4638:                                 fold (build1 (ABS_EXPR, type, arg1)))));
        !          4639:              }
        !          4640: 
        !          4641:          /* If this is A != 0 ? A : 0, this is simply A.  For ==, it is
        !          4642:             always zero.  */
        !          4643: 
        !          4644:          if (integer_zerop (TREE_OPERAND (arg0, 1)) && integer_zerop (arg2))
        !          4645:            {
        !          4646:              if (comp_code == NE_EXPR)
        !          4647:                return pedantic_non_lvalue (convert (type, arg1));
        !          4648:              else if (comp_code == EQ_EXPR)
        !          4649:                return pedantic_non_lvalue (convert (type, integer_zero_node));
        !          4650:            }
        !          4651: 
        !          4652:          /* If this is A op B ? A : B, this is either A, B, min (A, B),
        !          4653:             or max (A, B), depending on the operation.  */
        !          4654: 
        !          4655:          if (operand_equal_for_comparison_p (TREE_OPERAND (arg0, 1),
        !          4656:                                              arg2, TREE_OPERAND (arg0, 0)))
        !          4657:            switch (comp_code)
        !          4658:              {
        !          4659:              case EQ_EXPR:
        !          4660:                return pedantic_non_lvalue (convert (type, arg2));
        !          4661:              case NE_EXPR:
        !          4662:                return pedantic_non_lvalue (convert (type, arg1));
        !          4663:              case LE_EXPR:
        !          4664:              case LT_EXPR:
        !          4665:                return pedantic_non_lvalue
        !          4666:                  (fold (build (MIN_EXPR, type, arg1, arg2)));
        !          4667:              case GE_EXPR:
        !          4668:              case GT_EXPR:
        !          4669:                return pedantic_non_lvalue
        !          4670:                  (fold (build (MAX_EXPR, type, arg1, arg2)));
        !          4671:              }
        !          4672: 
        !          4673:          /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
        !          4674:             we might still be able to simplify this.  For example,
        !          4675:             if C1 is one less or one more than C2, this might have started
        !          4676:             out as a MIN or MAX and been transformed by this function.
        !          4677:             Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE.  */
        !          4678: 
        !          4679:          if (INTEGRAL_TYPE_P (type)
        !          4680:              && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
        !          4681:              && TREE_CODE (arg2) == INTEGER_CST)
        !          4682:            switch (comp_code)
        !          4683:              {
        !          4684:              case EQ_EXPR:
        !          4685:                /* We can replace A with C1 in this case.  */
        !          4686:                arg1 = TREE_OPERAND (t, 1)
        !          4687:                  = convert (type, TREE_OPERAND (arg0, 1));
        !          4688:                break;
        !          4689: 
        !          4690:              case LT_EXPR:
        !          4691:                /* If C1 is C2 + 1, this is min(A, C2).  */
        !          4692:                if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type), 1)
        !          4693:                    && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          4694:                                        const_binop (PLUS_EXPR, arg2,
        !          4695:                                                     integer_one_node, 0), 1))
        !          4696:                  return pedantic_non_lvalue
        !          4697:                    (fold (build (MIN_EXPR, type, arg1, arg2)));
        !          4698:                break;
        !          4699: 
        !          4700:              case LE_EXPR:
        !          4701:                /* If C1 is C2 - 1, this is min(A, C2).  */
        !          4702:                if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type), 1)
        !          4703:                    && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          4704:                                        const_binop (MINUS_EXPR, arg2,
        !          4705:                                                     integer_one_node, 0), 1))
        !          4706:                  return pedantic_non_lvalue
        !          4707:                    (fold (build (MIN_EXPR, type, arg1, arg2)));
        !          4708:                break;
        !          4709: 
        !          4710:              case GT_EXPR:
        !          4711:                /* If C1 is C2 - 1, this is max(A, C2).  */
        !          4712:                if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type), 1)
        !          4713:                    && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          4714:                                        const_binop (MINUS_EXPR, arg2,
        !          4715:                                                     integer_one_node, 0), 1))
        !          4716:                  return pedantic_non_lvalue
        !          4717:                    (fold (build (MAX_EXPR, type, arg1, arg2)));
        !          4718:                break;
        !          4719: 
        !          4720:              case GE_EXPR:
        !          4721:                /* If C1 is C2 + 1, this is max(A, C2).  */
        !          4722:                if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type), 1)
        !          4723:                    && operand_equal_p (TREE_OPERAND (arg0, 1),
        !          4724:                                        const_binop (PLUS_EXPR, arg2,
        !          4725:                                                     integer_one_node, 0), 1))
        !          4726:                  return pedantic_non_lvalue
        !          4727:                    (fold (build (MAX_EXPR, type, arg1, arg2)));
        !          4728:                break;
        !          4729:              }
        !          4730:        }
        !          4731: 
        !          4732:       /* Convert A ? 1 : 0 to simply A.  */
        !          4733:       if (integer_onep (TREE_OPERAND (t, 1))
        !          4734:          && integer_zerop (TREE_OPERAND (t, 2))
        !          4735:          /* If we try to convert TREE_OPERAND (t, 0) to our type, the
        !          4736:             call to fold will try to move the conversion inside 
        !          4737:             a COND, which will recurse.  In that case, the COND_EXPR
        !          4738:             is probably the best choice, so leave it alone.  */
        !          4739:          && type == TREE_TYPE (arg0))
        !          4740:        return pedantic_non_lvalue (arg0);
        !          4741: 
        !          4742: 
        !          4743:       /* Look for expressions of the form A & 2 ? 2 : 0.  The result of this
        !          4744:         operation is simply A & 2.  */
        !          4745: 
        !          4746:       if (integer_zerop (TREE_OPERAND (t, 2))
        !          4747:          && TREE_CODE (arg0) == NE_EXPR
        !          4748:          && integer_zerop (TREE_OPERAND (arg0, 1))
        !          4749:          && integer_pow2p (arg1)
        !          4750:          && TREE_CODE (TREE_OPERAND (arg0, 0)) == BIT_AND_EXPR
        !          4751:          && operand_equal_p (TREE_OPERAND (TREE_OPERAND (arg0, 0), 1),
        !          4752:                              arg1, 1))
        !          4753:        return pedantic_non_lvalue (convert (type, TREE_OPERAND (arg0, 0)));
        !          4754: 
        !          4755:       return t;
        !          4756: 
        !          4757:     case COMPOUND_EXPR:
        !          4758:       /* When pedantic, a compound expression can be neither an lvalue
        !          4759:         nor an integer constant expression.  */
        !          4760:       if (TREE_SIDE_EFFECTS (arg0) || pedantic)
        !          4761:        return t;
        !          4762:       /* Don't let (0, 0) be null pointer constant.  */
        !          4763:       if (integer_zerop (arg1))
        !          4764:        return non_lvalue (arg1);
        !          4765:       return arg1;
        !          4766: 
        !          4767:     case COMPLEX_EXPR:
        !          4768:       if (wins)
        !          4769:        return build_complex (arg0, arg1);
        !          4770:       return t;
        !          4771: 
        !          4772:     case REALPART_EXPR:
        !          4773:       if (TREE_CODE (TREE_TYPE (arg0)) != COMPLEX_TYPE)
        !          4774:        return t;
        !          4775:       else if (TREE_CODE (arg0) == COMPLEX_EXPR)
        !          4776:        return omit_one_operand (type, TREE_OPERAND (arg0, 0),
        !          4777:                                 TREE_OPERAND (arg0, 1));
        !          4778:       else if (TREE_CODE (arg0) == COMPLEX_CST)
        !          4779:        return TREE_REALPART (arg0);
        !          4780:       else if (TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR)
        !          4781:        return fold (build (TREE_CODE (arg0), type,
        !          4782:                            fold (build1 (REALPART_EXPR, type,
        !          4783:                                          TREE_OPERAND (arg0, 0))),
        !          4784:                            fold (build1 (REALPART_EXPR,
        !          4785:                                          type, TREE_OPERAND (arg0, 1)))));
        !          4786:       return t;
        !          4787: 
        !          4788:     case IMAGPART_EXPR:
        !          4789:       if (TREE_CODE (TREE_TYPE (arg0)) != COMPLEX_TYPE)
        !          4790:        return convert (type, integer_zero_node);
        !          4791:       else if (TREE_CODE (arg0) == COMPLEX_EXPR)
        !          4792:        return omit_one_operand (type, TREE_OPERAND (arg0, 1),
        !          4793:                                 TREE_OPERAND (arg0, 0));
        !          4794:       else if (TREE_CODE (arg0) == COMPLEX_CST)
        !          4795:        return TREE_IMAGPART (arg0);
        !          4796:       else if (TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR)
        !          4797:        return fold (build (TREE_CODE (arg0), type,
        !          4798:                            fold (build1 (IMAGPART_EXPR, type,
        !          4799:                                          TREE_OPERAND (arg0, 0))),
        !          4800:                            fold (build1 (IMAGPART_EXPR, type,
        !          4801:                                          TREE_OPERAND (arg0, 1)))));
        !          4802:       return t;
        !          4803: 
        !          4804:     default:
        !          4805:       return t;
        !          4806:     } /* switch (code) */
        !          4807: }

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