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Annotation of GNUtools/cc/rtlanal.c, revision 1.1

1.1     ! root        1: /* Analyze RTL for C-Compiler
        !             2:    Copyright (C) 1987, 1988, 1991, 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: 
        !            21: #include "config.h"
        !            22: #include "rtl.h"
        !            23: 
        !            24: void note_stores ();
        !            25: int reg_set_p ();
        !            26: 
        !            27: /* Bit flags that specify the machine subtype we are compiling for.
        !            28:    Bits are tested using macros TARGET_... defined in the tm.h file
        !            29:    and set by `-m...' switches.  Must be defined in rtlanal.c.  */
        !            30: 
        !            31: int target_flags;
        !            32: 
        !            33: /* Return 1 if the value of X is unstable
        !            34:    (would be different at a different point in the program).
        !            35:    The frame pointer, arg pointer, etc. are considered stable
        !            36:    (within one function) and so is anything marked `unchanging'.  */
        !            37: 
        !            38: int
        !            39: rtx_unstable_p (x)
        !            40:      rtx x;
        !            41: {
        !            42:   register RTX_CODE code = GET_CODE (x);
        !            43:   register int i;
        !            44:   register char *fmt;
        !            45: 
        !            46:   if (code == MEM)
        !            47:     return ! RTX_UNCHANGING_P (x);
        !            48: 
        !            49:   if (code == QUEUED)
        !            50:     return 1;
        !            51: 
        !            52:   if (code == CONST || code == CONST_INT)
        !            53:     return 0;
        !            54: 
        !            55:   if (code == REG)
        !            56:     return ! (REGNO (x) == FRAME_POINTER_REGNUM
        !            57:              || REGNO (x) == HARD_FRAME_POINTER_REGNUM
        !            58:              || REGNO (x) == ARG_POINTER_REGNUM
        !            59:              || RTX_UNCHANGING_P (x));
        !            60: 
        !            61:   fmt = GET_RTX_FORMAT (code);
        !            62:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !            63:     if (fmt[i] == 'e')
        !            64:       if (rtx_unstable_p (XEXP (x, i)))
        !            65:        return 1;
        !            66:   return 0;
        !            67: }
        !            68: 
        !            69: /* Return 1 if X has a value that can vary even between two
        !            70:    executions of the program.  0 means X can be compared reliably
        !            71:    against certain constants or near-constants.
        !            72:    The frame pointer and the arg pointer are considered constant.  */
        !            73: 
        !            74: int
        !            75: rtx_varies_p (x)
        !            76:      rtx x;
        !            77: {
        !            78:   register RTX_CODE code = GET_CODE (x);
        !            79:   register int i;
        !            80:   register char *fmt;
        !            81: 
        !            82:   switch (code)
        !            83:     {
        !            84:     case MEM:
        !            85:     case QUEUED:
        !            86:       return 1;
        !            87: 
        !            88:     case CONST:
        !            89:     case CONST_INT:
        !            90:     case CONST_DOUBLE:
        !            91:     case SYMBOL_REF:
        !            92:     case LABEL_REF:
        !            93:       return 0;
        !            94: 
        !            95:     case REG:
        !            96:       /* Note that we have to test for the actual rtx used for the frame
        !            97:         and arg pointers and not just the register number in case we have
        !            98:         eliminated the frame and/or arg pointer and are using it
        !            99:         for pseudos.  */
        !           100:       return ! (x == frame_pointer_rtx || x == hard_frame_pointer_rtx
        !           101:                || x == arg_pointer_rtx);
        !           102: 
        !           103:     case LO_SUM:
        !           104:       /* The operand 0 of a LO_SUM is considered constant
        !           105:         (in fact is it related specifically to operand 1).  */
        !           106:       return rtx_varies_p (XEXP (x, 1));
        !           107:     }
        !           108: 
        !           109:   fmt = GET_RTX_FORMAT (code);
        !           110:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !           111:     if (fmt[i] == 'e')
        !           112:       if (rtx_varies_p (XEXP (x, i)))
        !           113:        return 1;
        !           114:   return 0;
        !           115: }
        !           116: 
        !           117: /* Return 0 if the use of X as an address in a MEM can cause a trap.  */
        !           118: 
        !           119: int
        !           120: rtx_addr_can_trap_p (x)
        !           121:      register rtx x;
        !           122: {
        !           123:   register enum rtx_code code = GET_CODE (x);
        !           124: 
        !           125:   switch (code)
        !           126:     {
        !           127:     case SYMBOL_REF:
        !           128:     case LABEL_REF:
        !           129:       /* SYMBOL_REF is problematic due to the possible presence of
        !           130:         a #pragma weak, but to say that loads from symbols can trap is
        !           131:         *very* costly.  It's not at all clear what's best here.  For
        !           132:         now, we ignore the impact of #pragma weak.  */
        !           133:       return 0;
        !           134: 
        !           135:     case REG:
        !           136:       /* As in rtx_varies_p, we have to use the actual rtx, not reg number.  */
        !           137:       return ! (x == frame_pointer_rtx || x == hard_frame_pointer_rtx
        !           138:                || x == stack_pointer_rtx || x == arg_pointer_rtx);
        !           139: 
        !           140:     case CONST:
        !           141:       return rtx_addr_can_trap_p (XEXP (x, 0));
        !           142: 
        !           143:     case PLUS:
        !           144:       /* An address is assumed not to trap if it is an address that can't
        !           145:         trap plus a constant integer.  */
        !           146:       return (rtx_addr_can_trap_p (XEXP (x, 0))
        !           147:              || GET_CODE (XEXP (x, 1)) != CONST_INT);
        !           148: 
        !           149:     case LO_SUM:
        !           150:       return rtx_addr_can_trap_p (XEXP (x, 1));
        !           151:     }
        !           152: 
        !           153:   /* If it isn't one of the case above, it can cause a trap.  */
        !           154:   return 1;
        !           155: }
        !           156: 
        !           157: /* Return 1 if X refers to a memory location whose address 
        !           158:    cannot be compared reliably with constant addresses,
        !           159:    or if X refers to a BLKmode memory object.  */
        !           160: 
        !           161: int
        !           162: rtx_addr_varies_p (x)
        !           163:      rtx x;
        !           164: {
        !           165:   register enum rtx_code code;
        !           166:   register int i;
        !           167:   register char *fmt;
        !           168: 
        !           169:   if (x == 0)
        !           170:     return 0;
        !           171: 
        !           172:   code = GET_CODE (x);
        !           173:   if (code == MEM)
        !           174:     return GET_MODE (x) == BLKmode || rtx_varies_p (XEXP (x, 0));
        !           175: 
        !           176:   fmt = GET_RTX_FORMAT (code);
        !           177:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !           178:     if (fmt[i] == 'e')
        !           179:       if (rtx_addr_varies_p (XEXP (x, i)))
        !           180:        return 1;
        !           181:   return 0;
        !           182: }
        !           183: 
        !           184: /* Return the value of the integer term in X, if one is apparent;
        !           185:    otherwise return 0.
        !           186:    Only obvious integer terms are detected.
        !           187:    This is used in cse.c with the `related_value' field.*/
        !           188: 
        !           189: HOST_WIDE_INT
        !           190: get_integer_term (x)
        !           191:      rtx x;
        !           192: {
        !           193:   if (GET_CODE (x) == CONST)
        !           194:     x = XEXP (x, 0);
        !           195: 
        !           196:   if (GET_CODE (x) == MINUS
        !           197:       && GET_CODE (XEXP (x, 1)) == CONST_INT)
        !           198:     return - INTVAL (XEXP (x, 1));
        !           199:   if (GET_CODE (x) == PLUS
        !           200:       && GET_CODE (XEXP (x, 1)) == CONST_INT)
        !           201:     return INTVAL (XEXP (x, 1));
        !           202:   return 0;
        !           203: }
        !           204: 
        !           205: /* If X is a constant, return the value sans apparent integer term;
        !           206:    otherwise return 0.
        !           207:    Only obvious integer terms are detected.  */
        !           208: 
        !           209: rtx
        !           210: get_related_value (x)
        !           211:      rtx x;
        !           212: {
        !           213:   if (GET_CODE (x) != CONST)
        !           214:     return 0;
        !           215:   x = XEXP (x, 0);
        !           216:   if (GET_CODE (x) == PLUS
        !           217:       && GET_CODE (XEXP (x, 1)) == CONST_INT)
        !           218:     return XEXP (x, 0);
        !           219:   else if (GET_CODE (x) == MINUS
        !           220:           && GET_CODE (XEXP (x, 1)) == CONST_INT)
        !           221:     return XEXP (x, 0);
        !           222:   return 0;
        !           223: }
        !           224: 
        !           225: /* Nonzero if register REG appears somewhere within IN.
        !           226:    Also works if REG is not a register; in this case it checks
        !           227:    for a subexpression of IN that is Lisp "equal" to REG.  */
        !           228: 
        !           229: int
        !           230: reg_mentioned_p (reg, in)
        !           231:      register rtx reg, in;
        !           232: {
        !           233:   register char *fmt;
        !           234:   register int i;
        !           235:   register enum rtx_code code;
        !           236: 
        !           237:   if (in == 0)
        !           238:     return 0;
        !           239: 
        !           240:   if (reg == in)
        !           241:     return 1;
        !           242: 
        !           243:   if (GET_CODE (in) == LABEL_REF)
        !           244:     return reg == XEXP (in, 0);
        !           245: 
        !           246:   code = GET_CODE (in);
        !           247: 
        !           248:   switch (code)
        !           249:     {
        !           250:       /* Compare registers by number.  */
        !           251:     case REG:
        !           252:       return GET_CODE (reg) == REG && REGNO (in) == REGNO (reg);
        !           253: 
        !           254:       /* These codes have no constituent expressions
        !           255:         and are unique.  */
        !           256:     case SCRATCH:
        !           257:     case CC0:
        !           258:     case PC:
        !           259:       return 0;
        !           260: 
        !           261:     case CONST_INT:
        !           262:       return GET_CODE (reg) == CONST_INT && INTVAL (in) == INTVAL (reg);
        !           263:       
        !           264:     case CONST_DOUBLE:
        !           265:       /* These are kept unique for a given value.  */
        !           266:       return 0;
        !           267:     }
        !           268: 
        !           269:   if (GET_CODE (reg) == code && rtx_equal_p (reg, in))
        !           270:     return 1;
        !           271: 
        !           272:   fmt = GET_RTX_FORMAT (code);
        !           273: 
        !           274:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !           275:     {
        !           276:       if (fmt[i] == 'E')
        !           277:        {
        !           278:          register int j;
        !           279:          for (j = XVECLEN (in, i) - 1; j >= 0; j--)
        !           280:            if (reg_mentioned_p (reg, XVECEXP (in, i, j)))
        !           281:              return 1;
        !           282:        }
        !           283:       else if (fmt[i] == 'e'
        !           284:               && reg_mentioned_p (reg, XEXP (in, i)))
        !           285:        return 1;
        !           286:     }
        !           287:   return 0;
        !           288: }
        !           289: 
        !           290: /* Return 1 if in between BEG and END, exclusive of BEG and END, there is
        !           291:    no CODE_LABEL insn.  */
        !           292: 
        !           293: int
        !           294: no_labels_between_p (beg, end)
        !           295:      rtx beg, end;
        !           296: {
        !           297:   register rtx p;
        !           298:   for (p = NEXT_INSN (beg); p != end; p = NEXT_INSN (p))
        !           299:     if (GET_CODE (p) == CODE_LABEL)
        !           300:       return 0;
        !           301:   return 1;
        !           302: }
        !           303: 
        !           304: /* Nonzero if register REG is used in an insn between
        !           305:    FROM_INSN and TO_INSN (exclusive of those two).  */
        !           306: 
        !           307: int
        !           308: reg_used_between_p (reg, from_insn, to_insn)
        !           309:      rtx reg, from_insn, to_insn;
        !           310: {
        !           311:   register rtx insn;
        !           312: 
        !           313:   if (from_insn == to_insn)
        !           314:     return 0;
        !           315: 
        !           316:   for (insn = NEXT_INSN (from_insn); insn != to_insn; insn = NEXT_INSN (insn))
        !           317:     if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
        !           318:        && reg_overlap_mentioned_p (reg, PATTERN (insn)))
        !           319:       return 1;
        !           320:   return 0;
        !           321: }
        !           322: 
        !           323: /* Nonzero if the old value of X, a register, is referenced in BODY.  If X
        !           324:    is entirely replaced by a new value and the only use is as a SET_DEST,
        !           325:    we do not consider it a reference.  */
        !           326: 
        !           327: int
        !           328: reg_referenced_p (x, body)
        !           329:      rtx x;
        !           330:      rtx body;
        !           331: {
        !           332:   int i;
        !           333: 
        !           334:   switch (GET_CODE (body))
        !           335:     {
        !           336:     case SET:
        !           337:       if (reg_overlap_mentioned_p (x, SET_SRC (body)))
        !           338:        return 1;
        !           339: 
        !           340:       /* If the destination is anything other than CC0, PC, a REG or a SUBREG
        !           341:         of a REG that occupies all of the REG, the insn references X if
        !           342:         it is mentioned in the destination.  */
        !           343:       if (GET_CODE (SET_DEST (body)) != CC0
        !           344:          && GET_CODE (SET_DEST (body)) != PC
        !           345:          && GET_CODE (SET_DEST (body)) != REG
        !           346:          && ! (GET_CODE (SET_DEST (body)) == SUBREG
        !           347:                && GET_CODE (SUBREG_REG (SET_DEST (body))) == REG
        !           348:                && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (body))))
        !           349:                      + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)
        !           350:                    == ((GET_MODE_SIZE (GET_MODE (SET_DEST (body)))
        !           351:                         + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD)))
        !           352:          && reg_overlap_mentioned_p (x, SET_DEST (body)))
        !           353:        return 1;
        !           354:       break;
        !           355: 
        !           356:     case ASM_OPERANDS:
        !           357:       for (i = ASM_OPERANDS_INPUT_LENGTH (body) - 1; i >= 0; i--)
        !           358:        if (reg_overlap_mentioned_p (x, ASM_OPERANDS_INPUT (body, i)))
        !           359:          return 1;
        !           360:       break;
        !           361: 
        !           362:     case CALL:
        !           363:     case USE:
        !           364:       return reg_overlap_mentioned_p (x, body);
        !           365: 
        !           366:     case TRAP_IF:
        !           367:       return reg_overlap_mentioned_p (x, TRAP_CONDITION (body));
        !           368: 
        !           369:     case UNSPEC:
        !           370:     case UNSPEC_VOLATILE:
        !           371:     case PARALLEL:
        !           372:       for (i = XVECLEN (body, 0) - 1; i >= 0; i--)
        !           373:        if (reg_referenced_p (x, XVECEXP (body, 0, i)))
        !           374:          return 1;
        !           375:       break;
        !           376:     }
        !           377: 
        !           378:   return 0;
        !           379: }
        !           380: 
        !           381: /* Nonzero if register REG is referenced in an insn between
        !           382:    FROM_INSN and TO_INSN (exclusive of those two).  Sets of REG do
        !           383:    not count. */
        !           384: 
        !           385: int
        !           386: reg_referenced_between_p (reg, from_insn, to_insn)
        !           387:      rtx reg, from_insn, to_insn;
        !           388: {
        !           389:   register rtx insn;
        !           390: 
        !           391:   if (from_insn == to_insn)
        !           392:     return 0;
        !           393: 
        !           394:   for (insn = NEXT_INSN (from_insn); insn != to_insn; insn = NEXT_INSN (insn))
        !           395:     if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
        !           396:        && reg_referenced_p (reg, PATTERN (insn)))
        !           397:       return 1;
        !           398:   return 0;
        !           399: }
        !           400: 
        !           401: /* Nonzero if register REG is set or clobbered in an insn between
        !           402:    FROM_INSN and TO_INSN (exclusive of those two).  */
        !           403: 
        !           404: int
        !           405: reg_set_between_p (reg, from_insn, to_insn)
        !           406:      rtx reg, from_insn, to_insn;
        !           407: {
        !           408:   register rtx insn;
        !           409: 
        !           410:   if (from_insn == to_insn)
        !           411:     return 0;
        !           412: 
        !           413:   for (insn = NEXT_INSN (from_insn); insn != to_insn; insn = NEXT_INSN (insn))
        !           414:     if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
        !           415:        && reg_set_p (reg, insn))
        !           416:       return 1;
        !           417:   return 0;
        !           418: }
        !           419: 
        !           420: /* Internals of reg_set_between_p.  */
        !           421: 
        !           422: static rtx reg_set_reg;
        !           423: static int reg_set_flag;
        !           424: 
        !           425: void
        !           426: reg_set_p_1 (x)
        !           427:      rtx x;
        !           428: {
        !           429:   /* We don't want to return 1 if X is a MEM that contains a register
        !           430:      within REG_SET_REG.  */
        !           431: 
        !           432:   if ((GET_CODE (x) != MEM)
        !           433:       && reg_overlap_mentioned_p (reg_set_reg, x))
        !           434:     reg_set_flag = 1;
        !           435: }
        !           436: 
        !           437: int
        !           438: reg_set_p (reg, insn)
        !           439:      rtx reg, insn;
        !           440: {
        !           441:   rtx body = insn;
        !           442: 
        !           443:   /* We can be passed an insn or part of one.  If we are passed an insn,
        !           444:      check if a side-effect of the insn clobbers REG.  */
        !           445:   if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
        !           446:     {
        !           447:       if (FIND_REG_INC_NOTE (insn, reg)
        !           448:          || (GET_CODE (insn) == CALL_INSN
        !           449:              /* We'd like to test call_used_regs here, but rtlanal.c can't
        !           450:                 reference that variable due to its use in genattrtab.  So
        !           451:                 we'll just be more conservative.  */
        !           452:              && ((GET_CODE (reg) == REG
        !           453:                   && REGNO (reg) < FIRST_PSEUDO_REGISTER)
        !           454:                  || GET_CODE (reg) == MEM)))
        !           455:        return 1;
        !           456: 
        !           457:       body = PATTERN (insn);
        !           458:     }
        !           459: 
        !           460:   reg_set_reg = reg;
        !           461:   reg_set_flag = 0;
        !           462:   note_stores (body, reg_set_p_1);
        !           463:   return reg_set_flag;
        !           464: }
        !           465: 
        !           466: /* Similar to reg_set_between_p, but check all registers in X.  Return 0
        !           467:    only if none of them are modified between START and END.  Return 1 if
        !           468:    X contains a MEM; this routine does not perform any memory aliasing.  */
        !           469: 
        !           470: int
        !           471: modified_between_p (x, start, end)
        !           472:      rtx x;
        !           473:      rtx start, end;
        !           474: {
        !           475:   enum rtx_code code = GET_CODE (x);
        !           476:   char *fmt;
        !           477:   int i, j;
        !           478: 
        !           479:   switch (code)
        !           480:     {
        !           481:     case CONST_INT:
        !           482:     case CONST_DOUBLE:
        !           483:     case CONST:
        !           484:     case SYMBOL_REF:
        !           485:     case LABEL_REF:
        !           486:       return 0;
        !           487: 
        !           488:     case PC:
        !           489:     case CC0:
        !           490:       return 1;
        !           491: 
        !           492:     case MEM:
        !           493:       /* If the memory is not constant, assume it is modified.  If it is
        !           494:         constant, we still have to check the address.  */
        !           495:       if (! RTX_UNCHANGING_P (x))
        !           496:        return 1;
        !           497:       break;
        !           498: 
        !           499:     case REG:
        !           500:       return reg_set_between_p (x, start, end);
        !           501:     }
        !           502: 
        !           503:   fmt = GET_RTX_FORMAT (code);
        !           504:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !           505:     {
        !           506:       if (fmt[i] == 'e' && modified_between_p (XEXP (x, i), start, end))
        !           507:        return 1;
        !           508: 
        !           509:       if (fmt[i] == 'E')
        !           510:        for (j = XVECLEN (x, i) - 1; j >= 0; j--)
        !           511:          if (modified_between_p (XVECEXP (x, i, j), start, end))
        !           512:            return 1;
        !           513:     }
        !           514: 
        !           515:   return 0;
        !           516: }
        !           517: 
        !           518: /* Similar to reg_set_p, but check all registers in X.  Return 0 only if none
        !           519:    of them are modified in INSN.  Return 1 if X contains a MEM; this routine
        !           520:    does not perform any memory aliasing.  */
        !           521: 
        !           522: int
        !           523: modified_in_p (x, insn)
        !           524:      rtx x;
        !           525:      rtx insn;
        !           526: {
        !           527:   enum rtx_code code = GET_CODE (x);
        !           528:   char *fmt;
        !           529:   int i, j;
        !           530: 
        !           531:   switch (code)
        !           532:     {
        !           533:     case CONST_INT:
        !           534:     case CONST_DOUBLE:
        !           535:     case CONST:
        !           536:     case SYMBOL_REF:
        !           537:     case LABEL_REF:
        !           538:       return 0;
        !           539: 
        !           540:     case PC:
        !           541:     case CC0:
        !           542:       return 1;
        !           543: 
        !           544:     case MEM:
        !           545:       /* If the memory is not constant, assume it is modified.  If it is
        !           546:         constant, we still have to check the address.  */
        !           547:       if (! RTX_UNCHANGING_P (x))
        !           548:        return 1;
        !           549:       break;
        !           550: 
        !           551:     case REG:
        !           552:       return reg_set_p (x, insn);
        !           553:     }
        !           554: 
        !           555:   fmt = GET_RTX_FORMAT (code);
        !           556:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !           557:     {
        !           558:       if (fmt[i] == 'e' && modified_in_p (XEXP (x, i), insn))
        !           559:        return 1;
        !           560: 
        !           561:       if (fmt[i] == 'E')
        !           562:        for (j = XVECLEN (x, i) - 1; j >= 0; j--)
        !           563:          if (modified_in_p (XVECEXP (x, i, j), insn))
        !           564:            return 1;
        !           565:     }
        !           566: 
        !           567:   return 0;
        !           568: }
        !           569: 
        !           570: /* Given an INSN, return a SET expression if this insn has only a single SET.
        !           571:    It may also have CLOBBERs, USEs, or SET whose output
        !           572:    will not be used, which we ignore.  */
        !           573: 
        !           574: rtx
        !           575: single_set (insn)
        !           576:      rtx insn;
        !           577: {
        !           578:   rtx set;
        !           579:   int i;
        !           580:   
        !           581:   if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
        !           582:     return 0;
        !           583: 
        !           584:   if (GET_CODE (PATTERN (insn)) == SET)
        !           585:     return PATTERN (insn);
        !           586:   
        !           587:   else if (GET_CODE (PATTERN (insn)) == PARALLEL)
        !           588:     {
        !           589:       for (i = 0, set = 0; i < XVECLEN (PATTERN (insn), 0); i++)
        !           590:        if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == SET
        !           591:            && (! find_reg_note (insn, REG_UNUSED,
        !           592:                                 SET_DEST (XVECEXP (PATTERN (insn), 0, i)))
        !           593:                || side_effects_p (XVECEXP (PATTERN (insn), 0, i))))
        !           594:          {
        !           595:            if (set)
        !           596:              return 0;
        !           597:            else
        !           598:              set = XVECEXP (PATTERN (insn), 0, i);
        !           599:          }
        !           600:       return set;
        !           601:     }
        !           602:   
        !           603:   return 0;
        !           604: }
        !           605: 
        !           606: /* Return the last thing that X was assigned from before *PINSN.  Verify that
        !           607:    the object is not modified up to VALID_TO.  If it was, if we hit
        !           608:    a partial assignment to X, or hit a CODE_LABEL first, return X.  If we
        !           609:    found an assignment, update *PINSN to point to it.  */
        !           610: 
        !           611: rtx
        !           612: find_last_value (x, pinsn, valid_to)
        !           613:      rtx x;
        !           614:      rtx *pinsn;
        !           615:      rtx valid_to;
        !           616: {
        !           617:   rtx p;
        !           618: 
        !           619:   for (p = PREV_INSN (*pinsn); p && GET_CODE (p) != CODE_LABEL;
        !           620:        p = PREV_INSN (p))
        !           621:     if (GET_RTX_CLASS (GET_CODE (p)) == 'i')
        !           622:       {
        !           623:        rtx set = single_set (p);
        !           624:        rtx note = find_reg_note (p, REG_EQUAL, NULL_RTX);
        !           625: 
        !           626:        if (set && rtx_equal_p (x, SET_DEST (set)))
        !           627:          {
        !           628:            rtx src = SET_SRC (set);
        !           629: 
        !           630:            if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST)
        !           631:              src = XEXP (note, 0);
        !           632: 
        !           633:            if (! modified_between_p (src, PREV_INSN (p), valid_to)
        !           634:                /* Reject hard registers because we don't usually want
        !           635:                   to use them; we'd rather use a pseudo.  */
        !           636:                && ! (GET_CODE (src) == REG
        !           637:                      && REGNO (src) < FIRST_PSEUDO_REGISTER))
        !           638:              {
        !           639:                *pinsn = p;
        !           640:                return src;
        !           641:              }
        !           642:          }
        !           643:          
        !           644:        /* If set in non-simple way, we don't have a value.  */
        !           645:        if (reg_set_p (x, p))
        !           646:          break;
        !           647:       }
        !           648: 
        !           649:   return x;
        !           650: }     
        !           651: 
        !           652: /* Return nonzero if register in range [REGNO, ENDREGNO)
        !           653:    appears either explicitly or implicitly in X
        !           654:    other than being stored into.
        !           655: 
        !           656:    References contained within the substructure at LOC do not count.
        !           657:    LOC may be zero, meaning don't ignore anything.  */
        !           658: 
        !           659: int
        !           660: refers_to_regno_p (regno, endregno, x, loc)
        !           661:      int regno, endregno;
        !           662:      rtx x;
        !           663:      rtx *loc;
        !           664: {
        !           665:   register int i;
        !           666:   register RTX_CODE code;
        !           667:   register char *fmt;
        !           668: 
        !           669:  repeat:
        !           670:   /* The contents of a REG_NONNEG note is always zero, so we must come here
        !           671:      upon repeat in case the last REG_NOTE is a REG_NONNEG note.  */
        !           672:   if (x == 0)
        !           673:     return 0;
        !           674: 
        !           675:   code = GET_CODE (x);
        !           676: 
        !           677:   switch (code)
        !           678:     {
        !           679:     case REG:
        !           680:       i = REGNO (x);
        !           681: 
        !           682:       /* If we modifying the stack, frame, or argument pointer, it will
        !           683:         clobber a virtual register.  In fact, we could be more precise,
        !           684:         but it isn't worth it.  */
        !           685:       if ((i == STACK_POINTER_REGNUM
        !           686: #if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
        !           687:           || i == ARG_POINTER_REGNUM
        !           688: #endif
        !           689:           || i == FRAME_POINTER_REGNUM)
        !           690:          && regno >= FIRST_VIRTUAL_REGISTER && regno <= LAST_VIRTUAL_REGISTER)
        !           691:        return 1;
        !           692: 
        !           693:       return (endregno > i
        !           694:              && regno < i + (i < FIRST_PSEUDO_REGISTER 
        !           695:                              ? HARD_REGNO_NREGS (i, GET_MODE (x))
        !           696:                              : 1));
        !           697: 
        !           698:     case SUBREG:
        !           699:       /* If this is a SUBREG of a hard reg, we can see exactly which
        !           700:         registers are being modified.  Otherwise, handle normally.  */
        !           701:       if (GET_CODE (SUBREG_REG (x)) == REG
        !           702:          && REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER)
        !           703:        {
        !           704:          int inner_regno = REGNO (SUBREG_REG (x)) + SUBREG_WORD (x);
        !           705:          int inner_endregno
        !           706:            = inner_regno + (inner_regno < FIRST_PSEUDO_REGISTER
        !           707:                             ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);
        !           708: 
        !           709:          return endregno > inner_regno && regno < inner_endregno;
        !           710:        }
        !           711:       break;
        !           712: 
        !           713:     case CLOBBER:
        !           714:     case SET:
        !           715:       if (&SET_DEST (x) != loc
        !           716:          /* Note setting a SUBREG counts as referring to the REG it is in for
        !           717:             a pseudo but not for hard registers since we can
        !           718:             treat each word individually.  */
        !           719:          && ((GET_CODE (SET_DEST (x)) == SUBREG
        !           720:               && loc != &SUBREG_REG (SET_DEST (x))
        !           721:               && GET_CODE (SUBREG_REG (SET_DEST (x))) == REG
        !           722:               && REGNO (SUBREG_REG (SET_DEST (x))) >= FIRST_PSEUDO_REGISTER
        !           723:               && refers_to_regno_p (regno, endregno,
        !           724:                                     SUBREG_REG (SET_DEST (x)), loc))
        !           725:              || (GET_CODE (SET_DEST (x)) != REG
        !           726:                  && refers_to_regno_p (regno, endregno, SET_DEST (x), loc))))
        !           727:        return 1;
        !           728: 
        !           729:       if (code == CLOBBER || loc == &SET_SRC (x))
        !           730:        return 0;
        !           731:       x = SET_SRC (x);
        !           732:       goto repeat;
        !           733:     }
        !           734: 
        !           735:   /* X does not match, so try its subexpressions.  */
        !           736: 
        !           737:   fmt = GET_RTX_FORMAT (code);
        !           738:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !           739:     {
        !           740:       if (fmt[i] == 'e' && loc != &XEXP (x, i))
        !           741:        {
        !           742:          if (i == 0)
        !           743:            {
        !           744:              x = XEXP (x, 0);
        !           745:              goto repeat;
        !           746:            }
        !           747:          else
        !           748:            if (refers_to_regno_p (regno, endregno, XEXP (x, i), loc))
        !           749:              return 1;
        !           750:        }
        !           751:       else if (fmt[i] == 'E')
        !           752:        {
        !           753:          register int j;
        !           754:          for (j = XVECLEN (x, i) - 1; j >=0; j--)
        !           755:            if (loc != &XVECEXP (x, i, j)
        !           756:                && refers_to_regno_p (regno, endregno, XVECEXP (x, i, j), loc))
        !           757:              return 1;
        !           758:        }
        !           759:     }
        !           760:   return 0;
        !           761: }
        !           762: 
        !           763: /* Nonzero if modifying X will affect IN.  If X is a register or a SUBREG,
        !           764:    we check if any register number in X conflicts with the relevant register
        !           765:    numbers.  If X is a constant, return 0.  If X is a MEM, return 1 iff IN
        !           766:    contains a MEM (we don't bother checking for memory addresses that can't
        !           767:    conflict because we expect this to be a rare case.  */
        !           768: 
        !           769: int
        !           770: reg_overlap_mentioned_p (x, in)
        !           771:      rtx x, in;
        !           772: {
        !           773:   int regno, endregno;
        !           774: 
        !           775:   if (GET_CODE (x) == SUBREG)
        !           776:     {
        !           777:       regno = REGNO (SUBREG_REG (x));
        !           778:       if (regno < FIRST_PSEUDO_REGISTER)
        !           779:        regno += SUBREG_WORD (x);
        !           780:     }
        !           781:   else if (GET_CODE (x) == REG)
        !           782:     regno = REGNO (x);
        !           783:   else if (CONSTANT_P (x))
        !           784:     return 0;
        !           785:   else if (GET_CODE (x) == MEM)
        !           786:     {
        !           787:       char *fmt;
        !           788:       int i;
        !           789: 
        !           790:       if (GET_CODE (in) == MEM)
        !           791:        return 1;
        !           792: 
        !           793:       fmt = GET_RTX_FORMAT (GET_CODE (in));
        !           794: 
        !           795:       for (i = GET_RTX_LENGTH (GET_CODE (in)) - 1; i >= 0; i--)
        !           796:        if (fmt[i] == 'e' && reg_overlap_mentioned_p (x, XEXP (in, i)))
        !           797:          return 1;
        !           798: 
        !           799:       return 0;
        !           800:     }
        !           801:   else if (GET_CODE (x) == SCRATCH || GET_CODE (x) == PC
        !           802:           || GET_CODE (x) == CC0)
        !           803:     return reg_mentioned_p (x, in);
        !           804:   else
        !           805:     abort ();
        !           806: 
        !           807:   endregno = regno + (regno < FIRST_PSEUDO_REGISTER
        !           808:                      ? HARD_REGNO_NREGS (regno, GET_MODE (x)) : 1);
        !           809: 
        !           810:   return refers_to_regno_p (regno, endregno, in, NULL_PTR);
        !           811: }
        !           812: 
        !           813: /* Used for communications between the next few functions.  */
        !           814: 
        !           815: static int reg_set_last_unknown;
        !           816: static rtx reg_set_last_value;
        !           817: static int reg_set_last_first_regno, reg_set_last_last_regno;
        !           818: 
        !           819: /* Called via note_stores from reg_set_last.  */
        !           820: 
        !           821: static void
        !           822: reg_set_last_1 (x, pat)
        !           823:      rtx x;
        !           824:      rtx pat;
        !           825: {
        !           826:   int first, last;
        !           827: 
        !           828:   /* If X is not a register, or is not one in the range we care
        !           829:      about, ignore.  */
        !           830:   if (GET_CODE (x) != REG)
        !           831:     return;
        !           832: 
        !           833:   first = REGNO (x);
        !           834:   last = first + (first < FIRST_PSEUDO_REGISTER
        !           835:                  ? HARD_REGNO_NREGS (first, GET_MODE (x)) : 1);
        !           836: 
        !           837:   if (first >= reg_set_last_last_regno
        !           838:       || last <= reg_set_last_first_regno)
        !           839:     return;
        !           840: 
        !           841:   /* If this is a CLOBBER or is some complex LHS, or doesn't modify
        !           842:      exactly the registers we care about, show we don't know the value.  */
        !           843:   if (GET_CODE (pat) == CLOBBER || SET_DEST (pat) != x
        !           844:       || first != reg_set_last_first_regno
        !           845:       || last != reg_set_last_last_regno)
        !           846:     reg_set_last_unknown = 1;
        !           847:   else
        !           848:     reg_set_last_value = SET_SRC (pat);
        !           849: }
        !           850: 
        !           851: /* Return the last value to which REG was set prior to INSN.  If we can't
        !           852:    find it easily, return 0.
        !           853: 
        !           854:    We only return a REG, SUBREG, or constant because it is too hard to
        !           855:    check if a MEM remains unchanged.  */
        !           856: 
        !           857: rtx
        !           858: reg_set_last (x, insn)
        !           859:      rtx x;
        !           860:      rtx insn;
        !           861: {
        !           862:   rtx orig_insn = insn;
        !           863: 
        !           864:   reg_set_last_first_regno = REGNO (x);
        !           865: 
        !           866:   reg_set_last_last_regno
        !           867:     = reg_set_last_first_regno
        !           868:       + (reg_set_last_first_regno < FIRST_PSEUDO_REGISTER
        !           869:         ? HARD_REGNO_NREGS (reg_set_last_first_regno, GET_MODE (x)) : 1);
        !           870: 
        !           871:   reg_set_last_unknown = 0;
        !           872:   reg_set_last_value = 0;
        !           873: 
        !           874:   /* Scan backwards until reg_set_last_1 changed one of the above flags.
        !           875:      Stop when we reach a label or X is a hard reg and we reach a
        !           876:      CALL_INSN (if reg_set_last_last_regno is a hard reg).
        !           877: 
        !           878:      If we find a set of X, ensure that its SET_SRC remains unchanged.  */
        !           879: 
        !           880:   /* We compare with <= here, because reg_set_last_last_regno
        !           881:      is actually the number of the first reg *not* in X.  */
        !           882:   for (;
        !           883:        insn && GET_CODE (insn) != CODE_LABEL
        !           884:        && ! (GET_CODE (insn) == CALL_INSN
        !           885:             && reg_set_last_last_regno <= FIRST_PSEUDO_REGISTER);
        !           886:        insn = PREV_INSN (insn))
        !           887:     if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
        !           888:       {
        !           889:        note_stores (PATTERN (insn), reg_set_last_1);
        !           890:        if (reg_set_last_unknown)
        !           891:          return 0;
        !           892:        else if (reg_set_last_value)
        !           893:          {
        !           894:            if (CONSTANT_P (reg_set_last_value)
        !           895:                || ((GET_CODE (reg_set_last_value) == REG
        !           896:                     || GET_CODE (reg_set_last_value) == SUBREG)
        !           897:                    && ! reg_set_between_p (reg_set_last_value,
        !           898:                                            NEXT_INSN (insn), orig_insn)))
        !           899:              return reg_set_last_value;
        !           900:            else
        !           901:              return 0;
        !           902:          }
        !           903:       }
        !           904: 
        !           905:   return 0;
        !           906: }
        !           907: 
        !           908: /* This is 1 until after reload pass.  */
        !           909: int rtx_equal_function_value_matters;
        !           910: 
        !           911: /* Return 1 if X and Y are identical-looking rtx's.
        !           912:    This is the Lisp function EQUAL for rtx arguments.  */
        !           913: 
        !           914: int
        !           915: rtx_equal_p (x, y)
        !           916:      rtx x, y;
        !           917: {
        !           918:   register int i;
        !           919:   register int j;
        !           920:   register enum rtx_code code;
        !           921:   register char *fmt;
        !           922: 
        !           923:   if (x == y)
        !           924:     return 1;
        !           925:   if (x == 0 || y == 0)
        !           926:     return 0;
        !           927: 
        !           928:   code = GET_CODE (x);
        !           929:   /* Rtx's of different codes cannot be equal.  */
        !           930:   if (code != GET_CODE (y))
        !           931:     return 0;
        !           932: 
        !           933:   /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
        !           934:      (REG:SI x) and (REG:HI x) are NOT equivalent.  */
        !           935: 
        !           936:   if (GET_MODE (x) != GET_MODE (y))
        !           937:     return 0;
        !           938: 
        !           939:   /* REG, LABEL_REF, and SYMBOL_REF can be compared nonrecursively.  */
        !           940: 
        !           941:   if (code == REG)
        !           942:     /* Until rtl generation is complete, don't consider a reference to the
        !           943:        return register of the current function the same as the return from a
        !           944:        called function.  This eases the job of function integration.  Once the
        !           945:        distinction is no longer needed, they can be considered equivalent.  */
        !           946:     return (REGNO (x) == REGNO (y)
        !           947:            && (! rtx_equal_function_value_matters
        !           948:                || REG_FUNCTION_VALUE_P (x) == REG_FUNCTION_VALUE_P (y)));
        !           949:   else if (code == LABEL_REF)
        !           950:     return XEXP (x, 0) == XEXP (y, 0);
        !           951:   else if (code == SYMBOL_REF)
        !           952:     return XSTR (x, 0) == XSTR (y, 0);
        !           953:   else if (code == SCRATCH || code == CONST_DOUBLE)
        !           954:     return 0;
        !           955: 
        !           956:   /* Compare the elements.  If any pair of corresponding elements
        !           957:      fail to match, return 0 for the whole things.  */
        !           958: 
        !           959:   fmt = GET_RTX_FORMAT (code);
        !           960:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !           961:     {
        !           962:       switch (fmt[i])
        !           963:        {
        !           964:        case 'w':
        !           965:          if (XWINT (x, i) != XWINT (y, i))
        !           966:            return 0;
        !           967:          break;
        !           968: 
        !           969:        case 'n':
        !           970:        case 'i':
        !           971:          if (XINT (x, i) != XINT (y, i))
        !           972:            return 0;
        !           973:          break;
        !           974: 
        !           975:        case 'V':
        !           976:        case 'E':
        !           977:          /* Two vectors must have the same length.  */
        !           978:          if (XVECLEN (x, i) != XVECLEN (y, i))
        !           979:            return 0;
        !           980: 
        !           981:          /* And the corresponding elements must match.  */
        !           982:          for (j = 0; j < XVECLEN (x, i); j++)
        !           983:            if (rtx_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)) == 0)
        !           984:              return 0;
        !           985:          break;
        !           986: 
        !           987:        case 'e':
        !           988:          if (rtx_equal_p (XEXP (x, i), XEXP (y, i)) == 0)
        !           989:            return 0;
        !           990:          break;
        !           991: 
        !           992:        case 'S':
        !           993:        case 's':
        !           994:          if (strcmp (XSTR (x, i), XSTR (y, i)))
        !           995:            return 0;
        !           996:          break;
        !           997: 
        !           998:        case 'u':
        !           999:          /* These are just backpointers, so they don't matter.  */
        !          1000:          break;
        !          1001: 
        !          1002:        case '0':
        !          1003:          break;
        !          1004: 
        !          1005:          /* It is believed that rtx's at this level will never
        !          1006:             contain anything but integers and other rtx's,
        !          1007:             except for within LABEL_REFs and SYMBOL_REFs.  */
        !          1008:        default:
        !          1009:          abort ();
        !          1010:        }
        !          1011:     }
        !          1012:   return 1;
        !          1013: }
        !          1014: 
        !          1015: /* Call FUN on each register or MEM that is stored into or clobbered by X.
        !          1016:    (X would be the pattern of an insn).
        !          1017:    FUN receives two arguments:
        !          1018:      the REG, MEM, CC0 or PC being stored in or clobbered,
        !          1019:      the SET or CLOBBER rtx that does the store.
        !          1020: 
        !          1021:   If the item being stored in or clobbered is a SUBREG of a hard register,
        !          1022:   the SUBREG will be passed.  */
        !          1023:      
        !          1024: void
        !          1025: note_stores (x, fun)
        !          1026:      register rtx x;
        !          1027:      void (*fun) ();
        !          1028: {
        !          1029:   if ((GET_CODE (x) == SET || GET_CODE (x) == CLOBBER))
        !          1030:     {
        !          1031:       register rtx dest = SET_DEST (x);
        !          1032:       while ((GET_CODE (dest) == SUBREG
        !          1033:              && (GET_CODE (SUBREG_REG (dest)) != REG
        !          1034:                  || REGNO (SUBREG_REG (dest)) >= FIRST_PSEUDO_REGISTER))
        !          1035:             || GET_CODE (dest) == ZERO_EXTRACT
        !          1036:             || GET_CODE (dest) == SIGN_EXTRACT
        !          1037:             || GET_CODE (dest) == STRICT_LOW_PART)
        !          1038:        dest = XEXP (dest, 0);
        !          1039:       (*fun) (dest, x);
        !          1040:     }
        !          1041:   else if (GET_CODE (x) == PARALLEL)
        !          1042:     {
        !          1043:       register int i;
        !          1044:       for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
        !          1045:        {
        !          1046:          register rtx y = XVECEXP (x, 0, i);
        !          1047:          if (GET_CODE (y) == SET || GET_CODE (y) == CLOBBER)
        !          1048:            {
        !          1049:              register rtx dest = SET_DEST (y);
        !          1050:              while ((GET_CODE (dest) == SUBREG
        !          1051:                      && (GET_CODE (SUBREG_REG (dest)) != REG
        !          1052:                          || (REGNO (SUBREG_REG (dest))
        !          1053:                              >= FIRST_PSEUDO_REGISTER)))
        !          1054:                     || GET_CODE (dest) == ZERO_EXTRACT
        !          1055:                     || GET_CODE (dest) == SIGN_EXTRACT
        !          1056:                     || GET_CODE (dest) == STRICT_LOW_PART)
        !          1057:                dest = XEXP (dest, 0);
        !          1058:              (*fun) (dest, y);
        !          1059:            }
        !          1060:        }
        !          1061:     }
        !          1062: }
        !          1063: 
        !          1064: /* Return nonzero if X's old contents don't survive after INSN.
        !          1065:    This will be true if X is (cc0) or if X is a register and
        !          1066:    X dies in INSN or because INSN entirely sets X.
        !          1067: 
        !          1068:    "Entirely set" means set directly and not through a SUBREG,
        !          1069:    ZERO_EXTRACT or SIGN_EXTRACT, so no trace of the old contents remains.
        !          1070:    Likewise, REG_INC does not count.
        !          1071: 
        !          1072:    REG may be a hard or pseudo reg.  Renumbering is not taken into account,
        !          1073:    but for this use that makes no difference, since regs don't overlap
        !          1074:    during their lifetimes.  Therefore, this function may be used
        !          1075:    at any time after deaths have been computed (in flow.c).
        !          1076: 
        !          1077:    If REG is a hard reg that occupies multiple machine registers, this
        !          1078:    function will only return 1 if each of those registers will be replaced
        !          1079:    by INSN.  */
        !          1080: 
        !          1081: int
        !          1082: dead_or_set_p (insn, x)
        !          1083:      rtx insn;
        !          1084:      rtx x;
        !          1085: {
        !          1086:   register int regno, last_regno;
        !          1087:   register int i;
        !          1088: 
        !          1089:   /* Can't use cc0_rtx below since this file is used by genattrtab.c.  */
        !          1090:   if (GET_CODE (x) == CC0)
        !          1091:     return 1;
        !          1092: 
        !          1093:   if (GET_CODE (x) != REG)
        !          1094:     abort ();
        !          1095: 
        !          1096:   regno = REGNO (x);
        !          1097:   last_regno = (regno >= FIRST_PSEUDO_REGISTER ? regno
        !          1098:                : regno + HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1);
        !          1099: 
        !          1100:   for (i = regno; i <= last_regno; i++)
        !          1101:     if (! dead_or_set_regno_p (insn, i))
        !          1102:       return 0;
        !          1103: 
        !          1104:   return 1;
        !          1105: }
        !          1106: 
        !          1107: /* Utility function for dead_or_set_p to check an individual register.  Also
        !          1108:    called from flow.c.  */
        !          1109: 
        !          1110: int
        !          1111: dead_or_set_regno_p (insn, test_regno)
        !          1112:      rtx insn;
        !          1113:      int test_regno;
        !          1114: {
        !          1115:   int regno, endregno;
        !          1116:   rtx link;
        !          1117: 
        !          1118:   /* See if there is a death note for something that includes TEST_REGNO.  */
        !          1119:   for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
        !          1120:     {
        !          1121:       if (REG_NOTE_KIND (link) != REG_DEAD || GET_CODE (XEXP (link, 0)) != REG)
        !          1122:        continue;
        !          1123: 
        !          1124:       regno = REGNO (XEXP (link, 0));
        !          1125:       endregno = (regno >= FIRST_PSEUDO_REGISTER ? regno + 1
        !          1126:                  : regno + HARD_REGNO_NREGS (regno,
        !          1127:                                              GET_MODE (XEXP (link, 0))));
        !          1128: 
        !          1129:       if (test_regno >= regno && test_regno < endregno)
        !          1130:        return 1;
        !          1131:     }
        !          1132: 
        !          1133:   if (GET_CODE (PATTERN (insn)) == SET)
        !          1134:     {
        !          1135:       rtx dest = SET_DEST (PATTERN (insn));
        !          1136:  
        !          1137:       /* A value is totally replaced if it is the destination or the
        !          1138:         destination is a SUBREG of REGNO that does not change the number of
        !          1139:         words in it.  */
        !          1140:      if (GET_CODE (dest) == SUBREG
        !          1141:          && (((GET_MODE_SIZE (GET_MODE (dest))
        !          1142:                + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
        !          1143:              == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest)))
        !          1144:                   + UNITS_PER_WORD - 1) / UNITS_PER_WORD)))
        !          1145:        dest = SUBREG_REG (dest);
        !          1146: 
        !          1147:       if (GET_CODE (dest) != REG)
        !          1148:        return 0;
        !          1149: 
        !          1150:       regno = REGNO (dest);
        !          1151:       endregno = (regno >= FIRST_PSEUDO_REGISTER ? regno + 1
        !          1152:                  : regno + HARD_REGNO_NREGS (regno, GET_MODE (dest)));
        !          1153: 
        !          1154:       return (test_regno >= regno && test_regno < endregno);
        !          1155:     }
        !          1156:   else if (GET_CODE (PATTERN (insn)) == PARALLEL)
        !          1157:     {
        !          1158:       register int i;
        !          1159: 
        !          1160:       for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
        !          1161:        {
        !          1162:          rtx body = XVECEXP (PATTERN (insn), 0, i);
        !          1163: 
        !          1164:          if (GET_CODE (body) == SET || GET_CODE (body) == CLOBBER)
        !          1165:            {
        !          1166:              rtx dest = SET_DEST (body);
        !          1167: 
        !          1168:              if (GET_CODE (dest) == SUBREG
        !          1169:                  && (((GET_MODE_SIZE (GET_MODE (dest))
        !          1170:                        + UNITS_PER_WORD - 1) / UNITS_PER_WORD)
        !          1171:                      == ((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest)))
        !          1172:                           + UNITS_PER_WORD - 1) / UNITS_PER_WORD)))
        !          1173:                dest = SUBREG_REG (dest);
        !          1174: 
        !          1175:              if (GET_CODE (dest) != REG)
        !          1176:                continue;
        !          1177: 
        !          1178:              regno = REGNO (dest);
        !          1179:              endregno = (regno >= FIRST_PSEUDO_REGISTER ? regno + 1
        !          1180:                          : regno + HARD_REGNO_NREGS (regno, GET_MODE (dest)));
        !          1181: 
        !          1182:              if (test_regno >= regno && test_regno < endregno)
        !          1183:                return 1;
        !          1184:            }
        !          1185:        }
        !          1186:     }
        !          1187: 
        !          1188:   return 0;
        !          1189: }
        !          1190: 
        !          1191: /* Return the reg-note of kind KIND in insn INSN, if there is one.
        !          1192:    If DATUM is nonzero, look for one whose datum is DATUM.  */
        !          1193: 
        !          1194: rtx
        !          1195: find_reg_note (insn, kind, datum)
        !          1196:      rtx insn;
        !          1197:      enum reg_note kind;
        !          1198:      rtx datum;
        !          1199: {
        !          1200:   register rtx link;
        !          1201: 
        !          1202:   for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
        !          1203:     if (REG_NOTE_KIND (link) == kind
        !          1204:        && (datum == 0 || datum == XEXP (link, 0)))
        !          1205:       return link;
        !          1206:   return 0;
        !          1207: }
        !          1208: 
        !          1209: /* Return the reg-note of kind KIND in insn INSN which applies to register
        !          1210:    number REGNO, if any.  Return 0 if there is no such reg-note.  Note that
        !          1211:    the REGNO of this NOTE need not be REGNO if REGNO is a hard register;
        !          1212:    it might be the case that the note overlaps REGNO.  */
        !          1213: 
        !          1214: rtx
        !          1215: find_regno_note (insn, kind, regno)
        !          1216:      rtx insn;
        !          1217:      enum reg_note kind;
        !          1218:      int regno;
        !          1219: {
        !          1220:   register rtx link;
        !          1221: 
        !          1222:   for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
        !          1223:     if (REG_NOTE_KIND (link) == kind
        !          1224:        /* Verify that it is a register, so that scratch and MEM won't cause a
        !          1225:           problem here.  */
        !          1226:        && GET_CODE (XEXP (link, 0)) == REG
        !          1227:        && REGNO (XEXP (link, 0)) <= regno
        !          1228:        && ((REGNO (XEXP (link, 0))
        !          1229:             + (REGNO (XEXP (link, 0)) >= FIRST_PSEUDO_REGISTER ? 1
        !          1230:                : HARD_REGNO_NREGS (REGNO (XEXP (link, 0)),
        !          1231:                                    GET_MODE (XEXP (link, 0)))))
        !          1232:            > regno))
        !          1233:       return link;
        !          1234:   return 0;
        !          1235: }
        !          1236: 
        !          1237: /* Remove register note NOTE from the REG_NOTES of INSN.  */
        !          1238: 
        !          1239: void
        !          1240: remove_note (insn, note)
        !          1241:      register rtx note;
        !          1242:      register rtx insn;
        !          1243: {
        !          1244:   register rtx link;
        !          1245: 
        !          1246:   if (REG_NOTES (insn) == note)
        !          1247:     {
        !          1248:       REG_NOTES (insn) = XEXP (note, 1);
        !          1249:       return;
        !          1250:     }
        !          1251: 
        !          1252:   for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
        !          1253:     if (XEXP (link, 1) == note)
        !          1254:       {
        !          1255:        XEXP (link, 1) = XEXP (note, 1);
        !          1256:        return;
        !          1257:       }
        !          1258: 
        !          1259:   abort ();
        !          1260: }
        !          1261: 
        !          1262: /* Nonzero if X contains any volatile instructions.  These are instructions
        !          1263:    which may cause unpredictable machine state instructions, and thus no
        !          1264:    instructions should be moved or combined across them.  This includes
        !          1265:    only volatile asms and UNSPEC_VOLATILE instructions.  */
        !          1266: 
        !          1267: int
        !          1268: volatile_insn_p (x)
        !          1269:      rtx x;
        !          1270: {
        !          1271:   register RTX_CODE code;
        !          1272: 
        !          1273:   code = GET_CODE (x);
        !          1274:   switch (code)
        !          1275:     {
        !          1276:     case LABEL_REF:
        !          1277:     case SYMBOL_REF:
        !          1278:     case CONST_INT:
        !          1279:     case CONST:
        !          1280:     case CONST_DOUBLE:
        !          1281:     case CC0:
        !          1282:     case PC:
        !          1283:     case REG:
        !          1284:     case SCRATCH:
        !          1285:     case CLOBBER:
        !          1286:     case ASM_INPUT:
        !          1287:     case ADDR_VEC:
        !          1288:     case ADDR_DIFF_VEC:
        !          1289:     case CALL:
        !          1290:     case MEM:
        !          1291:       return 0;
        !          1292: 
        !          1293:     case UNSPEC_VOLATILE:
        !          1294:  /* case TRAP_IF: This isn't clear yet.  */
        !          1295:       return 1;
        !          1296: 
        !          1297:     case ASM_OPERANDS:
        !          1298:       if (MEM_VOLATILE_P (x))
        !          1299:        return 1;
        !          1300:     }
        !          1301: 
        !          1302:   /* Recursively scan the operands of this expression.  */
        !          1303: 
        !          1304:   {
        !          1305:     register char *fmt = GET_RTX_FORMAT (code);
        !          1306:     register int i;
        !          1307:     
        !          1308:     for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !          1309:       {
        !          1310:        if (fmt[i] == 'e')
        !          1311:          {
        !          1312:            if (volatile_refs_p (XEXP (x, i)))
        !          1313:              return 1;
        !          1314:          }
        !          1315:        if (fmt[i] == 'E')
        !          1316:          {
        !          1317:            register int j;
        !          1318:            for (j = 0; j < XVECLEN (x, i); j++)
        !          1319:              if (volatile_refs_p (XVECEXP (x, i, j)))
        !          1320:                return 1;
        !          1321:          }
        !          1322:       }
        !          1323:   }
        !          1324:   return 0;
        !          1325: }
        !          1326: 
        !          1327: /* Nonzero if X contains any volatile memory references
        !          1328:    UNSPEC_VOLATILE operations or volatile ASM_OPERANDS expressions.  */
        !          1329: 
        !          1330: int
        !          1331: volatile_refs_p (x)
        !          1332:      rtx x;
        !          1333: {
        !          1334:   register RTX_CODE code;
        !          1335: 
        !          1336:   code = GET_CODE (x);
        !          1337:   switch (code)
        !          1338:     {
        !          1339:     case LABEL_REF:
        !          1340:     case SYMBOL_REF:
        !          1341:     case CONST_INT:
        !          1342:     case CONST:
        !          1343:     case CONST_DOUBLE:
        !          1344:     case CC0:
        !          1345:     case PC:
        !          1346:     case REG:
        !          1347:     case SCRATCH:
        !          1348:     case CLOBBER:
        !          1349:     case ASM_INPUT:
        !          1350:     case ADDR_VEC:
        !          1351:     case ADDR_DIFF_VEC:
        !          1352:       return 0;
        !          1353: 
        !          1354:     case CALL:
        !          1355:     case UNSPEC_VOLATILE:
        !          1356:  /* case TRAP_IF: This isn't clear yet.  */
        !          1357:       return 1;
        !          1358: 
        !          1359:     case MEM:
        !          1360:     case ASM_OPERANDS:
        !          1361:       if (MEM_VOLATILE_P (x))
        !          1362:        return 1;
        !          1363:     }
        !          1364: 
        !          1365:   /* Recursively scan the operands of this expression.  */
        !          1366: 
        !          1367:   {
        !          1368:     register char *fmt = GET_RTX_FORMAT (code);
        !          1369:     register int i;
        !          1370:     
        !          1371:     for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !          1372:       {
        !          1373:        if (fmt[i] == 'e')
        !          1374:          {
        !          1375:            if (volatile_refs_p (XEXP (x, i)))
        !          1376:              return 1;
        !          1377:          }
        !          1378:        if (fmt[i] == 'E')
        !          1379:          {
        !          1380:            register int j;
        !          1381:            for (j = 0; j < XVECLEN (x, i); j++)
        !          1382:              if (volatile_refs_p (XVECEXP (x, i, j)))
        !          1383:                return 1;
        !          1384:          }
        !          1385:       }
        !          1386:   }
        !          1387:   return 0;
        !          1388: }
        !          1389: 
        !          1390: /* Similar to above, except that it also rejects register pre- and post-
        !          1391:    incrementing.  */
        !          1392: 
        !          1393: int
        !          1394: side_effects_p (x)
        !          1395:      rtx x;
        !          1396: {
        !          1397:   register RTX_CODE code;
        !          1398: 
        !          1399:   code = GET_CODE (x);
        !          1400:   switch (code)
        !          1401:     {
        !          1402:     case LABEL_REF:
        !          1403:     case SYMBOL_REF:
        !          1404:     case CONST_INT:
        !          1405:     case CONST:
        !          1406:     case CONST_DOUBLE:
        !          1407:     case CC0:
        !          1408:     case PC:
        !          1409:     case REG:
        !          1410:     case SCRATCH:
        !          1411:     case ASM_INPUT:
        !          1412:     case ADDR_VEC:
        !          1413:     case ADDR_DIFF_VEC:
        !          1414:       return 0;
        !          1415: 
        !          1416:     case CLOBBER:
        !          1417:       /* Reject CLOBBER with a non-VOID mode.  These are made by combine.c
        !          1418:         when some combination can't be done.  If we see one, don't think
        !          1419:         that we can simplify the expression.  */
        !          1420:       return (GET_MODE (x) != VOIDmode);
        !          1421: 
        !          1422:     case PRE_INC:
        !          1423:     case PRE_DEC:
        !          1424:     case POST_INC:
        !          1425:     case POST_DEC:
        !          1426:     case CALL:
        !          1427:     case UNSPEC_VOLATILE:
        !          1428:  /* case TRAP_IF: This isn't clear yet.  */
        !          1429:       return 1;
        !          1430: 
        !          1431:     case MEM:
        !          1432:     case ASM_OPERANDS:
        !          1433:       if (MEM_VOLATILE_P (x))
        !          1434:        return 1;
        !          1435:     }
        !          1436: 
        !          1437:   /* Recursively scan the operands of this expression.  */
        !          1438: 
        !          1439:   {
        !          1440:     register char *fmt = GET_RTX_FORMAT (code);
        !          1441:     register int i;
        !          1442:     
        !          1443:     for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !          1444:       {
        !          1445:        if (fmt[i] == 'e')
        !          1446:          {
        !          1447:            if (side_effects_p (XEXP (x, i)))
        !          1448:              return 1;
        !          1449:          }
        !          1450:        if (fmt[i] == 'E')
        !          1451:          {
        !          1452:            register int j;
        !          1453:            for (j = 0; j < XVECLEN (x, i); j++)
        !          1454:              if (side_effects_p (XVECEXP (x, i, j)))
        !          1455:                return 1;
        !          1456:          }
        !          1457:       }
        !          1458:   }
        !          1459:   return 0;
        !          1460: }
        !          1461: 
        !          1462: /* Return nonzero if evaluating rtx X might cause a trap.  */
        !          1463: 
        !          1464: int
        !          1465: may_trap_p (x)
        !          1466:      rtx x;
        !          1467: {
        !          1468:   int i;
        !          1469:   enum rtx_code code;
        !          1470:   char *fmt;
        !          1471: 
        !          1472:   if (x == 0)
        !          1473:     return 0;
        !          1474:   code = GET_CODE (x);
        !          1475:   switch (code)
        !          1476:     {
        !          1477:       /* Handle these cases quickly.  */
        !          1478:     case CONST_INT:
        !          1479:     case CONST_DOUBLE:
        !          1480:     case SYMBOL_REF:
        !          1481:     case LABEL_REF:
        !          1482:     case CONST:
        !          1483:     case PC:
        !          1484:     case CC0:
        !          1485:     case REG:
        !          1486:     case SCRATCH:
        !          1487:       return 0;
        !          1488: 
        !          1489:       /* Conditional trap can trap!  */
        !          1490:     case UNSPEC_VOLATILE:
        !          1491:     case TRAP_IF:
        !          1492:       return 1;
        !          1493: 
        !          1494:       /* Memory ref can trap unless it's a static var or a stack slot.  */
        !          1495:     case MEM:
        !          1496:       return rtx_addr_can_trap_p (XEXP (x, 0));
        !          1497: 
        !          1498:       /* Division by a non-constant might trap.  */
        !          1499:     case DIV:
        !          1500:     case MOD:
        !          1501:     case UDIV:
        !          1502:     case UMOD:
        !          1503:       if (! CONSTANT_P (XEXP (x, 1)))
        !          1504:        return 1;
        !          1505:       /* This was const0_rtx, but by not using that,
        !          1506:         we can link this file into other programs.  */
        !          1507:       if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) == 0)
        !          1508:        return 1;
        !          1509:     default:
        !          1510:       /* Any floating arithmetic may trap.  */
        !          1511:       if (GET_MODE_CLASS (GET_MODE (x)) == MODE_FLOAT)
        !          1512:        return 1;
        !          1513:     }
        !          1514: 
        !          1515:   fmt = GET_RTX_FORMAT (code);
        !          1516:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !          1517:     {
        !          1518:       if (fmt[i] == 'e')
        !          1519:        {
        !          1520:          if (may_trap_p (XEXP (x, i)))
        !          1521:            return 1;
        !          1522:        }
        !          1523:       else if (fmt[i] == 'E')
        !          1524:        {
        !          1525:          register int j;
        !          1526:          for (j = 0; j < XVECLEN (x, i); j++)
        !          1527:            if (may_trap_p (XVECEXP (x, i, j)))
        !          1528:              return 1;
        !          1529:        }
        !          1530:     }
        !          1531:   return 0;
        !          1532: }
        !          1533: 
        !          1534: /* Return nonzero if X contains a comparison that is not either EQ or NE,
        !          1535:    i.e., an inequality.  */
        !          1536: 
        !          1537: int
        !          1538: inequality_comparisons_p (x)
        !          1539:      rtx x;
        !          1540: {
        !          1541:   register char *fmt;
        !          1542:   register int len, i;
        !          1543:   register enum rtx_code code = GET_CODE (x);
        !          1544: 
        !          1545:   switch (code)
        !          1546:     {
        !          1547:     case REG:
        !          1548:     case SCRATCH:
        !          1549:     case PC:
        !          1550:     case CC0:
        !          1551:     case CONST_INT:
        !          1552:     case CONST_DOUBLE:
        !          1553:     case CONST:
        !          1554:     case LABEL_REF:
        !          1555:     case SYMBOL_REF:
        !          1556:       return 0;
        !          1557: 
        !          1558:     case LT:
        !          1559:     case LTU:
        !          1560:     case GT:
        !          1561:     case GTU:
        !          1562:     case LE:
        !          1563:     case LEU:
        !          1564:     case GE:
        !          1565:     case GEU:
        !          1566:       return 1;
        !          1567:     }
        !          1568: 
        !          1569:   len = GET_RTX_LENGTH (code);
        !          1570:   fmt = GET_RTX_FORMAT (code);
        !          1571: 
        !          1572:   for (i = 0; i < len; i++)
        !          1573:     {
        !          1574:       if (fmt[i] == 'e')
        !          1575:        {
        !          1576:          if (inequality_comparisons_p (XEXP (x, i)))
        !          1577:            return 1;
        !          1578:        }
        !          1579:       else if (fmt[i] == 'E')
        !          1580:        {
        !          1581:          register int j;
        !          1582:          for (j = XVECLEN (x, i) - 1; j >= 0; j--)
        !          1583:            if (inequality_comparisons_p (XVECEXP (x, i, j)))
        !          1584:              return 1;
        !          1585:        }
        !          1586:     }
        !          1587:            
        !          1588:   return 0;
        !          1589: }
        !          1590: 
        !          1591: /* Replace any occurrence of FROM in X with TO.
        !          1592: 
        !          1593:    Note that copying is not done so X must not be shared unless all copies
        !          1594:    are to be modified.  */
        !          1595: 
        !          1596: rtx
        !          1597: replace_rtx (x, from, to)
        !          1598:      rtx x, from, to;
        !          1599: {
        !          1600:   register int i, j;
        !          1601:   register char *fmt;
        !          1602: 
        !          1603:   if (x == from)
        !          1604:     return to;
        !          1605: 
        !          1606:   /* Allow this function to make replacements in EXPR_LISTs.  */
        !          1607:   if (x == 0)
        !          1608:     return 0;
        !          1609: 
        !          1610:   fmt = GET_RTX_FORMAT (GET_CODE (x));
        !          1611:   for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
        !          1612:     {
        !          1613:       if (fmt[i] == 'e')
        !          1614:        XEXP (x, i) = replace_rtx (XEXP (x, i), from, to);
        !          1615:       else if (fmt[i] == 'E')
        !          1616:        for (j = XVECLEN (x, i) - 1; j >= 0; j--)
        !          1617:          XVECEXP (x, i, j) = replace_rtx (XVECEXP (x, i, j), from, to);
        !          1618:     }
        !          1619: 
        !          1620:   return x;
        !          1621: }  
        !          1622: 
        !          1623: /* Throughout the rtx X, replace many registers according to REG_MAP.
        !          1624:    Return the replacement for X (which may be X with altered contents).
        !          1625:    REG_MAP[R] is the replacement for register R, or 0 for don't replace.
        !          1626:    NREGS is the length of REG_MAP; regs >= NREGS are not mapped.  
        !          1627: 
        !          1628:    We only support REG_MAP entries of REG or SUBREG.  Also, hard registers
        !          1629:    should not be mapped to pseudos or vice versa since validate_change
        !          1630:    is not called.
        !          1631: 
        !          1632:    If REPLACE_DEST is 1, replacements are also done in destinations;
        !          1633:    otherwise, only sources are replaced.  */
        !          1634: 
        !          1635: rtx
        !          1636: replace_regs (x, reg_map, nregs, replace_dest)
        !          1637:      rtx x;
        !          1638:      rtx *reg_map;
        !          1639:      int nregs;
        !          1640:      int replace_dest;
        !          1641: {
        !          1642:   register enum rtx_code code;
        !          1643:   register int i;
        !          1644:   register char *fmt;
        !          1645: 
        !          1646:   if (x == 0)
        !          1647:     return x;
        !          1648: 
        !          1649:   code = GET_CODE (x);
        !          1650:   switch (code)
        !          1651:     {
        !          1652:     case SCRATCH:
        !          1653:     case PC:
        !          1654:     case CC0:
        !          1655:     case CONST_INT:
        !          1656:     case CONST_DOUBLE:
        !          1657:     case CONST:
        !          1658:     case SYMBOL_REF:
        !          1659:     case LABEL_REF:
        !          1660:       return x;
        !          1661: 
        !          1662:     case REG:
        !          1663:       /* Verify that the register has an entry before trying to access it.  */
        !          1664:       if (REGNO (x) < nregs && reg_map[REGNO (x)] != 0)
        !          1665:        return reg_map[REGNO (x)];
        !          1666:       return x;
        !          1667: 
        !          1668:     case SUBREG:
        !          1669:       /* Prevent making nested SUBREGs.  */
        !          1670:       if (GET_CODE (SUBREG_REG (x)) == REG && REGNO (SUBREG_REG (x)) < nregs
        !          1671:          && reg_map[REGNO (SUBREG_REG (x))] != 0
        !          1672:          && GET_CODE (reg_map[REGNO (SUBREG_REG (x))]) == SUBREG)
        !          1673:        {
        !          1674:          rtx map_val = reg_map[REGNO (SUBREG_REG (x))];
        !          1675:          rtx map_inner = SUBREG_REG (map_val);
        !          1676: 
        !          1677:          if (GET_MODE (x) == GET_MODE (map_inner))
        !          1678:            return map_inner;
        !          1679:          else
        !          1680:            {
        !          1681:              /* We cannot call gen_rtx here since we may be linked with
        !          1682:                 genattrtab.c.  */
        !          1683:              /* Let's try clobbering the incoming SUBREG and see
        !          1684:                 if this is really safe.  */
        !          1685:              SUBREG_REG (x) = map_inner;
        !          1686:              SUBREG_WORD (x) += SUBREG_WORD (map_val);
        !          1687:              return x;
        !          1688: #if 0
        !          1689:              rtx new = rtx_alloc (SUBREG);
        !          1690:              PUT_MODE (new, GET_MODE (x));
        !          1691:              SUBREG_REG (new) = map_inner;
        !          1692:              SUBREG_WORD (new) = SUBREG_WORD (x) + SUBREG_WORD (map_val);
        !          1693: #endif
        !          1694:            }
        !          1695:        }
        !          1696:       break;
        !          1697: 
        !          1698:     case SET:
        !          1699:       if (replace_dest)
        !          1700:        SET_DEST (x) = replace_regs (SET_DEST (x), reg_map, nregs, 0);
        !          1701: 
        !          1702:       else if (GET_CODE (SET_DEST (x)) == MEM
        !          1703:               || GET_CODE (SET_DEST (x)) == STRICT_LOW_PART)
        !          1704:        /* Even if we are not to replace destinations, replace register if it
        !          1705:           is CONTAINED in destination (destination is memory or
        !          1706:           STRICT_LOW_PART).  */
        !          1707:        XEXP (SET_DEST (x), 0) = replace_regs (XEXP (SET_DEST (x), 0),
        !          1708:                                               reg_map, nregs, 0);
        !          1709:       else if (GET_CODE (SET_DEST (x)) == ZERO_EXTRACT)
        !          1710:        /* Similarly, for ZERO_EXTRACT we replace all operands.  */
        !          1711:        break;
        !          1712: 
        !          1713:       SET_SRC (x) = replace_regs (SET_SRC (x), reg_map, nregs, 0);
        !          1714:       return x;
        !          1715:     }
        !          1716: 
        !          1717:   fmt = GET_RTX_FORMAT (code);
        !          1718:   for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
        !          1719:     {
        !          1720:       if (fmt[i] == 'e')
        !          1721:        XEXP (x, i) = replace_regs (XEXP (x, i), reg_map, nregs, replace_dest);
        !          1722:       if (fmt[i] == 'E')
        !          1723:        {
        !          1724:          register int j;
        !          1725:          for (j = 0; j < XVECLEN (x, i); j++)
        !          1726:            XVECEXP (x, i, j) = replace_regs (XVECEXP (x, i, j), reg_map,
        !          1727:                                              nregs, replace_dest);
        !          1728:        }
        !          1729:     }
        !          1730:   return x;
        !          1731: }

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