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

1.1     ! root        1: /* OSF/rose half-pic support functions.
        !             2:    Copyright (C) 1992 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: /* The OSF/rose half-pic model assumes that the non-library code does
        !            21:    not need to have full PIC (position independent code), but rather,
        !            22:    that pointers to external references are put into the data section
        !            23:    and dereferenced as normal pointers.  References to static data does
        !            24:    not need to be PIC-ized.
        !            25: 
        !            26:    Another optimization is to have the compiler know what symbols are
        !            27:    in the shared libraries, and to only lay down the pointers to
        !            28:    things which in the library proper.  */
        !            29: 
        !            30: #include "config.h"
        !            31: 
        !            32: #ifdef HALF_PIC_INIT
        !            33: 
        !            34: #include "tree.h"
        !            35: #include "rtl.h"
        !            36: #include <stdio.h>
        !            37: #include "obstack.h"
        !            38: 
        !            39: #define obstack_chunk_alloc xmalloc
        !            40: #define obstack_chunk_free free
        !            41: 
        !            42: extern char *xmalloc ();
        !            43: extern void  free ();
        !            44: extern rtx eliminate_constant_term ();
        !            45: extern void assemble_name ();
        !            46: extern void output_addr_const ();
        !            47: 
        !            48: int flag_half_pic              = 0;    /* Global half-pic flag.  */
        !            49: int half_pic_number_ptrs       = 0;    /* # distinct pointers found */
        !            50: int half_pic_number_refs       = 0;    /* # half-pic references */
        !            51: int (*ptr_half_pic_address_p)() = half_pic_address_p;
        !            52: 
        !            53: /* Obstack to hold generated pic names.  */
        !            54: static struct obstack half_pic_obstack;
        !            55: 
        !            56: /* List of pointers created to pic references.  */
        !            57: 
        !            58: struct all_refs {
        !            59:   struct all_refs *hash_next;  /* next name in hash chain */
        !            60:   struct all_refs *next;       /* next name created */
        !            61:   int             external_p;  /* name is an external reference */
        !            62:   int             pointer_p;   /* pointer created.  */
        !            63:   char           *ref_name;    /* reference name to ptr to real_name */
        !            64:   int             ref_len;     /* reference name length */
        !            65:   char           *real_name;   /* real function/data name */
        !            66:   int             real_len;    /* strlen (real_name) */
        !            67: };
        !            68: 
        !            69: static struct all_refs *half_pic_names;
        !            70: 
        !            71: static char *half_pic_prefix;
        !            72: static int   half_pic_prefix_len;
        !            73: 
        !            74: 
        !            75: /* Return the hash bucket of a name or NULL.  The hash chain is
        !            76:    organized as a self reorganizing circularly linked chain.  It is
        !            77:    assumed that any name passed to use will never be reallocated.  For
        !            78:    names in SYMBOL_REF's this is true, because the names are allocated
        !            79:    on the permanent obstack.  */
        !            80: 
        !            81: #ifndef MAX_HASH_TABLE
        !            82: #define MAX_HASH_TABLE 1009
        !            83: #endif
        !            84: 
        !            85: #define HASHBITS 30
        !            86: 
        !            87: static struct all_refs *
        !            88: half_pic_hash (name, len, create_p)
        !            89:      char *name;               /* name to hash */
        !            90:      int len;                  /* length of the name (or 0 to call strlen) */
        !            91:      int create_p;             /* != 0 to create new hash bucket if new */
        !            92: {
        !            93:   static struct all_refs *hash_table[MAX_HASH_TABLE];
        !            94:   static struct all_refs  zero_all_refs;
        !            95: 
        !            96:   unsigned char *uname;
        !            97:   int hash;
        !            98:   int i;
        !            99:   int ch;
        !           100:   struct all_refs *first;
        !           101:   struct all_refs *ptr;
        !           102: 
        !           103:   if (len == 0)
        !           104:     len = strlen (name);
        !           105: 
        !           106:   /* Compute hash code */
        !           107:   uname = (unsigned char *)name;
        !           108:   ch = uname[0];
        !           109:   hash = len * 613 + ch;
        !           110:   for (i = 1; i < len; i += 2)
        !           111:     hash = (hash * 613) + uname[i];
        !           112: 
        !           113:   hash &= (1 << HASHBITS) - 1;
        !           114:   hash %= MAX_HASH_TABLE;
        !           115: 
        !           116:   /* See if the name is in the hash table.  */
        !           117:   ptr = first = hash_table[hash];
        !           118:   if (ptr)
        !           119:     {
        !           120:       do
        !           121:        {
        !           122:          if (len == ptr->real_len
        !           123:              && ch == *(ptr->real_name)
        !           124:              && !strcmp (name, ptr->real_name))
        !           125:            {
        !           126:              hash_table[hash] = ptr;
        !           127:              return ptr;
        !           128:            }
        !           129: 
        !           130:          ptr = ptr->hash_next;
        !           131:        }
        !           132:       while (ptr != first);
        !           133:     }
        !           134: 
        !           135:   /* name not in hash table.  */
        !           136:   if (!create_p)
        !           137:     return (struct all_refs *)0;
        !           138: 
        !           139:   ptr = (struct all_refs *) obstack_alloc (&half_pic_obstack, sizeof (struct all_refs));
        !           140:   *ptr = zero_all_refs;
        !           141: 
        !           142:   ptr->real_name = name;
        !           143:   ptr->real_len  = len;
        !           144: 
        !           145:   /* Update circular links.  */
        !           146:   if (first == (struct all_refs *)0)
        !           147:     ptr->hash_next = ptr;
        !           148: 
        !           149:   else
        !           150:     {
        !           151:       ptr->hash_next = first->hash_next;
        !           152:       first->hash_next = ptr;
        !           153:     }
        !           154: 
        !           155:   hash_table[hash] = ptr;
        !           156:   return ptr;
        !           157: }
        !           158: 
        !           159: 
        !           160: /* Do any half-pic initializations.  */
        !           161: 
        !           162: void
        !           163: half_pic_init ()
        !           164: {
        !           165:   flag_half_pic = TRUE;
        !           166:   half_pic_prefix = HALF_PIC_PREFIX;
        !           167:   half_pic_prefix_len = strlen (half_pic_prefix);
        !           168:   obstack_init (&half_pic_obstack);
        !           169: }
        !           170: 
        !           171: 
        !           172: /* Write out all pointers to pic references.  */
        !           173: 
        !           174: void
        !           175: half_pic_finish (stream)
        !           176:      FILE *stream;
        !           177: {
        !           178:   struct all_refs *p = half_pic_names;
        !           179: 
        !           180:   if (!p)
        !           181:     return;
        !           182: 
        !           183:   data_section ();
        !           184:   for (; p != 0; p = p->next)
        !           185:     {
        !           186:       /* Emit the pointer if used.  */
        !           187:       if (p->pointer_p)
        !           188:        {
        !           189:          ASM_OUTPUT_LABEL (stream, p->ref_name);
        !           190:          ASM_OUTPUT_INT (stream, gen_rtx (SYMBOL_REF, Pmode, p->real_name));
        !           191:        }
        !           192:     }
        !           193: }
        !           194: 
        !           195: 
        !           196: /* Encode in a declaration whether or not it is half-pic.  */
        !           197: 
        !           198: void
        !           199: half_pic_encode (decl)
        !           200:      tree decl;
        !           201: {
        !           202:   enum tree_code code = TREE_CODE (decl);
        !           203:   tree asm_name;
        !           204:   struct all_refs *ptr;
        !           205: 
        !           206:   if (!flag_half_pic)
        !           207:     return;
        !           208: 
        !           209:   if (code != VAR_DECL && code != FUNCTION_DECL)
        !           210:     return;
        !           211: 
        !           212:   asm_name = DECL_ASSEMBLER_NAME (decl);
        !           213: 
        !           214:   if (!asm_name)
        !           215:     return;
        !           216: 
        !           217: #ifdef HALF_PIC_DEBUG
        !           218:   if (HALF_PIC_DEBUG)
        !           219:     {
        !           220:       if (HALF_PIC_DEBUG)
        !           221:        fprintf (stderr, "\n========== Half_pic_encode %.*s\n",
        !           222:                 IDENTIFIER_LENGTH (asm_name),
        !           223:                 IDENTIFIER_POINTER (asm_name));
        !           224:       debug_tree (decl);
        !           225:     }
        !           226: #endif
        !           227: 
        !           228:   /* If this is not an external reference, it can't be half-pic.  */
        !           229:   if (!DECL_EXTERNAL (decl) && (code != VAR_DECL || !TREE_PUBLIC (decl)))
        !           230:     return;
        !           231: 
        !           232:   ptr = half_pic_hash (IDENTIFIER_POINTER (asm_name),
        !           233:                       IDENTIFIER_LENGTH (asm_name),
        !           234:                       TRUE);
        !           235: 
        !           236:   ptr->external_p = TRUE;
        !           237: 
        !           238: #ifdef HALF_PIC_DEBUG
        !           239:   if (HALF_PIC_DEBUG)
        !           240:     fprintf (stderr, "\n%.*s is half-pic\n",
        !           241:             IDENTIFIER_LENGTH (asm_name),
        !           242:             IDENTIFIER_POINTER (asm_name));
        !           243: #endif
        !           244: }
        !           245: 
        !           246: 
        !           247: /* Mark that an object is now local, and no longer needs half-pic.  */
        !           248: 
        !           249: void
        !           250: half_pic_declare (name)
        !           251:      char *name;
        !           252: {
        !           253:   struct all_refs *ptr;
        !           254: 
        !           255:   if (!flag_half_pic)
        !           256:     return;
        !           257: 
        !           258:   ptr = half_pic_hash (name, 0, FALSE);
        !           259:   if (!ptr)
        !           260:     return;
        !           261: 
        !           262:   ptr->external_p = FALSE;
        !           263: 
        !           264: #ifdef HALF_PIC_DEBUG
        !           265:   if (HALF_PIC_DEBUG)
        !           266:     fprintf (stderr, "\n========== Half_pic_declare %s\n", name);
        !           267: #endif
        !           268: }
        !           269: 
        !           270: 
        !           271: /* Mark that an object is explicitly external.  */
        !           272: 
        !           273: void
        !           274: half_pic_external (name)
        !           275:      char *name;
        !           276: {
        !           277:   struct all_refs *ptr;
        !           278: 
        !           279:   if (!flag_half_pic)
        !           280:     return;
        !           281: 
        !           282:   ptr = half_pic_hash (name, 0, TRUE);
        !           283:   if (!ptr)
        !           284:     return;
        !           285: 
        !           286:   ptr->external_p = TRUE;
        !           287: 
        !           288: #ifdef HALF_PIC_DEBUG
        !           289:   if (HALF_PIC_DEBUG)
        !           290:     fprintf (stderr, "\n========== Half_pic_external %s\n", name);
        !           291: #endif
        !           292: }
        !           293: 
        !           294: 
        !           295: /* Return whether an address is half-pic.  */
        !           296: 
        !           297: int
        !           298: half_pic_address_p (addr)
        !           299:      rtx addr;
        !           300: {
        !           301:   char *name;
        !           302:   int len;
        !           303:   struct all_refs *ptr;
        !           304: 
        !           305:   if (!flag_half_pic)
        !           306:     return FALSE;
        !           307: 
        !           308:   switch (GET_CODE (addr))
        !           309:     {
        !           310:     default:
        !           311:       break;
        !           312: 
        !           313:     case CONST:
        !           314:       {
        !           315:        rtx offset = const0_rtx;
        !           316:        addr = eliminate_constant_term (XEXP (addr, 0), &offset);
        !           317:        if (GET_CODE (addr) != SYMBOL_REF)
        !           318:          return FALSE;
        !           319:       }
        !           320:       /* fall through */
        !           321: 
        !           322:     case SYMBOL_REF:
        !           323:       name = XSTR (addr, 0);
        !           324: 
        !           325: #ifdef HALF_PIC_DEBUG
        !           326:       if (HALF_PIC_DEBUG)
        !           327:        fprintf (stderr, "\n========== Half_pic_address_p %s\n", name);
        !           328: #endif
        !           329: 
        !           330:       /* If this is a label, it will have a '*' in front of it.  */
        !           331:       if (name[0] == '*')
        !           332:        return FALSE;
        !           333: 
        !           334:       /* If this is a reference to the actual half-pic pointer, it
        !           335:         is obviously not half-pic.  */
        !           336: 
        !           337:       len = strlen (name);
        !           338:       if (len > half_pic_prefix_len
        !           339:          && half_pic_prefix[0] == name[0]
        !           340:          && !strncmp (name, half_pic_prefix, half_pic_prefix_len))
        !           341:        return FALSE;
        !           342: 
        !           343:       ptr = half_pic_hash (name, len, FALSE);
        !           344:       if (ptr == (struct all_refs *)0)
        !           345:        return FALSE;
        !           346: 
        !           347:       if (ptr->external_p)
        !           348:        {
        !           349: #ifdef HALF_PIC_DEBUG
        !           350:          if (HALF_PIC_DEBUG)
        !           351:            fprintf (stderr, "%s is half-pic\n", name);
        !           352: #endif
        !           353:          return TRUE;
        !           354:        }
        !           355:     }
        !           356: 
        !           357:   return FALSE;
        !           358: }
        !           359: 
        !           360: 
        !           361: /* Return the name of the pointer to the PIC function, allocating
        !           362:    it if need be.  */
        !           363: 
        !           364: struct rtx_def *
        !           365: half_pic_ptr (operand)
        !           366:      rtx operand;
        !           367: {
        !           368:   char *name;
        !           369:   struct all_refs *p;
        !           370:   int len;
        !           371: 
        !           372:   if (GET_CODE (operand) != SYMBOL_REF)
        !           373:     return operand;
        !           374: 
        !           375:   name = XSTR (operand, 0);
        !           376:   len = strlen (name);
        !           377:   p = half_pic_hash (name, len, FALSE);
        !           378:   if (p == (struct all_refs *)0 || !p->external_p)
        !           379:     return operand;
        !           380: 
        !           381:   if (!p->pointer_p)
        !           382:     {                          /* first time, create pointer */
        !           383:       obstack_grow (&half_pic_obstack, half_pic_prefix, half_pic_prefix_len);
        !           384:       obstack_grow (&half_pic_obstack, name, len+1);
        !           385: 
        !           386:       p->next      = half_pic_names;
        !           387:       p->ref_name  = (char *) obstack_finish (&half_pic_obstack);
        !           388:       p->ref_len   = len + half_pic_prefix_len;
        !           389:       p->pointer_p = TRUE;
        !           390: 
        !           391:       half_pic_names = p;
        !           392:       half_pic_number_ptrs++;
        !           393:     }
        !           394: 
        !           395:   half_pic_number_refs++;
        !           396:   return gen_rtx (SYMBOL_REF, Pmode, p->ref_name);
        !           397: }
        !           398: 
        !           399: #endif /* HALF_PIC_INIT */

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