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400 lines
9.0 KiB
C
400 lines
9.0 KiB
C
/* OSF/rose half-pic support functions.
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Copyright (C) 1992, 1997, 1998, 1999 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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/* The OSF/rose half-pic model assumes that the non-library code does
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not need to have full PIC (position independent code), but rather,
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that pointers to external references are put into the data section
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and dereferenced as normal pointers. References to static data does
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not need to be PIC-ized.
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Another optimization is to have the compiler know what symbols are
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in the shared libraries, and to only lay down the pointers to
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things which in the library proper. */
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#include "config.h"
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#ifdef HALF_PIC_INIT
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#include "system.h"
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#include "tree.h"
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#include "rtl.h"
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#include "expr.h"
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#include "output.h"
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#include "obstack.h"
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#include "halfpic.h"
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#define obstack_chunk_alloc xmalloc
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#define obstack_chunk_free free
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int flag_half_pic = 0; /* Global half-pic flag. */
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int half_pic_number_ptrs = 0; /* # distinct pointers found */
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int half_pic_number_refs = 0; /* # half-pic references */
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int (*ptr_half_pic_address_p) PARAMS ((rtx)) = half_pic_address_p;
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/* Obstack to hold generated pic names. */
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static struct obstack half_pic_obstack;
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/* List of pointers created to pic references. */
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struct all_refs {
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struct all_refs *hash_next; /* next name in hash chain */
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struct all_refs *next; /* next name created */
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int external_p; /* name is an external reference */
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int pointer_p; /* pointer created. */
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const char *ref_name; /* reference name to ptr to real_name */
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int ref_len; /* reference name length */
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const char *real_name; /* real function/data name */
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int real_len; /* strlen (real_name) */
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};
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static struct all_refs *half_pic_names;
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static const char *half_pic_prefix;
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static int half_pic_prefix_len;
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/* Return the hash bucket of a name or NULL. The hash chain is
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organized as a self reorganizing circularly linked chain. It is
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assumed that any name passed to use will never be reallocated. For
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names in SYMBOL_REF's this is true, because the names are allocated
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on the permanent obstack. */
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#ifndef MAX_HASH_TABLE
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#define MAX_HASH_TABLE 1009
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#endif
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#define HASHBITS 30
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static struct all_refs *half_pic_hash PARAMS ((const char *, int, int));
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static struct all_refs *
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half_pic_hash (name, len, create_p)
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const char *name; /* name to hash */
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int len; /* length of the name (or 0 to call strlen) */
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int create_p; /* != 0 to create new hash bucket if new */
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{
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static struct all_refs *hash_table[MAX_HASH_TABLE];
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static struct all_refs zero_all_refs;
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const unsigned char *uname;
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int hash;
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int i;
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int ch;
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struct all_refs *first;
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struct all_refs *ptr;
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if (len == 0)
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len = strlen (name);
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/* Compute hash code */
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uname = (const unsigned char *)name;
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ch = uname[0];
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hash = len * 613 + ch;
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for (i = 1; i < len; i += 2)
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hash = (hash * 613) + uname[i];
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hash &= (1 << HASHBITS) - 1;
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hash %= MAX_HASH_TABLE;
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/* See if the name is in the hash table. */
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ptr = first = hash_table[hash];
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if (ptr)
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{
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do
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{
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if (len == ptr->real_len
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&& ch == *(ptr->real_name)
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&& !strcmp (name, ptr->real_name))
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{
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hash_table[hash] = ptr;
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return ptr;
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}
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ptr = ptr->hash_next;
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}
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while (ptr != first);
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}
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/* name not in hash table. */
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if (!create_p)
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return (struct all_refs *) 0;
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ptr = (struct all_refs *) obstack_alloc (&half_pic_obstack, sizeof (struct all_refs));
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*ptr = zero_all_refs;
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ptr->real_name = name;
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ptr->real_len = len;
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/* Update circular links. */
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if (first == (struct all_refs *) 0)
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ptr->hash_next = ptr;
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else
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{
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ptr->hash_next = first->hash_next;
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first->hash_next = ptr;
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}
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hash_table[hash] = ptr;
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return ptr;
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}
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/* Do any half-pic initializations. */
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void
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half_pic_init ()
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{
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flag_half_pic = TRUE;
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half_pic_prefix = HALF_PIC_PREFIX;
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half_pic_prefix_len = strlen (half_pic_prefix);
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obstack_init (&half_pic_obstack);
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}
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/* Write out all pointers to pic references. */
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void
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half_pic_finish (stream)
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FILE *stream;
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{
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struct all_refs *p = half_pic_names;
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if (!p)
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return;
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data_section ();
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for (; p != 0; p = p->next)
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{
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/* Emit the pointer if used. */
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if (p->pointer_p)
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{
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ASM_OUTPUT_LABEL (stream, p->ref_name);
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assemble_aligned_integer (POINTER_SIZE / BITS_PER_UNIT,
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gen_rtx_SYMBOL_REF (Pmode, p->real_name));
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}
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}
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}
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/* Encode in a declaration whether or not it is half-pic. */
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void
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half_pic_encode (decl)
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tree decl;
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{
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enum tree_code code = TREE_CODE (decl);
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tree asm_name;
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struct all_refs *ptr;
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if (!flag_half_pic)
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return;
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if (code != VAR_DECL && code != FUNCTION_DECL)
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return;
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asm_name = DECL_ASSEMBLER_NAME (decl);
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if (!asm_name)
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return;
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#ifdef HALF_PIC_DEBUG
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if (HALF_PIC_DEBUG)
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{
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fprintf (stderr, "\n========== Half_pic_encode %.*s\n",
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IDENTIFIER_LENGTH (asm_name),
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IDENTIFIER_POINTER (asm_name));
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debug_tree (decl);
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}
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#endif
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/* If this is not an external reference, it can't be half-pic. */
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if (!DECL_EXTERNAL (decl) && (code != VAR_DECL || !TREE_PUBLIC (decl)))
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return;
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ptr = half_pic_hash (IDENTIFIER_POINTER (asm_name),
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IDENTIFIER_LENGTH (asm_name),
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TRUE);
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ptr->external_p = TRUE;
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#ifdef HALF_PIC_DEBUG
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if (HALF_PIC_DEBUG)
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fprintf (stderr, "\n%.*s is half-pic\n",
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IDENTIFIER_LENGTH (asm_name),
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IDENTIFIER_POINTER (asm_name));
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#endif
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}
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/* Mark that an object is now local, and no longer needs half-pic. */
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void
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half_pic_declare (name)
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const char *name;
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{
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struct all_refs *ptr;
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if (!flag_half_pic)
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return;
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ptr = half_pic_hash (name, 0, FALSE);
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if (!ptr)
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return;
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ptr->external_p = FALSE;
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#ifdef HALF_PIC_DEBUG
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if (HALF_PIC_DEBUG)
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fprintf (stderr, "\n========== Half_pic_declare %s\n", name);
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#endif
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}
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/* Mark that an object is explicitly external. */
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void
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half_pic_external (name)
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const char *name;
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{
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struct all_refs *ptr;
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if (!flag_half_pic)
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return;
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ptr = half_pic_hash (name, 0, TRUE);
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if (!ptr)
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return;
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ptr->external_p = TRUE;
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#ifdef HALF_PIC_DEBUG
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if (HALF_PIC_DEBUG)
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fprintf (stderr, "\n========== Half_pic_external %s\n", name);
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#endif
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}
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/* Return whether an address is half-pic. */
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int
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half_pic_address_p (addr)
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rtx addr;
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{
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const char *name;
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int len;
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struct all_refs *ptr;
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if (!flag_half_pic)
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return FALSE;
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switch (GET_CODE (addr))
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{
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default:
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break;
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case CONST:
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{
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rtx offset = const0_rtx;
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addr = eliminate_constant_term (XEXP (addr, 0), &offset);
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if (GET_CODE (addr) != SYMBOL_REF)
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return FALSE;
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}
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/* fall through */
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case SYMBOL_REF:
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name = XSTR (addr, 0);
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#ifdef HALF_PIC_DEBUG
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if (HALF_PIC_DEBUG)
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fprintf (stderr, "\n========== Half_pic_address_p %s\n", name);
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#endif
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/* If this is a label, it will have a '*' in front of it. */
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if (name[0] == '*')
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return FALSE;
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/* If this is a reference to the actual half-pic pointer, it
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is obviously not half-pic. */
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len = strlen (name);
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if (len > half_pic_prefix_len
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&& half_pic_prefix[0] == name[0]
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&& !strncmp (name, half_pic_prefix, half_pic_prefix_len))
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return FALSE;
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ptr = half_pic_hash (name, len, FALSE);
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if (ptr == (struct all_refs *) 0)
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return FALSE;
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if (ptr->external_p)
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{
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#ifdef HALF_PIC_DEBUG
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if (HALF_PIC_DEBUG)
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fprintf (stderr, "%s is half-pic\n", name);
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#endif
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return TRUE;
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}
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}
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return FALSE;
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}
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/* Return the name of the pointer to the PIC function, allocating
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it if need be. */
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struct rtx_def *
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half_pic_ptr (operand)
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rtx operand;
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{
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const char *name;
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struct all_refs *p;
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int len;
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if (GET_CODE (operand) != SYMBOL_REF)
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return operand;
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name = XSTR (operand, 0);
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len = strlen (name);
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p = half_pic_hash (name, len, FALSE);
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if (p == (struct all_refs *) 0 || !p->external_p)
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return operand;
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if (!p->pointer_p)
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{ /* first time, create pointer */
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obstack_grow (&half_pic_obstack, half_pic_prefix, half_pic_prefix_len);
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obstack_grow (&half_pic_obstack, name, len+1);
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p->next = half_pic_names;
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p->ref_name = (char *) obstack_finish (&half_pic_obstack);
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p->ref_len = len + half_pic_prefix_len;
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p->pointer_p = TRUE;
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half_pic_names = p;
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half_pic_number_ptrs++;
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}
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half_pic_number_refs++;
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return gen_rtx_SYMBOL_REF (Pmode, p->ref_name);
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}
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#endif /* HALF_PIC_INIT */
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