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gcc.gnu.org Git - gcc.git/blob - gcc/halfpic.c
1 /* OSF/rose half-pic support functions.
2 Copyright (C) 1992 Free Software Foundation, Inc.
4 This file is part of GNU CC.
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)
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.
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. */
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.
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. */
39 #define obstack_chunk_alloc xmalloc
40 #define obstack_chunk_free free
42 extern char *xmalloc ();
44 extern rtx
eliminate_constant_term ();
45 extern void assemble_name ();
46 extern void output_addr_const ();
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
;
53 /* Obstack to hold generated pic names. */
54 static struct obstack half_pic_obstack
;
56 /* List of pointers created to pic references. */
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) */
69 static struct all_refs
*half_pic_names
;
71 static char *half_pic_prefix
;
72 static int half_pic_prefix_len
;
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. */
81 #ifndef MAX_HASH_TABLE
82 #define MAX_HASH_TABLE 1009
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 */
93 static struct all_refs
*hash_table
[MAX_HASH_TABLE
];
94 static struct all_refs zero_all_refs
;
100 struct all_refs
*first
;
101 struct all_refs
*ptr
;
106 /* Compute hash code */
107 uname
= (unsigned char *)name
;
109 hash
= len
* 613 + ch
;
110 for (i
= 1; i
< len
; i
+= 2)
111 hash
= (hash
* 613) + uname
[i
];
113 hash
&= (1 << HASHBITS
) - 1;
114 hash
%= MAX_HASH_TABLE
;
116 /* See if the name is in the hash table. */
117 ptr
= first
= hash_table
[hash
];
122 if (len
== ptr
->real_len
123 && ch
== *(ptr
->real_name
)
124 && !strcmp (name
, ptr
->real_name
))
126 hash_table
[hash
] = ptr
;
130 ptr
= ptr
->hash_next
;
132 while (ptr
!= first
);
135 /* name not in hash table. */
137 return (struct all_refs
*)0;
139 ptr
= (struct all_refs
*) obstack_alloc (&half_pic_obstack
, sizeof (struct all_refs
));
140 *ptr
= zero_all_refs
;
142 ptr
->real_name
= name
;
145 /* Update circular links. */
146 if (first
== (struct all_refs
*)0)
147 ptr
->hash_next
= ptr
;
151 ptr
->hash_next
= first
->hash_next
;
152 first
->hash_next
= ptr
;
155 hash_table
[hash
] = ptr
;
160 /* Do any half-pic initializations. */
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
);
172 /* Write out all pointers to pic references. */
175 half_pic_finish (stream
)
178 struct all_refs
*p
= half_pic_names
;
184 for (; p
!= 0; p
= p
->next
)
186 /* Emit the pointer if used. */
189 ASM_OUTPUT_LABEL (stream
, p
->ref_name
);
190 ASM_OUTPUT_INT (stream
, gen_rtx (SYMBOL_REF
, Pmode
, p
->real_name
));
196 /* Encode in a declaration whether or not it is half-pic. */
199 half_pic_encode (decl
)
202 enum tree_code code
= TREE_CODE (decl
);
204 struct all_refs
*ptr
;
209 if (code
!= VAR_DECL
&& code
!= FUNCTION_DECL
)
212 asm_name
= DECL_ASSEMBLER_NAME (decl
);
217 #ifdef HALF_PIC_DEBUG
221 fprintf (stderr
, "\n========== Half_pic_encode %.*s\n",
222 IDENTIFIER_LENGTH (asm_name
),
223 IDENTIFIER_POINTER (asm_name
));
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
)))
232 ptr
= half_pic_hash (IDENTIFIER_POINTER (asm_name
),
233 IDENTIFIER_LENGTH (asm_name
),
236 ptr
->external_p
= TRUE
;
238 #ifdef HALF_PIC_DEBUG
240 fprintf (stderr
, "\n%.*s is half-pic\n",
241 IDENTIFIER_LENGTH (asm_name
),
242 IDENTIFIER_POINTER (asm_name
));
247 /* Mark that an object is now local, and no longer needs half-pic. */
250 half_pic_declare (name
)
253 struct all_refs
*ptr
;
258 ptr
= half_pic_hash (name
, 0, FALSE
);
262 ptr
->external_p
= FALSE
;
264 #ifdef HALF_PIC_DEBUG
266 fprintf (stderr
, "\n========== Half_pic_declare %s\n", name
);
271 /* Return whether an address is half-pic. */
274 half_pic_address_p (addr
)
279 struct all_refs
*ptr
;
284 switch (GET_CODE (addr
))
291 rtx offset
= const0_rtx
;
292 addr
= eliminate_constant_term (XEXP (addr
, 0), &offset
);
293 if (GET_CODE (addr
) != SYMBOL_REF
)
299 name
= XSTR (addr
, 0);
301 #ifdef HALF_PIC_DEBUG
303 fprintf (stderr
, "\n========== Half_pic_address_p %s\n", name
);
306 /* If this is a label, it will have a '*' in front of it. */
310 /* If this is a reference to the actual half-pic pointer, it
311 is obviously not half-pic. */
314 if (len
> half_pic_prefix_len
315 && half_pic_prefix
[0] == name
[0]
316 && !strncmp (name
, half_pic_prefix
, half_pic_prefix_len
))
319 ptr
= half_pic_hash (name
, len
, FALSE
);
320 if (ptr
== (struct all_refs
*)0)
325 #ifdef HALF_PIC_DEBUG
327 fprintf (stderr
, "%s is half-pic\n", name
);
337 /* Return the name of the pointer to the PIC function, allocating
341 half_pic_ptr (operand
)
348 if (GET_CODE (operand
) != SYMBOL_REF
)
351 name
= XSTR (operand
, 0);
353 p
= half_pic_hash (name
, len
, FALSE
);
354 if (p
== (struct all_refs
*)0 || !p
->external_p
)
358 { /* first time, create pointer */
359 obstack_grow (&half_pic_obstack
, half_pic_prefix
, half_pic_prefix_len
);
360 obstack_grow (&half_pic_obstack
, name
, len
+1);
362 p
->next
= half_pic_names
;
363 p
->ref_name
= (char *) obstack_finish (&half_pic_obstack
);
364 p
->ref_len
= len
+ half_pic_prefix_len
;
368 half_pic_number_ptrs
++;
371 half_pic_number_refs
++;
372 return gen_rtx (SYMBOL_REF
, Pmode
, p
->ref_name
);
375 #endif /* HALF_PIC_INIT */
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