1 /* obstack.h - object stack macros
2 Copyright (C) 1988-1994,1996-1999,2003,2004,2005
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library 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 GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
19 Boston, MA 02110-1301, USA. */
23 All the apparent functions defined here are macros. The idea
24 is that you would use these pre-tested macros to solve a
25 very specific set of problems, and they would run fast.
26 Caution: no side-effects in arguments please!! They may be
27 evaluated MANY times!!
29 These macros operate a stack of objects. Each object starts life
30 small, and may grow to maturity. (Consider building a word syllable
31 by syllable.) An object can move while it is growing. Once it has
32 been "finished" it never changes address again. So the "top of the
33 stack" is typically an immature growing object, while the rest of the
34 stack is of mature, fixed size and fixed address objects.
36 These routines grab large chunks of memory, using a function you
37 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
38 by calling `obstack_chunk_free'. You must define them and declare
39 them before using any obstack macros.
41 Each independent stack is represented by a `struct obstack'.
42 Each of the obstack macros expects a pointer to such a structure
43 as the first argument.
45 One motivation for this package is the problem of growing char strings
46 in symbol tables. Unless you are "fascist pig with a read-only mind"
47 --Gosper's immortal quote from HAKMEM item 154, out of context--you
48 would not like to put any arbitrary upper limit on the length of your
51 In practice this often means you will build many short symbols and a
52 few long symbols. At the time you are reading a symbol you don't know
53 how long it is. One traditional method is to read a symbol into a
54 buffer, realloc()ating the buffer every time you try to read a symbol
55 that is longer than the buffer. This is beaut, but you still will
56 want to copy the symbol from the buffer to a more permanent
57 symbol-table entry say about half the time.
59 With obstacks, you can work differently. Use one obstack for all symbol
60 names. As you read a symbol, grow the name in the obstack gradually.
61 When the name is complete, finalize it. Then, if the symbol exists already,
62 free the newly read name.
64 The way we do this is to take a large chunk, allocating memory from
65 low addresses. When you want to build a symbol in the chunk you just
66 add chars above the current "high water mark" in the chunk. When you
67 have finished adding chars, because you got to the end of the symbol,
68 you know how long the chars are, and you can create a new object.
69 Mostly the chars will not burst over the highest address of the chunk,
70 because you would typically expect a chunk to be (say) 100 times as
71 long as an average object.
73 In case that isn't clear, when we have enough chars to make up
74 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
75 so we just point to it where it lies. No moving of chars is
76 needed and this is the second win: potentially long strings need
77 never be explicitly shuffled. Once an object is formed, it does not
78 change its address during its lifetime.
80 When the chars burst over a chunk boundary, we allocate a larger
81 chunk, and then copy the partly formed object from the end of the old
82 chunk to the beginning of the new larger chunk. We then carry on
83 accreting characters to the end of the object as we normally would.
85 A special macro is provided to add a single char at a time to a
86 growing object. This allows the use of register variables, which
87 break the ordinary 'growth' macro.
90 We allocate large chunks.
91 We carve out one object at a time from the current chunk.
92 Once carved, an object never moves.
93 We are free to append data of any size to the currently
95 Exactly one object is growing in an obstack at any one time.
96 You can run one obstack per control block.
97 You may have as many control blocks as you dare.
98 Because of the way we do it, you can `unwind' an obstack
99 back to a previous state. (You may remove objects much
100 as you would with a stack.)
104 /* Don't do the contents of this file more than once. */
109 #include "../begin.h"
111 /* We need the type of a pointer subtraction. If __PTRDIFF_TYPE__ is
112 defined, as with GNU C, use that; that way we don't pollute the
113 namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h>
114 and use ptrdiff_t. */
116 #ifdef __PTRDIFF_TYPE__
117 # define PTR_INT_TYPE __PTRDIFF_TYPE__
120 # define PTR_INT_TYPE ptrdiff_t
123 /* If B is the base of an object addressed by P, return the result of
124 aligning P to the next multiple of A + 1. B and P must be of type
125 char *. A + 1 must be a power of 2. */
127 #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
129 /* Similiar to _BPTR_ALIGN (B, P, A), except optimize the common case
130 where pointers can be converted to integers, aligned as integers,
131 and converted back again. If PTR_INT_TYPE is narrower than a
132 pointer (e.g., the AS/400), play it safe and compute the alignment
133 relative to B. Otherwise, use the faster strategy of computing the
134 alignment relative to 0. */
136 #define __PTR_ALIGN(B, P, A) \
137 __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \
143 struct _obstack_chunk /* Lives at front of each chunk. */
145 char *limit; /* 1 past end of this chunk */
146 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
147 char contents[4]; /* objects begin here */
150 struct obstack /* control current object in current chunk */
152 PTR_INT_TYPE chunk_size; /* preferred size to allocate chunks in */
153 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
154 char *object_base; /* address of object we are building */
155 char *next_free; /* where to add next char to current object */
156 char *chunk_limit; /* address of char after current chunk */
159 PTR_INT_TYPE tempint;
161 } temp; /* Temporary for some macros. */
162 int alignment_mask; /* Mask of alignment for each object. */
163 /* These prototypes vary based on `use_extra_arg', and we use
164 casts to the prototypeless function type in all assignments,
165 but having prototypes here quiets -Wstrict-prototypes. */
166 struct _obstack_chunk *(*chunkfun) (void *, PTR_INT_TYPE);
167 void (*freefun) (void *, struct _obstack_chunk *);
168 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
169 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
170 unsigned maybe_empty_object:1;/* There is a possibility that the current
171 chunk contains a zero-length object. This
172 prevents freeing the chunk if we allocate
173 a bigger chunk to replace it. */
174 unsigned alloc_failed:1; /* No longer used, as we now call the failed
175 handler on error, but retained for binary
179 /* Declare the external functions we use; they are in obstack.c. */
181 extern void _obstack_newchunk (struct obstack *, PTR_INT_TYPE);
182 extern int _obstack_begin (struct obstack *, int, int,
183 void *(*) (PTR_INT_TYPE), void (*) (void *));
184 extern int _obstack_begin_1 (struct obstack *, int, int,
185 void *(*) (void *, PTR_INT_TYPE),
186 void (*) (void *, void *), void *);
187 extern PTR_INT_TYPE _obstack_memory_used (struct obstack *);
189 void obstack_free (struct obstack *obstack, void *block);
192 /* Error handler called when `obstack_chunk_alloc' failed to allocate
193 more memory. This can be set to a user defined function which
194 should either abort gracefully or use longjump - but shouldn't
195 return. The default action is to print a message and abort. */
196 extern void (*obstack_alloc_failed_handler) (void);
198 /* Exit value used when `print_and_abort' is used. */
199 extern int obstack_exit_failure;
201 /* Pointer to beginning of object being allocated or to be allocated next.
202 Note that this might not be the final address of the object
203 because a new chunk might be needed to hold the final size. */
205 #define obstack_base(h) ((void *) (h)->object_base)
207 /* Size for allocating ordinary chunks. */
209 #define obstack_chunk_size(h) ((h)->chunk_size)
211 /* Pointer to next byte not yet allocated in current chunk. */
213 #define obstack_next_free(h) ((h)->next_free)
215 /* Mask specifying low bits that should be clear in address of an object. */
217 #define obstack_alignment_mask(h) ((h)->alignment_mask)
219 /* To prevent prototype warnings provide complete argument list. */
220 #define obstack_init(h) \
221 _obstack_begin ((h), 0, 0, \
222 (void *(*) (PTR_INT_TYPE)) obstack_chunk_alloc, \
223 (void (*) (void *)) obstack_chunk_free)
225 #define obstack_begin(h, size) \
226 _obstack_begin ((h), (size), 0, \
227 (void *(*) (PTR_INT_TYPE)) obstack_chunk_alloc, \
228 (void (*) (void *)) obstack_chunk_free)
230 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
231 _obstack_begin ((h), (size), (alignment), \
232 (void *(*) (PTR_INT_TYPE)) (chunkfun), \
233 (void (*) (void *)) (freefun))
235 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
236 _obstack_begin_1 ((h), (size), (alignment), \
237 (void *(*) (void *, PTR_INT_TYPE)) (chunkfun), \
238 (void (*) (void *, void *)) (freefun), (arg))
240 #define obstack_chunkfun(h, newchunkfun) \
241 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, PTR_INT_TYPE)) (newchunkfun))
243 #define obstack_freefun(h, newfreefun) \
244 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
246 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar))
248 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
250 #define obstack_memory_used(h) _obstack_memory_used (h)
252 #if defined __GNUC__ && defined __STDC__ && __STDC__
253 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
254 does not implement __extension__. But that compiler doesn't define
256 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
257 # define __extension__
260 /* For GNU C, if not -traditional,
261 we can define these macros to compute all args only once
262 without using a global variable.
263 Also, we can avoid using the `temp' slot, to make faster code. */
265 # define obstack_object_size(OBSTACK) \
267 ({ struct obstack const *__o = (OBSTACK); \
268 (unsigned) (__o->next_free - __o->object_base); })
270 # define obstack_room(OBSTACK) \
272 ({ struct obstack const *__o = (OBSTACK); \
273 (unsigned) (__o->chunk_limit - __o->next_free); })
275 # define obstack_make_room(OBSTACK,length) \
277 ({ struct obstack *__o = (OBSTACK); \
278 int __len = (length); \
279 if (__o->chunk_limit - __o->next_free < __len) \
280 _obstack_newchunk (__o, __len); \
283 # define obstack_empty_p(OBSTACK) \
285 ({ struct obstack const *__o = (OBSTACK); \
286 (__o->chunk->prev == 0 \
287 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \
288 __o->chunk->contents, \
289 __o->alignment_mask)); })
291 # define obstack_grow(OBSTACK,where,length) \
293 ({ struct obstack *__o = (OBSTACK); \
294 int __len = (length); \
295 if (__o->next_free + __len > __o->chunk_limit) \
296 _obstack_newchunk (__o, __len); \
297 memcpy (__o->next_free, where, __len); \
298 __o->next_free += __len; \
301 # define obstack_grow0(OBSTACK,where,length) \
303 ({ struct obstack *__o = (OBSTACK); \
304 int __len = (length); \
305 if (__o->next_free + __len + 1 > __o->chunk_limit) \
306 _obstack_newchunk (__o, __len + 1); \
307 memcpy (__o->next_free, where, __len); \
308 __o->next_free += __len; \
309 *(__o->next_free)++ = 0; \
312 # define obstack_1grow(OBSTACK,datum) \
314 ({ struct obstack *__o = (OBSTACK); \
315 if (__o->next_free + 1 > __o->chunk_limit) \
316 _obstack_newchunk (__o, 1); \
317 obstack_1grow_fast (__o, datum); \
320 /* These assume that the obstack alignment is good enough for pointers
321 or ints, and that the data added so far to the current object
322 shares that much alignment. */
324 # define obstack_ptr_grow(OBSTACK,datum) \
326 ({ struct obstack *__o = (OBSTACK); \
327 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
328 _obstack_newchunk (__o, sizeof (void *)); \
329 obstack_ptr_grow_fast (__o, datum); }) \
331 # define obstack_int_grow(OBSTACK,datum) \
333 ({ struct obstack *__o = (OBSTACK); \
334 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
335 _obstack_newchunk (__o, sizeof (int)); \
336 obstack_int_grow_fast (__o, datum); })
338 # define obstack_ptr_grow_fast(OBSTACK,aptr) \
340 ({ struct obstack *__o1 = (OBSTACK); \
341 *(const void **) __o1->next_free = (aptr); \
342 __o1->next_free += sizeof (const void *); \
345 # define obstack_int_grow_fast(OBSTACK,aint) \
347 ({ struct obstack *__o1 = (OBSTACK); \
348 *(int *) __o1->next_free = (aint); \
349 __o1->next_free += sizeof (int); \
352 # define obstack_blank(OBSTACK,length) \
354 ({ struct obstack *__o = (OBSTACK); \
355 int __len = (length); \
356 if (__o->chunk_limit - __o->next_free < __len) \
357 _obstack_newchunk (__o, __len); \
358 obstack_blank_fast (__o, __len); \
361 # define obstack_alloc(OBSTACK,length) \
363 ({ struct obstack *__h = (OBSTACK); \
364 obstack_blank (__h, (length)); \
365 obstack_finish (__h); })
367 # define obstack_copy(OBSTACK,where,length) \
369 ({ struct obstack *__h = (OBSTACK); \
370 obstack_grow (__h, (where), (length)); \
371 obstack_finish (__h); })
373 # define obstack_copy0(OBSTACK,where,length) \
375 ({ struct obstack *__h = (OBSTACK); \
376 obstack_grow0 (__h, (where), (length)); \
377 obstack_finish (__h); })
379 /* The local variable is named __o1 to avoid a name conflict
380 when obstack_blank is called. */
381 # define obstack_finish(OBSTACK) \
383 ({ struct obstack *__o1 = (OBSTACK); \
384 void *__value = (void *) __o1->object_base; \
385 if (__o1->next_free == __value) \
386 __o1->maybe_empty_object = 1; \
388 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \
389 __o1->alignment_mask); \
390 if (__o1->next_free - (char *)__o1->chunk \
391 > __o1->chunk_limit - (char *)__o1->chunk) \
392 __o1->next_free = __o1->chunk_limit; \
393 __o1->object_base = __o1->next_free; \
396 # define obstack_free(OBSTACK, OBJ) \
398 ({ struct obstack *__o = (OBSTACK); \
399 void *__obj = (OBJ); \
400 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
401 __o->next_free = __o->object_base = (char *)__obj; \
402 else (obstack_free) (__o, __obj); })
404 #else /* not __GNUC__ or not __STDC__ */
406 # define obstack_object_size(h) \
407 (unsigned) ((h)->next_free - (h)->object_base)
409 # define obstack_room(h) \
410 (unsigned) ((h)->chunk_limit - (h)->next_free)
412 # define obstack_empty_p(h) \
413 ((h)->chunk->prev == 0 \
414 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \
415 (h)->chunk->contents, \
416 (h)->alignment_mask))
418 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
419 so that we can avoid having void expressions
420 in the arms of the conditional expression.
421 Casting the third operand to void was tried before,
422 but some compilers won't accept it. */
424 # define obstack_make_room(h,length) \
425 ( (h)->temp.tempint = (length), \
426 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
427 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0))
429 # define obstack_grow(h,where,length) \
430 ( (h)->temp.tempint = (length), \
431 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
432 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
433 memcpy ((h)->next_free, where, (h)->temp.tempint), \
434 (h)->next_free += (h)->temp.tempint)
436 # define obstack_grow0(h,where,length) \
437 ( (h)->temp.tempint = (length), \
438 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \
439 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \
440 memcpy ((h)->next_free, where, (h)->temp.tempint), \
441 (h)->next_free += (h)->temp.tempint, \
442 *((h)->next_free)++ = 0)
444 # define obstack_1grow(h,datum) \
445 ( (((h)->next_free + 1 > (h)->chunk_limit) \
446 ? (_obstack_newchunk ((h), 1), 0) : 0), \
447 obstack_1grow_fast (h, datum))
449 # define obstack_ptr_grow(h,datum) \
450 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
451 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
452 obstack_ptr_grow_fast (h, datum))
454 # define obstack_int_grow(h,datum) \
455 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
456 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
457 obstack_int_grow_fast (h, datum))
459 # define obstack_ptr_grow_fast(h,aptr) \
460 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr))
462 # define obstack_int_grow_fast(h,aint) \
463 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint))
465 # define obstack_blank(h,length) \
466 ( (h)->temp.tempint = (length), \
467 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \
468 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
469 obstack_blank_fast (h, (h)->temp.tempint))
471 # define obstack_alloc(h,length) \
472 (obstack_blank ((h), (length)), obstack_finish ((h)))
474 # define obstack_copy(h,where,length) \
475 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
477 # define obstack_copy0(h,where,length) \
478 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
480 # define obstack_finish(h) \
481 ( ((h)->next_free == (h)->object_base \
482 ? (((h)->maybe_empty_object = 1), 0) \
484 (h)->temp.tempptr = (h)->object_base, \
486 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \
487 (h)->alignment_mask), \
488 (((h)->next_free - (char *) (h)->chunk \
489 > (h)->chunk_limit - (char *) (h)->chunk) \
490 ? ((h)->next_free = (h)->chunk_limit) : 0), \
491 (h)->object_base = (h)->next_free, \
494 # define obstack_free(h,obj) \
495 ( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \
496 ((((h)->temp.tempint > 0 \
497 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \
498 ? (int) ((h)->next_free = (h)->object_base \
499 = (h)->temp.tempint + (char *) (h)->chunk) \
500 : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0)))
502 #endif /* not __GNUC__ or not __STDC__ */
505 # define FIRM_NOTHROW throw ()
507 # define FIRM_NOTHROW
511 # define FIRM_PRINTF(a,b) __attribute__ ((__format__ (__printf__, a, b)))
513 # define FIRM_PRINTF(a,b)
516 /** prints formated string (printf-style format) to an obstack.
517 * This is done by "growing" the obstack with the obstack_*grow*
518 * functions. Note: Does NOT append a null-byte. */
519 int obstack_printf(struct obstack *obst, const char *fmt, ...)
520 FIRM_NOTHROW FIRM_PRINTF(2, 3);
521 int obstack_vprintf(struct obstack *obst, const char *fmt, va_list ap)
522 FIRM_NOTHROW FIRM_PRINTF(2, 0);