2 * Copyright (c) 1996-1998 by Silicon Graphics. All rights reserved.
4 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
7 * Permission is hereby granted to use or copy this program
8 * for any purpose, provided the above notices are retained on all copies.
9 * Permission to modify the code and to distribute modified code is granted,
10 * provided the above notices are retained, and a notice that the code was
11 * modified is included with the above copyright notice.
15 // This is a revision of gc_alloc.h for SGI STL versions > 3.0
16 // Unlike earlier versions, it supplements the standard "alloc.h"
17 // instead of replacing it.
19 // This is sloppy about variable names used in header files.
20 // It also doesn't yet understand the new header file names or
23 // This assumes the collector has been compiled with -DATOMIC_UNCOLLECTABLE.
24 // The user should also consider -DREDIRECT_MALLOC=GC_uncollectable_malloc,
25 // to ensure that object allocated through malloc are traced.
27 // Some of this could be faster in the explicit deallocation case.
28 // In particular, we spend too much time clearing objects on the
29 // free lists. That could be avoided.
31 // This uses template classes with static members, and hence does not work
32 // with g++ 2.7.2 and earlier.
34 // Unlike its predecessor, this one simply defines
36 // single_client_gc_alloc
38 // single_client_traceable_alloc
40 // It does not redefine alloc. Nor does it change the default allocator,
41 // though the user may wish to do so. (The argument against changing
42 // the default allocator is that it may introduce subtle link compatibility
43 // problems. The argument for changing it is that the usual default
44 // allocator is usually a very bad choice for a garbage collected environment.)
46 // This code assumes that the collector itself has been compiled with a
47 // compiler that defines __STDC__ .
55 # include <stack> // A more portable way to get stl_alloc.h .
57 # include <bits/stl_alloc.h>
58 # ifndef __STL_BEGIN_NAMESPACE
59 # define __STL_BEGIN_NAMESPACE namespace std {
60 # define __STL_END_NAMESPACE };
62 #ifndef __STL_USE_STD_ALLOCATORS
63 #define __STL_USE_STD_ALLOCATORS
73 // The following need to match collector data structures.
74 // We can't include gc_priv.h, since that pulls in way too much stuff.
75 // This should eventually be factored out into another include file.
78 extern void ** const GC_objfreelist_ptr;
79 extern void ** const GC_aobjfreelist_ptr;
80 extern void ** const GC_uobjfreelist_ptr;
81 extern void ** const GC_auobjfreelist_ptr;
83 extern void GC_incr_words_allocd(size_t words);
84 extern void GC_incr_mem_freed(size_t words);
86 extern char * GC_generic_malloc_words_small(size_t word, int kind);
89 // Object kinds; must match PTRFREE, NORMAL, UNCOLLECTABLE, and
90 // AUNCOLLECTABLE in gc_priv.h.
92 enum { GC_PTRFREE = 0, GC_NORMAL = 1, GC_UNCOLLECTABLE = 2,
93 GC_AUNCOLLECTABLE = 3 };
95 enum { GC_max_fast_bytes = 255 };
97 enum { GC_bytes_per_word = sizeof(char *) };
99 enum { GC_byte_alignment = 8 };
101 enum { GC_word_alignment = GC_byte_alignment/GC_bytes_per_word };
103 inline void * &GC_obj_link(void * p)
104 { return *(void **)p; }
106 // Compute a number of words >= n+1 bytes.
107 // The +1 allows for pointers one past the end.
108 inline size_t GC_round_up(size_t n)
110 return ((n + GC_byte_alignment)/GC_byte_alignment)*GC_word_alignment;
113 // The same but don't allow for extra byte.
114 inline size_t GC_round_up_uncollectable(size_t n)
116 return ((n + GC_byte_alignment - 1)/GC_byte_alignment)*GC_word_alignment;
120 class GC_aux_template {
122 // File local count of allocated words. Occasionally this is
123 // added into the global count. A separate count is necessary since the
124 // real one must be updated with a procedure call.
125 static size_t GC_words_recently_allocd;
127 // Same for uncollectable mmory. Not yet reflected in either
128 // GC_words_recently_allocd or GC_non_gc_bytes.
129 static size_t GC_uncollectable_words_recently_allocd;
131 // Similar counter for explicitly deallocated memory.
132 static size_t GC_mem_recently_freed;
134 // Again for uncollectable memory.
135 static size_t GC_uncollectable_mem_recently_freed;
137 static void * GC_out_of_line_malloc(size_t nwords, int kind);
141 size_t GC_aux_template<dummy>::GC_words_recently_allocd = 0;
144 size_t GC_aux_template<dummy>::GC_uncollectable_words_recently_allocd = 0;
147 size_t GC_aux_template<dummy>::GC_mem_recently_freed = 0;
150 size_t GC_aux_template<dummy>::GC_uncollectable_mem_recently_freed = 0;
153 void * GC_aux_template<dummy>::GC_out_of_line_malloc(size_t nwords, int kind)
155 GC_words_recently_allocd += GC_uncollectable_words_recently_allocd;
157 GC_bytes_per_word * GC_uncollectable_words_recently_allocd;
158 GC_uncollectable_words_recently_allocd = 0;
160 GC_mem_recently_freed += GC_uncollectable_mem_recently_freed;
162 GC_bytes_per_word * GC_uncollectable_mem_recently_freed;
163 GC_uncollectable_mem_recently_freed = 0;
165 GC_incr_words_allocd(GC_words_recently_allocd);
166 GC_words_recently_allocd = 0;
168 GC_incr_mem_freed(GC_mem_recently_freed);
169 GC_mem_recently_freed = 0;
171 return GC_generic_malloc_words_small(nwords, kind);
174 typedef GC_aux_template<0> GC_aux;
176 // A fast, single-threaded, garbage-collected allocator
177 // We assume the first word will be immediately overwritten.
178 // In this version, deallocation is not a noop, and explicit
179 // deallocation is likely to help performance.
181 class single_client_gc_alloc_template {
183 static void * allocate(size_t n)
185 size_t nwords = GC_round_up(n);
189 if (n > GC_max_fast_bytes) return GC_malloc(n);
190 flh = GC_objfreelist_ptr + nwords;
191 if (0 == (op = *flh)) {
192 return GC_aux::GC_out_of_line_malloc(nwords, GC_NORMAL);
194 *flh = GC_obj_link(op);
195 GC_aux::GC_words_recently_allocd += nwords;
198 static void * ptr_free_allocate(size_t n)
200 size_t nwords = GC_round_up(n);
204 if (n > GC_max_fast_bytes) return GC_malloc_atomic(n);
205 flh = GC_aobjfreelist_ptr + nwords;
206 if (0 == (op = *flh)) {
207 return GC_aux::GC_out_of_line_malloc(nwords, GC_PTRFREE);
209 *flh = GC_obj_link(op);
210 GC_aux::GC_words_recently_allocd += nwords;
213 static void deallocate(void *p, size_t n)
215 size_t nwords = GC_round_up(n);
218 if (n > GC_max_fast_bytes) {
221 flh = GC_objfreelist_ptr + nwords;
222 GC_obj_link(p) = *flh;
223 memset((char *)p + GC_bytes_per_word, 0,
224 GC_bytes_per_word * (nwords - 1));
226 GC_aux::GC_mem_recently_freed += nwords;
229 static void ptr_free_deallocate(void *p, size_t n)
231 size_t nwords = GC_round_up(n);
234 if (n > GC_max_fast_bytes) {
237 flh = GC_aobjfreelist_ptr + nwords;
238 GC_obj_link(p) = *flh;
240 GC_aux::GC_mem_recently_freed += nwords;
245 typedef single_client_gc_alloc_template<0> single_client_gc_alloc;
247 // Once more, for uncollectable objects.
249 class single_client_traceable_alloc_template {
251 static void * allocate(size_t n)
253 size_t nwords = GC_round_up_uncollectable(n);
257 if (n > GC_max_fast_bytes) return GC_malloc_uncollectable(n);
258 flh = GC_uobjfreelist_ptr + nwords;
259 if (0 == (op = *flh)) {
260 return GC_aux::GC_out_of_line_malloc(nwords, GC_UNCOLLECTABLE);
262 *flh = GC_obj_link(op);
263 GC_aux::GC_uncollectable_words_recently_allocd += nwords;
266 static void * ptr_free_allocate(size_t n)
268 size_t nwords = GC_round_up_uncollectable(n);
272 if (n > GC_max_fast_bytes) return GC_malloc_atomic_uncollectable(n);
273 flh = GC_auobjfreelist_ptr + nwords;
274 if (0 == (op = *flh)) {
275 return GC_aux::GC_out_of_line_malloc(nwords, GC_AUNCOLLECTABLE);
277 *flh = GC_obj_link(op);
278 GC_aux::GC_uncollectable_words_recently_allocd += nwords;
281 static void deallocate(void *p, size_t n)
283 size_t nwords = GC_round_up_uncollectable(n);
286 if (n > GC_max_fast_bytes) {
289 flh = GC_uobjfreelist_ptr + nwords;
290 GC_obj_link(p) = *flh;
292 GC_aux::GC_uncollectable_mem_recently_freed += nwords;
295 static void ptr_free_deallocate(void *p, size_t n)
297 size_t nwords = GC_round_up_uncollectable(n);
300 if (n > GC_max_fast_bytes) {
303 flh = GC_auobjfreelist_ptr + nwords;
304 GC_obj_link(p) = *flh;
306 GC_aux::GC_uncollectable_mem_recently_freed += nwords;
311 typedef single_client_traceable_alloc_template<0> single_client_traceable_alloc;
313 template < int dummy >
314 class gc_alloc_template {
316 static void * allocate(size_t n) { return GC_malloc(n); }
317 static void * ptr_free_allocate(size_t n)
318 { return GC_malloc_atomic(n); }
319 static void deallocate(void *, size_t) { }
320 static void ptr_free_deallocate(void *, size_t) { }
323 typedef gc_alloc_template < 0 > gc_alloc;
325 template < int dummy >
326 class traceable_alloc_template {
328 static void * allocate(size_t n) { return GC_malloc_uncollectable(n); }
329 static void * ptr_free_allocate(size_t n)
330 { return GC_malloc_atomic_uncollectable(n); }
331 static void deallocate(void *p, size_t) { GC_free(p); }
332 static void ptr_free_deallocate(void *p, size_t) { GC_free(p); }
335 typedef traceable_alloc_template < 0 > traceable_alloc;
337 // We want to specialize simple_alloc so that it does the right thing
338 // for all pointerfree types. At the moment there is no portable way to
339 // even approximate that. The following approximation should work for
340 // SGI compilers, and recent versions of g++.
342 # define __GC_SPECIALIZE(T,alloc) \
343 class simple_alloc<T, alloc> { \
345 static T *allocate(size_t n) \
346 { return 0 == n? 0 : \
347 (T*) alloc::ptr_free_allocate(n * sizeof (T)); } \
348 static T *allocate(void) \
349 { return (T*) alloc::ptr_free_allocate(sizeof (T)); } \
350 static void deallocate(T *p, size_t n) \
351 { if (0 != n) alloc::ptr_free_deallocate(p, n * sizeof (T)); } \
352 static void deallocate(T *p) \
353 { alloc::ptr_free_deallocate(p, sizeof (T)); } \
356 __STL_BEGIN_NAMESPACE
358 __GC_SPECIALIZE(char, gc_alloc)
359 __GC_SPECIALIZE(int, gc_alloc)
360 __GC_SPECIALIZE(unsigned, gc_alloc)
361 __GC_SPECIALIZE(float, gc_alloc)
362 __GC_SPECIALIZE(double, gc_alloc)
364 __GC_SPECIALIZE(char, traceable_alloc)
365 __GC_SPECIALIZE(int, traceable_alloc)
366 __GC_SPECIALIZE(unsigned, traceable_alloc)
367 __GC_SPECIALIZE(float, traceable_alloc)
368 __GC_SPECIALIZE(double, traceable_alloc)
370 __GC_SPECIALIZE(char, single_client_gc_alloc)
371 __GC_SPECIALIZE(int, single_client_gc_alloc)
372 __GC_SPECIALIZE(unsigned, single_client_gc_alloc)
373 __GC_SPECIALIZE(float, single_client_gc_alloc)
374 __GC_SPECIALIZE(double, single_client_gc_alloc)
376 __GC_SPECIALIZE(char, single_client_traceable_alloc)
377 __GC_SPECIALIZE(int, single_client_traceable_alloc)
378 __GC_SPECIALIZE(unsigned, single_client_traceable_alloc)
379 __GC_SPECIALIZE(float, single_client_traceable_alloc)
380 __GC_SPECIALIZE(double, single_client_traceable_alloc)
384 #ifdef __STL_USE_STD_ALLOCATORS
386 __STL_BEGIN_NAMESPACE
389 struct _Alloc_traits<_T, gc_alloc >
391 static const bool _S_instanceless = true;
392 typedef simple_alloc<_T, gc_alloc > _Alloc_type;
393 typedef __allocator<_T, gc_alloc > allocator_type;
396 inline bool operator==(const gc_alloc&,
402 inline bool operator!=(const gc_alloc&,
409 struct _Alloc_traits<_T, single_client_gc_alloc >
411 static const bool _S_instanceless = true;
412 typedef simple_alloc<_T, single_client_gc_alloc > _Alloc_type;
413 typedef __allocator<_T, single_client_gc_alloc > allocator_type;
416 inline bool operator==(const single_client_gc_alloc&,
417 const single_client_gc_alloc&)
422 inline bool operator!=(const single_client_gc_alloc&,
423 const single_client_gc_alloc&)
429 struct _Alloc_traits<_T, traceable_alloc >
431 static const bool _S_instanceless = true;
432 typedef simple_alloc<_T, traceable_alloc > _Alloc_type;
433 typedef __allocator<_T, traceable_alloc > allocator_type;
436 inline bool operator==(const traceable_alloc&,
437 const traceable_alloc&)
442 inline bool operator!=(const traceable_alloc&,
443 const traceable_alloc&)
449 struct _Alloc_traits<_T, single_client_traceable_alloc >
451 static const bool _S_instanceless = true;
452 typedef simple_alloc<_T, single_client_traceable_alloc > _Alloc_type;
453 typedef __allocator<_T, single_client_traceable_alloc > allocator_type;
456 inline bool operator==(const single_client_traceable_alloc&,
457 const single_client_traceable_alloc&)
462 inline bool operator!=(const single_client_traceable_alloc&,
463 const single_client_traceable_alloc&)
470 #endif /* __STL_USE_STD_ALLOCATORS */
472 #endif /* GC_ALLOC_H */