460 lines
14 KiB
C++
460 lines
14 KiB
C++
/*
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* Copyright (c) 1996-1998 by Silicon Graphics. All rights reserved.
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*
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* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
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* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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*
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* Permission is hereby granted to use or copy this program
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* for any purpose, provided the above notices are retained on all copies.
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* Permission to modify the code and to distribute modified code is granted,
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* provided the above notices are retained, and a notice that the code was
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* modified is included with the above copyright notice.
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*/
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//
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// This is a revision of gc_alloc.h for SGI STL versions > 3.0
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// Unlike earlier versions, it supplements the standard "alloc.h"
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// instead of replacing it.
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//
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// This is sloppy about variable names used in header files.
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// It also doesn't yet understand the new header file names or
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// namespaces.
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//
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// This assumes the collector has been compiled with -DATOMIC_UNCOLLECTABLE.
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// The user should also consider -DREDIRECT_MALLOC=GC_uncollectable_malloc,
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// to ensure that object allocated through malloc are traced.
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//
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// Some of this could be faster in the explicit deallocation case.
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// In particular, we spend too much time clearing objects on the
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// free lists. That could be avoided.
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//
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// This uses template classes with static members, and hence does not work
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// with g++ 2.7.2 and earlier.
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//
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// Unlike its predecessor, this one simply defines
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// gc_alloc
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// single_client_gc_alloc
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// traceable_alloc
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// single_client_traceable_alloc
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//
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// It does not redefine alloc. Nor does it change the default allocator,
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// though the user may wish to do so. (The argument against changing
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// the default allocator is that it may introduce subtle link compatibility
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// problems. The argument for changing it is that the usual default
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// allocator is usually a very bad choice for a garbage collected environment.)
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//
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// This code assumes that the collector itself has been compiled with a
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// compiler that defines __STDC__ .
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//
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#ifndef GC_ALLOC_H
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#include "gc.h"
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#include <stack> // A more portable way to get stl_alloc.h .
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#define GC_ALLOC_H
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#include <stddef.h>
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#include <string.h>
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// The following need to match collector data structures.
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// We can't include gc_priv.h, since that pulls in way too much stuff.
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// This should eventually be factored out into another include file.
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extern "C" {
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extern void ** const GC_objfreelist_ptr;
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extern void ** const GC_aobjfreelist_ptr;
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extern void ** const GC_uobjfreelist_ptr;
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extern void ** const GC_auobjfreelist_ptr;
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extern void GC_incr_words_allocd(size_t words);
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extern void GC_incr_mem_freed(size_t words);
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extern char * GC_generic_malloc_words_small(size_t word, int kind);
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}
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// Object kinds; must match PTRFREE, NORMAL, UNCOLLECTABLE, and
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// AUNCOLLECTABLE in gc_priv.h.
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enum { GC_PTRFREE = 0, GC_NORMAL = 1, GC_UNCOLLECTABLE = 2,
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GC_AUNCOLLECTABLE = 3 };
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enum { GC_max_fast_bytes = 255 };
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enum { GC_bytes_per_word = sizeof(char *) };
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enum { GC_byte_alignment = 8 };
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enum { GC_word_alignment = GC_byte_alignment/GC_bytes_per_word };
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inline void * &GC_obj_link(void * p)
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{ return *(void **)p; }
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// Compute a number of words >= n+1 bytes.
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// The +1 allows for pointers one past the end.
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inline size_t GC_round_up(size_t n)
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{
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return ((n + GC_byte_alignment)/GC_byte_alignment)*GC_word_alignment;
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}
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// The same but don't allow for extra byte.
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inline size_t GC_round_up_uncollectable(size_t n)
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{
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return ((n + GC_byte_alignment - 1)/GC_byte_alignment)*GC_word_alignment;
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}
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template <int dummy>
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class GC_aux_template {
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public:
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// File local count of allocated words. Occasionally this is
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// added into the global count. A separate count is necessary since the
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// real one must be updated with a procedure call.
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static size_t GC_words_recently_allocd;
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// Same for uncollectable mmory. Not yet reflected in either
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// GC_words_recently_allocd or GC_non_gc_bytes.
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static size_t GC_uncollectable_words_recently_allocd;
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// Similar counter for explicitly deallocated memory.
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static size_t GC_mem_recently_freed;
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// Again for uncollectable memory.
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static size_t GC_uncollectable_mem_recently_freed;
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static void * GC_out_of_line_malloc(size_t nwords, int kind);
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};
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template <int dummy>
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size_t GC_aux_template<dummy>::GC_words_recently_allocd = 0;
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template <int dummy>
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size_t GC_aux_template<dummy>::GC_uncollectable_words_recently_allocd = 0;
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template <int dummy>
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size_t GC_aux_template<dummy>::GC_mem_recently_freed = 0;
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template <int dummy>
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size_t GC_aux_template<dummy>::GC_uncollectable_mem_recently_freed = 0;
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template <int dummy>
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void * GC_aux_template<dummy>::GC_out_of_line_malloc(size_t nwords, int kind)
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{
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GC_words_recently_allocd += GC_uncollectable_words_recently_allocd;
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GC_non_gc_bytes +=
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GC_bytes_per_word * GC_uncollectable_words_recently_allocd;
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GC_uncollectable_words_recently_allocd = 0;
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GC_mem_recently_freed += GC_uncollectable_mem_recently_freed;
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GC_non_gc_bytes -=
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GC_bytes_per_word * GC_uncollectable_mem_recently_freed;
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GC_uncollectable_mem_recently_freed = 0;
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GC_incr_words_allocd(GC_words_recently_allocd);
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GC_words_recently_allocd = 0;
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GC_incr_mem_freed(GC_mem_recently_freed);
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GC_mem_recently_freed = 0;
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return GC_generic_malloc_words_small(nwords, kind);
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}
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typedef GC_aux_template<0> GC_aux;
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// A fast, single-threaded, garbage-collected allocator
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// We assume the first word will be immediately overwritten.
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// In this version, deallocation is not a noop, and explicit
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// deallocation is likely to help performance.
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template <int dummy>
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class single_client_gc_alloc_template {
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public:
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static void * allocate(size_t n)
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{
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size_t nwords = GC_round_up(n);
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void ** flh;
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void * op;
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if (n > GC_max_fast_bytes) return GC_malloc(n);
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flh = GC_objfreelist_ptr + nwords;
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if (0 == (op = *flh)) {
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return GC_aux::GC_out_of_line_malloc(nwords, GC_NORMAL);
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}
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*flh = GC_obj_link(op);
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GC_aux::GC_words_recently_allocd += nwords;
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return op;
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}
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static void * ptr_free_allocate(size_t n)
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{
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size_t nwords = GC_round_up(n);
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void ** flh;
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void * op;
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if (n > GC_max_fast_bytes) return GC_malloc_atomic(n);
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flh = GC_aobjfreelist_ptr + nwords;
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if (0 == (op = *flh)) {
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return GC_aux::GC_out_of_line_malloc(nwords, GC_PTRFREE);
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}
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*flh = GC_obj_link(op);
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GC_aux::GC_words_recently_allocd += nwords;
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return op;
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}
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static void deallocate(void *p, size_t n)
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{
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size_t nwords = GC_round_up(n);
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void ** flh;
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if (n > GC_max_fast_bytes) {
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GC_free(p);
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} else {
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flh = GC_objfreelist_ptr + nwords;
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GC_obj_link(p) = *flh;
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memset((char *)p + GC_bytes_per_word, 0,
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GC_bytes_per_word * (nwords - 1));
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*flh = p;
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GC_aux::GC_mem_recently_freed += nwords;
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}
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}
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static void ptr_free_deallocate(void *p, size_t n)
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{
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size_t nwords = GC_round_up(n);
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void ** flh;
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if (n > GC_max_fast_bytes) {
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GC_free(p);
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} else {
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flh = GC_aobjfreelist_ptr + nwords;
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GC_obj_link(p) = *flh;
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*flh = p;
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GC_aux::GC_mem_recently_freed += nwords;
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}
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}
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};
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typedef single_client_gc_alloc_template<0> single_client_gc_alloc;
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// Once more, for uncollectable objects.
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template <int dummy>
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class single_client_traceable_alloc_template {
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public:
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static void * allocate(size_t n)
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{
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size_t nwords = GC_round_up_uncollectable(n);
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void ** flh;
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void * op;
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if (n > GC_max_fast_bytes) return GC_malloc_uncollectable(n);
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flh = GC_uobjfreelist_ptr + nwords;
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if (0 == (op = *flh)) {
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return GC_aux::GC_out_of_line_malloc(nwords, GC_UNCOLLECTABLE);
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}
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*flh = GC_obj_link(op);
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GC_aux::GC_uncollectable_words_recently_allocd += nwords;
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return op;
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}
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static void * ptr_free_allocate(size_t n)
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{
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size_t nwords = GC_round_up_uncollectable(n);
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void ** flh;
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void * op;
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if (n > GC_max_fast_bytes) return GC_malloc_atomic_uncollectable(n);
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flh = GC_auobjfreelist_ptr + nwords;
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if (0 == (op = *flh)) {
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return GC_aux::GC_out_of_line_malloc(nwords, GC_AUNCOLLECTABLE);
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}
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*flh = GC_obj_link(op);
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GC_aux::GC_uncollectable_words_recently_allocd += nwords;
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return op;
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}
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static void deallocate(void *p, size_t n)
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{
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size_t nwords = GC_round_up_uncollectable(n);
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void ** flh;
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if (n > GC_max_fast_bytes) {
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GC_free(p);
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} else {
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flh = GC_uobjfreelist_ptr + nwords;
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GC_obj_link(p) = *flh;
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*flh = p;
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GC_aux::GC_uncollectable_mem_recently_freed += nwords;
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}
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}
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static void ptr_free_deallocate(void *p, size_t n)
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{
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size_t nwords = GC_round_up_uncollectable(n);
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void ** flh;
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if (n > GC_max_fast_bytes) {
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GC_free(p);
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} else {
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flh = GC_auobjfreelist_ptr + nwords;
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GC_obj_link(p) = *flh;
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*flh = p;
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GC_aux::GC_uncollectable_mem_recently_freed += nwords;
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}
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}
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};
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typedef single_client_traceable_alloc_template<0> single_client_traceable_alloc;
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template < int dummy >
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class gc_alloc_template {
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public:
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static void * allocate(size_t n) { return GC_malloc(n); }
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static void * ptr_free_allocate(size_t n)
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{ return GC_malloc_atomic(n); }
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static void deallocate(void *, size_t) { }
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static void ptr_free_deallocate(void *, size_t) { }
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};
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typedef gc_alloc_template < 0 > gc_alloc;
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template < int dummy >
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class traceable_alloc_template {
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public:
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static void * allocate(size_t n) { return GC_malloc_uncollectable(n); }
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static void * ptr_free_allocate(size_t n)
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{ return GC_malloc_atomic_uncollectable(n); }
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static void deallocate(void *p, size_t) { GC_free(p); }
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static void ptr_free_deallocate(void *p, size_t) { GC_free(p); }
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};
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typedef traceable_alloc_template < 0 > traceable_alloc;
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// We want to specialize simple_alloc so that it does the right thing
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// for all pointerfree types. At the moment there is no portable way to
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// even approximate that. The following approximation should work for
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// SGI compilers, and recent versions of g++.
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# define __GC_SPECIALIZE(T,alloc) \
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class simple_alloc<T, alloc> { \
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public: \
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static T *allocate(size_t n) \
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{ return 0 == n? 0 : \
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(T*) alloc::ptr_free_allocate(n * sizeof (T)); } \
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static T *allocate(void) \
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{ return (T*) alloc::ptr_free_allocate(sizeof (T)); } \
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static void deallocate(T *p, size_t n) \
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{ if (0 != n) alloc::ptr_free_deallocate(p, n * sizeof (T)); } \
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static void deallocate(T *p) \
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{ alloc::ptr_free_deallocate(p, sizeof (T)); } \
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};
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__STL_BEGIN_NAMESPACE
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__GC_SPECIALIZE(char, gc_alloc)
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__GC_SPECIALIZE(int, gc_alloc)
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__GC_SPECIALIZE(unsigned, gc_alloc)
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__GC_SPECIALIZE(float, gc_alloc)
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__GC_SPECIALIZE(double, gc_alloc)
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__GC_SPECIALIZE(char, traceable_alloc)
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__GC_SPECIALIZE(int, traceable_alloc)
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__GC_SPECIALIZE(unsigned, traceable_alloc)
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__GC_SPECIALIZE(float, traceable_alloc)
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__GC_SPECIALIZE(double, traceable_alloc)
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__GC_SPECIALIZE(char, single_client_gc_alloc)
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__GC_SPECIALIZE(int, single_client_gc_alloc)
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__GC_SPECIALIZE(unsigned, single_client_gc_alloc)
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__GC_SPECIALIZE(float, single_client_gc_alloc)
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__GC_SPECIALIZE(double, single_client_gc_alloc)
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__GC_SPECIALIZE(char, single_client_traceable_alloc)
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__GC_SPECIALIZE(int, single_client_traceable_alloc)
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__GC_SPECIALIZE(unsigned, single_client_traceable_alloc)
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__GC_SPECIALIZE(float, single_client_traceable_alloc)
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__GC_SPECIALIZE(double, single_client_traceable_alloc)
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__STL_END_NAMESPACE
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#ifdef __STL_USE_STD_ALLOCATORS
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__STL_BEGIN_NAMESPACE
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template <class _T>
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struct _Alloc_traits<_T, gc_alloc >
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{
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static const bool _S_instanceless = true;
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typedef simple_alloc<_T, gc_alloc > _Alloc_type;
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typedef __allocator<_T, gc_alloc > allocator_type;
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};
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inline bool operator==(const gc_alloc&,
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const gc_alloc&)
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{
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return true;
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}
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inline bool operator!=(const gc_alloc&,
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const gc_alloc&)
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{
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return false;
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}
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template <class _T>
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struct _Alloc_traits<_T, single_client_gc_alloc >
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{
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static const bool _S_instanceless = true;
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typedef simple_alloc<_T, single_client_gc_alloc > _Alloc_type;
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typedef __allocator<_T, single_client_gc_alloc > allocator_type;
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};
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inline bool operator==(const single_client_gc_alloc&,
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const single_client_gc_alloc&)
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{
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return true;
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}
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inline bool operator!=(const single_client_gc_alloc&,
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const single_client_gc_alloc&)
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{
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return false;
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}
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template <class _T>
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struct _Alloc_traits<_T, traceable_alloc >
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{
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static const bool _S_instanceless = true;
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typedef simple_alloc<_T, traceable_alloc > _Alloc_type;
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typedef __allocator<_T, traceable_alloc > allocator_type;
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};
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inline bool operator==(const traceable_alloc&,
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const traceable_alloc&)
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{
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return true;
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}
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inline bool operator!=(const traceable_alloc&,
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const traceable_alloc&)
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{
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return false;
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}
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template <class _T>
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struct _Alloc_traits<_T, single_client_traceable_alloc >
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{
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static const bool _S_instanceless = true;
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typedef simple_alloc<_T, single_client_traceable_alloc > _Alloc_type;
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typedef __allocator<_T, single_client_traceable_alloc > allocator_type;
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};
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inline bool operator==(const single_client_traceable_alloc&,
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const single_client_traceable_alloc&)
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{
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return true;
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}
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inline bool operator!=(const single_client_traceable_alloc&,
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const single_client_traceable_alloc&)
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{
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return false;
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}
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__STL_END_NAMESPACE
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#endif /* __STL_USE_STD_ALLOCATORS */
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#endif /* GC_ALLOC_H */
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