/* * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers * Copyright (c) 1991-1995 by Xerox Corporation. All rights reserved. * Copyright (c) 2005 Hewlett-Packard Development Company, L.P. * Copyright (c) 2008-2022 Ivan Maidanski * * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. * * Permission is hereby granted to use or copy this program * for any purpose, provided the above notices are retained on all copies. * Permission to modify the code and to distribute modified code is granted, * provided the above notices are retained, and a notice that the code was * modified is included with the above copyright notice. */ #ifndef GC_INLINE_H #define GC_INLINE_H /* WARNING: */ /* Note that for these routines, it is the clients responsibility to */ /* add the extra byte at the end to deal with one-past-the-end */ /* pointers. In the standard collector configuration, the collector */ /* assumes that such a byte has been added, and hence does not trace */ /* the last "pointer-sized" word in the resulting object. This is not */ /* an issue if GC_get_all_interior_pointers() returns 0 or */ /* if GC_get_dont_add_byte_at_end() returns 1. */ /* This interface is most useful for compilers that generate C. It is */ /* also used internally for thread-local allocation. A manual use is */ /* hereby discouraged. Clients should include atomic_ops.h (or */ /* similar) before this header. There is no debugging version of this */ /* allocation API. */ #include "gc.h" #include "gc_tiny_fl.h" #if GC_GNUC_PREREQ(3, 0) || defined(__clang__) # define GC_EXPECT(expr, outcome) __builtin_expect(expr, outcome) /* Equivalent to (expr), but predict that usually (expr)==outcome. */ #else # define GC_EXPECT(expr, outcome) (expr) #endif #ifndef GC_ASSERT # ifdef NDEBUG # define GC_ASSERT(expr) /* empty */ # else # include # define GC_ASSERT(expr) assert(expr) # endif #endif #ifndef GC_PREFETCH_FOR_WRITE # if (GC_GNUC_PREREQ(3, 0) || defined(__clang__)) \ && !defined(GC_NO_PREFETCH_FOR_WRITE) # define GC_PREFETCH_FOR_WRITE(x) __builtin_prefetch((x), 1 /* write */) # elif defined(_MSC_VER) && !defined(GC_NO_PREFETCH_FOR_WRITE) \ && (defined(_M_IX86) || defined(_M_X64)) && !defined(_CHPE_ONLY_) \ && (_MSC_VER >= 1900) /* VS 2015+ */ # include # define GC_PREFETCH_FOR_WRITE(x) _m_prefetchw(x) /* TODO: Support also _M_ARM (__prefetchw). */ # else # define GC_PREFETCH_FOR_WRITE(x) (void)0 # endif #endif #ifdef __cplusplus extern "C" { #endif /* Object kinds (exposed to public). */ #define GC_I_PTRFREE 0 #define GC_I_NORMAL 1 /* Determine if the collector has been configured not to pad the */ /* allocated objects even in the all-interior-pointers mode. */ /* Meaningful only if GC_get_all_interior_pointers() returns 1. */ GC_API int GC_CALL GC_get_dont_add_byte_at_end(void); /* Return a list of one or more objects of the indicated size, linked */ /* through the first pointer in each object. This has the advantage */ /* that it acquires the allocator lock only once, and may greatly */ /* reduce time wasted contending for the allocator lock. Typical usage */ /* would be in a thread that requires many items of the same size. */ /* It would keep its own free list in a thread-local storage, and call */ /* GC_malloc_many or friends to replenish it. (We do not round up */ /* object sizes, since a call indicates the intention to consume many */ /* objects of exactly this size.) We assume that the size is non-zero */ /* and a multiple of GC_GRANULE_BYTES, and that the size already */ /* includes the value returned by GC_get_all_interior_pointers() */ /* (unless GC_get_dont_add_byte_at_end() returns a non-zero value). */ /* We return the free-list by assigning it to (*result), since it is */ /* not safe to return, e.g. a linked list of pointer-free objects, */ /* since the collector would not retain the entire list if it were */ /* invoked just as we were returning; the client must make sure that */ /* (*result) is traced even if objects are pointer-free. Note also */ /* that the client should usually clear the link field. */ GC_API void GC_CALL GC_generic_malloc_many(size_t /* lb_adjusted */, int /* k */, void ** /* result */); /* Generalized version of GC_malloc and GC_malloc_atomic. */ /* Uses appropriately the thread-local (if available) or the global */ /* free-list of the specified kind. */ GC_API GC_ATTR_MALLOC GC_ATTR_ALLOC_SIZE(1) void * GC_CALL GC_malloc_kind(size_t /* lb */, int /* k */); #ifdef GC_THREADS /* Same as above but uses only the global free-list. */ GC_API GC_ATTR_MALLOC GC_ATTR_ALLOC_SIZE(1) void * GC_CALL GC_malloc_kind_global(size_t /* lb */, int /* k */); #else # define GC_malloc_kind_global GC_malloc_kind #endif /* An internal macro to update the free-list pointer atomically (if */ /* the AO primitives are available) to avoid race with the marker. */ #if !defined(GC_THREADS) || !defined(AO_HAVE_store) # define GC_FAST_M_AO_STORE(my_fl, next) (void)(*(my_fl) = (next)) #elif defined(__SIZEOF_POINTER__) && (__SIZEOF_POINTER__ > __SIZEOF_SIZE_T__) /* Directly use the GCC atomic intrinsic as the size of a pointer is */ /* bigger than that of AO_t. */ # define GC_FAST_M_AO_STORE(my_fl, next) \ __atomic_store_n(my_fl, next, __ATOMIC_RELAXED) #else # define GC_FAST_M_AO_STORE(my_fl, next) \ AO_store((volatile AO_t *)(my_fl), (size_t)(next)) #endif /* The ultimately general inline allocation macro. Allocate an object */ /* of size lg (in granules), putting the resulting pointer in result. */ /* Tiny_fl is a "tiny" free-list array, which will be used first, if */ /* the size is appropriate. If lg argument is too large, we allocate */ /* with default_expr instead. If we need to refill the free list, we */ /* use GC_generic_malloc_many with the indicated kind. */ /* Tiny_fl should be an array of GC_TINY_FREELISTS void * pointers. */ /* If num_direct is nonzero, and the individual free-list pointers */ /* are initialized to (void *)1, then we allocate num_direct granules */ /* directly using generic_malloc before putting multiple objects into */ /* the tiny_fl entry. If num_direct is zero, then the free lists may */ /* also be initialized to NULL. */ /* Note that we use the zeroth free list to hold objects 1 granule in */ /* size that are used to satisfy size 0 allocation requests. */ /* We rely on much of this hopefully getting optimized away in the */ /* case of num_direct is 0. Particularly, if lg argument is constant, */ /* this should generate a small amount of code. */ #define GC_FAST_MALLOC_GRANS(result, lg, tiny_fl, num_direct, k, \ default_expr, init) \ do { \ if (GC_EXPECT((lg) >= GC_TINY_FREELISTS, 0)) { \ result = (default_expr); \ } else { \ void **my_fl = (tiny_fl) + (lg); \ void *my_entry = *my_fl; \ void *next; \ \ for (;;) { \ if (GC_EXPECT((GC_word)my_entry \ > (num_direct) + GC_TINY_FREELISTS + 1, 1)) { \ next = *(void **)(my_entry); \ result = my_entry; \ GC_FAST_M_AO_STORE(my_fl, next); \ init; \ GC_PREFETCH_FOR_WRITE(next); \ if ((k) != GC_I_PTRFREE) { \ GC_end_stubborn_change(my_fl); \ GC_reachable_here(next); \ } \ GC_ASSERT(GC_size(result) >= (lg) * GC_GRANULE_BYTES); \ GC_ASSERT((k) == GC_I_PTRFREE \ || 0 /* NULL */ == ((void **)result)[1]); \ break; \ } \ /* Entry contains counter or NULL */ \ if ((GC_signed_word)my_entry - (GC_signed_word)(num_direct) <= 0 \ /* (GC_word)my_entry <= (num_direct) */ \ && my_entry != 0 /* NULL */) { \ /* Small counter value, not NULL */ \ GC_FAST_M_AO_STORE(my_fl, (char *)my_entry + (lg) + 1); \ result = (default_expr); \ break; \ } else { \ /* Large counter or NULL */ \ GC_generic_malloc_many(0 == (lg) ? GC_GRANULE_BYTES \ : GC_RAW_BYTES_FROM_INDEX(lg), \ k, my_fl); \ my_entry = *my_fl; \ if (my_entry == 0) { \ result = (*GC_get_oom_fn())((lg) * GC_GRANULE_BYTES); \ break; \ } \ } \ } \ } \ } while (0) /* Allocate n "pointer-sized" words. The allocation size is */ /* rounded up to a granule size. The pointer is stored to result. */ /* Should not be used unless GC_get_all_interior_pointers() returns 0 */ /* or if GC_get_dont_add_byte_at_end() returns 1. Does not acquire the */ /* allocator lock. The caller is responsible for supplying a cleared */ /* tiny_fl free-list array. For single-threaded applications, this may */ /* be a global array. */ #define GC_MALLOC_WORDS_KIND(result, n, tiny_fl, k, init) \ do { \ size_t lg = GC_PTRS_TO_WHOLE_GRANULES(n); \ \ GC_FAST_MALLOC_GRANS(result, lg, tiny_fl, 0 /* num_direct */, k, \ GC_malloc_kind(lg * GC_GRANULE_BYTES, k), init); \ } while (0) #define GC_MALLOC_WORDS(result, n, tiny_fl) \ GC_MALLOC_WORDS_KIND(result, n, tiny_fl, GC_I_NORMAL, \ (void)(*(void **)(result) = 0 /* NULL */)) #define GC_MALLOC_ATOMIC_WORDS(result, n, tiny_fl) \ GC_MALLOC_WORDS_KIND(result, n, tiny_fl, GC_I_PTRFREE, (void)0) /* And one more for two-pointer initialized objects: */ #define GC_CONS(result, first, second, tiny_fl) \ do { \ void *l = (void *)(first); \ void *r = (void *)(second); \ GC_MALLOC_WORDS_KIND(result, 2, tiny_fl, GC_I_NORMAL, (void)0); \ if ((result) != 0 /* NULL */) { \ *(void **)(result) = l; \ GC_ptr_store_and_dirty((void **)(result) + 1, r); \ GC_reachable_here(l); \ } \ } while (0) /* Print address of each object in the free list for the given kind and */ /* size (in granules). The caller should hold the allocator lock at */ /* least in the reader mode. Defined only if the library has been */ /* compiled without NO_DEBUGGING. */ GC_API void GC_CALL GC_print_free_list(int /* k */, size_t /* lg */); #ifdef __cplusplus } /* extern "C" */ #endif #endif /* !GC_INLINE_H */