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8a9a593115
GCC 4.9.0 added the alloc_align attribute to say that a function argument specifies the alignment of the returned pointer. Clang supports the attribute too. Using the attribute can allow a compiler to generate better code if it knows the returned pointer has a minimum alignment. See https://gcc.gnu.org/PR60092 for more details. GCC implicitly knows the semantics of aligned_alloc and posix_memalign, but not the obsolete memalign. As a result, GCC generates worse code when memalign is used, compared to aligned_alloc. Clang knows about aligned_alloc and memalign, but not posix_memalign. This change adds a new __attribute_alloc_align__ macro to <sys/cdefs.h> and then uses it on memalign (where it helps GCC) and aligned_alloc (where GCC and Clang already know the semantics, but it doesn't hurt) and xposix_memalign. It can't be used on posix_memalign because that doesn't return a pointer (the allocated pointer is returned via a void** parameter instead). Unlike the alloc_size attribute, alloc_align only allows a single argument. That means the new __attribute_alloc_align__ macro doesn't really need to be used with double parentheses to protect a comma between its arguments. For consistency with __attribute_alloc_size__ this patch defines it the same way, so that double parentheses are required. Signed-off-by: Jonathan Wakely <jwakely@redhat.com> Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
162 lines
5.8 KiB
C
162 lines
5.8 KiB
C
/* Prototypes and definition for malloc implementation.
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Copyright (C) 1996-2021 Free Software Foundation, Inc.
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Copyright The GNU Toolchain Authors.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _MALLOC_H
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#define _MALLOC_H 1
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#include <features.h>
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#include <stddef.h>
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#include <stdio.h>
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#ifdef _LIBC
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# define __MALLOC_HOOK_VOLATILE
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# define __MALLOC_DEPRECATED
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#else
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# define __MALLOC_HOOK_VOLATILE volatile
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# define __MALLOC_DEPRECATED __attribute_deprecated__
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#endif
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__BEGIN_DECLS
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/* Allocate SIZE bytes of memory. */
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extern void *malloc (size_t __size) __THROW __attribute_malloc__
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__attribute_alloc_size__ ((1)) __wur;
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/* Allocate NMEMB elements of SIZE bytes each, all initialized to 0. */
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extern void *calloc (size_t __nmemb, size_t __size)
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__THROW __attribute_malloc__ __attribute_alloc_size__ ((1, 2)) __wur;
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/* Re-allocate the previously allocated block in __ptr, making the new
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block SIZE bytes long. */
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/* __attribute_malloc__ is not used, because if realloc returns
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the same pointer that was passed to it, aliasing needs to be allowed
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between objects pointed by the old and new pointers. */
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extern void *realloc (void *__ptr, size_t __size)
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__THROW __attribute_warn_unused_result__ __attribute_alloc_size__ ((2));
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/* Re-allocate the previously allocated block in PTR, making the new
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block large enough for NMEMB elements of SIZE bytes each. */
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/* __attribute_malloc__ is not used, because if reallocarray returns
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the same pointer that was passed to it, aliasing needs to be allowed
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between objects pointed by the old and new pointers. */
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extern void *reallocarray (void *__ptr, size_t __nmemb, size_t __size)
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__THROW __attribute_warn_unused_result__ __attribute_alloc_size__ ((2, 3))
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__attr_dealloc_free;
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/* Free a block allocated by `malloc', `realloc' or `calloc'. */
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extern void free (void *__ptr) __THROW;
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/* Allocate SIZE bytes allocated to ALIGNMENT bytes. */
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extern void *memalign (size_t __alignment, size_t __size)
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__THROW __attribute_malloc__ __attribute_alloc_align__ ((1))
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__attribute_alloc_size__ ((2)) __wur __attr_dealloc_free;
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/* Allocate SIZE bytes on a page boundary. */
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extern void *valloc (size_t __size) __THROW __attribute_malloc__
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__attribute_alloc_size__ ((1)) __wur __attr_dealloc_free;
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/* Equivalent to valloc(minimum-page-that-holds(n)), that is, round up
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__size to nearest pagesize. */
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extern void *pvalloc (size_t __size) __THROW __attribute_malloc__
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__wur __attr_dealloc_free;
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/* SVID2/XPG mallinfo structure */
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struct mallinfo
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{
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int arena; /* non-mmapped space allocated from system */
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int ordblks; /* number of free chunks */
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int smblks; /* number of fastbin blocks */
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int hblks; /* number of mmapped regions */
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int hblkhd; /* space in mmapped regions */
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int usmblks; /* always 0, preserved for backwards compatibility */
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int fsmblks; /* space available in freed fastbin blocks */
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int uordblks; /* total allocated space */
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int fordblks; /* total free space */
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int keepcost; /* top-most, releasable (via malloc_trim) space */
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};
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/* SVID2/XPG mallinfo2 structure which can handle allocations
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bigger than 4GB. */
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struct mallinfo2
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{
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size_t arena; /* non-mmapped space allocated from system */
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size_t ordblks; /* number of free chunks */
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size_t smblks; /* number of fastbin blocks */
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size_t hblks; /* number of mmapped regions */
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size_t hblkhd; /* space in mmapped regions */
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size_t usmblks; /* always 0, preserved for backwards compatibility */
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size_t fsmblks; /* space available in freed fastbin blocks */
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size_t uordblks; /* total allocated space */
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size_t fordblks; /* total free space */
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size_t keepcost; /* top-most, releasable (via malloc_trim) space */
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};
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/* Returns a copy of the updated current mallinfo. */
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extern struct mallinfo mallinfo (void) __THROW __MALLOC_DEPRECATED;
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/* Returns a copy of the updated current mallinfo. */
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extern struct mallinfo2 mallinfo2 (void) __THROW;
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/* SVID2/XPG mallopt options */
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#ifndef M_MXFAST
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# define M_MXFAST 1 /* maximum request size for "fastbins" */
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#endif
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#ifndef M_NLBLKS
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# define M_NLBLKS 2 /* UNUSED in this malloc */
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#endif
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#ifndef M_GRAIN
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# define M_GRAIN 3 /* UNUSED in this malloc */
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#endif
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#ifndef M_KEEP
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# define M_KEEP 4 /* UNUSED in this malloc */
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#endif
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/* mallopt options that actually do something */
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#define M_TRIM_THRESHOLD -1
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#define M_TOP_PAD -2
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#define M_MMAP_THRESHOLD -3
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#define M_MMAP_MAX -4
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#define M_CHECK_ACTION -5
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#define M_PERTURB -6
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#define M_ARENA_TEST -7
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#define M_ARENA_MAX -8
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/* General SVID/XPG interface to tunable parameters. */
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extern int mallopt (int __param, int __val) __THROW;
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/* Release all but __pad bytes of freed top-most memory back to the
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system. Return 1 if successful, else 0. */
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extern int malloc_trim (size_t __pad) __THROW;
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/* Report the number of usable allocated bytes associated with allocated
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chunk __ptr. */
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extern size_t malloc_usable_size (void *__ptr) __THROW;
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/* Prints brief summary statistics on stderr. */
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extern void malloc_stats (void) __THROW;
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/* Output information about state of allocator to stream FP. */
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extern int malloc_info (int __options, FILE *__fp) __THROW;
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__END_DECLS
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#endif /* malloc.h */
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