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PR libstdc++/86861 Meet precondition for Solaris memalign

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Solaris memalign requires alignment to be at least sizeof(int), so
increase it as needed.

Also move the check for valid alignments from the fallback
implementation of aligned_alloc into operator new, as it's required for
all of aligned_alloc, memalign, posix_memalign and __aligned_malloc.
This adds a branch to check for undefined behaviour which we could just
ignore, so the check could just be removed. It should certainly be
removed if PR 86878 is implemented to issue a warning about calls with
invalid alignments.

	PR libstdc++/86861
	* libsupc++/new_opa.cc [_GLIBCXX_HAVE_MEMALIGN] (aligned_alloc):
	Replace macro with inline function.
	[__sun]: Increase alignment to meet memalign precondition.
	[!HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN]
	(aligned_alloc): Move check for valid alignment to operator new.
	Remove redundant check for non-zero size, it's enforced by the caller.
	(operator new): Move check for valid alignment here. Use
	__builtin_expect on check for zero size.

From-SVN: r263360
This commit is contained in:
Jonathan Wakely 2018-08-07 17:10:29 +01:00 committed by Jonathan Wakely
parent e81c3c1e9c
commit 1d1b732865
2 changed files with 29 additions and 9 deletions
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10
libstdc++-v3/ChangeLog
View File

@ -1,5 +1,15 @@
2018-08-07 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/86861
* libsupc++/new_opa.cc [_GLIBCXX_HAVE_MEMALIGN] (aligned_alloc):
Replace macro with inline function.
[__sun]: Increase alignment to meet memalign precondition.
[!HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN]
(aligned_alloc): Move check for valid alignment to operator new.
Remove redundant check for non-zero size, it's enforced by the caller.
(operator new): Move check for valid alignment here. Use
__builtin_expect on check for zero size.
* config/abi/pre/gnu.ver: Export monotonic_buffer_resource members.
* include/std/memory_resource (monotonic_buffer_resource::release):
Call _M_release_buffers to free buffers.

28
libstdc++-v3/libsupc++/new_opa.cc
View File

@ -39,6 +39,7 @@ static inline void*
aligned_alloc (std::size_t al, std::size_t sz)
{
void *ptr;
// posix_memalign has additional requirement, not present on aligned_alloc:
// The value of alignment shall be a power of two multiple of sizeof(void *).
if (al < sizeof(void*))
al = sizeof(void*);
@ -53,20 +54,24 @@ aligned_alloc (std::size_t al, std::size_t sz)
#else
extern "C" void *memalign(std::size_t boundary, std::size_t size);
#endif
#define aligned_alloc memalign
#else
static inline void*
aligned_alloc (std::size_t al, std::size_t sz)
{
#ifdef __sun
// Solaris 10 memalign requires that alignment is greater than or equal to
// the size of a word.
if (al < sizeof(int))
al = sizeof(int);
#endif
return memalign (al, sz);
}
#else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN
#include <stdint.h>
// The C library doesn't provide any aligned allocation functions, define one.
// This is a modified version of code from gcc/config/i386/gmm_malloc.h
static inline void*
aligned_alloc (std::size_t al, std::size_t sz)
{
// Alignment must be a power of two.
if (al & (al - 1))
return nullptr;
else if (!sz)
return nullptr;
// We need extra bytes to store the original value returned by malloc.
if (al < sizeof(void*))
al = sizeof(void*);
@ -90,8 +95,13 @@ operator new (std::size_t sz, std::align_val_t al)
void *p;
std::size_t align = (std::size_t)al;
/* Alignment must be a power of two. */
/* XXX This should be checked by the compiler (PR 86878). */
if (__builtin_expect (align & (align - 1), false))
_GLIBCXX_THROW_OR_ABORT(bad_alloc());
/* malloc (0) is unpredictable; avoid it. */
if (sz == 0)
if (__builtin_expect (sz == 0, false))
sz = 1;
#if _GLIBCXX_HAVE_ALIGNED_ALLOC