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| author | Jonathan Wakely <jwakely@redhat.com> | 2024-01-09 15:22:46 +0000 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2024-01-11 17:35:57 +0000 |
| commit | f50f2efae9fb0965d8ccdb62cfdb698336d5a933 (patch) | |
| tree | 3dac68bdc47fc804bd0bfde20a633fc7995de3f0 | |
| parent | 8f67953d0198fe9e053cc925eb631d2f29005466 (diff) | |
| download | gcc-f50f2efae9fb0965d8ccdb62cfdb698336d5a933.zip gcc-f50f2efae9fb0965d8ccdb62cfdb698336d5a933.tar.gz gcc-f50f2efae9fb0965d8ccdb62cfdb698336d5a933.tar.bz2 | |
libstdc++: Prefer posix_memalign for aligned-new [PR113258]
As described in PR libstdc++/113258 there are old versions of tcmalloc
which replace malloc and related APIs, but do not repalce aligned_alloc
because it didn't exist at the time they were released. This means that
when operator new(size_t, align_val_t) uses aligned_alloc to obtain
memory, it comes from libc's aligned_alloc not from tcmalloc. But when
operator delete(void*, size_t, align_val_t) uses free to deallocate the
memory, that goes to tcmalloc's replacement version of free, which
doesn't know how to free it.
If we give preference to the older posix_memalign instead of
aligned_alloc then we're more likely to use a function that will be
compatible with the replacement version of free. Because posix_memalign
has been around for longer, it's more likely that old third-party malloc
replacements will also replace posix_memalign alongside malloc and free.
libstdc++-v3/ChangeLog:
PR libstdc++/113258
* libsupc++/new_opa.cc: Prefer to use posix_memalign if
available.
| -rw-r--r-- | libstdc++-v3/libsupc++/new_opa.cc | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/libstdc++-v3/libsupc++/new_opa.cc b/libstdc++-v3/libsupc++/new_opa.cc index 8326b74..35606e1 100644 --- a/libstdc++-v3/libsupc++/new_opa.cc +++ b/libstdc++-v3/libsupc++/new_opa.cc @@ -46,12 +46,12 @@ using std::bad_alloc; using std::size_t; extern "C" { -# if _GLIBCXX_HAVE_ALIGNED_ALLOC +# if _GLIBCXX_HAVE_POSIX_MEMALIGN + void *posix_memalign(void **, size_t alignment, size_t size); +# elif _GLIBCXX_HAVE_ALIGNED_ALLOC void *aligned_alloc(size_t alignment, size_t size); # elif _GLIBCXX_HAVE__ALIGNED_MALLOC void *_aligned_malloc(size_t size, size_t alignment); -# elif _GLIBCXX_HAVE_POSIX_MEMALIGN - void *posix_memalign(void **, size_t alignment, size_t size); # elif _GLIBCXX_HAVE_MEMALIGN void *memalign(size_t alignment, size_t size); # else @@ -63,13 +63,10 @@ extern "C" #endif namespace __gnu_cxx { -#if _GLIBCXX_HAVE_ALIGNED_ALLOC -using ::aligned_alloc; -#elif _GLIBCXX_HAVE__ALIGNED_MALLOC -static inline void* -aligned_alloc (std::size_t al, std::size_t sz) -{ return _aligned_malloc(sz, al); } -#elif _GLIBCXX_HAVE_POSIX_MEMALIGN +// Prefer posix_memalign if available, because it's older than aligned_alloc +// and so more likely to be provided by replacement malloc libraries that +// predate the addition of aligned_alloc. See PR libstdc++/113258. +#if _GLIBCXX_HAVE_POSIX_MEMALIGN static inline void* aligned_alloc (std::size_t al, std::size_t sz) { @@ -83,6 +80,12 @@ aligned_alloc (std::size_t al, std::size_t sz) return ptr; return nullptr; } +#elif _GLIBCXX_HAVE_ALIGNED_ALLOC +using ::aligned_alloc; +#elif _GLIBCXX_HAVE__ALIGNED_MALLOC +static inline void* +aligned_alloc (std::size_t al, std::size_t sz) +{ return _aligned_malloc(sz, al); } #elif _GLIBCXX_HAVE_MEMALIGN static inline void* aligned_alloc (std::size_t al, std::size_t sz) @@ -128,7 +131,8 @@ operator new (std::size_t sz, std::align_val_t al) if (__builtin_expect (sz == 0, false)) sz = 1; -#if _GLIBCXX_HAVE_ALIGNED_ALLOC +#if _GLIBCXX_HAVE_POSIX_MEMALIGN +#elif _GLIBCXX_HAVE_ALIGNED_ALLOC # if defined _AIX || defined __APPLE__ /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement * that alignment is a multiple of sizeof(void*). |