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| author | Jonathan Wakely <jwakely@redhat.com> | 2021-07-22 14:38:34 +0100 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2021-07-22 14:38:34 +0100 |
| commit | c9ca352186226ae757688e160e7c6f394c9f26aa (patch) | |
| tree | 5c348a4cd218bf519e980632707a36b962000e00 | |
| parent | aca7a0253d6e3116f846ad530b19d89644a64267 (diff) | |
| download | gcc-c9ca352186226ae757688e160e7c6f394c9f26aa.zip gcc-c9ca352186226ae757688e160e7c6f394c9f26aa.tar.gz gcc-c9ca352186226ae757688e160e7c6f394c9f26aa.tar.bz2 | |
libstdc++: Use __builtin_operator_new when available [PR94295]
Clang provides __builtin_operator_new and __builtin_operator_delete,
which have the same semantics as ::operator new and ::operator delete
except that the compiler is allowed to elide calls to them. This changes
std::allocator to use those built-in functions so that memory allocated
by std::allocator can be optimized away when using Clang. This avoids an
abstraction penalty for using std::allocator to allocate storage rather
than a new-expression.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/94295
* include/ext/new_allocator.h (_GLIBCXX_OPERATOR_NEW)
(_GLIBCXX_OPERATOR_DELETE, _GLIBCXX_SIZED_DEALLOC): Define.
(allocator::allocate, allocator::deallocate): Use new macros.
| -rw-r--r-- | libstdc++-v3/include/ext/new_allocator.h | 38 |
1 files changed, 25 insertions, 13 deletions
diff --git a/libstdc++-v3/include/ext/new_allocator.h b/libstdc++-v3/include/ext/new_allocator.h index 3fb893b..7c48c82 100644 --- a/libstdc++-v3/include/ext/new_allocator.h +++ b/libstdc++-v3/include/ext/new_allocator.h @@ -97,6 +97,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { return std::__addressof(__x); } #endif +#if __has_builtin(__builtin_operator_new) >= 201802L +# define _GLIBCXX_OPERATOR_NEW __builtin_operator_new +# define _GLIBCXX_OPERATOR_DELETE __builtin_operator_delete +#else +# define _GLIBCXX_OPERATOR_NEW ::operator new +# define _GLIBCXX_OPERATOR_DELETE ::operator delete +#endif + // NB: __n is permitted to be 0. The C++ standard says nothing // about what the return value is when __n == 0. _GLIBCXX_NODISCARD _Tp* @@ -121,34 +129,38 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) { std::align_val_t __al = std::align_val_t(alignof(_Tp)); - return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al)); + return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp), + __al)); } #endif - return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); + return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp))); } // __p is not permitted to be a null pointer. void - deallocate(_Tp* __p, size_type __t __attribute__ ((__unused__))) + deallocate(_Tp* __p, size_type __n __attribute__ ((__unused__))) { +#if __cpp_sized_deallocation +# define _GLIBCXX_SIZED_DEALLOC(p, n) (p), (n) * sizeof(_Tp) +#else +# define _GLIBCXX_SIZED_DEALLOC(p, n) (p) +#endif + #if __cpp_aligned_new if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) { - ::operator delete(__p, -# if __cpp_sized_deallocation - __t * sizeof(_Tp), -# endif - std::align_val_t(alignof(_Tp))); + _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n), + std::align_val_t(alignof(_Tp))); return; } #endif - ::operator delete(__p -#if __cpp_sized_deallocation - , __t * sizeof(_Tp) -#endif - ); + _GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n)); } +#undef _GLIBCXX_SIZED_DEALLOC +#undef _GLIBCXX_OPERATOR_DELETE +#undef _GLIBCXX_OPERATOR_NEW + #if __cplusplus <= 201703L size_type max_size() const _GLIBCXX_USE_NOEXCEPT |