Substantially reduce instantiations and debug size of std::function
std::function uses a standard allocator to manage its memory, however
standard allocators are templates and using them correctly requires
a stupid amount of instantiations. This leads to a substantial increase
in debug info and object sizes.
This patch addresses the issue by dropping the allocator when possible
and using raw new and delete to get memory.
This change decreases the object file size for the test func.wrap.func.con/F.pass.cpp by 33% and the final binary by 29% (when compiled with -g -ggnu-pubnames -gpubnames).
It also roughly halfs the number of entries in the pubnames and pubtype
sections.
llvm-svn: 362865
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: d63dd874ecbdcbc9bdcfc4fde4e372ad2f605ba5
diff --git a/include/memory b/include/memory
index 8d88617..6a8755e 100644
--- a/include/memory
+++ b/include/memory
@@ -5668,6 +5668,52 @@
>
: true_type {};
+// __builtin_new_allocator -- A non-templated helper for allocating and
+// deallocating memory using __builtin_operator_new and
+// __builtin_operator_delete. It should be used in preference to
+// `std::allocator<T>` to avoid additional instantiations.
+struct __builtin_new_allocator {
+ struct __builtin_new_deleter {
+ typedef void* pointer_type;
+
+ _LIBCPP_CONSTEXPR explicit __builtin_new_deleter(size_t __size, size_t __align)
+ : __size_(__size), __align_(__align) {}
+
+ void operator()(void* p) const _NOEXCEPT {
+ std::__libcpp_deallocate(p, __size_, __align_);
+ }
+
+ private:
+ size_t __size_;
+ size_t __align_;
+ };
+
+ typedef unique_ptr<void, __builtin_new_deleter> __holder_t;
+
+ static __holder_t __allocate_bytes(size_t __s, size_t __align) {
+ return __holder_t(std::__libcpp_allocate(__s, __align),
+ __builtin_new_deleter(__s, __align));
+ }
+
+ static void __deallocate_bytes(void* __p, size_t __s,
+ size_t __align) _NOEXCEPT {
+ std::__libcpp_deallocate(__p, __s, __align);
+ }
+
+ template <class _Tp>
+ _LIBCPP_NODEBUG _LIBCPP_ALWAYS_INLINE
+ static __holder_t __allocate_type(size_t __n) {
+ return __allocate_bytes(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
+ }
+
+ template <class _Tp>
+ _LIBCPP_NODEBUG _LIBCPP_ALWAYS_INLINE
+ static void __deallocate_type(void* __p, size_t __n) _NOEXCEPT {
+ __deallocate_bytes(__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
+ }
+};
+
+
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS