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Author: poor-circle

libcxx/docs/ReleaseNotes/22.rst

@@ -83,7 +83,7 @@ Improvements and New Features
   iterators, resulting in a performance improvement for ``std::deque<short>`` and
   ``std::join_view<vector<vector<short>>>`` iterators.
 
-- The performance of ``align`` has been improved about 3x by making it an inline function.
+- The performance of ``align`` has been improved about 2x by making it an inline function.
 
 Deprecations and Removals
 -------------------------

libcxx/include/CMakeLists.txt

@@ -570,6 +570,7 @@ set(files
   __mdspan/mdspan.h
   __memory/addressof.h
   __memory/align.h
+  __memory/align_impl.h
   __memory/aligned_alloc.h
   __memory/allocate_at_least.h
   __memory/allocation_guard.h

libcxx/include/__configuration/abi.h

@@ -97,18 +97,19 @@
 // so disable it.
 #    define _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
 #  endif
-// The PE/COFF format reports a linking error when encountering multiple symbol definitions where at least one is a
-// strong symbol. So we can't inlining a function without ABI breakchange.
-#  if defined(_LIBCPP_OBJECT_FORMAT_COFF)
-#    define _LIBCPP_DISABLE_INLINE_OPTIMIZE_BECAUSE_MULTIPLY_SYMBOLS_ERROR
-#  endif
 // Feature macros for disabling pre ABI v1 features. All of these options
 // are deprecated.
 #  if defined(__FreeBSD__)
 #    define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
 #  endif
 #endif
 
+// The PE/COFF format reports a linking error when encountering multiple symbol definitions where at least one is a
+// strong symbol. So we can't inlining a non-inline function without ABI break change.
+#if defined(_LIBCPP_OBJECT_FORMAT_COFF)
+#  define _LIBCPP_DISABLE_INLINE_OPTIMIZE_BECAUSE_MULTIPLY_SYMBOLS_ERROR
+#endif
+
 // TODO(LLVM 22): Remove this check
 #if defined(_LIBCPP_ABI_NO_ITERATOR_BASES) && !defined(_LIBCPP_ABI_NO_REVERSE_ITERATOR_SECOND_MEMBER)
 #  ifndef _LIBCPP_ONLY_NO_ITERATOR_BASES

libcxx/include/__memory/align.h

@@ -9,46 +9,27 @@
 #ifndef _LIBCPP___MEMORY_ALIGN_H
 #define _LIBCPP___MEMORY_ALIGN_H
 
+#include "align_impl.h"
 #include <__config>
-#include <__cstddef/size_t.h>
-#include <cstdint>
+#include <__memory/align_impl.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE inline void*
-__align_impl(size_t __align, size_t __sz, void*& __ptr, size_t& __space) {
-  void* __r = nullptr;
-  if (__sz <= __space) {
-    char* __p1 = static_cast<char*>(__ptr);
-    char* __p2 = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(__p1 + (__align - 1)) & -__align);
-    size_t __d = static_cast<size_t>(__p2 - __p1);
-    if (__d <= __space - __sz) {
-      __r   = __p2;
-      __ptr = __r;
-      __space -= __d;
-    }
-  }
-  return __r;
-}
-
-#ifndef _LIBCPP_EXPORT_ALIGN_SYMBOL
-#  ifdef _LIBCPP_DISABLE_INLINE_OPTIMIZE_BECAUSE_MULTIPLY_SYMBOLS_ERROR
+#if defined(_LIBCPP_DISABLE_INLINE_OPTIMIZE_BECAUSE_MULTIPLY_SYMBOLS_ERROR) && !defined(_LIBCPP_ABI_DO_NOT_EXPORT_ALIGN)
 
 _LIBCPP_EXPORTED_FROM_ABI void* align(size_t __align, size_t __sz, void*& __ptr, size_t& __space);
 
-#  else
+#else
 
 inline _LIBCPP_HIDE_FROM_ABI void* align(size_t __align, size_t __sz, void*& __ptr, size_t& __space) {
-  return __align_impl(__align, __sz, __ptr, __space);
+  return align_impl(__align, __sz, __ptr, __space);
 }
 
-#  endif //  _LIBCPP_DISABLE_INLINE_OPTIMIZE_BECAUSE_MULTIPLY_SYMBOLS_ERROR
-
-#endif // _LIBCPP_EXPORT_ALIGN_SYMBOL
+#endif //  _LIBCPP_DISABLE_INLINE_OPTIMIZE_BECAUSE_MULTIPLY_SYMBOLS_ERROR
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__memory/align_impl.h

@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___MEMORY_ALIGN_IMPL_H
+#define _LIBCPP___MEMORY_ALIGN_IMPL_H
+
+#include <__config>
+#include <__cstddef/size_t.h>
+#include <cstdint>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+inline _LIBCPP_HIDE_FROM_ABI void* align_impl(size_t __align, size_t __sz, void*& __ptr, size_t& __space) {
+  void* __r = nullptr;
+  if (__sz <= __space) {
+    char* __p1 = static_cast<char*>(__ptr);
+    char* __p2 = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(__p1 + (__align - 1)) & -__align);
+    size_t __d = static_cast<size_t>(__p2 - __p1);
+    if (__d <= __space - __sz) {
+      __r   = __p2;
+      __ptr = __r;
+      __space -= __d;
+    }
+  }
+  return __r;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___MEMORY_ALIGN_IMPL_H

libcxx/src/CMakeLists.txt

@@ -1,6 +1,7 @@
 # Get sources
 set(LIBCXX_SOURCES
   algorithm.cpp
+  align.cpp
   any.cpp
   bind.cpp
   call_once.cpp

libcxx/src/align.cpp

@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#include <__memory/align_impl.h>
+
+#if !defined(_LIBCPP_ABI_DO_NOT_EXPORT_ALIGN)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_EXPORTED_FROM_ABI void* align(size_t alignment, size_t size, void*& ptr, size_t& space) {
+  return align_impl(alignment, size, ptr, space);
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_ABI_DO_NOT_EXPORT_ALIGN

libcxx/src/memory.cpp

@@ -10,9 +10,6 @@
 #ifdef _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
 #  define _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS
 #endif
-#ifndef _LIBCPP_ABI_DO_NOT_EXPORT_ALIGN
-#  define _LIBCPP_EXPORT_ALIGN_SYMBOL
-#endif
 
 #include <__functional/hash.h>
 #include <memory>
@@ -135,12 +132,4 @@ __sp_mut& __get_sp_mut(const void* p) {
 
 #endif // _LIBCPP_HAS_THREADS
 
-#if defined(_LIBCPP_EXPORT_ALIGN_SYMBOL)
-
-_LIBCPP_EXPORTED_FROM_ABI void* align(size_t alignment, size_t size, void*& ptr, size_t& space) {
-  return __align_impl(alignment, size, ptr, space);
-}
-
-#endif // _LIBCPP_EXPORT_ALIGN_SYMBOL
-
 _LIBCPP_END_NAMESPACE_STD

libcxx/test/benchmarks/memory/align.bench.cpp

@@ -9,17 +9,29 @@
 // UNSUPPORTED: c++03
 
 #include <memory>
+#include <iostream>
 
 #include "benchmark/benchmark.h"
-#include "test_macros.h"
+
+struct Input {
+  std::size_t align;
+  std::size_t size;
+  void* ptr;
+  std::size_t buffer_size;
+};
 
 static void BM_align(benchmark::State& state) {
   char buffer[1024];
-  void* data = buffer + 123;
-  std::size_t sz{sizeof(buffer) - 123};
-
+  Input input{};
+  void* ptr               = buffer + 123;
+  std::size_t buffer_size = sizeof(buffer) - 123;
+  input.align             = state.range();
+  input.size              = state.range();
   for (auto _ : state) {
-    benchmark::DoNotOptimize(std::align(state.range(), state.range(), data, sz));
+    input.ptr         = ptr;
+    input.buffer_size = buffer_size;
+    benchmark::DoNotOptimize(input);
+    benchmark::DoNotOptimize(std::align(input.align, input.size, input.ptr, input.buffer_size));
   }
 }
 BENCHMARK(BM_align)->Range(1, 256);