[libcxx-commits] [libcxx] [libc++] Mark libc++ deallocation helpers as noexcept (PR #110884)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne created https://github.com/llvm/llvm-project/pull/110884

They already can't throw exceptions and they are called from noexcept functions, but they were not marked as noexcept. Depending on compiler inlining, this might not make a difference or this might improve the codegen a bit by removing the implicit try-catch block that Clang generates around non-noexcept functions called from noexcept functions.

The original issue also mentioned that one occurrence of std::allocator::deallocate was missing noexcept, however it has since then been removed.

Fixes #66100

>From 2f53dd9c4776f1761d0d68d007df745ad817ec19 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Wed, 2 Oct 2024 12:46:47 -0400
Subject: [PATCH] [libc++] Mark libc++ deallocation helpers as noexcept

They already can't throw exceptions and they are called from noexcept
functions, but they were not marked as noexcept. Depending on compiler
inlining, this might not make a difference or this might improve the
codegen a bit by removing the implicit try-catch block that Clang
generates around non-noexcept functions called from noexcept functions.

The original issue also mentioned that one occurrence of
std::allocator::deallocate was missing noexcept, however
it has since then been removed.

Fixes #66100
---
 libcxx/include/new | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libcxx/include/new b/libcxx/include/new
index 3252b0bb1abcdb..8d7d1eb5fdc7b9 100644
--- a/libcxx/include/new
+++ b/libcxx/include/new
@@ -275,7 +275,7 @@ _LIBCPP_HIDE_FROM_ABI void* __libcpp_operator_new(_Args... __args) {
 }
 
 template <class... _Args>
-_LIBCPP_HIDE_FROM_ABI void __libcpp_operator_delete(_Args... __args) {
+_LIBCPP_HIDE_FROM_ABI void __libcpp_operator_delete(_Args... __args) _NOEXCEPT {
 #if __has_builtin(__builtin_operator_new) && __has_builtin(__builtin_operator_delete)
   __builtin_operator_delete(__args...);
 #else
@@ -296,7 +296,7 @@ inline _LIBCPP_HIDE_FROM_ABI void* __libcpp_allocate(size_t __size, size_t __ali
 }
 
 template <class... _Args>
-_LIBCPP_HIDE_FROM_ABI void __do_deallocate_handle_size(void* __ptr, size_t __size, _Args... __args) {
+_LIBCPP_HIDE_FROM_ABI void __do_deallocate_handle_size(void* __ptr, size_t __size, _Args... __args) _NOEXCEPT {
 #ifdef _LIBCPP_HAS_NO_SIZED_DEALLOCATION
   (void)__size;
   return std::__libcpp_operator_delete(__ptr, __args...);
@@ -305,7 +305,7 @@ _LIBCPP_HIDE_FROM_ABI void __do_deallocate_handle_size(void* __ptr, size_t __siz
 #endif
 }
 
-inline _LIBCPP_HIDE_FROM_ABI void __libcpp_deallocate(void* __ptr, size_t __size, size_t __align) {
+inline _LIBCPP_HIDE_FROM_ABI void __libcpp_deallocate(void* __ptr, size_t __size, size_t __align) _NOEXCEPT {
 #if defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
   (void)__align;
   return __do_deallocate_handle_size(__ptr, __size);
@@ -319,7 +319,7 @@ inline _LIBCPP_HIDE_FROM_ABI void __libcpp_deallocate(void* __ptr, size_t __size
 #endif
 }
 
-inline _LIBCPP_HIDE_FROM_ABI void __libcpp_deallocate_unsized(void* __ptr, size_t __align) {
+inline _LIBCPP_HIDE_FROM_ABI void __libcpp_deallocate_unsized(void* __ptr, size_t __align) _NOEXCEPT {
 #if defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
   (void)__align;
   return __libcpp_operator_delete(__ptr);