[libcxx-commits] [libcxx] [libc++] Simplify the implementation of __libcpp_{, de}allocate (PR #147989)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/147989

GCC 15 also supports `__buitin_operator_{new,delete}` now, so the `#else` cases are dead code. This patch inlines the calls to the wrapper functions and simplifies some surrounding code.


>From 8ef1cad37eb9b446a18ffbbd10dcd48064c7cb17 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Thu, 10 Jul 2025 17:47:17 +0200
Subject: [PATCH] [libc++] Simplify the implementation of
 __libcpp_{,de}allocate

GCC 15 also supports `__buitin_operator_{new,delete}` now, so the `#else` cases are dead code. This patch inlines the calls to the wrapper functions and simplifies some surrounding code.
---
 libcxx/include/__new/allocate.h | 71 ++++++++++-----------------------
 1 file changed, 20 insertions(+), 51 deletions(-)

diff --git a/libcxx/include/__new/allocate.h b/libcxx/include/__new/allocate.h
index 738fa62af4d61..9bfe19aedb79f 100644
--- a/libcxx/include/__new/allocate.h
+++ b/libcxx/include/__new/allocate.h
@@ -31,37 +31,16 @@ _LIBCPP_CONSTEXPR inline _LIBCPP_HIDE_FROM_ABI bool __is_overaligned_for_new(siz
 #endif
 }
 
-template <class... _Args>
-_LIBCPP_HIDE_FROM_ABI void* __libcpp_operator_new(_Args... __args) {
-#if __has_builtin(__builtin_operator_new) && __has_builtin(__builtin_operator_delete)
-  return __builtin_operator_new(__args...);
-#else
-  return ::operator new(__args...);
-#endif
-}
-
-template <class... _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
-  ::operator delete(__args...);
-#endif
-}
-
 template <class _Tp>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_NO_CFI _Tp*
-__libcpp_allocate(__element_count __n, size_t __align = _LIBCPP_ALIGNOF(_Tp)) {
+__libcpp_allocate(__element_count __n, [[__maybe_unused__]] size_t __align = _LIBCPP_ALIGNOF(_Tp)) {
   size_t __size = static_cast<size_t>(__n) * sizeof(_Tp);
 #if _LIBCPP_HAS_ALIGNED_ALLOCATION
-  if (__is_overaligned_for_new(__align)) {
-    const align_val_t __align_val = static_cast<align_val_t>(__align);
-    return static_cast<_Tp*>(std::__libcpp_operator_new(__size, __align_val));
-  }
+  if (__is_overaligned_for_new(__align))
+    return static_cast<_Tp*>(__builtin_operator_new(__size, static_cast<align_val_t>(__align)));
 #endif
 
-  (void)__align;
-  return static_cast<_Tp*>(std::__libcpp_operator_new(__size));
+  return static_cast<_Tp*>(__builtin_operator_new(__size));
 }
 
 #if _LIBCPP_HAS_SIZED_DEALLOCATION
@@ -71,39 +50,29 @@ __libcpp_allocate(__element_count __n, size_t __align = _LIBCPP_ALIGNOF(_Tp)) {
 #endif
 
 template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI void __libcpp_deallocate(
-    __type_identity_t<_Tp>* __ptr, __element_count __n, size_t __align = _LIBCPP_ALIGNOF(_Tp)) _NOEXCEPT {
-  size_t __size = static_cast<size_t>(__n) * sizeof(_Tp);
-  (void)__size;
-#if !_LIBCPP_HAS_ALIGNED_ALLOCATION
-  (void)__align;
-  return std::__libcpp_operator_delete(__ptr _LIBCPP_ONLY_IF_SIZED_DEALLOCATION(, __size));
-#else
-  if (__is_overaligned_for_new(__align)) {
-    const align_val_t __align_val = static_cast<align_val_t>(__align);
-    return std::__libcpp_operator_delete(__ptr _LIBCPP_ONLY_IF_SIZED_DEALLOCATION(, __size), __align_val);
-  } else {
-    return std::__libcpp_operator_delete(__ptr _LIBCPP_ONLY_IF_SIZED_DEALLOCATION(, __size));
-  }
+inline _LIBCPP_HIDE_FROM_ABI void
+__libcpp_deallocate(__type_identity_t<_Tp>* __ptr,
+                    __element_count __n,
+                    [[__maybe_unused__]] size_t __align = _LIBCPP_ALIGNOF(_Tp)) _NOEXCEPT {
+  [[__maybe_unused__]] size_t __size = static_cast<size_t>(__n) * sizeof(_Tp);
+#if _LIBCPP_HAS_ALIGNED_ALLOCATION
+  if (__is_overaligned_for_new(__align))
+    return __builtin_operator_delete(
+        __ptr _LIBCPP_ONLY_IF_SIZED_DEALLOCATION(, __size), static_cast<align_val_t>(__align));
 #endif
+  return __builtin_operator_delete(__ptr _LIBCPP_ONLY_IF_SIZED_DEALLOCATION(, __size));
 }
 
 #undef _LIBCPP_ONLY_IF_SIZED_DEALLOCATION
 
 template <class _Tp>
-inline _LIBCPP_HIDE_FROM_ABI void
-__libcpp_deallocate_unsized(__type_identity_t<_Tp>* __ptr, size_t __align = _LIBCPP_ALIGNOF(_Tp)) _NOEXCEPT {
-#if !_LIBCPP_HAS_ALIGNED_ALLOCATION
-  (void)__align;
-  return std::__libcpp_operator_delete(__ptr);
-#else
-  if (__is_overaligned_for_new(__align)) {
-    const align_val_t __align_val = static_cast<align_val_t>(__align);
-    return std::__libcpp_operator_delete(__ptr, __align_val);
-  } else {
-    return std::__libcpp_operator_delete(__ptr);
-  }
+inline _LIBCPP_HIDE_FROM_ABI void __libcpp_deallocate_unsized(
+    __type_identity_t<_Tp>* __ptr, [[__maybe_unused__]] size_t __align = _LIBCPP_ALIGNOF(_Tp)) _NOEXCEPT {
+#if _LIBCPP_HAS_ALIGNED_ALLOCATION
+  if (__is_overaligned_for_new(__align))
+    return __builtin_operator_delete(__ptr, static_cast<align_val_t>(__align));
 #endif
+  return __builtin_operator_delete(__ptr);
 }
 _LIBCPP_END_NAMESPACE_STD