1//===-- Libc specific custom operator new and delete ------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_LIBC_SRC___SUPPORT_CPP_NEW_H
10#define LLVM_LIBC_SRC___SUPPORT_CPP_NEW_H
11
12#include "hdr/func/aligned_alloc.h"
13#include "hdr/func/free.h"
14#include "hdr/func/malloc.h"
15#include "src/__support/common.h"
16#include "src/__support/macros/config.h"
17#include "src/__support/macros/properties/os.h"
18
19#include <stddef.h> // For size_t
20
21// Defining members in the std namespace is not preferred. But, we do it here
22// so that we can use it to define the operator new which takes std::align_val_t
23// argument.
24namespace std {
25
26enum class align_val_t : size_t {};
27
28} // namespace std
29
30namespace LIBC_NAMESPACE_DECL {
31
32namespace cpp {
33template <class T> [[nodiscard]] constexpr T *launder(T *p) {
34 static_assert(__has_builtin(__builtin_launder),
35 "cpp::launder requires __builtin_launder");
36 return __builtin_launder(p);
37}
38} // namespace cpp
39
40class AllocChecker {
41 bool success = false;
42
43 LIBC_INLINE AllocChecker &operator=(bool status) {
44 success = status;
45 return *this;
46 }
47
48public:
49 LIBC_INLINE AllocChecker() = default;
50
51 LIBC_INLINE operator bool() const { return success; }
52
53 LIBC_INLINE static void *alloc(size_t s, AllocChecker &ac) {
54 void *mem = ::malloc(s);
55 ac = (mem != nullptr);
56 return mem;
57 }
58
59 LIBC_INLINE static void *aligned_alloc(size_t s, std::align_val_t align,
60 AllocChecker &ac) {
61#ifdef LIBC_TARGET_OS_IS_WINDOWS
62 // std::aligned_alloc is not available on Windows because std::free on
63 // Windows cannot deallocate any over-aligned memory. Microsoft provides an
64 // alternative for std::aligned_alloc named _aligned_malloc, but it must be
65 // paired with _aligned_free instead of std::free.
66 void *mem = ::_aligned_malloc(static_cast<size_t>(align), s);
67#else
68 void *mem = ::aligned_alloc(static_cast<size_t>(align), s);
69#endif
70 ac = (mem != nullptr);
71 return mem;
72 }
73};
74
75} // namespace LIBC_NAMESPACE_DECL
76
77LIBC_INLINE void *operator new(size_t size,
78 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
79 return LIBC_NAMESPACE::AllocChecker::alloc(size, ac);
80}
81
82LIBC_INLINE void *operator new(size_t size, std::align_val_t align,
83 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
84 return LIBC_NAMESPACE::AllocChecker::aligned_alloc(size, align, ac);
85}
86
87LIBC_INLINE void *operator new[](size_t size,
88 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
89 return LIBC_NAMESPACE::AllocChecker::alloc(size, ac);
90}
91
92LIBC_INLINE void *operator new[](size_t size, std::align_val_t align,
93 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
94 return LIBC_NAMESPACE::AllocChecker::aligned_alloc(size, align, ac);
95}
96
97LIBC_INLINE void *operator new(size_t, void *p) { return p; }
98
99LIBC_INLINE void *operator new[](size_t, void *p) { return p; }
100
101// The ideal situation would be to define the various flavors of operator delete
102// inlinelike we do with operator new above. However, since we need operator
103// delete prototypes to match those specified by the C++ standard, we cannot
104// define them inline as the C++ standard does not allow inline definitions of
105// replacement operator delete implementations. Note also that we assign a
106// special linkage name to each of these replacement operator delete functions.
107// This is because, if we do not give them a special libc internal linkage name,
108// they will replace operator delete for the entire application. Including this
109// header file in all libc source files where operator delete is called ensures
110// that only libc call sites use these replacement operator delete functions.
111
112#define DELETE_NAME(name) \
113 __asm__(LIBC_MACRO_TO_STRING(LIBC_NAMESPACE) "_" LIBC_MACRO_TO_STRING(name))
114
115void operator delete(void *) noexcept DELETE_NAME(delete);
116void operator delete(void *, std::align_val_t) noexcept
117 DELETE_NAME(delete_aligned);
118void operator delete(void *, size_t) noexcept DELETE_NAME(delete_sized);
119void operator delete(void *, size_t, std::align_val_t) noexcept
120 DELETE_NAME(delete_sized_aligned);
121void operator delete[](void *) noexcept DELETE_NAME(delete_array);
122void operator delete[](void *, std::align_val_t) noexcept
123 DELETE_NAME(delete_array_aligned);
124void operator delete[](void *, size_t) noexcept DELETE_NAME(delete_array_sized);
125void operator delete[](void *, size_t, std::align_val_t) noexcept
126 DELETE_NAME(delete_array_sized_aligned);
127
128#undef DELETE_NAME
129
130#endif // LLVM_LIBC_SRC___SUPPORT_CPP_NEW_H
131

source code of libc/src/__support/CPP/new.h