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.
24 namespace std {
25
26 enum class align_val_t : size_t {};
27
28 } // namespace std
29
30 namespace LIBC_NAMESPACE_DECL {
31
32 class AllocChecker {
33 bool success = false;
34
35 LIBC_INLINE AllocChecker &operator=(bool status) {
36 success = status;
37 return *this;
38 }
39
40 public:
41 LIBC_INLINE AllocChecker() = default;
42
43 LIBC_INLINE operator bool() const { return success; }
44
alloc(size_t s,AllocChecker & ac)45 LIBC_INLINE static void *alloc(size_t s, AllocChecker &ac) {
46 void *mem = ::malloc(s);
47 ac = (mem != nullptr);
48 return mem;
49 }
50
aligned_alloc(size_t s,std::align_val_t align,AllocChecker & ac)51 LIBC_INLINE static void *aligned_alloc(size_t s, std::align_val_t align,
52 AllocChecker &ac) {
53 #ifdef LIBC_TARGET_OS_IS_WINDOWS
54 // std::aligned_alloc is not available on Windows because std::free on
55 // Windows cannot deallocate any over-aligned memory. Microsoft provides an
56 // alternative for std::aligned_alloc named _aligned_malloc, but it must be
57 // paired with _aligned_free instead of std::free.
58 void *mem = ::_aligned_malloc(static_cast<size_t>(align), s);
59 #else
60 void *mem = ::aligned_alloc(static_cast<size_t>(align), s);
61 #endif
62 ac = (mem != nullptr);
63 return mem;
64 }
65 };
66
67 } // namespace LIBC_NAMESPACE_DECL
68
new(size_t size,LIBC_NAMESPACE::AllocChecker & ac)69 LIBC_INLINE void *operator new(size_t size,
70 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
71 return LIBC_NAMESPACE::AllocChecker::alloc(size, ac);
72 }
73
new(size_t size,std::align_val_t align,LIBC_NAMESPACE::AllocChecker & ac)74 LIBC_INLINE void *operator new(size_t size, std::align_val_t align,
75 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
76 return LIBC_NAMESPACE::AllocChecker::aligned_alloc(size, align, ac);
77 }
78
79 LIBC_INLINE void *operator new[](size_t size,
80 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
81 return LIBC_NAMESPACE::AllocChecker::alloc(size, ac);
82 }
83
84 LIBC_INLINE void *operator new[](size_t size, std::align_val_t align,
85 LIBC_NAMESPACE::AllocChecker &ac) noexcept {
86 return LIBC_NAMESPACE::AllocChecker::aligned_alloc(size, align, ac);
87 }
88
new(size_t,void * p)89 LIBC_INLINE void *operator new(size_t, void *p) { return p; }
90
91 LIBC_INLINE void *operator new[](size_t, void *p) { return p; }
92
93 // The ideal situation would be to define the various flavors of operator delete
94 // inlinelike we do with operator new above. However, since we need operator
95 // delete prototypes to match those specified by the C++ standard, we cannot
96 // define them inline as the C++ standard does not allow inline definitions of
97 // replacement operator delete implementations. Note also that we assign a
98 // special linkage name to each of these replacement operator delete functions.
99 // This is because, if we do not give them a special libc internal linkage name,
100 // they will replace operator delete for the entire application. Including this
101 // header file in all libc source files where operator delete is called ensures
102 // that only libc call sites use these replacement operator delete functions.
103
104 #define DELETE_NAME(name) \
105 __asm__(LIBC_MACRO_TO_STRING(LIBC_NAMESPACE) "_" LIBC_MACRO_TO_STRING(name))
106
107 void operator delete(void *) noexcept DELETE_NAME(delete);
108 void operator delete(void *, std::align_val_t) noexcept
109 DELETE_NAME(delete_aligned);
110 void operator delete(void *, size_t) noexcept DELETE_NAME(delete_sized);
111 void operator delete(void *, size_t, std::align_val_t) noexcept
112 DELETE_NAME(delete_sized_aligned);
113 void operator delete[](void *) noexcept DELETE_NAME(delete_array);
114 void operator delete[](void *, std::align_val_t) noexcept
115 DELETE_NAME(delete_array_aligned);
116 void operator delete[](void *, size_t) noexcept DELETE_NAME(delete_array_sized);
117 void operator delete[](void *, size_t, std::align_val_t) noexcept
118 DELETE_NAME(delete_array_sized_aligned);
119
120 #undef DELETE_NAME
121
122 #endif // LLVM_LIBC_SRC___SUPPORT_CPP_NEW_H
123