libc/src/__support/CPP/new.h

   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 "src/__support/common.h"
  13
  14 #include <stddef.h> // For size_t
  15 #include <stdlib.h> // For malloc, free etc.
  16
  17 // Defining members in the std namespace is not preferred. But, we do it here
  18 // so that we can use it to define the operator new which takes std::align_val_t
  19 // argument.
  20 namespace std {
  21
  22 enum class align_val_t : size_t {};
  23
  24 } // namespace std
  25
  26 namespace LIBC_NAMESPACE {
  27
  28 class AllocChecker {
  29   bool success = false;
  30
  31   LIBC_INLINE AllocChecker &operator=(bool status) {
  32     success = status;
  33     return *this;
  34   }
  35
  36 public:
  37   LIBC_INLINE AllocChecker() = default;
  38
  39   LIBC_INLINE operator bool() const { return success; }
  40
  41   LIBC_INLINE static void *alloc(size_t s, AllocChecker &ac) {
  42     void *mem = ::malloc(s);
  43     ac = (mem != nullptr);
  44     return mem;
  45   }
  46
  47   LIBC_INLINE static void *aligned_alloc(size_t s, std::align_val_t align,
  48                                          AllocChecker &ac) {
  49     void *mem = ::aligned_alloc(static_cast<size_t>(align), s);
  50     ac = (mem != nullptr);
  51     return mem;
  52   }
  53 };
  54
  55 } // namespace LIBC_NAMESPACE
  56
  57 LIBC_INLINE void *operator new(size_t size,
  58                                LIBC_NAMESPACE::AllocChecker &ac) noexcept {
  59   return LIBC_NAMESPACE::AllocChecker::alloc(size, ac);
  60 }
  61
  62 LIBC_INLINE void *operator new(size_t size, std::align_val_t align,
  63                                LIBC_NAMESPACE::AllocChecker &ac) noexcept {
  64   return LIBC_NAMESPACE::AllocChecker::aligned_alloc(size, align, ac);
  65 }
  66
  67 LIBC_INLINE void *operator new[](size_t size,
  68                                  LIBC_NAMESPACE::AllocChecker &ac) noexcept {
  69   return LIBC_NAMESPACE::AllocChecker::alloc(size, ac);
  70 }
  71
  72 LIBC_INLINE void *operator new[](size_t size, std::align_val_t align,
  73                                  LIBC_NAMESPACE::AllocChecker &ac) noexcept {
  74   return LIBC_NAMESPACE::AllocChecker::aligned_alloc(size, align, ac);
  75 }
  76
  77 // The ideal situation would be to define the various flavors of operator delete
  78 // inlinelike we do with operator new above. However, since we need operator
  79 // delete prototypes to match those specified by the C++ standard, we cannot
  80 // define them inline as the C++ standard does not allow inline definitions of
  81 // replacement operator delete implementations. Note also that we assign a
  82 // special linkage name to each of these replacement operator delete functions.
  83 // This is because, if we do not give them a special libc internal linkage name,
  84 // they will replace operator delete for the entire application. Including this
  85 // header file in all libc source files where operator delete is called ensures
  86 // that only libc call sites use these replacement operator delete functions.
  87
  88 #define DELETE_NAME(name)                                                      \
  89   __asm__(LIBC_MACRO_TO_STRING(LIBC_NAMESPACE) "_" LIBC_MACRO_TO_STRING(name))
  90
  91 void operator delete(void *) noexcept DELETE_NAME(delete);
  92 void operator delete(void *, std::align_val_t) noexcept
  93     DELETE_NAME(delete_aligned);
  94 void operator delete(void *, size_t) noexcept DELETE_NAME(delete_sized);
  95 void operator delete(void *, size_t, std::align_val_t) noexcept
  96     DELETE_NAME(delete_sized_aligned);
  97 void operator delete[](void *) noexcept DELETE_NAME(delete_array);
  98 void operator delete[](void *, std::align_val_t) noexcept
  99     DELETE_NAME(delete_array_aligned);
 100 void operator delete[](void *, size_t) noexcept DELETE_NAME(delete_array_sized);
 101 void operator delete[](void *, size_t, std::align_val_t) noexcept
 102     DELETE_NAME(delete_array_sized_aligned);
 103
 104 #undef DELETE_NAME
 105
 106 #endif // LLVM_LIBC_SRC___SUPPORT_CPP_NEW_H