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 __llvm_libc {
  27
  28 class AllocChecker {
  29   bool success = false;
  30   AllocChecker &operator=(bool status) {
  31     success = status;
  32     return *this;
  33   }
  34
  35 public:
  36   AllocChecker() = default;
  37   operator bool() const { return success; }
  38
  39   LIBC_INLINE static void *alloc(size_t s, AllocChecker &ac) {
  40     void *mem = ::malloc(s);
  41     ac = (mem != nullptr);
  42     return mem;
  43   }
  44
  45   LIBC_INLINE static void *aligned_alloc(size_t s, std::align_val_t align,
  46                                          AllocChecker &ac) {
  47     void *mem = ::aligned_alloc(static_cast<size_t>(align), s);
  48     ac = (mem != nullptr);
  49     return mem;
  50   }
  51 };
  52
  53 } // namespace __llvm_libc
  54
  55 LIBC_INLINE void *operator new(size_t size,
  56                                __llvm_libc::AllocChecker &ac) noexcept {
  57   return __llvm_libc::AllocChecker::alloc(size, ac);
  58 }
  59
  60 LIBC_INLINE void *operator new(size_t size, std::align_val_t align,
  61                                __llvm_libc::AllocChecker &ac) noexcept {
  62   return __llvm_libc::AllocChecker::aligned_alloc(size, align, ac);
  63 }
  64
  65 LIBC_INLINE void *operator new[](size_t size,
  66                                  __llvm_libc::AllocChecker &ac) noexcept {
  67   return __llvm_libc::AllocChecker::alloc(size, ac);
  68 }
  69
  70 LIBC_INLINE void *operator new[](size_t size, std::align_val_t align,
  71                                  __llvm_libc::AllocChecker &ac) noexcept {
  72   return __llvm_libc::AllocChecker::aligned_alloc(size, align, ac);
  73 }
  74
  75 // The ideal situation would be to define the various flavors of operator delete
  76 // inlinelike we do with operator new above. However, since we need operator
  77 // delete prototypes to match those specified by the C++ standard, we cannot
  78 // define them inline as the C++ standard does not allow inline definitions of
  79 // replacement operator delete implementations. Note also that we assign a
  80 // special linkage name to each of these replacement operator delete functions.
  81 // This is because, if we do not give them a special libc internal linkage name,
  82 // they will replace operator delete for the entire application. Including this
  83 // header file in all libc source files where operator delete is called ensures
  84 // that only libc call sites use these replacement operator delete functions.
  85 void operator delete(void *) noexcept __asm__("__llvm_libc_delete");
  86 void operator delete(void *, std::align_val_t) noexcept
  87     __asm__("__llvm_libc_delete_aligned");
  88 void operator delete(void *, size_t) noexcept
  89     __asm__("__llvm_libc_delete_sized");
  90 void operator delete(void *, size_t, std::align_val_t) noexcept
  91     __asm__("__llvm_libc_delete_sized_aligned");
  92 void operator delete[](void *) noexcept __asm__("__llvm_libc_delete_array");
  93 void operator delete[](void *, std::align_val_t) noexcept
  94     __asm__("__llvm_libc_delete_array_aligned");
  95 void operator delete[](void *, size_t) noexcept
  96     __asm__("__llvm_libc_delete_array_sized");
  97 void operator delete[](void *, size_t, std::align_val_t) noexcept
  98     __asm__("__llvm_libc_delete_array_sized_aligned");
  99
 100 #endif // LLVM_LIBC_SRC_SUPPORT_CPP_NEW_H