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llvm-project/libcxx/include/new
Eric Fiselier f25b75b91b Implement sized deallocation for std::allocator and friends. 
Summary:
C++14 sized deallocation is disabled by default due to ABI concerns. However, when a user manually enables it then libc++ should take advantage of it since sized deallocation can provide a significant performance win depending on the underlying malloc implementation. (Note that libc++'s definitions of sized delete don't do anything special yet, but users are free to provide their own).

This patch updates __libcpp_deallocate to selectively call sized operator delete when it's available. `__libcpp_deallocate_unsized` should be used when the size of the allocation is unknown.

On Apple this patch makes no attempt to determine if the sized operator delete is unavailable, only that the language feature is enabled. This could cause a compile error when using `std::allocator`, but the same compile error would occur whenever the user calls `new`, so I don't think it's a problem.

Reviewers: ldionne, mclow.lists

Reviewed By: ldionne

Subscribers: rsmith, ckennelly, libcxx-commits, christof

Differential Revision: https://reviews.llvm.org/D53120

llvm-svn: 345281
2018-10-25 17:21:30 +00:00

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// -*- C++ -*-
//===----------------------------- new ------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP_NEW
#define _LIBCPP_NEW
/*
new synopsis
namespace std
{
class bad_alloc
: public exception
{
public:
bad_alloc() noexcept;
bad_alloc(const bad_alloc&) noexcept;
bad_alloc& operator=(const bad_alloc&) noexcept;
virtual const char* what() const noexcept;
};
class bad_array_length : public bad_alloc // FIXME: Not part of C++
{
public:
bad_array_length() noexcept;
};
class bad_array_new_length : public bad_alloc // C++14
{
public:
bad_array_new_length() noexcept;
};
enum class align_val_t : size_t {}; // C++17
struct nothrow_t {};
extern const nothrow_t nothrow;
typedef void (*new_handler)();
new_handler set_new_handler(new_handler new_p) noexcept;
new_handler get_new_handler() noexcept;
// 21.6.4, pointer optimization barrier
template <class T> constexpr T* launder(T* p) noexcept; // C++17
} // std
void* operator new(std::size_t size); // replaceable, nodiscard in C++2a
void* operator new(std::size_t size, std::align_val_t alignment); // replaceable, C++17, nodiscard in C++2a
void* operator new(std::size_t size, const std::nothrow_t&) noexcept; // replaceable, nodiscard in C++2a
void* operator new(std::size_t size, std::align_val_t alignment,
const std::nothrow_t&) noexcept; // replaceable, C++17, nodiscard in C++2a
void operator delete(void* ptr) noexcept; // replaceable
void operator delete(void* ptr, std::size_t size) noexcept; // replaceable, C++14
void operator delete(void* ptr, std::align_val_t alignment) noexcept; // replaceable, C++17
void operator delete(void* ptr, std::size_t size,
std::align_val_t alignment) noexcept; // replaceable, C++17
void operator delete(void* ptr, const std::nothrow_t&) noexcept; // replaceable
void operator delete(void* ptr, std:align_val_t alignment,
const std::nothrow_t&) noexcept; // replaceable, C++17
void* operator new[](std::size_t size); // replaceable, nodiscard in C++2a
void* operator new[](std::size_t size,
std::align_val_t alignment) noexcept; // replaceable, C++17, nodiscard in C++2a
void* operator new[](std::size_t size, const std::nothrow_t&) noexcept; // replaceable, nodiscard in C++2a
void* operator new[](std::size_t size, std::align_val_t alignment,
const std::nothrow_t&) noexcept; // replaceable, C++17, nodiscard in C++2a
void operator delete[](void* ptr) noexcept; // replaceable
void operator delete[](void* ptr, std::size_t size) noexcept; // replaceable, C++14
void operator delete[](void* ptr,
std::align_val_t alignment) noexcept; // replaceable, C++17
void operator delete[](void* ptr, std::size_t size,
std::align_val_t alignment) noexcept; // replaceable, C++17
void operator delete[](void* ptr, const std::nothrow_t&) noexcept; // replaceable
void operator delete[](void* ptr, std::align_val_t alignment,
const std::nothrow_t&) noexcept; // replaceable, C++17
void* operator new (std::size_t size, void* ptr) noexcept; // nodiscard in C++2a
void* operator new[](std::size_t size, void* ptr) noexcept; // nodiscard in C++2a
void operator delete (void* ptr, void*) noexcept;
void operator delete[](void* ptr, void*) noexcept;
*/
#include <__config>
#include <exception>
#include <type_traits>
#include <cstddef>
#include <version>
#ifdef _LIBCPP_NO_EXCEPTIONS
#include <cstdlib>
#endif
#if defined(_LIBCPP_ABI_MICROSOFT) && !defined(_LIBCPP_NO_VCRUNTIME)
#include <new.h>
#endif
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
#if !defined(__cpp_sized_deallocation) || __cpp_sized_deallocation < 201309L
#define _LIBCPP_HAS_NO_LANGUAGE_SIZED_DEALLOCATION
#endif
#if !defined(_LIBCPP_BUILDING_LIBRARY) && _LIBCPP_STD_VER < 14 && \
defined(_LIBCPP_HAS_NO_LANGUAGE_SIZED_DEALLOCATION)
# define _LIBCPP_HAS_NO_LIBRARY_SIZED_DEALLOCATION
#endif
#if defined(_LIBCPP_HAS_NO_LIBRARY_SIZED_DEALLOCATION) || \
defined(_LIBCPP_HAS_NO_LANGUAGE_SIZED_DEALLOCATION)
# define _LIBCPP_HAS_NO_SIZED_DEALLOCATION
#endif
#if !__has_builtin(__builtin_operator_new) || \
__has_builtin(__builtin_operator_new) < 201802L
#define _LIBCPP_HAS_NO_BUILTIN_OVERLOADED_OPERATOR_NEW_DELETE
#endif
namespace std // purposefully not using versioning namespace
{
#if !defined(_LIBCPP_ABI_MICROSOFT) || defined(_LIBCPP_NO_VCRUNTIME)
struct _LIBCPP_TYPE_VIS nothrow_t {};
extern _LIBCPP_FUNC_VIS const nothrow_t nothrow;
class _LIBCPP_EXCEPTION_ABI bad_alloc
: public exception
{
public:
bad_alloc() _NOEXCEPT;
virtual ~bad_alloc() _NOEXCEPT;
virtual const char* what() const _NOEXCEPT;
};
class _LIBCPP_EXCEPTION_ABI bad_array_new_length
: public bad_alloc
{
public:
bad_array_new_length() _NOEXCEPT;
virtual ~bad_array_new_length() _NOEXCEPT;
virtual const char* what() const _NOEXCEPT;
};
typedef void (*new_handler)();
_LIBCPP_FUNC_VIS new_handler set_new_handler(new_handler) _NOEXCEPT;
_LIBCPP_FUNC_VIS new_handler get_new_handler() _NOEXCEPT;
#endif // !_LIBCPP_ABI_MICROSOFT || _LIBCPP_NO_VCRUNTIME
_LIBCPP_NORETURN _LIBCPP_FUNC_VIS void __throw_bad_alloc(); // not in C++ spec
#if defined(_LIBCPP_BUILDING_LIBRARY) || (_LIBCPP_STD_VER > 11)
class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_ARRAY_LENGTH
bad_array_length : public bad_alloc {
public:
bad_array_length() _NOEXCEPT;
virtual ~bad_array_length() _NOEXCEPT;
virtual const char* what() const _NOEXCEPT;
};
#define _LIBCPP_BAD_ARRAY_LENGTH_DEFINED
#endif // defined(_LIBCPP_BUILDING_LIBRARY) || (_LIBCPP_STD_VER > 11)
#if !defined(_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION) && \
!defined(_LIBCPP_DEFER_NEW_TO_VCRUNTIME)
#ifndef _LIBCPP_CXX03_LANG
enum class _LIBCPP_ENUM_VIS align_val_t : size_t { };
#else
enum align_val_t { __zero = 0, __max = (size_t)-1 };
#endif
#endif
} // std
#if defined(_LIBCPP_CXX03_LANG)
#define _THROW_BAD_ALLOC throw(std::bad_alloc)
#else
#define _THROW_BAD_ALLOC
#endif
#if !defined(_LIBCPP_DEFER_NEW_TO_VCRUNTIME)
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new(std::size_t __sz) _THROW_BAD_ALLOC;
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new(std::size_t __sz, const std::nothrow_t&) _NOEXCEPT _NOALIAS;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete(void* __p) _NOEXCEPT;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete(void* __p, const std::nothrow_t&) _NOEXCEPT;
#ifndef _LIBCPP_HAS_NO_LIBRARY_SIZED_DEALLOCATION
_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void operator delete(void* __p, std::size_t __sz) _NOEXCEPT;
#endif
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new[](std::size_t __sz) _THROW_BAD_ALLOC;
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new[](std::size_t __sz, const std::nothrow_t&) _NOEXCEPT _NOALIAS;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete[](void* __p) _NOEXCEPT;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete[](void* __p, const std::nothrow_t&) _NOEXCEPT;
#ifndef _LIBCPP_HAS_NO_LIBRARY_SIZED_DEALLOCATION
_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void operator delete[](void* __p, std::size_t __sz) _NOEXCEPT;
#endif
#ifndef _LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new(std::size_t __sz, std::align_val_t) _THROW_BAD_ALLOC;
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new(std::size_t __sz, std::align_val_t, const std::nothrow_t&) _NOEXCEPT _NOALIAS;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete(void* __p, std::align_val_t) _NOEXCEPT;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete(void* __p, std::align_val_t, const std::nothrow_t&) _NOEXCEPT;
#ifndef _LIBCPP_HAS_NO_LIBRARY_SIZED_DEALLOCATION
_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void operator delete(void* __p, std::size_t __sz, std::align_val_t) _NOEXCEPT;
#endif
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new[](std::size_t __sz, std::align_val_t) _THROW_BAD_ALLOC;
_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new[](std::size_t __sz, std::align_val_t, const std::nothrow_t&) _NOEXCEPT _NOALIAS;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete[](void* __p, std::align_val_t) _NOEXCEPT;
_LIBCPP_OVERRIDABLE_FUNC_VIS void operator delete[](void* __p, std::align_val_t, const std::nothrow_t&) _NOEXCEPT;
#ifndef _LIBCPP_HAS_NO_LIBRARY_SIZED_DEALLOCATION
_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void operator delete[](void* __p, std::size_t __sz, std::align_val_t) _NOEXCEPT;
#endif
#endif
_LIBCPP_NODISCARD_AFTER_CXX17 inline _LIBCPP_INLINE_VISIBILITY void* operator new (std::size_t, void* __p) _NOEXCEPT {return __p;}
_LIBCPP_NODISCARD_AFTER_CXX17 inline _LIBCPP_INLINE_VISIBILITY void* operator new[](std::size_t, void* __p) _NOEXCEPT {return __p;}
inline _LIBCPP_INLINE_VISIBILITY void operator delete (void*, void*) _NOEXCEPT {}
inline _LIBCPP_INLINE_VISIBILITY void operator delete[](void*, void*) _NOEXCEPT {}
#endif // !_LIBCPP_DEFER_NEW_TO_VCRUNTIME
_LIBCPP_BEGIN_NAMESPACE_STD
_LIBCPP_CONSTEXPR inline _LIBCPP_INLINE_VISIBILITY bool __is_overaligned_for_new(size_t __align) _NOEXCEPT {
#ifdef __STDCPP_DEFAULT_NEW_ALIGNMENT__
return __align > __STDCPP_DEFAULT_NEW_ALIGNMENT__;
#else
return __align > alignment_of<max_align_t>::value;
#endif
}
inline _LIBCPP_INLINE_VISIBILITY void *__libcpp_allocate(size_t __size, size_t __align) {
#ifndef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
if (__is_overaligned_for_new(__align)) {
const align_val_t __align_val = static_cast<align_val_t>(__align);
# ifdef _LIBCPP_HAS_NO_BUILTIN_OVERLOADED_OPERATOR_NEW_DELETE
return ::operator new(__size, __align_val);
# else
return __builtin_operator_new(__size, __align_val);
# endif
}
#else
((void)__align);
#endif
#ifdef _LIBCPP_HAS_NO_BUILTIN_OPERATOR_NEW_DELETE
return ::operator new(__size);
#else
return __builtin_operator_new(__size);
#endif
}
struct _DeallocateCaller {
static inline _LIBCPP_INLINE_VISIBILITY
void __do_deallocate_handle_size_align(void *__ptr, size_t __size, size_t __align) {
#if defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
((void)__align);
return __do_deallocate_handle_size(__ptr, __size);
#else
if (__is_overaligned_for_new(__align)) {
const align_val_t __align_val = static_cast<align_val_t>(__align);
return __do_deallocate_handle_size(__ptr, __size, __align_val);
} else {
return __do_deallocate_handle_size(__ptr, __size);
}
#endif
}
static inline _LIBCPP_INLINE_VISIBILITY
void __do_deallocate_handle_align(void *__ptr, size_t __align) {
#if defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
((void)__align);
return __do_call(__ptr);
#else
if (__is_overaligned_for_new(__align)) {
const align_val_t __align_val = static_cast<align_val_t>(__align);
return __do_call(__ptr, __align_val);
} else {
return __do_call(__ptr);
}
#endif
}
private:
static inline void __do_deallocate_handle_size(void *__ptr, size_t __size) {
#ifdef _LIBCPP_HAS_NO_SIZED_DEALLOCATION
((void)__size);
return __do_call(__ptr);
#else
return __do_call(__ptr, __size);
#endif
}
#ifndef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
static inline void __do_deallocate_handle_size(void *__ptr, size_t __size, align_val_t __align) {
#ifdef _LIBCPP_HAS_NO_SIZED_DEALLOCATION
((void)__size);
return __do_call(__ptr, __align);
#else
return __do_call(__ptr, __size, __align);
#endif
}
#endif
private:
template <class _A1, class _A2>
static inline void __do_call(void *__ptr, _A1 __a1, _A2 __a2) {
#if defined(_LIBCPP_HAS_NO_BUILTIN_OPERATOR_NEW_DELETE) || \
defined(_LIBCPP_HAS_NO_BUILTIN_OVERLOADED_OPERATOR_NEW_DELETE)
return ::operator delete(__ptr, __a1, __a2);
#else
return __builtin_operator_delete(__ptr, __a1, __a2);
#endif
}
template <class _A1>
static inline void __do_call(void *__ptr, _A1 __a1) {
#if defined(_LIBCPP_HAS_NO_BUILTIN_OPERATOR_NEW_DELETE) || \
defined(_LIBCPP_HAS_NO_BUILTIN_OVERLOADED_OPERATOR_NEW_DELETE)
return ::operator delete(__ptr, __a1);
#else
return __builtin_operator_delete(__ptr, __a1);
#endif
}
static inline void __do_call(void *__ptr) {
#ifdef _LIBCPP_HAS_NO_BUILTIN_OPERATOR_NEW_DELETE
return ::operator delete(__ptr);
#else
return __builtin_operator_delete(__ptr);
#endif
}
};
inline _LIBCPP_INLINE_VISIBILITY void __libcpp_deallocate(void* __ptr, size_t __size, size_t __align) {
_DeallocateCaller::__do_deallocate_handle_size_align(__ptr, __size, __align);
}
inline _LIBCPP_INLINE_VISIBILITY void __libcpp_deallocate_unsized(void* __ptr, size_t __align) {
_DeallocateCaller::__do_deallocate_handle_align(__ptr, __align);
}
#ifdef _LIBCPP_BAD_ARRAY_LENGTH_DEFINED
_LIBCPP_NORETURN inline _LIBCPP_INLINE_VISIBILITY
#ifndef _LIBCPP_NO_EXCEPTIONS
_LIBCPP_AVAILABILITY_BAD_ARRAY_LENGTH
#endif
void __throw_bad_array_length()
{
#ifndef _LIBCPP_NO_EXCEPTIONS
throw bad_array_length();
#else
_VSTD::abort();
#endif
}
#endif
template <class _Tp>
_LIBCPP_NODISCARD_AFTER_CXX17 inline
_LIBCPP_CONSTEXPR _Tp* __launder(_Tp* __p) _NOEXCEPT
{
static_assert (!(is_function<_Tp>::value), "can't launder functions" );
static_assert (!(is_same<void, typename remove_cv<_Tp>::type>::value), "can't launder cv-void" );
#ifdef _LIBCPP_COMPILER_HAS_BUILTIN_LAUNDER
return __builtin_launder(__p);
#else
return __p;
#endif
}
#if _LIBCPP_STD_VER > 14
template <class _Tp>
_LIBCPP_NODISCARD_AFTER_CXX17 inline _LIBCPP_INLINE_VISIBILITY
constexpr _Tp* launder(_Tp* __p) noexcept
{
return _VSTD::__launder(__p);
}
#endif
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_NEW
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