diff --git a/BUILD.gn b/BUILD.gn index d55c4f3cf9..f80ccaa164 100644 --- a/BUILD.gn +++ b/BUILD.gn @@ -2513,6 +2513,7 @@ v8_component("v8_libbase") { "src/base/macros.h", "src/base/once.cc", "src/base/once.h", + "src/base/optional.h", "src/base/platform/condition-variable.cc", "src/base/platform/condition-variable.h", "src/base/platform/elapsed-timer.h", diff --git a/src/asmjs/asm-parser.cc b/src/asmjs/asm-parser.cc index 6b84cfd467..4d72593562 100644 --- a/src/asmjs/asm-parser.cc +++ b/src/asmjs/asm-parser.cc @@ -11,6 +11,7 @@ #include "src/asmjs/asm-js.h" #include "src/asmjs/asm-types.h" +#include "src/base/optional.h" #include "src/objects-inl.h" // TODO(mstarzinger): Temporary cycle breaker. #include "src/parsing/scanner.h" #include "src/wasm/wasm-opcodes.h" @@ -2014,8 +2015,7 @@ AsmType* AsmJsParser::ValidateCall() { // both cases we might be seeing the {function_name} for the first time and // hence allocate a {VarInfo} here, all subsequent uses of the same name then // need to match the information stored at this point. - // TODO(mstarzinger): Consider using Chromiums base::Optional instead. - std::unique_ptr tmp; + base::Optional tmp; if (Check('[')) { RECURSEn(EqualityExpression()); EXPECT_TOKENn('&'); @@ -2050,8 +2050,8 @@ AsmType* AsmJsParser::ValidateCall() { current_function_builder_->EmitI32Const(function_info->index); current_function_builder_->Emit(kExprI32Add); // We have to use a temporary for the correct order of evaluation. - tmp.reset(new TemporaryVariableScope(this)); - current_function_builder_->EmitSetLocal(tmp.get()->get()); + tmp.emplace(this); + current_function_builder_->EmitSetLocal(tmp->get()); // The position of function table calls is after the table lookup. call_pos = static_cast(scanner_.Position()); } else { @@ -2285,7 +2285,7 @@ AsmType* AsmJsParser::ValidateCall() { } } if (function_info->kind == VarKind::kTable) { - current_function_builder_->EmitGetLocal(tmp.get()->get()); + current_function_builder_->EmitGetLocal(tmp->get()); current_function_builder_->AddAsmWasmOffset(call_pos, to_number_pos); current_function_builder_->Emit(kExprCallIndirect); current_function_builder_->EmitU32V(signature_index); diff --git a/src/base/optional.h b/src/base/optional.h new file mode 100644 index 0000000000..a229745f84 --- /dev/null +++ b/src/base/optional.h @@ -0,0 +1,493 @@ +// Copyright 2016 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +// This file is a clone of "base/optional.h" in chromium. +// Keep in sync, especially when fixing bugs. +// Copyright 2017 the V8 project authors. All rights reserved. + +#ifndef V8_BASE_OPTIONAL_H_ +#define V8_BASE_OPTIONAL_H_ + +#include + +#include "src/base/logging.h" + +namespace v8 { +namespace base { + +// Specification: +// http://en.cppreference.com/w/cpp/utility/optional/in_place_t +struct in_place_t {}; + +// Specification: +// http://en.cppreference.com/w/cpp/utility/optional/nullopt_t +struct nullopt_t { + constexpr explicit nullopt_t(int) {} +}; + +// Specification: +// http://en.cppreference.com/w/cpp/utility/optional/in_place +constexpr in_place_t in_place = {}; + +// Specification: +// http://en.cppreference.com/w/cpp/utility/optional/nullopt +constexpr nullopt_t nullopt(0); + +namespace internal { + +template ::value> +struct OptionalStorage { + // Initializing |empty_| here instead of using default member initializing + // to avoid errors in g++ 4.8. + constexpr OptionalStorage() : empty_('\0') {} + + constexpr explicit OptionalStorage(const T& value) + : is_null_(false), value_(value) {} + + // TODO(alshabalin): Can't use 'constexpr' with std::move until C++14. + explicit OptionalStorage(T&& value) + : is_null_(false), value_(std::move(value)) {} + + // TODO(alshabalin): Can't use 'constexpr' with std::forward until C++14. + template + explicit OptionalStorage(base::in_place_t, Args&&... args) + : is_null_(false), value_(std::forward(args)...) {} + + // When T is not trivially destructible we must call its + // destructor before deallocating its memory. + ~OptionalStorage() { + if (!is_null_) value_.~T(); + } + + bool is_null_ = true; + union { + // |empty_| exists so that the union will always be initialized, even when + // it doesn't contain a value. Union members must be initialized for the + // constructor to be 'constexpr'. + char empty_; + T value_; + }; +}; + +template +struct OptionalStorage { + // Initializing |empty_| here instead of using default member initializing + // to avoid errors in g++ 4.8. + constexpr OptionalStorage() : empty_('\0') {} + + constexpr explicit OptionalStorage(const T& value) + : is_null_(false), value_(value) {} + + // TODO(alshabalin): Can't use 'constexpr' with std::move until C++14. + explicit OptionalStorage(T&& value) + : is_null_(false), value_(std::move(value)) {} + + // TODO(alshabalin): Can't use 'constexpr' with std::forward until C++14. + template + explicit OptionalStorage(base::in_place_t, Args&&... args) + : is_null_(false), value_(std::forward(args)...) {} + + // When T is trivially destructible (i.e. its destructor does nothing) there + // is no need to call it. Explicitly defaulting the destructor means it's not + // user-provided. Those two together make this destructor trivial. + ~OptionalStorage() = default; + + bool is_null_ = true; + union { + // |empty_| exists so that the union will always be initialized, even when + // it doesn't contain a value. Union members must be initialized for the + // constructor to be 'constexpr'. + char empty_; + T value_; + }; +}; + +} // namespace internal + +// base::Optional is a Chromium version of the C++17 optional class: +// std::optional documentation: +// http://en.cppreference.com/w/cpp/utility/optional +// Chromium documentation: +// https://chromium.googlesource.com/chromium/src/+/master/docs/optional.md +// +// These are the differences between the specification and the implementation: +// - The constructor and emplace method using initializer_list are not +// implemented because 'initializer_list' is banned from Chromium. +// - Constructors do not use 'constexpr' as it is a C++14 extension. +// - 'constexpr' might be missing in some places for reasons specified locally. +// - No exceptions are thrown, because they are banned from Chromium. +// - All the non-members are in the 'base' namespace instead of 'std'. +template +class Optional { + public: + using value_type = T; + + constexpr Optional() {} + + explicit constexpr Optional(base::nullopt_t) {} + + Optional(const Optional& other) { + if (!other.storage_.is_null_) Init(other.value()); + } + + Optional(Optional&& other) { + if (!other.storage_.is_null_) Init(std::move(other.value())); + } + + explicit constexpr Optional(const T& value) : storage_(value) {} + + // TODO(alshabalin): Can't use 'constexpr' with std::move until C++14. + explicit Optional(T&& value) : storage_(std::move(value)) {} + + // TODO(alshabalin): Can't use 'constexpr' with std::forward until C++14. + template + explicit Optional(base::in_place_t, Args&&... args) + : storage_(base::in_place, std::forward(args)...) {} + + ~Optional() = default; + + Optional& operator=(base::nullopt_t) { + FreeIfNeeded(); + return *this; + } + + Optional& operator=(const Optional& other) { + if (other.storage_.is_null_) { + FreeIfNeeded(); + return *this; + } + + InitOrAssign(other.value()); + return *this; + } + + Optional& operator=(Optional&& other) { + if (other.storage_.is_null_) { + FreeIfNeeded(); + return *this; + } + + InitOrAssign(std::move(other.value())); + return *this; + } + + template + typename std::enable_if, T>::value, + Optional&>::type + operator=(U&& value) { + InitOrAssign(std::forward(value)); + return *this; + } + + // TODO(mlamouri): can't use 'constexpr' with DCHECK. + const T* operator->() const { + DCHECK(!storage_.is_null_); + return &value(); + } + + // TODO(mlamouri): using 'constexpr' here breaks compiler that assume it was + // meant to be 'constexpr const'. + T* operator->() { + DCHECK(!storage_.is_null_); + return &value(); + } + + constexpr const T& operator*() const & { return value(); } + + // TODO(mlamouri): using 'constexpr' here breaks compiler that assume it was + // meant to be 'constexpr const'. + T& operator*() & { return value(); } + + constexpr const T&& operator*() const && { return std::move(value()); } + + // TODO(mlamouri): using 'constexpr' here breaks compiler that assume it was + // meant to be 'constexpr const'. + T&& operator*() && { return std::move(value()); } + + constexpr explicit operator bool() const { return !storage_.is_null_; } + + constexpr bool has_value() const { return !storage_.is_null_; } + + // TODO(mlamouri): using 'constexpr' here breaks compiler that assume it was + // meant to be 'constexpr const'. + T& value() & { + DCHECK(!storage_.is_null_); + return storage_.value_; + } + + // TODO(mlamouri): can't use 'constexpr' with DCHECK. + const T& value() const & { + DCHECK(!storage_.is_null_); + return storage_.value_; + } + + // TODO(mlamouri): using 'constexpr' here breaks compiler that assume it was + // meant to be 'constexpr const'. + T&& value() && { + DCHECK(!storage_.is_null_); + return std::move(storage_.value_); + } + + // TODO(mlamouri): can't use 'constexpr' with DCHECK. + const T&& value() const && { + DCHECK(!storage_.is_null_); + return std::move(storage_.value_); + } + + template + constexpr T value_or(U&& default_value) const & { + // TODO(mlamouri): add the following assert when possible: + // static_assert(std::is_copy_constructible::value, + // "T must be copy constructible"); + static_assert(std::is_convertible::value, + "U must be convertible to T"); + return storage_.is_null_ ? static_cast(std::forward(default_value)) + : value(); + } + + template + T value_or(U&& default_value) && { + // TODO(mlamouri): add the following assert when possible: + // static_assert(std::is_move_constructible::value, + // "T must be move constructible"); + static_assert(std::is_convertible::value, + "U must be convertible to T"); + return storage_.is_null_ ? static_cast(std::forward(default_value)) + : std::move(value()); + } + + void swap(Optional& other) { + if (storage_.is_null_ && other.storage_.is_null_) return; + + if (storage_.is_null_ != other.storage_.is_null_) { + if (storage_.is_null_) { + Init(std::move(other.storage_.value_)); + other.FreeIfNeeded(); + } else { + other.Init(std::move(storage_.value_)); + FreeIfNeeded(); + } + return; + } + + DCHECK(!storage_.is_null_ && !other.storage_.is_null_); + using std::swap; + swap(**this, *other); + } + + void reset() { FreeIfNeeded(); } + + template + void emplace(Args&&... args) { + FreeIfNeeded(); + Init(std::forward(args)...); + } + + private: + void Init(const T& value) { + DCHECK(storage_.is_null_); + new (&storage_.value_) T(value); + storage_.is_null_ = false; + } + + void Init(T&& value) { + DCHECK(storage_.is_null_); + new (&storage_.value_) T(std::move(value)); + storage_.is_null_ = false; + } + + template + void Init(Args&&... args) { + DCHECK(storage_.is_null_); + new (&storage_.value_) T(std::forward(args)...); + storage_.is_null_ = false; + } + + void InitOrAssign(const T& value) { + if (storage_.is_null_) + Init(value); + else + storage_.value_ = value; + } + + void InitOrAssign(T&& value) { + if (storage_.is_null_) + Init(std::move(value)); + else + storage_.value_ = std::move(value); + } + + void FreeIfNeeded() { + if (storage_.is_null_) return; + storage_.value_.~T(); + storage_.is_null_ = true; + } + + internal::OptionalStorage storage_; +}; + +template +constexpr bool operator==(const Optional& lhs, const Optional& rhs) { + return !!lhs != !!rhs ? false : lhs == nullopt || (*lhs == *rhs); +} + +template +constexpr bool operator!=(const Optional& lhs, const Optional& rhs) { + return !(lhs == rhs); +} + +template +constexpr bool operator<(const Optional& lhs, const Optional& rhs) { + return rhs == nullopt ? false : (lhs == nullopt ? true : *lhs < *rhs); +} + +template +constexpr bool operator<=(const Optional& lhs, const Optional& rhs) { + return !(rhs < lhs); +} + +template +constexpr bool operator>(const Optional& lhs, const Optional& rhs) { + return rhs < lhs; +} + +template +constexpr bool operator>=(const Optional& lhs, const Optional& rhs) { + return !(lhs < rhs); +} + +template +constexpr bool operator==(const Optional& opt, base::nullopt_t) { + return !opt; +} + +template +constexpr bool operator==(base::nullopt_t, const Optional& opt) { + return !opt; +} + +template +constexpr bool operator!=(const Optional& opt, base::nullopt_t) { + return !!opt; +} + +template +constexpr bool operator!=(base::nullopt_t, const Optional& opt) { + return !!opt; +} + +template +constexpr bool operator<(const Optional& opt, base::nullopt_t) { + return false; +} + +template +constexpr bool operator<(base::nullopt_t, const Optional& opt) { + return !!opt; +} + +template +constexpr bool operator<=(const Optional& opt, base::nullopt_t) { + return !opt; +} + +template +constexpr bool operator<=(base::nullopt_t, const Optional& opt) { + return true; +} + +template +constexpr bool operator>(const Optional& opt, base::nullopt_t) { + return !!opt; +} + +template +constexpr bool operator>(base::nullopt_t, const Optional& opt) { + return false; +} + +template +constexpr bool operator>=(const Optional& opt, base::nullopt_t) { + return true; +} + +template +constexpr bool operator>=(base::nullopt_t, const Optional& opt) { + return !opt; +} + +template +constexpr bool operator==(const Optional& opt, const T& value) { + return opt != nullopt ? *opt == value : false; +} + +template +constexpr bool operator==(const T& value, const Optional& opt) { + return opt == value; +} + +template +constexpr bool operator!=(const Optional& opt, const T& value) { + return !(opt == value); +} + +template +constexpr bool operator!=(const T& value, const Optional& opt) { + return !(opt == value); +} + +template +constexpr bool operator<(const Optional& opt, const T& value) { + return opt != nullopt ? *opt < value : true; +} + +template +constexpr bool operator<(const T& value, const Optional& opt) { + return opt != nullopt ? value < *opt : false; +} + +template +constexpr bool operator<=(const Optional& opt, const T& value) { + return !(opt > value); +} + +template +constexpr bool operator<=(const T& value, const Optional& opt) { + return !(value > opt); +} + +template +constexpr bool operator>(const Optional& opt, const T& value) { + return value < opt; +} + +template +constexpr bool operator>(const T& value, const Optional& opt) { + return opt < value; +} + +template +constexpr bool operator>=(const Optional& opt, const T& value) { + return !(opt < value); +} + +template +constexpr bool operator>=(const T& value, const Optional& opt) { + return !(value < opt); +} + +template +constexpr Optional::type> make_optional(T&& value) { + return Optional::type>(std::forward(value)); +} + +template +void swap(Optional& lhs, Optional& rhs) { + lhs.swap(rhs); +} + +} // namespace base +} // namespace v8 + +#endif // V8_BASE_OPTIONAL_H_ diff --git a/src/v8.gyp b/src/v8.gyp index 3ccad2a6f5..0da448dd13 100644 --- a/src/v8.gyp +++ b/src/v8.gyp @@ -2011,6 +2011,7 @@ 'base/macros.h', 'base/once.cc', 'base/once.h', + 'base/optional.h', 'base/platform/elapsed-timer.h', 'base/platform/time.cc', 'base/platform/time.h',