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| -rw-r--r-- | js/src/frontend/PrivateOpEmitter.h | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/js/src/frontend/PrivateOpEmitter.h b/js/src/frontend/PrivateOpEmitter.h new file mode 100644 index 0000000000..558541b05c --- /dev/null +++ b/js/src/frontend/PrivateOpEmitter.h @@ -0,0 +1,231 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: set ts=8 sts=2 et sw=2 tw=80: + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef frontend_PrivateOpEmitter_h +#define frontend_PrivateOpEmitter_h + +#include "mozilla/Attributes.h" +#include "mozilla/Maybe.h" + +#include <stddef.h> + +#include "frontend/NameAnalysisTypes.h" // NameLocation +#include "frontend/ParserAtom.h" // TaggedParserAtomIndex + +namespace js { +namespace frontend { + +struct BytecodeEmitter; +enum class ValueUsage; + +// Class for emitting bytecode for operations on private members of objects. +// +// Usage is similar to PropOpEmitter, but the name of the private member must +// be passed to the constructor; prepare*() methods aren't necessary; and +// `delete obj.#member` and `super.#member` aren't supported because both are +// SyntaxErrors. +// +// Usage: (error checking is omitted for simplicity) +// +// `obj.#member;` +// PrivateOpEmitter xoe(this, +// privateName, +// PrivateOpEmitter::Kind::Get); +// emit(obj); +// xoe.emitReference(); +// xoe.emitGet(); +// +// `obj.#member();` +// PrivateOpEmitter xoe(this, +// privateName, +// PrivateOpEmitter::Kind::Call); +// emit(obj); +// xoe.emitReference(); +// xoe.emitGet(); +// emit_call_here(); +// +// `new obj.#member();` +// The same, but use PrivateOpEmitter::Kind::Get. +// +// `obj.#field++;` +// PrivateOpEmitter xoe(this, +// privateName, +// PrivateOpEmitter::Kind::PostIncrement); +// emit(obj); +// xoe.emitReference(); +// xoe.emitIncDec(); +// +// `obj.#field = value;` +// PrivateOpEmitter xoe(this, +// privateName, +// PrivateOpEmitter::Kind::SimpleAssignment); +// emit(obj); +// xoe.emitReference(); +// emit(value); +// xoe.emitAssignment(); +// +// `obj.#field += value;` +// PrivateOpEmitter xoe(this, +// privateName, +// PrivateOpEmitter::Kind::CompoundAssignment); +// emit(obj); +// xoe.emitReference(); +// emit(JSOp::Dup2); +// xoe.emitGet(); +// emit(value); +// emit_add_op_here(); +// xoe.emitAssignment(); +// +class MOZ_STACK_CLASS PrivateOpEmitter { + public: + enum class Kind { + Get, + Call, + Delete, + PostIncrement, + PreIncrement, + PostDecrement, + PreDecrement, + SimpleAssignment, + PropInit, + CompoundAssignment, + ErgonomicBrandCheck, + }; + + private: + BytecodeEmitter* bce_; + + Kind kind_; + + // Name of the private member, e.g. "#field". + TaggedParserAtomIndex name_; + + // Location of the slot containing the private name symbol; or, for a + // non-static private method, the slot containing the method. + mozilla::Maybe<NameLocation> loc_; + + // For non-static private method accesses, the location of the relevant + // `.privateBrand` binding. Otherwise, `Nothing`. + mozilla::Maybe<NameLocation> brandLoc_{}; + +#ifdef DEBUG + // The state of this emitter. + // + // emitReference + // +-------+ skipReference +-----------+ + // | Start |---------------->| Reference | + // +-------+ +-----+-----+ + // | + // +---------------------------+ + // | + // | + // | [Get] + // | emitGet + // | [Call] [Get] [CompoundAssignment] + // | emitGetForCallOrNew +-----+ emitAssignment + // +---------------------->| Get |-------------------+ + // | +-----+ | + // | [PostIncrement] | + // | [PreIncrement] | + // | [PostDecrement] | + // | [PreDecrement] | + // | emitIncDec | + // +------------------------------------------------>+ + // | | + // | [SimpleAssignment] | + // | [PropInit] V + // | emitAssignment +------------+ + // +------------------------------------------>| Assignment | + // +------------+ + enum class State { + // The initial state. + Start, + + // After calling emitReference or skipReference. + Reference, + + // After calling emitGet. + Get, + + // After calling emitAssignment or emitIncDec. + Assignment, + }; + State state_ = State::Start; +#endif + + public: + PrivateOpEmitter(BytecodeEmitter* bce, Kind kind, TaggedParserAtomIndex name); + + private: + [[nodiscard]] bool isCall() const { return kind_ == Kind::Call; } + + [[nodiscard]] bool isSimpleAssignment() const { + return kind_ == Kind::SimpleAssignment; + } + + [[nodiscard]] bool isFieldInit() const { return kind_ == Kind::PropInit; } + + [[nodiscard]] bool isBrandCheck() const { + return kind_ == Kind::ErgonomicBrandCheck; + } + + [[nodiscard]] bool isCompoundAssignment() const { + return kind_ == Kind::CompoundAssignment; + } + + [[nodiscard]] bool isIncDec() const { + return isPostIncDec() || isPreIncDec(); + } + + [[nodiscard]] bool isPostIncDec() const { + return kind_ == Kind::PostIncrement || kind_ == Kind::PostDecrement; + } + + [[nodiscard]] bool isPreIncDec() const { + return kind_ == Kind::PreIncrement || kind_ == Kind::PreDecrement; + } + + [[nodiscard]] bool isInc() const { + return kind_ == Kind::PostIncrement || kind_ == Kind::PreIncrement; + } + + [[nodiscard]] bool init(); + + // Emit a GetAliasedLexical or similar instruction. + [[nodiscard]] bool emitLoad(TaggedParserAtomIndex name, + const NameLocation& loc); + + [[nodiscard]] bool emitLoadPrivateBrand(); + + public: + // Emit bytecode to check for the presence/absence of a private field/brand. + // + // Given OBJ KEY on the stack, where KEY is a private name symbol, the + // emitted code will throw if OBJ does not have the given KEY. + // + // If `isFieldInit()`, the check is reversed: the code will throw if OBJ + // already has the KEY. + // + // If `isBrandCheck()`, the check verifies RHS is an object (throwing if not). + // + // The bytecode leaves OBJ KEY BOOL on the stack. Caller is responsible for + // consuming or popping it. + [[nodiscard]] bool emitBrandCheck(); + + [[nodiscard]] bool emitReference(); + [[nodiscard]] bool skipReference(); + [[nodiscard]] bool emitGet(); + [[nodiscard]] bool emitGetForCallOrNew(); + [[nodiscard]] bool emitAssignment(); + [[nodiscard]] bool emitIncDec(ValueUsage valueUsage); + + [[nodiscard]] size_t numReferenceSlots() { return 2; } +}; + +} /* namespace frontend */ +} /* namespace js */ + +#endif /* frontend_PrivateOpEmitter_h */ |