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/* -*- 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_OptionalEmitter_h
#define frontend_OptionalEmitter_h
#include "mozilla/Attributes.h"
#include "frontend/JumpList.h"
#include "frontend/TDZCheckCache.h"
namespace js {
namespace frontend {
struct BytecodeEmitter;
// Class for emitting bytecode for optional expressions.
//
// Usage: (check for the return value is omitted for simplicity)
//
// `obj?.prop;`
// OptionalEmitter oe(this);
// PropOpEmitter poe(this,
// PropOpEmitter::Kind::Get,
// PropOpEmitter::ObjKind::Other);
// poe.prepareForObj();
// emit(obj);
// oe.emitJumpShortCircuit();
// poe.emitGet(atom_of_prop);
// oe.emitOptionalJumpTarget(JSOp::Undefined);
//
// `delete obj?.prop;`
// OptionalEmitter oe(this);
// OptionalPropOpEmitter poe(this,
// PropOpEmitter::Kind::Delete,
// PropOpEmitter::ObjKind::Other);
// poe.prepareForObj();
// emit(obj);
// oe.emitJumpShortCircuit();
// poe.emitDelete(atom_of_prop);
// oe.emitOptionalJumpTarget(JSOp:True);
//
// `obj?.[key];`
// OptionalEmitter oe(this);
// ElemOpEmitter eoe(this,
// ElemOpEmitter::Kind::Get,
// ElemOpEmitter::ObjKind::Other);
// eoe.prepareForObj();
// emit(obj);
// oe.emitJumpShortCircuit();
// eoe.prepareForKey();
// emit(key);
// eoe.emitGet();
// oe.emitOptionalJumpTarget(JSOp::Undefined);
//
// `delete obj?.[key];`
// OptionalEmitter oe(this);
// ElemOpEmitter eoe(this,
// ElemOpEmitter::Kind::Delete,
// ElemOpEmitter::ObjKind::Other);
// eoe.prepareForObj();
// emit(obj);
// oe.emitJumpShortCircuit();
// eoe.prepareForKey();
// emit(key);
// eoe.emitDelete();
// oe.emitOptionalJumpTarget(JSOp::True);
//
// `print?.(arg);`
// OptionalEmitter oe(this);
// CallOrNewEmitter cone(this, JSOp::Call,
// CallOrNewEmitter::ArgumentsKind::Other,
// ValueUsage::WantValue);
// cone.emitNameCallee(print);
// cone.emitThis();
// oe.emitShortCircuitForCall();
// cone.prepareForNonSpreadArguments();
// emit(arg);
// cone.emitEnd(1, offset_of_callee);
// oe.emitOptionalJumpTarget(JSOp::Undefined);
//
// `callee.prop?.(arg1, arg2);`
// OptionalEmitter oe(this);
// CallOrNewEmitter cone(this, JSOp::Call,
// CallOrNewEmitter::ArgumentsKind::Other,
// ValueUsage::WantValue);
// PropOpEmitter& poe = cone.prepareForPropCallee(false);
// ... emit `callee.prop` with `poe` here...
// cone.emitThis();
// oe.emitShortCircuitForCall();
// cone.prepareForNonSpreadArguments();
// emit(arg1);
// emit(arg2);
// cone.emitEnd(2, offset_of_callee);
// oe.emitOptionalJumpTarget(JSOp::Undefined);
//
// `callee[key]?.(arg);`
// OptionalEmitter oe(this);
// CallOrNewEmitter cone(this, JSOp::Call,
// CallOrNewEmitter::ArgumentsKind::Other,
// ValueUsage::WantValue);
// ElemOpEmitter& eoe = cone.prepareForElemCallee(false);
// ... emit `callee[key]` with `eoe` here...
// cone.emitThis();
// oe.emitShortCircuitForCall();
// cone.prepareForNonSpreadArguments();
// emit(arg);
// cone.emitEnd(1, offset_of_callee);
// oe.emitOptionalJumpTarget(JSOp::Undefined);
//
// `(function() { ... })?.(arg);`
// OptionalEmitter oe(this);
// CallOrNewEmitter cone(this, JSOp::Call,
// CallOrNewEmitter::ArgumentsKind::Other,
// ValueUsage::WantValue);
// cone.prepareForFunctionCallee();
// emit(function);
// cone.emitThis();
// oe.emitShortCircuitForCall();
// cone.prepareForNonSpreadArguments();
// emit(arg);
// cone.emitEnd(1, offset_of_callee);
// oe.emitOptionalJumpTarget(JSOp::Undefined);
//
// `(a?b)();`
// OptionalEmitter oe(this);
// CallOrNewEmitter cone(this, JSOp::Call,
// CallOrNewEmitter::ArgumentsKind::Other,
// ValueUsage::WantValue);
// cone.prepareForFunctionCallee();
// emit(optionalChain);
// cone.emitThis();
// oe.emitOptionalJumpTarget(JSOp::Undefined,
// OptionalEmitter::Kind::Reference);
// oe.emitShortCircuitForCall();
// cone.prepareForNonSpreadArguments();
// emit(arg);
// cone.emitEnd(1, offset_of_callee);
// oe.emitOptionalJumpTarget(JSOp::Undefined);
//
class MOZ_RAII OptionalEmitter {
public:
OptionalEmitter(BytecodeEmitter* bce, int32_t initialDepth);
private:
BytecodeEmitter* bce_;
TDZCheckCache tdzCache_;
// jumptarget for ShortCircuiting code, which has null or undefined values
JumpList jumpShortCircuit_;
// jumpTarget for code that does not shortCircuit
JumpList jumpFinish_;
// jumpTarget for code that does not shortCircuit
int32_t initialDepth_;
// The state of this emitter.
//
// +-------+ emitJumpShortCircuit +--------------+
// | Start |-+---------------------------->| ShortCircuit |-----------+
// +-------+ | +--------------+ |
// +----->| |
// | | emitJumpShortCircuitForCall +---------------------+ v
// | +---------------------------->| ShortCircuitForCall |--->+
// | +---------------------+ |
// | |
// ---------------------------------------------------------------+
// |
// |
// +------------------------------------------------------------------+
// |
// | emitOptionalJumpTarget +---------+
// +----------------------->| JumpEnd |
// +---------+
//
#ifdef DEBUG
enum class State {
// The initial state.
Start,
// for shortcircuiting in most cases.
ShortCircuit,
// for shortcircuiting from references, which have two items on
// the stack. For example function calls.
ShortCircuitForCall,
// internally used, end of the jump code
JumpEnd
};
State state_ = State::Start;
#endif
public:
enum class Kind {
// Requires two values on the stack
Reference,
// Requires one value on the stack
Other
};
[[nodiscard]] bool emitJumpShortCircuit();
[[nodiscard]] bool emitJumpShortCircuitForCall();
// JSOp is the op code to be emitted, Kind is if we are dealing with a
// reference (in which case we need two elements on the stack) or other value
// (which needs one element on the stack)
[[nodiscard]] bool emitOptionalJumpTarget(JSOp op, Kind kind = Kind::Other);
};
} /* namespace frontend */
} /* namespace js */
#endif /* frontend_OptionalEmitter_h */
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