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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
#include "frontend/ElemOpEmitter.h"
#include "frontend/BytecodeEmitter.h"
#include "frontend/SharedContext.h"
#include "vm/Opcodes.h"
#include "vm/ThrowMsgKind.h" // ThrowMsgKind
using namespace js;
using namespace js::frontend;
ElemOpEmitter::ElemOpEmitter(BytecodeEmitter* bce, Kind kind, ObjKind objKind)
: bce_(bce), kind_(kind), objKind_(objKind) {}
bool ElemOpEmitter::prepareForObj() {
MOZ_ASSERT(state_ == State::Start);
#ifdef DEBUG
state_ = State::Obj;
#endif
return true;
}
bool ElemOpEmitter::prepareForKey() {
MOZ_ASSERT(state_ == State::Obj);
if (isCall()) {
if (!bce_->emit1(JSOp::Dup)) {
// [stack] # if Super
// [stack] THIS THIS
// [stack] # otherwise
// [stack] OBJ OBJ
return false;
}
}
#ifdef DEBUG
state_ = State::Key;
#endif
return true;
}
bool ElemOpEmitter::emitGet() {
MOZ_ASSERT(state_ == State::Key);
// Inc/dec and compound assignment use the KEY twice, but if it's an object,
// it must be converted ToPropertyKey only once, per spec.
if (isIncDec() || isCompoundAssignment()) {
if (!bce_->emit1(JSOp::ToPropertyKey)) {
// [stack] # if Super
// [stack] THIS KEY
// [stack] # otherwise
// [stack] OBJ KEY
return false;
}
}
if (isSuper()) {
if (!bce_->emitSuperBase()) {
// [stack] THIS? THIS KEY SUPERBASE
return false;
}
}
if (isIncDec() || isCompoundAssignment()) {
if (isSuper()) {
if (!bce_->emitDupAt(2, 3)) {
// [stack] THIS KEY SUPERBASE THIS KEY SUPERBASE
return false;
}
} else {
if (!bce_->emit1(JSOp::Dup2)) {
// [stack] OBJ KEY OBJ KEY
return false;
}
}
}
JSOp op;
if (isSuper()) {
op = JSOp::GetElemSuper;
} else {
op = JSOp::GetElem;
}
if (!bce_->emitElemOpBase(op)) {
// [stack] # if Get
// [stack] ELEM
// [stack] # if Call
// [stack] THIS ELEM
// [stack] # if Inc/Dec/Assignment, with Super
// [stack] THIS KEY SUPERBASE ELEM
// [stack] # if Inc/Dec/Assignment, other
// [stack] OBJ KEY ELEM
return false;
}
if (isCall()) {
if (!bce_->emit1(JSOp::Swap)) {
// [stack] ELEM THIS
return false;
}
}
#ifdef DEBUG
state_ = State::Get;
#endif
return true;
}
bool ElemOpEmitter::prepareForRhs() {
MOZ_ASSERT(isSimpleAssignment() || isPropInit() || isCompoundAssignment());
MOZ_ASSERT_IF(isSimpleAssignment() || isPropInit(), state_ == State::Key);
MOZ_ASSERT_IF(isCompoundAssignment(), state_ == State::Get);
if (isSimpleAssignment() || isPropInit()) {
// For CompoundAssignment, SuperBase is already emitted by emitGet.
if (isSuper()) {
if (!bce_->emitSuperBase()) {
// [stack] THIS KEY SUPERBASE
return false;
}
}
}
#ifdef DEBUG
state_ = State::Rhs;
#endif
return true;
}
bool ElemOpEmitter::skipObjAndKeyAndRhs() {
MOZ_ASSERT(state_ == State::Start);
MOZ_ASSERT(isSimpleAssignment() || isPropInit());
#ifdef DEBUG
state_ = State::Rhs;
#endif
return true;
}
bool ElemOpEmitter::emitDelete() {
MOZ_ASSERT(state_ == State::Key);
MOZ_ASSERT(isDelete());
if (isSuper()) {
if (!bce_->emit1(JSOp::ToPropertyKey)) {
// [stack] THIS KEY
return false;
}
if (!bce_->emitSuperBase()) {
// [stack] THIS KEY SUPERBASE
return false;
}
// Unconditionally throw when attempting to delete a super-reference.
if (!bce_->emit2(JSOp::ThrowMsg, uint8_t(ThrowMsgKind::CantDeleteSuper))) {
// [stack] THIS KEY SUPERBASE
return false;
}
// Another wrinkle: Balance the stack from the emitter's point of view.
// Execution will not reach here, as the last bytecode threw.
if (!bce_->emitPopN(2)) {
// [stack] THIS
return false;
}
} else {
JSOp op = bce_->sc->strict() ? JSOp::StrictDelElem : JSOp::DelElem;
if (!bce_->emitElemOpBase(op)) {
// SUCCEEDED
return false;
}
}
#ifdef DEBUG
state_ = State::Delete;
#endif
return true;
}
bool ElemOpEmitter::emitAssignment() {
MOZ_ASSERT(isSimpleAssignment() || isPropInit() || isCompoundAssignment());
MOZ_ASSERT(state_ == State::Rhs);
MOZ_ASSERT_IF(isPropInit(), !isSuper());
JSOp setOp = isPropInit() ? JSOp::InitElem
: isSuper() ? bce_->sc->strict() ? JSOp::StrictSetElemSuper
: JSOp::SetElemSuper
: bce_->sc->strict() ? JSOp::StrictSetElem
: JSOp::SetElem;
if (!bce_->emitElemOpBase(setOp)) {
// [stack] ELEM
return false;
}
#ifdef DEBUG
state_ = State::Assignment;
#endif
return true;
}
bool ElemOpEmitter::emitIncDec(ValueUsage valueUsage) {
MOZ_ASSERT(state_ == State::Key);
MOZ_ASSERT(isIncDec());
if (!emitGet()) {
// [stack] ... ELEM
return false;
}
MOZ_ASSERT(state_ == State::Get);
JSOp incOp = isInc() ? JSOp::Inc : JSOp::Dec;
if (!bce_->emit1(JSOp::ToNumeric)) {
// [stack] ... N
return false;
}
if (isPostIncDec() && valueUsage == ValueUsage::WantValue) {
// [stack] OBJ KEY SUPERBASE? N
if (!bce_->emit1(JSOp::Dup)) {
// [stack] ... N N
return false;
}
if (!bce_->emit2(JSOp::Unpick, 3 + isSuper())) {
// [stack] N OBJ KEY SUPERBASE? N
return false;
}
}
if (!bce_->emit1(incOp)) {
// [stack] ... N+1
return false;
}
JSOp setOp =
isSuper()
? (bce_->sc->strict() ? JSOp::StrictSetElemSuper : JSOp::SetElemSuper)
: (bce_->sc->strict() ? JSOp::StrictSetElem : JSOp::SetElem);
if (!bce_->emitElemOpBase(setOp)) {
// [stack] N? N+1
return false;
}
if (isPostIncDec() && valueUsage == ValueUsage::WantValue) {
if (!bce_->emit1(JSOp::Pop)) {
// [stack] N
return false;
}
}
#ifdef DEBUG
state_ = State::IncDec;
#endif
return true;
}