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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* 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/. */
#include "frontend/ElemOpEmitter.h"
#include "frontend/BytecodeEmitter.h"
#include "frontend/SharedContext.h"
#include "vm/Opcodes.h"
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 (!isSuper() && isIncDec()) {
if (!bce_->emit1(JSOP_CHECKOBJCOERCIBLE)) { // OBJ
return false;
}
}
if (isCall()) {
// We need a second |this| that will be consumed during computation of
// the property value. (The original |this| is passed to the call.)
if (!bce_->emit1(JSOP_DUP)) { // [Super]
// // THIS THIS
// // [Other]
// // OBJ OBJ
return false;
}
}
#ifdef DEBUG
state_ = State::Key;
#endif
return true;
}
bool
ElemOpEmitter::emitGet()
{
MOZ_ASSERT(state_ == State::Key);
// We need to convert the key to an object id first, so that we do not do
// it inside both the GETELEM and the SETELEM.
if (isIncDec() || isCompoundAssignment()) {
if (!bce_->emit1(JSOP_TOID)) { // [Super]
// // THIS KEY
// // [Other]
// // OBJ KEY
return false;
}
}
if (isSuper()) {
if (!bce_->emit1(JSOP_SUPERBASE)) { // THIS? THIS KEY SUPERBASE
return false;
}
}
if (isIncDec() || isCompoundAssignment()) {
if (isSuper()) {
// There's no such thing as JSOP_DUP3, so we have to be creative.
// Note that pushing things again is no fewer JSOps.
if (!bce_->emitDupAt(2)) { // THIS KEY SUPERBASE THIS
return false;
}
if (!bce_->emitDupAt(2)) { // THIS KEY SUPERBASE THIS KEY
return false;
}
if (!bce_->emitDupAt(2)) { // THIS KEY SUPERBASE THIS KEY SUPERBASE
return false;
}
} else {
if (!bce_->emit1(JSOP_DUP2)) { // OBJ KEY OBJ KEY
return false;
}
}
}
JSOp op;
if (isSuper()) {
op = JSOP_GETELEM_SUPER;
} else if (isCall()) {
op = JSOP_CALLELEM;
} else {
op = JSOP_GETELEM;
}
if (!bce_->emitElemOpBase(op)) { // [Get]
// // ELEM
// // [Call]
// // THIS ELEM
// // [Inc/Dec/Assignment,
// // Super]
// // THIS KEY SUPERBASE ELEM
// // [Inc/Dec/Assignment,
// // Other]
// // OBJ KEY ELEM
return false;
}
if (isCall()) {
if (!bce_->emit1(JSOP_SWAP)) { // 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_->emit1(JSOP_SUPERBASE)) { // 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_TOID)) { // THIS KEY
return false;
}
if (!bce_->emit1(JSOP_SUPERBASE)) { // THIS KEY SUPERBASE
return false;
}
// Unconditionally throw when attempting to delete a super-reference.
if (!bce_->emitUint16Operand(JSOP_THROWMSG, JSMSG_CANT_DELETE_SUPER)) {
return false; // THIS KEY SUPERBASE
}
// 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)) { // 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_STRICTSETELEM_SUPER : JSOP_SETELEM_SUPER
: bce_->sc->strict() ? JSOP_STRICTSETELEM : JSOP_SETELEM;
if (!bce_->emitElemOpBase(setOp)) { // ELEM
return false;
}
#ifdef DEBUG
state_ = State::Assignment;
#endif
return true;
}
bool
ElemOpEmitter::emitIncDec()
{
MOZ_ASSERT(state_ == State::Key);
MOZ_ASSERT(isIncDec());
if (!emitGet()) { // ... ELEM
return false;
}
MOZ_ASSERT(state_ == State::Get);
JSOp incOp = isInc() ? JSOP_INC : JSOP_DEC;
if (!bce_->emit1(JSOP_TONUMERIC)) { // ... N
return false;
}
if (isPostIncDec()) {
if (!bce_->emit1(JSOP_DUP)) { // ... N? N
return false;
}
}
if (!bce_->emit1(incOp)) { // ... N? N+1
return false;
}
if (isPostIncDec()) {
if (isSuper()) { // THIS KEY OBJ N N+1
if (!bce_->emit2(JSOP_PICK, 4)) { // KEY SUPERBASE N N+1 THIS
return false;
}
if (!bce_->emit2(JSOP_PICK, 4)) { // SUPERBASE N N+1 THIS KEY
return false;
}
if (!bce_->emit2(JSOP_PICK, 4)) { // N N+1 THIS KEY SUPERBASE
return false;
}
if (!bce_->emit2(JSOP_PICK, 3)) { // N THIS KEY SUPERBASE N+1
return false;
}
} else { // OBJ KEY N N+1
if (!bce_->emit2(JSOP_PICK, 3)) { // KEY N N+1 OBJ
return false;
}
if (!bce_->emit2(JSOP_PICK, 3)) { // N N+1 OBJ KEY
return false;
}
if (!bce_->emit2(JSOP_PICK, 2)) { // N OBJ KEY N+1
return false;
}
}
}
JSOp setOp = isSuper()
? (bce_->sc->strict() ? JSOP_STRICTSETELEM_SUPER : JSOP_SETELEM_SUPER)
: (bce_->sc->strict() ? JSOP_STRICTSETELEM : JSOP_SETELEM);
if (!bce_->emitElemOpBase(setOp)) { // N? N+1
return false;
}
if (isPostIncDec()) {
if (!bce_->emit1(JSOP_POP)) { // N
return false;
}
}
#ifdef DEBUG
state_ = State::IncDec;
#endif
return true;
}
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