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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/. */
#include "frontend/OptionalEmitter.h"
#include "frontend/BytecodeEmitter.h"
#include "frontend/IfEmitter.h" // IfEmitter, InternalIfEmitter, CondEmitter
#include "frontend/SharedContext.h"
#include "vm/Opcodes.h"
#include "vm/StringType.h"
using namespace js;
using namespace js::frontend;
OptionalEmitter::OptionalEmitter(BytecodeEmitter* bce, int32_t initialDepth)
: bce_(bce), tdzCache_(bce), initialDepth_(initialDepth) {}
bool OptionalEmitter::emitJumpShortCircuit() {
MOZ_ASSERT(state_ == State::Start || state_ == State::ShortCircuit ||
state_ == State::ShortCircuitForCall);
MOZ_ASSERT(initialDepth_ + 1 == bce_->bytecodeSection().stackDepth());
InternalIfEmitter ifEmitter(bce_);
if (!bce_->emitPushNotUndefinedOrNull()) {
// [stack] OBJ NOT-UNDEFINED-OR-NULL
return false;
}
if (!bce_->emit1(JSOp::Not)) {
// [stack] OBJ UNDEFINED-OR-NULL
return false;
}
if (!ifEmitter.emitThen()) {
return false;
}
if (!bce_->emitJump(JSOp::Goto, &jumpShortCircuit_)) {
// [stack] UNDEFINED-OR-NULL
return false;
}
if (!ifEmitter.emitEnd()) {
return false;
}
#ifdef DEBUG
state_ = State::ShortCircuit;
#endif
return true;
}
bool OptionalEmitter::emitJumpShortCircuitForCall() {
MOZ_ASSERT(state_ == State::Start || state_ == State::ShortCircuit ||
state_ == State::ShortCircuitForCall);
int32_t depth = bce_->bytecodeSection().stackDepth();
MOZ_ASSERT(initialDepth_ + 2 == depth);
if (!bce_->emit1(JSOp::Swap)) {
// [stack] THIS CALLEE
return false;
}
InternalIfEmitter ifEmitter(bce_);
if (!bce_->emitPushNotUndefinedOrNull()) {
// [stack] THIS CALLEE NOT-UNDEFINED-OR-NULL
return false;
}
if (!bce_->emit1(JSOp::Not)) {
// [stack] THIS CALLEE UNDEFINED-OR-NULL
return false;
}
if (!ifEmitter.emitThen()) {
return false;
}
if (!bce_->emit1(JSOp::Pop)) {
// [stack] THIS
return false;
}
if (!bce_->emitJump(JSOp::Goto, &jumpShortCircuit_)) {
// [stack] UNDEFINED-OR-NULL
return false;
}
if (!ifEmitter.emitEnd()) {
return false;
}
bce_->bytecodeSection().setStackDepth(depth);
if (!bce_->emit1(JSOp::Swap)) {
// [stack] THIS CALLEE
return false;
}
#ifdef DEBUG
state_ = State::ShortCircuitForCall;
#endif
return true;
}
bool OptionalEmitter::emitOptionalJumpTarget(JSOp op,
Kind kind /* = Kind::Other */) {
#ifdef DEBUG
int32_t depth = bce_->bytecodeSection().stackDepth();
#endif
MOZ_ASSERT(state_ == State::ShortCircuit ||
state_ == State::ShortCircuitForCall);
// if we get to this point, it means that the optional chain did not short
// circuit, so we should skip the short circuiting bytecode.
if (!bce_->emitJump(JSOp::Goto, &jumpFinish_)) {
// [stack] # if call
// [stack] CALLEE THIS
// [stack] # otherwise, if defined
// [stack] VAL
// [stack] # otherwise
// [stack] UNDEFINED-OR-NULL
return false;
}
if (!bce_->emitJumpTargetAndPatch(jumpShortCircuit_)) {
// [stack] UNDEFINED-OR-NULL
return false;
}
// reset stack depth to the depth when we jumped
bce_->bytecodeSection().setStackDepth(initialDepth_ + 1);
if (!bce_->emit1(JSOp::Pop)) {
// [stack]
return false;
}
if (!bce_->emit1(op)) {
// [stack] JSOP
return false;
}
if (kind == Kind::Reference) {
if (!bce_->emit1(op)) {
// [stack] JSOP JSOP
return false;
}
}
MOZ_ASSERT(depth == bce_->bytecodeSection().stackDepth());
if (!bce_->emitJumpTargetAndPatch(jumpFinish_)) {
// [stack] # if call
// [stack] CALLEE THIS
// [stack] # otherwise
// [stack] VAL
return false;
}
#ifdef DEBUG
state_ = State::JumpEnd;
#endif
return true;
}
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