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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/AsyncEmitter.h"
#include "mozilla/Assertions.h" // MOZ_ASSERT
#include "frontend/BytecodeEmitter.h" // BytecodeEmitter
#include "frontend/NameOpEmitter.h" // NameOpEmitter
#include "frontend/ParserAtom.h" // TaggedParserAtomIndex
#include "vm/AsyncFunctionResolveKind.h" // AsyncFunctionResolveKind
#include "vm/Opcodes.h" // JSOp
using namespace js;
using namespace js::frontend;
bool AsyncEmitter::prepareForParamsWithExpressionOrDestructuring() {
MOZ_ASSERT(state_ == State::Start);
#ifdef DEBUG
state_ = State::Parameters;
#endif
rejectTryCatch_.emplace(bce_, TryEmitter::Kind::TryCatch,
TryEmitter::ControlKind::NonSyntactic);
return rejectTryCatch_->emitTry();
}
bool AsyncEmitter::prepareForParamsWithoutExpressionOrDestructuring() {
MOZ_ASSERT(state_ == State::Start);
#ifdef DEBUG
state_ = State::Parameters;
#endif
return true;
}
bool AsyncEmitter::emitParamsEpilogue() {
MOZ_ASSERT(state_ == State::Parameters);
if (rejectTryCatch_) {
// If we get here, we need to reset the TryEmitter. Parameters can't reuse
// the reject try-catch block from the function body, because the body
// may have pushed an additional var-environment. This messes up scope
// resolution for the |.generator| variable, because we'd need different
// hops to reach |.generator| depending on whether the error was thrown
// from the parameters or the function body.
if (!emitRejectCatch()) {
return false;
}
}
#ifdef DEBUG
state_ = State::PostParams;
#endif
return true;
}
bool AsyncEmitter::prepareForModule() {
// Unlike functions, modules do not have params that we need to worry about.
// Instead, this code is for setting up the required generator that will be
// used for top level await. Before we can start using top-level await in
// modules, we need to emit a
// |.generator| which we can use to pause and resume execution.
MOZ_ASSERT(state_ == State::Start);
MOZ_ASSERT(bce_->lookupName(TaggedParserAtomIndex::WellKnown::dotGenerator())
.hasKnownSlot());
NameOpEmitter noe(bce_, TaggedParserAtomIndex::WellKnown::dotGenerator(),
NameOpEmitter::Kind::Initialize);
if (!noe.prepareForRhs()) {
// [stack]
return false;
}
if (!bce_->emit1(JSOp::Generator)) {
// [stack] GEN
return false;
}
if (!noe.emitAssignment()) {
// [stack] GEN
return false;
}
if (!bce_->emit1(JSOp::Pop)) {
// [stack]
return false;
}
#ifdef DEBUG
state_ = State::ModulePrologue;
#endif
return true;
}
bool AsyncEmitter::prepareForBody() {
MOZ_ASSERT(state_ == State::PostParams || state_ == State::ModulePrologue);
rejectTryCatch_.emplace(bce_, TryEmitter::Kind::TryCatch,
TryEmitter::ControlKind::NonSyntactic);
#ifdef DEBUG
state_ = State::Body;
#endif
return rejectTryCatch_->emitTry();
}
bool AsyncEmitter::emitEndFunction() {
#ifdef DEBUG
MOZ_ASSERT(state_ == State::Body);
#endif
// The final yield has already been emitted
// by FunctionScriptEmitter::emitEndBody().
if (!emitRejectCatch()) {
return false;
}
#ifdef DEBUG
state_ = State::End;
#endif
return true;
}
bool AsyncEmitter::emitEndModule() {
#ifdef DEBUG
MOZ_ASSERT(state_ == State::Body);
#endif
if (!emitFinalYield()) {
return false;
}
if (!emitRejectCatch()) {
return false;
}
#ifdef DEBUG
state_ = State::End;
#endif
return true;
}
bool AsyncEmitter::emitFinalYield() {
if (!bce_->emit1(JSOp::Undefined)) {
// [stack] UNDEF
return false;
}
if (!bce_->emitGetDotGeneratorInInnermostScope()) {
// [stack] UNDEF GEN
return false;
}
if (!bce_->emit2(JSOp::AsyncResolve,
uint8_t(AsyncFunctionResolveKind::Fulfill))) {
// [stack] PROMISE
return false;
}
if (!bce_->emit1(JSOp::SetRval)) {
// [stack]
return false;
}
if (!bce_->emitGetDotGeneratorInInnermostScope()) {
// [stack] GEN
return false;
}
if (!bce_->emitYieldOp(JSOp::FinalYieldRval)) {
// [stack]
return false;
}
return true;
}
bool AsyncEmitter::emitRejectCatch() {
if (!rejectTryCatch_->emitCatch()) {
// [stack] EXC
return false;
}
if (!bce_->emitGetDotGeneratorInInnermostScope()) {
// [stack] EXC GEN
return false;
}
if (!bce_->emit2(JSOp::AsyncResolve,
uint8_t(AsyncFunctionResolveKind::Reject))) {
// [stack] PROMISE
return false;
}
if (!bce_->emit1(JSOp::SetRval)) {
// [stack]
return false;
}
if (!bce_->emitGetDotGeneratorInInnermostScope()) {
// [stack] GEN
return false;
}
if (!bce_->emitYieldOp(JSOp::FinalYieldRval)) {
// [stack]
return false;
}
if (!rejectTryCatch_->emitEnd()) {
return false;
}
rejectTryCatch_.reset();
return true;
}
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