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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/WhileEmitter.h"
#include "frontend/BytecodeEmitter.h"
#include "frontend/SourceNotes.h"
#include "vm/Opcodes.h"
#include "vm/StencilEnums.h" // TryNoteKind
using namespace js;
using namespace js::frontend;
using mozilla::Maybe;
WhileEmitter::WhileEmitter(BytecodeEmitter* bce) : bce_(bce) {}
bool WhileEmitter::emitCond(const Maybe<uint32_t>& whilePos,
const Maybe<uint32_t>& condPos,
const Maybe<uint32_t>& endPos) {
MOZ_ASSERT(state_ == State::Start);
// If we have a single-line while, like "while (x) ;", we want to emit the
// line note before the loop, so that the debugger sees a single entry point.
// This way, if there is a breakpoint on the line, it will only fire once; and
// "next"ing will skip the whole loop. However, for the multi-line case we
// want to emit the line note for the JSOp::LoopHead, so that "cont" stops on
// each iteration -- but without a stop before the first iteration.
if (whilePos && endPos &&
bce_->parser->errorReporter().lineAt(*whilePos) ==
bce_->parser->errorReporter().lineAt(*endPos)) {
if (!bce_->updateSourceCoordNotes(*whilePos)) {
return false;
}
// Emit a Nop to ensure the source position is not part of the loop.
if (!bce_->emit1(JSOp::Nop)) {
return false;
}
}
loopInfo_.emplace(bce_, StatementKind::WhileLoop);
if (!loopInfo_->emitLoopHead(bce_, condPos)) {
return false;
}
#ifdef DEBUG
state_ = State::Cond;
#endif
return true;
}
bool WhileEmitter::emitBody() {
MOZ_ASSERT(state_ == State::Cond);
if (!bce_->emitJump(JSOp::IfEq, &loopInfo_->breaks)) {
return false;
}
tdzCacheForBody_.emplace(bce_);
#ifdef DEBUG
state_ = State::Body;
#endif
return true;
}
bool WhileEmitter::emitEnd() {
MOZ_ASSERT(state_ == State::Body);
tdzCacheForBody_.reset();
if (!loopInfo_->emitContinueTarget(bce_)) {
return false;
}
if (!loopInfo_->emitLoopEnd(bce_, JSOp::Goto, TryNoteKind::Loop)) {
return false;
}
loopInfo_.reset();
#ifdef DEBUG
state_ = State::End;
#endif
return true;
}
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