js/src/frontend/ExpressionStatementEmitter.cpp
author Tooru Fujisawa <arai_a@mac.com>
Sat, 01 Dec 2018 04:52:05 +0900
changeset 505471 66eb1f485c1a3ea81372758bc92292c9428b17cd
parent 505464 e4712449ba4303cef134ba0b3f1bea13fbd50c4a
child 505863 49a3abc14837005b7e77b0b280f406af0d06a139
permissions -rw-r--r--
Bug 1511393 - Use c-basic-offset: 2 in Emacs mode line for C/C++ code. r=nbp

/* -*- 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/ExpressionStatementEmitter.h"

#include "frontend/BytecodeEmitter.h"
#include "vm/Opcodes.h"

using namespace js;
using namespace js::frontend;

using mozilla::Maybe;

ExpressionStatementEmitter::ExpressionStatementEmitter(BytecodeEmitter* bce,
                                                       ValueUsage valueUsage)
    : bce_(bce), valueUsage_(valueUsage) {}

bool ExpressionStatementEmitter::prepareForExpr(
    const Maybe<uint32_t>& beginPos) {
  MOZ_ASSERT(state_ == State::Start);

  if (beginPos) {
    if (!bce_->updateSourceCoordNotes(*beginPos)) {
      return false;
    }
  }

#ifdef DEBUG
  depth_ = bce_->stackDepth;
  state_ = State::Expr;
#endif
  return true;
}

bool ExpressionStatementEmitter::emitEnd() {
  MOZ_ASSERT(state_ == State::Expr);
  MOZ_ASSERT(bce_->stackDepth == depth_ + 1);

  //                        [stack] VAL

  JSOp op = valueUsage_ == ValueUsage::WantValue ? JSOP_SETRVAL : JSOP_POP;
  if (!bce_->emit1(op)) {
    //                    [stack] # if WantValue
    //                    [stack] VAL
    //                    [stack] # otherwise
    //                    [stack]
    return false;
  }

#ifdef DEBUG
  state_ = State::End;
#endif
  return true;
}