js/src/frontend/DoWhileEmitter.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "frontend/DoWhileEmitter.h"
   8
   9 #include "frontend/BytecodeEmitter.h"
  10 #include "vm/Opcodes.h"
  11 #include "vm/StencilEnums.h"  // TryNoteKind
  12
  13 using namespace js;
  14 using namespace js::frontend;
  15
  16 DoWhileEmitter::DoWhileEmitter(BytecodeEmitter* bce) : bce_(bce) {}
  17
  18 bool DoWhileEmitter::emitBody(uint32_t doPos, uint32_t bodyPos) {
  19   MOZ_ASSERT(state_ == State::Start);
  20
  21   // Ensure that the column of the 'do' is set properly.
  22   if (!bce_->updateSourceCoordNotes(doPos)) {
  23     return false;
  24   }
  25
  26   // We need a nop here to make it possible to set a breakpoint on `do`.
  27   if (!bce_->emit1(JSOp::Nop)) {
  28     return false;
  29   }
  30
  31   loopInfo_.emplace(bce_, StatementKind::DoLoop);
  32
  33   if (!loopInfo_->emitLoopHead(bce_, mozilla::Some(bodyPos))) {
  34     return false;
  35   }
  36
  37 #ifdef DEBUG
  38   state_ = State::Body;
  39 #endif
  40   return true;
  41 }
  42
  43 bool DoWhileEmitter::emitCond() {
  44   MOZ_ASSERT(state_ == State::Body);
  45
  46   if (!loopInfo_->emitContinueTarget(bce_)) {
  47     return false;
  48   }
  49
  50 #ifdef DEBUG
  51   state_ = State::Cond;
  52 #endif
  53   return true;
  54 }
  55
  56 bool DoWhileEmitter::emitEnd() {
  57   MOZ_ASSERT(state_ == State::Cond);
  58
  59   if (!loopInfo_->emitLoopEnd(bce_, JSOp::JumpIfTrue, TryNoteKind::Loop)) {
  60     return false;
  61   }
  62
  63   loopInfo_.reset();
  64
  65 #ifdef DEBUG
  66   state_ = State::End;
  67 #endif
  68   return true;
  69 }