[turbofan] Introduce explicit loop exits markers.

src/compiler/control-builders.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/control-builders.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
@@ skipping 18 matching lines @@
 void IfBuilder::End() {
   then_environment_->Merge(environment());
   set_environment(then_environment_);
 }
 
 
 void LoopBuilder::BeginLoop(BitVector* assigned, bool is_osr) {
   loop_environment_ = environment()->CopyForLoop(assigned, is_osr);
   continue_environment_ = environment()->CopyAsUnreachable();
   break_environment_ = environment()->CopyAsUnreachable();
+  assigned_ = assigned;
 }
 
 
 void LoopBuilder::Continue() {
   continue_environment_->Merge(environment());
   environment()->MarkAsUnreachable();
 }
 
 
 void LoopBuilder::Break() {
   break_environment_->Merge(environment());
   environment()->MarkAsUnreachable();
 }
 
 
 void LoopBuilder::EndBody() {
   continue_environment_->Merge(environment());
   set_environment(continue_environment_);
 }
 
 
 void LoopBuilder::EndLoop() {
   loop_environment_->Merge(environment());
   set_environment(break_environment_);
+  ExitLoop();
 }
 
 
 void LoopBuilder::BreakUnless(Node* condition) {
   IfBuilder control_if(builder_);
   control_if.If(condition);
   control_if.Then();
   control_if.Else();
   Break();
   control_if.End();
 }
 
 
 void LoopBuilder::BreakWhen(Node* condition) {
   IfBuilder control_if(builder_);
   control_if.If(condition);
   control_if.Then();
   Break();
   control_if.Else();
   control_if.End();
 }
 
+void LoopBuilder::ExitLoop(Node** extra_value_to_rename) {
+  if (environment()->IsMarkedAsUnreachable()) return;

[Michael Starzinger, 2016/07/14 12:13:36]

Please move the unreachability check into Environment::PrepareForLoopExit.

[Jarin, 2016/07/14 12:51:34]

Done.

+  builder_->BuildLoopExit(loop_environment_->GetControlDependency(), assigned_,
+                          extra_value_to_rename);
+}
 
 void SwitchBuilder::BeginSwitch() {
   body_environment_ = environment()->CopyAsUnreachable();
   label_environment_ = environment()->CopyAsUnreachable();
   break_environment_ = environment()->CopyAsUnreachable();
 }
 
 
 void SwitchBuilder::BeginLabel(int index, Node* condition) {
   builder_->NewBranch(condition);
@@ skipping 128 matching lines @@
 }
 
 
 void TryFinallyBuilder::EndFinally() {
   // Nothing to be done here.
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8