[turbofan] Implement OSR for outer loops.

src/compiler/ast-graph-builder.cc

Index: src/compiler/ast-graph-builder.cc
diff --git a/src/compiler/ast-graph-builder.cc b/src/compiler/ast-graph-builder.cc
index cde5e7182df0cba24ed1147a4b503d62a9b0a9e9..5c91b95153d6448fda9816f1340546aac6952186 100644
--- a/src/compiler/ast-graph-builder.cc
+++ b/src/compiler/ast-graph-builder.cc
@@ -62,10 +62,17 @@ bool AstGraphBuilder::CreateGraph() {
   int parameter_count = info()->num_parameters();
   graph()->SetStart(graph()->NewNode(common()->Start(parameter_count)));
 
+  Node* start = graph()->start();
   // Initialize the top-level environment.
-  Environment env(this, scope, graph()->start());
+  Environment env(this, scope, start);
   set_environment(&env);
 
+  if (info()->is_osr()) {
+    // Use OSR normal entry as the start of the top-level environment.
+    // It will be replaced with {Dead} after typing and optimizations.
+    NewNode(common()->OsrNormalEntry());
+  }
+
   // Initialize the incoming context.
   Node* outer_context = GetFunctionContext();
   set_current_context(outer_context);
@@ -589,7 +596,7 @@ void AstGraphBuilder::VisitSwitchStatement(SwitchStatement* stmt) {
 
 void AstGraphBuilder::VisitDoWhileStatement(DoWhileStatement* stmt) {
   LoopBuilder while_loop(this);
-  while_loop.BeginLoop(GetVariablesAssignedInLoop(stmt));
+  while_loop.BeginLoop(GetVariablesAssignedInLoop(stmt), IsOsrLoopEntry(stmt));
   VisitIterationBody(stmt, &while_loop, 0);
   while_loop.EndBody();
   VisitForTest(stmt->cond());
@@ -601,7 +608,7 @@ void AstGraphBuilder::VisitDoWhileStatement(DoWhileStatement* stmt) {
 
 void AstGraphBuilder::VisitWhileStatement(WhileStatement* stmt) {
   LoopBuilder while_loop(this);
-  while_loop.BeginLoop(GetVariablesAssignedInLoop(stmt));
+  while_loop.BeginLoop(GetVariablesAssignedInLoop(stmt), IsOsrLoopEntry(stmt));
   VisitForTest(stmt->cond());
   Node* condition = environment()->Pop();
   while_loop.BreakUnless(condition);
@@ -614,7 +621,7 @@ void AstGraphBuilder::VisitWhileStatement(WhileStatement* stmt) {
 void AstGraphBuilder::VisitForStatement(ForStatement* stmt) {
   LoopBuilder for_loop(this);
   VisitIfNotNull(stmt->init());
-  for_loop.BeginLoop(GetVariablesAssignedInLoop(stmt));
+  for_loop.BeginLoop(GetVariablesAssignedInLoop(stmt), IsOsrLoopEntry(stmt));
   if (stmt->cond() != NULL) {
     VisitForTest(stmt->cond());
     Node* condition = environment()->Pop();
@@ -690,7 +697,8 @@ void AstGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
         environment()->Push(jsgraph()->ZeroConstant());
         // PrepareForBailoutForId(stmt->BodyId(), NO_REGISTERS);
         LoopBuilder for_loop(this);
-        for_loop.BeginLoop(GetVariablesAssignedInLoop(stmt));
+        for_loop.BeginLoop(GetVariablesAssignedInLoop(stmt),
+                           IsOsrLoopEntry(stmt));
         // Check loop termination condition.
         Node* index = environment()->Peek(0);
         Node* exit_cond =
@@ -2209,6 +2217,11 @@ Node* AstGraphBuilder::BuildStackCheck() {
 }
 
 
+bool AstGraphBuilder::IsOsrLoopEntry(IterationStatement* stmt) {
+  return info()->osr_ast_id() == stmt->OsrEntryId();
+}
+
+
 void AstGraphBuilder::PrepareFrameState(Node* node, BailoutId ast_id,
                                         OutputFrameStateCombine combine) {
   if (OperatorProperties::HasFrameStateInput(node->op())) {