[turbofan] Fix value output count for the Start node.

The value output count for Start is currently off by 1 for code stubs,
because the CommonOperatorBuilder hardcodes the receiver parameter.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/1217553005

Cr-Commit-Position: refs/heads/master@{#29490}

src/compiler/ast-graph-builder.cc

@@ -502,9 +502,10 @@ bool AstGraphBuilder::CreateGraph(bool constant_context, bool stack_check) {
   Scope* scope = info()->scope();
   DCHECK(graph() != NULL);
 
-  // Set up the basic structure of the graph.
-  int parameter_count = info()->num_parameters();
-  graph()->SetStart(graph()->NewNode(common()->Start(parameter_count)));
+  // Set up the basic structure of the graph. Outputs for {Start} are the formal
+  // parameters (including the receiver) plus context and closure.
+  int actual_parameter_count = info()->num_parameters_including_this() + 2;
+  graph()->SetStart(graph()->NewNode(common()->Start(actual_parameter_count)));
 
   // Initialize the top-level environment.
   Environment env(this, scope, graph()->start());

src/compiler/common-operator.cc

@@ -441,9 +441,7 @@ const Operator* CommonOperatorBuilder::IfValue(int32_t index) {
 }
 
 
-const Operator* CommonOperatorBuilder::Start(int num_formal_parameters) {
-  // Outputs are formal parameters, plus context, receiver, and JSFunction.
-  const int value_output_count = num_formal_parameters + 3;
+const Operator* CommonOperatorBuilder::Start(int value_output_count) {
   return new (zone()) Operator(               // --
       IrOpcode::kStart, Operator::kFoldable,  // opcode
       "Start",                                // name

src/compiler/common-operator.h

@@ -124,7 +124,7 @@ class CommonOperatorBuilder final : public ZoneObject {
   const Operator* Return();
   const Operator* Terminate();
 
-  const Operator* Start(int num_formal_parameters);
+  const Operator* Start(int value_output_count);
   const Operator* Loop(int control_input_count);
   const Operator* Merge(int control_input_count);
   const Operator* Parameter(int index, const char* debug_name = nullptr);

src/compiler/verifier.cc

@@ -318,13 +318,13 @@ void Verifier::Visitor::Check(Node* node) {
     case IrOpcode::kParameter: {
       // Parameters have the start node as inputs.
       CHECK_EQ(1, input_count);
-      CHECK_EQ(IrOpcode::kStart,
-               NodeProperties::GetValueInput(node, 0)->opcode());
       // Parameter has an input that produces enough values.
-      int index = OpParameter<int>(node);
-      Node* input = NodeProperties::GetValueInput(node, 0);
+      int const index = ParameterIndexOf(node->op());
+      Node* const start = NodeProperties::GetValueInput(node, 0);
+      CHECK_EQ(IrOpcode::kStart, start->opcode());
       // Currently, parameter indices start at -1 instead of 0.
-      CHECK_GT(input->op()->ValueOutputCount(), index + 1);
+      CHECK_LE(-1, index);
+      CHECK_LT(index + 1, start->op()->ValueOutputCount());
       // Type can be anything.
       CheckUpperIs(node, Type::Any());
       break;

test/cctest/compiler/simplified-graph-builder.cc

@@ -23,7 +23,7 @@ SimplifiedGraphBuilder::SimplifiedGraphBuilder(
 
 void SimplifiedGraphBuilder::Begin(int num_parameters) {
   DCHECK(graph()->start() == NULL);
-  Node* start = graph()->NewNode(common()->Start(num_parameters));
+  Node* start = graph()->NewNode(common()->Start(num_parameters + 3));
   graph()->SetStart(start);
   effect_ = start;
 }

test/cctest/compiler/test-run-stubs.cc

@@ -40,7 +40,7 @@ TEST(RunMathFloorStub) {
   JSGraph js(isolate, &graph, &common, &javascript, &machine);
 
   // FunctionTester (ab)uses a 2-argument function
-  Node* start = graph.NewNode(common.Start(2));
+  Node* start = graph.NewNode(common.Start(4));
   // Parameter 0 is the number to round
   Node* numberParam = graph.NewNode(common.Parameter(1), start);
   Unique<HeapObject> u = Unique<HeapObject>::CreateImmovable(code);
@@ -76,7 +76,7 @@ TEST(RunStringLengthTFStub) {
   Graph graph(zone);
   CommonOperatorBuilder common(zone);
   // FunctionTester (ab)uses a 4-argument function
-  Node* start = graph.NewNode(common.Start(4));
+  Node* start = graph.NewNode(common.Start(6));
   // Parameter 0 is the receiver
   Node* receiverParam = graph.NewNode(common.Parameter(1), start);
   Node* nameParam = graph.NewNode(common.Parameter(2), start);
@@ -122,7 +122,7 @@ TEST(RunStringAddTFStub) {
   Graph graph(zone);
   CommonOperatorBuilder common(zone);
   // FunctionTester (ab)uses a 2-argument function
-  Node* start = graph.NewNode(common.Start(2));
+  Node* start = graph.NewNode(common.Start(4));
   // Parameter 0 is the receiver
   Node* leftParam = graph.NewNode(common.Parameter(1), start);
   Node* rightParam = graph.NewNode(common.Parameter(2), start);