Ensure environment does not contain nil values.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/436553003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22766 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/ast-graph-builder.cc

@@ -177,18 +177,14 @@ AstGraphBuilder::Environment::Environment(AstGraphBuilder* builder,
   ASSERT_EQ(scope->num_parameters() + 1, parameters_count());
 
   // Bind the receiver variable.
-  values()->insert(values()->end(), parameters_count(),
-                   static_cast<Node*>(NULL));
   Node* receiver = builder->graph()->NewNode(common()->Parameter(0));
-  Bind(scope->receiver(), receiver);
+  values()->push_back(receiver);
 
   // Bind all parameter variables. The parameter indices are shifted by 1
   // (receiver is parameter index -1 but environment index 0).
   for (int i = 0; i < scope->num_parameters(); ++i) {
-    // Unused parameters are allocated to Variable::UNALLOCATED.
-    if (!scope->parameter(i)->IsParameter()) continue;
     Node* parameter = builder->graph()->NewNode(common()->Parameter(i + 1));
-    Bind(scope->parameter(i), parameter);
+    values()->push_back(parameter);
   }
 
   // Bind all local variables to undefined.

src/compiler/graph-builder.cc

@@ -145,7 +145,6 @@ void StructuredGraphBuilder::Environment::Merge(Environment* other) {
   // Introduce Phi nodes for values that have differing input at merge points,
   // potentially extending an existing Phi node if possible.
   for (int i = 0; i < static_cast<int>(values_.size()); ++i) {
-    if (values_[i] == NULL) continue;
     values_[i] = builder_->MergeValue(values_[i], other->values_[i], control);
   }
 }
@@ -154,7 +153,6 @@ void StructuredGraphBuilder::Environment::Merge(Environment* other) {
 void StructuredGraphBuilder::Environment::PrepareForLoop() {
   Node* control = GetControlDependency();
   for (int i = 0; i < static_cast<int>(values()->size()); ++i) {
-    if (values()->at(i) == NULL) continue;
     Node* phi = builder_->NewPhi(1, values()->at(i), control);
     values()->at(i) = phi;
   }