[turbofan] Move context specialization into JSContextSpecializer.

src/compiler/js-context-specialization.cc

 // Copyright 2014 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/js-context-specialization.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 #include "src/contexts.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 Reduction JSContextSpecializer::Reduce(Node* node) {
-  if (node->opcode() == IrOpcode::kJSLoadContext) {
-    return ReduceJSLoadContext(node);
-  }
-  if (node->opcode() == IrOpcode::kJSStoreContext) {
-    return ReduceJSStoreContext(node);
+  switch (node->opcode()) {
+    case IrOpcode::kParameter:
+      return ReduceParameter(node);
+    case IrOpcode::kJSLoadContext:
+      return ReduceJSLoadContext(node);
+    case IrOpcode::kJSStoreContext:
+      return ReduceJSStoreContext(node);
+    default:
+      break;
   }
   return NoChange();
 }
+
+
+Reduction JSContextSpecializer::ReduceParameter(Node* node) {
+  DCHECK_EQ(IrOpcode::kParameter, node->opcode());
+  Handle<Context> context_constant;
+  if (ParameterIndexOf(node->op()) == context_index() &&
+      context().ToHandle(&context_constant)) {
+    return Replace(jsgraph()->Constant(context_constant));
+  }
+  return NoChange();
+}
 
 
 Reduction JSContextSpecializer::ReduceJSLoadContext(Node* node) {
   DCHECK_EQ(IrOpcode::kJSLoadContext, node->opcode());
 
   HeapObjectMatcher m(NodeProperties::GetValueInput(node, 0));
   // If the context is not constant, no reduction can occur.
   if (!m.HasValue()) {
     return NoChange();
   }
@@ skipping 69 matching lines @@
 Isolate* JSContextSpecializer::isolate() const { return jsgraph()->isolate(); }
 
 
 JSOperatorBuilder* JSContextSpecializer::javascript() const {
   return jsgraph()->javascript();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8