[turbofan] Add new JSFrameSpecialization reducer.

src/compiler/js-frame-specialization.cc

+// Copyright 2015 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-frame-specialization.h"
+
+#include "src/compiler/js-graph.h"
+#include "src/compiler/linkage.h"
+#include "src/frames-inl.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+Reduction JSFrameSpecialization::Reduce(Node* node) {
+  switch (node->opcode()) {
+    case IrOpcode::kOsrValue:
+      return ReduceOsrValue(node);
+    case IrOpcode::kParameter:
+      return ReduceParameter(node);
+    default:
+      break;
+  }
+  return NoChange();
+}
+
+
+Reduction JSFrameSpecialization::ReduceOsrValue(Node* node) {
+  DCHECK_EQ(IrOpcode::kOsrValue, node->opcode());
+  DisallowHeapAllocation no_gc;
+  Object* object;
+  int const index = OpParameter<int>(node);
+  int const parameters_count = frame()->ComputeParametersCount() + 1;
+  if (index == Linkage::kOsrContextSpillSlotIndex) {
+    object = frame()->context();
+  } else if (index >= parameters_count) {
+    object = frame()->GetExpression(index - parameters_count);
+  } else {
+    // The OsrValue index 0 is the receiver.
+    object = index ? frame()->GetParameter(index - 1) : frame()->receiver();
+  }
+  return Replace(jsgraph()->Constant(handle(object, isolate())));
+}
+
+
+Reduction JSFrameSpecialization::ReduceParameter(Node* node) {
+  DCHECK_EQ(IrOpcode::kParameter, node->opcode());
+  DisallowHeapAllocation no_gc;
+  Object* object;
+  int const index = ParameterIndexOf(node->op());
+  int const parameters_count = frame()->ComputeParametersCount() + 1;
+  if (index == Linkage::kJSFunctionCallClosureParamIndex) {
+    object = frame()->function();
+  } else if (index == parameters_count) {
+    // The Parameter index (arity + 1) is the context.
+    object = frame()->context();
+  } else {
+    // The Parameter index 0 is the receiver.
+    object = index ? frame()->GetParameter(index - 1) : frame()->receiver();
+  }
+  return Replace(jsgraph()->Constant(handle(object, isolate())));
+}
+
+
+Isolate* JSFrameSpecialization::isolate() const { return jsgraph()->isolate(); }
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8