Recognize leaf functions: skip stack check and populating the pc slot, store the pc slot lazily in …

runtime/vm/flow_graph_optimizer.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_FLOW_GRAPH_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 
 namespace dart {
@@ skipping 28 matching lines @@
   bool TryReplaceWithUnaryOp(InstanceCallComp* comp, Token::Kind op_kind);
 
   bool TryInlineInstanceGetter(InstanceCallComp* comp);
   bool TryInlineInstanceSetter(InstanceSetterComp* comp);
 
   bool TryInlineInstanceMethod(InstanceCallComp* comp);
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphOptimizer);
 };
 
+
+// Analyze the generated flow graph. Currently only if it is a leaf
+// method, i.e., does not contain any calls to runtime or other Dart code.
+class FlowGraphAnalyzer : public ValueObject {
+ public:
+  explicit FlowGraphAnalyzer(const GrowableArray<BlockEntryInstr*>& blocks);
+  virtual ~FlowGraphAnalyzer() {}
+
+  void Analyze();
+
+  bool is_leaf() const { return is_leaf_; }
+
+ private:
+  const GrowableArray<BlockEntryInstr*>& blocks_;
+  bool is_leaf_;
+
+  DISALLOW_COPY_AND_ASSIGN(FlowGraphAnalyzer);
+};
+
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_