Add enough compiler support to compile empty functions on x64.

runtime/vm/intermediate_language.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_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
 #include "vm/handles_impl.h"
 #include "vm/object.h"
 
 namespace dart {
 
 class LocalVariable;
+class ConstantValue;
+class TempValue;
 
 // Computations and values.
 //
 // <Computation> ::= <Value>
 //                 | AssertAssignable <Value> <AbstractType>
 //                 | InstanceCall <cstring> <Value> ...
 //                 | StaticCall <Function> <Value> ...
 //                 | LoadLocal <LocalVariable>
 //                 | StoreLocal <LocalVariable> <Value>
 //
 // <Value> ::= Temp <int>
 //           | Constant <Instance>
 
 class Computation : public ZoneAllocated {
  public:
   Computation() { }
 
   // Prints a computation without indentation or trailing newlines.
   virtual void Print() const = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(Computation);
 };
 
 
 class Value : public Computation {
  public:
   Value() { }
 
+  virtual TempValue* AsTemp() { return NULL; }
+  virtual ConstantValue* AsConstant() { return NULL; }
+
+  bool IsTemp() { return AsTemp() != NULL; }
+  bool IsConstant() { return AsConstant() != NULL; }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(Value);
 };
 
 
 class AssertAssignableComp : public Computation {
  public:
   AssertAssignableComp(Value* value, const AbstractType& type)
       : value_(value), type_(type) { }
 
@@ skipping 64 matching lines @@
   Value* value_;
 
   DISALLOW_COPY_AND_ASSIGN(StoreLocalComp);
 };
 
 
 class TempValue : public Value {
  public:
   explicit TempValue(intptr_t index) : index_(index) { }
 
+  virtual TempValue* AsTemp() { return this; }
   virtual void Print() const;
 
  private:
   intptr_t index_;
 
   DISALLOW_COPY_AND_ASSIGN(TempValue);
 };
 
 
 class ConstantValue: public Value {
  public:
   explicit ConstantValue(const Instance& instance) : instance_(instance) { }
 
+  virtual ConstantValue* AsConstant() { return this; }
   virtual void Print() const;
 
+  const Instance& instance() const { return instance_; }
+
  private:
   const Instance& instance_;
 
   DISALLOW_COPY_AND_ASSIGN(ConstantValue);
 };
 
 
 // Instructions.
 //
 // <Instruction> ::= Do <Computation> <Instruction>
@@ skipping 219 matching lines @@
 #undef DECLARE_INSTRUCTION
 
 
 class InstructionVisitor {
  public:
   InstructionVisitor() { }
   virtual ~InstructionVisitor() { }
 
   // Visit each block in the array list in reverse, and for each block its
   // instructions in order from the block entry to exit.
-  void VisitBlocks(const GrowableArray<BlockEntryInstr*>& block_order);
+  virtual void VisitBlocks(const GrowableArray<BlockEntryInstr*>& block_order);
 
 #define DECLARE_VISIT(type)                             \
   virtual void Visit##type(type##Instr* instr) { }
   FOR_EACH_INSTRUCTION(DECLARE_VISIT)
 #undef DECLARE_VISIT
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InstructionVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_