Add a HBreak instruction for debugging

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 85 matching lines @@
   V(CheckSmiOrInt32)                           \
   V(ClampToUint8)                              \
   V(ClassOfTestAndBranch)                      \
   V(CompareIDAndBranch)                        \
   V(CompareGeneric)                            \
   V(CompareObjectEqAndBranch)                  \
   V(CompareMap)                                \
   V(CompareConstantEqAndBranch)                \
   V(Constant)                                  \
   V(Context)                                   \
+  V(DebugBreak)                                \
   V(DeclareGlobals)                            \
   V(DeleteProperty)                            \
   V(Deoptimize)                                \
   V(Div)                                       \
   V(DummyUse)                                  \
   V(ElementsKind)                              \
   V(EnterInlined)                              \
   V(FixedArrayBaseLength)                      \
   V(ForceRepresentation)                       \
   V(FunctionLiteral)                           \
@@ skipping 1340 matching lines @@
 class HSoftDeoptimize: public HTemplateInstruction<0> {
  public:
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::None();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(SoftDeoptimize)
 };
 
 
+// Inserts an int3/stop break instruction for debugging purposes.
+class HDebugBreak: public HTemplateInstruction<0> {
+ public:
+  virtual Representation RequiredInputRepresentation(int index) {
+    return Representation::None();
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(DebugBreak)
+};
+
+
 class HDeoptimize: public HControlInstruction {
  public:
   HDeoptimize(int environment_length, Zone* zone)
       : values_(environment_length, zone) { }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::None();
   }
 
   virtual int OperandCount() { return values_.length(); }
@@ skipping 4973 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_