Adds branch instructions and labels to the MIPS simulator, assembler, disassembler.

runtime/vm/constants_mips.h

 // Copyright (c) 2013, 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_CONSTANTS_MIPS_H_
 #define VM_CONSTANTS_MIPS_H_
 
 namespace dart {
 
 enum Register {
@@ skipping 156 matching lines @@
   kSaShift = 6,
   kSaBits = 5,
   kFunctionShift = 0,
   kFunctionBits = 6,
   kImmShift = 0,
   kImmBits = 16,
   kInstrShift = 0,
   kInstrBits = 26,
   kBreakCodeShift = 5,
   kBreakCodeBits = 20,
+
+  kBranchOffsetMask = 0x0000ffff,
 };
 
 
 enum Opcode {
   SPECIAL = 0,
   REGIMM = 1,
   J = 2,
   JAL = 3,
   BEQ = 4,
   BNE = 5,
@@ skipping 172 matching lines @@
   }
 
   inline int32_t BreakCodeField() const {
     return Bits(kBreakCodeShift, kBreakCodeBits);
   }
 
   inline SpecialFunction FunctionField() const {
     return static_cast<SpecialFunction>(Bits(kFunctionShift, kFunctionBits));
   }
 
+  inline RtRegImm RegImmFnField() const {
+    return static_cast<RtRegImm>(Bits(kRtShift, kRtBits));
+  }
+
   inline bool IsBreakPoint() {
     return (OpcodeField() == SPECIAL) && (FunctionField() == BREAK);
   }
 
   // Instructions are read out of a code stream. The only way to get a
   // reference to an instruction is to convert a pc. There is no way
   // to allocate or create instances of class Instr.
   // Use the At(pc) function to create references to Instr.
   static Instr* At(uword pc) { return reinterpret_cast<Instr*>(pc); }
 
  private:
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Instr);
 };
 
 }  // namespace dart
 
 #endif  // VM_CONSTANTS_MIPS_H_