Avoids MIPS32r2 instructions on MIPS32.

runtime/vm/cpu_mips.h

 // Copyright (c) 2014, 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_CPU_MIPS_H_
 #define VM_CPU_MIPS_H_
 
 #include "vm/allocation.h"
 
 namespace dart {
 
 // TargetCPUFeatures gives CPU features for the architecture that we are
 // generating code for. HostCPUFeatures gives the CPU features for the
 // architecture that we are actually running on. When the architectures
 // are the same, TargetCPUFeatures will query HostCPUFeatures. When they are
 // different (i.e. we are running in a simulator), HostCPUFeatures will
 // additionally mock the options needed for the target architecture so that
 // they may be altered for testing.
 
+enum MIPSVersion {
+  MIPS32,
+  MIPS32r2,
+  MIPSvUnknown,
+};
+
 class HostCPUFeatures: public AllStatic {
  public:
   static void InitOnce();
   static void Cleanup();
   static const char* hardware() {
     DEBUG_ASSERT(initialized_);
     return hardware_;
   }
+  static MIPSVersion mips_version() {
+    DEBUG_ASSERT(initialized_);
+    return mips_version_;
+  }
 
  private:
   static const char* hardware_;
+  static MIPSVersion mips_version_;
 #if defined(DEBUG)
   static bool initialized_;
 #endif
 };
 
 class TargetCPUFeatures : public AllStatic {
  public:
   static void InitOnce() {
     HostCPUFeatures::InitOnce();
   }
   static void Cleanup() {
     HostCPUFeatures::Cleanup();
   }
   static const char* hardware() {
     return HostCPUFeatures::hardware();
   }
   static bool double_truncate_round_supported() {
     return false;
   }
+  static MIPSVersion mips_version() {
+    return HostCPUFeatures::mips_version();
+  }
 };
 
 }  // namespace dart
 
 #endif  // VM_CPU_MIPS_H_