Optimize redundant HCompareMap instructions with known successors.

src/mips/lithium-mips.cc

 // 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 927 matching lines @@
   ToBooleanStub::Types expected = instr->expected_input_types();
   if (rep.IsTagged() && !type.IsSmi() && !type.IsBoolean() &&
       !expected.IsGeneric()) {
     return AssignEnvironment(result);
   }
   return result;
 }
 
 
 LInstruction* LChunkBuilder::DoCompareMap(HCompareMap* instr) {
+  LInstruction* goto_instr = CheckElideControlInstruction(instr);
+  if (goto_instr != NULL) return goto_instr;
+
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* value = UseRegisterAtStart(instr->value());
   LOperand* temp = TempRegister();
   return new(zone()) LCmpMapAndBranch(value, temp);
 }
 
 
 LInstruction* LChunkBuilder::DoArgumentsLength(HArgumentsLength* length) {
   info()->MarkAsRequiresFrame();
   return DefineAsRegister(
@@ skipping 1438 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseRegister(instr->index());
   return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal