Eliminate map checks of constant values.

src/arm/lithium-arm.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 2017 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
   LInstruction* result = new(zone()) LCheckInstanceType(value);
   return AssignEnvironment(result);
 }
 
 
 LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
-  LUnallocated* temp1 = TempRegister();
-  LOperand* temp2 = TempRegister();
+  LUnallocated* temp1 = NULL;
+  LOperand* temp2 = NULL;
+  if (!instr->CanOmitPrototypeChecks()) {
+    temp1 = TempRegister();
+    temp2 = TempRegister();
+  }
   LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp1, temp2);
+  if (instr->CanOmitPrototypeChecks()) return result;
   return AssignEnvironment(result);
 }
 
 
 LInstruction* LChunkBuilder::DoCheckFunction(HCheckFunction* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
   return AssignEnvironment(new(zone()) LCheckFunction(value));
 }
 
 
 LInstruction* LChunkBuilder::DoCheckMaps(HCheckMaps* instr) {
-  LOperand* value = UseRegisterAtStart(instr->value());
+  LOperand* value = NULL;
+  if (!instr->CanOmitMapChecks()) value = UseRegisterAtStart(instr->value());
   LInstruction* result = new(zone()) LCheckMaps(value);
+  if (instr->CanOmitMapChecks()) return result;
   return AssignEnvironment(result);
 }
 
 
 LInstruction* LChunkBuilder::DoClampToUint8(HClampToUint8* instr) {
   HValue* value = instr->value();
   Representation input_rep = value->representation();
   LOperand* reg = UseRegister(value);
   if (input_rep.IsDouble()) {
     return DefineAsRegister(new(zone()) LClampDToUint8(reg, FixedTemp(d11)));
@@ skipping 576 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