BoundsCheck should be extended to support array_bounds_checks_elimination

src/ia32/lithium-ia32.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 1641 matching lines @@
 
 LInstruction* LChunkBuilder::DoDateField(HDateField* instr) {
   LOperand* date = UseFixed(instr->value(), eax);
   LDateField* result =
       new(zone()) LDateField(date, FixedTemp(ecx), instr->index());
   return MarkAsCall(DefineFixed(result, eax), instr);
 }
 
 
 LInstruction* LChunkBuilder::DoBoundsCheck(HBoundsCheck* instr) {
-  return AssignEnvironment(new(zone()) LBoundsCheck(
-      UseRegisterOrConstantAtStart(instr->index()),
-      UseAtStart(instr->length())));
+  if (instr->index()->IsConstant() ||
+      (instr->lower_offset() == 0 && instr->upper_offset() == 0)) {
+    return AssignEnvironment(new(zone()) LBoundsCheck(
+        UseRegisterOrConstantAtStart(instr->index()),
+        UseAtStart(instr->length()), NULL));
+  } else {
+    return AssignEnvironment(new(zone()) LBoundsCheck(
+        UseRegisterOrConstant(instr->index()),
+        UseAtStart(instr->length()), TempRegister()));
+  }
 }
 
 
 LInstruction* LChunkBuilder::DoAbnormalExit(HAbnormalExit* instr) {
   // The control instruction marking the end of a block that completed
   // abruptly (e.g., threw an exception).  There is nothing specific to do.
   return NULL;
 }
 
 
@@ skipping 773 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32