BoundsCheck should be extended to support array_bounds_checks_elimination

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
===================================================================
--- src/x64/lithium-x64.cc	(revision 11854)
+++ src/x64/lithium-x64.cc	(working copy)
@@ -1601,9 +1601,16 @@
 
 
 LInstruction* LChunkBuilder::DoBoundsCheck(HBoundsCheck* instr) {
-  LOperand* value = UseRegisterOrConstantAtStart(instr->index());
-  LOperand* length = Use(instr->length());
-  return AssignEnvironment(new(zone()) LBoundsCheck(value, length));
+  if (instr->index()->IsConstant() ||
+      (instr->lower_offset() == 0 && instr->upper_offset() == 0)) {
+    return AssignEnvironment(new(zone()) LBoundsCheck(
+                UseRegisterOrConstantAtStart(instr->index()),
+                Use(instr->length()), NULL));
+  } else {
+    return AssignEnvironment(new(zone()) LBoundsCheck(
+                UseRegisterOrConstant(instr->index()),
+                Use(instr->length()), TempRegister()));
+  }
 }