BoundsCheck should be extended to support array_bounds_checks_elimination

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
===================================================================
--- src/ia32/lithium-ia32.cc	(revision 11854)
+++ src/ia32/lithium-ia32.cc	(working copy)
@@ -1659,9 +1659,16 @@
 
 
 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()));
+  }
 }