Elide hole checks on KeyedLoads of holey double arrays.

src/hydrogen-instructions.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 2663 matching lines @@
 
 bool HLoadKeyed::UsesMustHandleHole() const {
   if (IsFastPackedElementsKind(elements_kind())) {
     return false;
   }
 
   if (IsExternalArrayElementsKind(elements_kind())) {
     return false;
   }
 
-  if (hole_mode() == ALLOW_RETURN_HOLE) return true;
+  if (hole_mode() == ALLOW_RETURN_HOLE) {
+    if (IsFastDoubleElementsKind(elements_kind())) {
+      return AllUsesCanTreatHoleAsNaN();
+    }
+    return true;
+  }
 
   if (IsFastDoubleElementsKind(elements_kind())) {
     return false;
   }
 
   for (HUseIterator it(uses()); !it.Done(); it.Advance()) {
     HValue* use = it.value();
     if (!use->IsChange()) {
       return false;
     }
   }
 
   return true;
 }
 
 
+bool HLoadKeyed::AllUsesCanTreatHoleAsNaN() const {
+  if (!IsFastDoubleElementsKind(elements_kind())) {
+    return false;
+  }
+
+  for (HUseIterator it(uses()); !it.Done(); it.Advance()) {
+    HValue* use = it.value();
+    if (use->CheckFlag(HValue::kDeoptimizeOnUndefined)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+
 bool HLoadKeyed::RequiresHoleCheck() const {
   if (IsFastPackedElementsKind(elements_kind())) {
     return false;
   }
 
   if (IsExternalArrayElementsKind(elements_kind())) {
     return false;
   }
 
   return !UsesMustHandleHole();
@@ skipping 919 matching lines @@
 
 
 void HCheckFunction::Verify() {
   HInstruction::Verify();
   ASSERT(HasNoUses());
 }
 
 #endif
 
 } }  // namespace v8::internal