Add boolean flag to HChange and LNumberUntagD to not convert undefined to NaN.

src/arm/lithium-arm.h

Index: src/arm/lithium-arm.h
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 70f47c4734d70d39cbca2f486d6d092eae0ec01f..0ac3510f40ffc36086c30e370b673f8d579f12f7 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -1656,11 +1656,17 @@ class LSmiTag: public LTemplateInstruction<1, 1, 0> {
 
 class LNumberUntagD: public LTemplateInstruction<1, 1, 0> {
  public:
-  explicit LNumberUntagD(LOperand* value) {
+  LNumberUntagD(LOperand* value, bool deoptimize_on_undefined)
+      : deoptimize_on_undefined_(deoptimize_on_undefined) {
     inputs_[0] = value;
   }
 
+  bool deoptimize_on_undefined() { return deoptimize_on_undefined_; }

[fschneider, 2011/06/09 10:57:22]

I think you can change this to

{ return hydrogen()->deoptimize_on_undefined(); }

and declare a hydrogen() accessor. Then there is no need for an extra private
data member.

+
   DECLARE_CONCRETE_INSTRUCTION(NumberUntagD, "double-untag")

[fschneider, 2011/06/09 10:57:22]

Add DECLARE_HYDROGEN_ACCESSOR(Change) here.

The same applies for the other platforms as well.

[William Hesse, 2011/06/09 12:26:32]

Done.

+
+ private:
+  bool deoptimize_on_undefined_;
 };