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

src/arm/lithium-arm.h

 // Copyright 2011 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
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@@ skipping 1638 matching lines @@
   explicit LSmiTag(LOperand* value) {
     inputs_[0] = value;
   }
 
   DECLARE_CONCRETE_INSTRUCTION(SmiTag, "smi-tag")
 };
 
 
 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_;
 };
 
 
 class LSmiUntag: public LTemplateInstruction<1, 1, 0> {
  public:
   LSmiUntag(LOperand* value, bool needs_check)
       : needs_check_(needs_check) {
     inputs_[0] = value;
   }
 
@@ skipping 644 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_LITHIUM_ARM_H_