Infer the range of Math.abs

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 4a8a406eb3befbc126c4f0f6aa15119892ef316f..a4b2e0990dd44d5d5fa90e2581c6f04afb631555 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -271,6 +271,14 @@ class Range: public ZoneObject {
   bool IsInSmiRange() const {
     return lower_ >= Smi::kMinValue && upper_ <= Smi::kMaxValue;
   }
+  void TruncateToSmi() {

[Sven Panne, 2013/06/07 06:40:54]

I think that "ClampToSmi" is a better name. "Clamping" is the common name for
this kind of operation, "truncation" is more associated with floating point
stuff.

+    lower_ = Max(lower_, Smi::kMinValue);
+    upper_ = Min(upper_, Smi::kMaxValue);
+  }
+  void TruncateToInt32() {

[Jakob Kummerow, 2013/06/07 08:21:05]

Considering that lower_ and upper_ are int32_t, this function is always a no-op.
I don't think we need no-op functions :-)

+    lower_ = Max(lower_, kMinInt);
+    upper_ = Min(upper_, kMaxInt);
+  }
   void KeepOrder();
 #ifdef DEBUG
   void Verify() const;
@@ -2644,6 +2652,8 @@ class HUnaryMathOperation: public HTemplateInstruction<2> {
     }
   }
 
+  virtual Range* InferRange(Zone* zone);
+
   virtual HValue* Canonicalize();
 
   BuiltinFunctionId op() const { return op_; }