Disable aggressive optimizations on the last optimization attempt.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 4a23f2a327ef4d41e19481c84c6279ee779a1907..de003477315395d95cfb9d24bf244cf5461e4833 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -773,6 +773,10 @@ class HInstruction: public HValue {
   virtual void Verify() const;
 #endif
 
+  // Conservative indication of whether the instruction can
+  // deoptimize. Allowed to have false positives.

[Kevin Millikin (Chromium), 2011/01/18 11:18:39]

The comment is also confusing.  The predicate has false negatives (not every
instruction that can deoptimize says true).

[Vitaly Repeshko, 2011/01/18 12:24:56]

I renamed the function and the comment is much clearer now.

+  virtual bool CanDeoptimize() const { return false; }

[fschneider, 2011/01/18 10:45:51]

I'd rather name this predicate IsCheckInstruction() because 
in the long run we want the logic for deciding if an instructions can deoptimize
factored out into a platform-specific part.

[Vitaly Repeshko, 2011/01/18 12:24:56]

Done.

+
   DECLARE_INSTRUCTION(Instruction)
 
  protected:
@@ -1504,6 +1508,8 @@ class HCheckMap: public HUnaryOperation {
     SetFlag(kDependsOnMaps);
   }
 
+  virtual bool CanDeoptimize() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1537,6 +1543,8 @@ class HCheckFunction: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool CanDeoptimize() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1573,6 +1581,8 @@ class HCheckInstanceType: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool CanDeoptimize() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1610,6 +1620,8 @@ class HCheckNonSmi: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool CanDeoptimize() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1632,6 +1644,8 @@ class HCheckPrototypeMaps: public HInstruction {
     SetFlag(kDependsOnMaps);
   }
 
+  virtual bool CanDeoptimize() const { return true; }
+
 #ifdef DEBUG
   virtual void Verify() const;
 #endif
@@ -1668,6 +1682,8 @@ class HCheckSmi: public HUnaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool CanDeoptimize() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Tagged();
   }
@@ -1996,6 +2012,8 @@ class HBoundsCheck: public HBinaryOperation {
     SetFlag(kUseGVN);
   }
 
+  virtual bool CanDeoptimize() const { return true; }
+
   virtual Representation RequiredInputRepresentation(int index) const {
     return Representation::Integer32();
   }