Improve dead phi elimination....

src/hydrogen.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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 216 matching lines @@
   const ZoneList<HBasicBlock*>* blocks() const { return &blocks_; }
   const ZoneList<HPhi*>* phi_list() const { return phi_list_; }
   HEnvironment* start_environment() const { return start_environment_; }
 
   void InitializeInferredTypes();
   void InsertTypeConversions();
   void InsertRepresentationChanges();
   void ComputeMinusZeroChecks();
   bool ProcessArgumentsObject();
   void EliminateRedundantPhis();
+  void EliminateDeadPhis();

[Kevin Millikin (Chromium), 2011/03/08 08:51:03]

"Dead" is ambiguous.  Maybe "Unreachable" is more accurate (that is, not
reachable in any use-def chain from the non-phi uses).

[fschneider, 2011/03/08 10:03:39]

Done.

   void Canonicalize();
   void OrderBlocks();
   void AssignDominators();
 
   // Returns false if there are phi-uses of the arguments-object
   // which are not supported by the optimizing compiler.
   bool CollectPhis();
 
   Handle<Code> Compile(CompilationInfo* info);
 
@@ skipping 881 matching lines @@
   const char* filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_