Allocation folding integrated into the GVN phase.

src/hydrogen.h

 // Copyright 2012 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 215 matching lines @@
   void Advance() { current_++; }
 
  private:
   const ZoneList<HBasicBlock*>* predecessor_list_;
   int current_;
 };
 
 
 class HInstructionIterator BASE_EMBEDDED {
  public:
-  explicit HInstructionIterator(HBasicBlock* block) : instr_(block->first()) { }
+  explicit HInstructionIterator(HBasicBlock* block)
+      : instr_(block->first()) {
+    next_ = Done() ? NULL : instr_->next();
+  }
 
   bool Done() { return instr_ == NULL; }

[titzer, 2013/07/09 08:34:39]

While you're here, would you mind adding "inline" and "const" keywords?

[Hannes Payer (out of office), 2013/07/09 09:01:33]

Done.

   HInstruction* Current() { return instr_; }
-  void Advance() { instr_ = instr_->next(); }
+  void Advance() {
+    instr_ = next_;
+    next_ = Done() ? NULL : instr_->next();
+  }
 
  private:
   HInstruction* instr_;
+  HInstruction* next_;
 };
 
 
 class HLoopInformation: public ZoneObject {
  public:
   HLoopInformation(HBasicBlock* loop_header, Zone* zone)
       : back_edges_(4, zone),
         loop_header_(loop_header),
         blocks_(8, zone),
         stack_check_(NULL) {
@@ skipping 1851 matching lines @@
   EmbeddedVector<char, 64> filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_