Reduce memory usage due to fixpoint iteration of GVN.

src/hydrogen-gvn.cc

 // Copyright 2013 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 360 matching lines @@
         visited_on_paths_(graph->blocks()->length(), zone()) {
     ASSERT(!AllowHandleAllocation::IsAllowed());
     block_side_effects_.AddBlock(GVNFlagSet(), graph->blocks()->length(),
                                  zone());
     loop_side_effects_.AddBlock(GVNFlagSet(), graph->blocks()->length(),
                                 zone());
 }
 
 
 void HGlobalValueNumberingPhase::Reset() {
-  block_side_effects_.Clear();
-  loop_side_effects_.Clear();
+  ASSERT(block_side_effects_.length() == graph()->blocks()->length());
+  ASSERT(loop_side_effects_.length() == graph()->blocks()->length());
+  for (int i = 0; i < graph()->blocks()->length(); ++i) {
+    block_side_effects_[i] = GVNFlagSet();
+    loop_side_effects_[i] = GVNFlagSet();
+  }
   visited_on_paths_.Clear();
-  block_side_effects_.AddBlock(GVNFlagSet(), graph()->blocks()->length(),
-                               zone());
-  loop_side_effects_.AddBlock(GVNFlagSet(), graph()->blocks()->length(),
-                              zone());
 }
 
 
 void HGlobalValueNumberingPhase::Analyze() {
   removed_side_effects_ = false;
   ComputeBlockSideEffects();
   if (FLAG_loop_invariant_code_motion) {
     LoopInvariantCodeMotion();
   }
   AnalyzeGraph();
@@ skipping 464 matching lines @@
                                                       dominated);
         successor_map->Kill(side_effects_on_all_paths);
         successor_dominators->Kill(side_effects_on_all_paths);
       }
     }
     current = next;
   }
 }
 
 } }  // namespace v8::internal