Reorder switch clauses using newly-introduced execution counters in

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
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@@ skipping 386 matching lines @@
     loop_side_effects_[i].RemoveAll();
   }
   for (int i = graph_->blocks()->length() - 1; i >= 0; --i) {
     // Compute side effects for the block.
     HBasicBlock* block = graph_->blocks()->at(i);
     HInstruction* instr = block->first();
     int id = block->block_id();
     GVNFlagSet side_effects;
     while (instr != NULL) {
       side_effects.Add(instr->ChangesFlags());
-      if (instr->IsSoftDeoptimize()) {
+      if (instr->IsSoftDeoptimize() ||
+          instr->IsDeoptCounter() || instr->IsDeoptCounterAdd()) {

[Sven Panne, 2013/06/03 07:30:44]

This is a no-go: We're doing something wrong if we have to change GVN for a
localized performance improvement.

[indutny, 2013/06/03 07:50:53]

Well, its just DeoptCounterAdd that behaves like SoftDeoptimize in some cases.

         block_side_effects_[id].RemoveAll();
         side_effects.RemoveAll();
         break;
       }
       instr = instr->next();
     }
     block_side_effects_[id].Add(side_effects);
 
     // Loop headers are part of their loop.
     if (block->IsLoopHeader()) {
@@ skipping 431 matching lines @@
                                                       dominated);
         successor_map->Kill(side_effects_on_all_paths);
         successor_dominators->Kill(side_effects_on_all_paths);
       }
     }
     current = next;
   }
 }
 
 } }  // namespace v8::internal