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28 #ifndef V8_HYDROGEN_GVN_H_
29 #define V8_HYDROGEN_GVN_H_
32 #include "hydrogen-instructions.h"
39 // Perform common subexpression elimination and loop-invariant code motion.
40 class HGlobalValueNumberingPhase : public HPhase {
42 explicit HGlobalValueNumberingPhase(HGraph* graph);
47 GVNFlagSet CollectSideEffectsOnPathsToDominatedBlock(
48 HBasicBlock* dominator,
49 HBasicBlock* dominated);
51 void ComputeBlockSideEffects();
52 void LoopInvariantCodeMotion();
53 void ProcessLoopBlock(HBasicBlock* block,
54 HBasicBlock* before_loop,
55 GVNFlagSet loop_kills);
56 bool AllowCodeMotion();
57 bool ShouldMove(HInstruction* instr, HBasicBlock* loop_header);
59 bool removed_side_effects_;
61 // A map of block IDs to their side effects.
62 ZoneList<GVNFlagSet> block_side_effects_;
64 // A map of loop header block IDs to their loop's side effects.
65 ZoneList<GVNFlagSet> loop_side_effects_;
67 // Used when collecting side effects on paths from dominator to
69 BitVector visited_on_paths_;
71 DISALLOW_COPY_AND_ASSIGN(HGlobalValueNumberingPhase);
75 } } // namespace v8::internal
77 #endif // V8_HYDROGEN_GVN_H_