| // 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: |
| // |
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| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
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| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| |
| #ifndef V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ |
| #define V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ |
| |
| |
| #include "hydrogen.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| |
| // Trims live ranges of environment slots by doing explicit liveness analysis. |
| // Values in the environment are kept alive by every subsequent LInstruction |
| // that is assigned an LEnvironment, which creates register pressure and |
| // unnecessary spill slot moves. Therefore it is beneficial to trim the |
| // live ranges of environment slots by zapping them with a constant after |
| // the last lookup that refers to them. |
| // Slots are identified by their index and only affected if whitelisted in |
| // HOptimizedGraphBuilder::IsEligibleForEnvironmentLivenessAnalysis(). |
| class HEnvironmentLivenessAnalysisPhase : public HPhase { |
| public: |
| explicit HEnvironmentLivenessAnalysisPhase(HGraph* graph); |
| |
| void Run(); |
| |
| private: |
| void ZapEnvironmentSlot(int index, HSimulate* simulate); |
| void ZapEnvironmentSlotsInSuccessors(HBasicBlock* block, BitVector* live); |
| void ZapEnvironmentSlotsForInstruction(HEnvironmentMarker* marker); |
| void UpdateLivenessAtBlockEnd(HBasicBlock* block, BitVector* live); |
| void UpdateLivenessAtInstruction(HInstruction* instr, BitVector* live); |
| |
| int block_count_; |
| |
| // Largest number of local variables in any environment in the graph |
| // (including inlined environments). |
| int maximum_environment_size_; |
| |
| // Per-block data. All these lists are indexed by block_id. |
| ZoneList<BitVector*> live_at_block_start_; |
| ZoneList<HSimulate*> first_simulate_; |
| ZoneList<BitVector*> first_simulate_invalid_for_index_; |
| |
| // List of all HEnvironmentMarker instructions for quick iteration/deletion. |
| // It is populated during the first pass over the graph, controlled by |
| // |collect_markers_|. |
| ZoneList<HEnvironmentMarker*> markers_; |
| bool collect_markers_; |
| |
| // Keeps track of the last simulate seen, as well as the environment slots |
| // for which a new live range has started since (so they must not be zapped |
| // in that simulate when the end of another live range of theirs is found). |
| HSimulate* last_simulate_; |
| BitVector went_live_since_last_simulate_; |
| |
| DISALLOW_COPY_AND_ASSIGN(HEnvironmentLivenessAnalysisPhase); |
| }; |
| |
| |
| } } // namespace v8::internal |
| |
| #endif /* V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ */ |