OLD | NEW |
(Empty) | |
| 1 // Copyright 2013 the V8 project authors. All rights reserved. |
| 2 // Redistribution and use in source and binary forms, with or without |
| 3 // modification, are permitted provided that the following conditions are |
| 4 // met: |
| 5 // |
| 6 // * Redistributions of source code must retain the above copyright |
| 7 // notice, this list of conditions and the following disclaimer. |
| 8 // * Redistributions in binary form must reproduce the above |
| 9 // copyright notice, this list of conditions and the following |
| 10 // disclaimer in the documentation and/or other materials provided |
| 11 // with the distribution. |
| 12 // * Neither the name of Google Inc. nor the names of its |
| 13 // contributors may be used to endorse or promote products derived |
| 14 // from this software without specific prior written permission. |
| 15 // |
| 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 |
| 28 #ifndef V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ |
| 29 #define V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ |
| 30 |
| 31 |
| 32 #include "hydrogen.h" |
| 33 |
| 34 namespace v8 { |
| 35 namespace internal { |
| 36 |
| 37 |
| 38 // Trims live ranges of environment slots by doing explicit liveness analysis. |
| 39 // Values in the environment are kept alive by every subsequent LInstruction |
| 40 // that is assigned an LEnvironment, which creates register pressure and |
| 41 // unnecessary spill slot moves. Therefore it is beneficial to trim the |
| 42 // live ranges of environment slots by zapping them with a constant after |
| 43 // the last lookup that refers to them. |
| 44 // Slots are identified by their index and only affected if whitelisted in |
| 45 // HOptimizedGraphBuilder::IsEligibleForEnvironmentLivenessAnalysis(). |
| 46 class EnvironmentSlotLivenessAnalyzer { |
| 47 public: |
| 48 explicit EnvironmentSlotLivenessAnalyzer(HGraph* graph); |
| 49 |
| 50 void AnalyzeAndTrim(); |
| 51 |
| 52 private: |
| 53 void ZapEnvironmentSlot(int index, HSimulate* simulate); |
| 54 void ZapEnvironmentSlotsInSuccessors(HBasicBlock* block, BitVector* live); |
| 55 void ZapEnvironmentSlotsForInstruction(HEnvironmentMarker* marker); |
| 56 void UpdateLivenessAtBlockEnd(HBasicBlock* block, BitVector* live); |
| 57 void UpdateLivenessAtInstruction(HInstruction* instr, BitVector* live); |
| 58 |
| 59 Zone* zone() { return &zone_; } |
| 60 |
| 61 HGraph* graph_; |
| 62 // Use a dedicated Zone for this phase, with a ZoneScope to ensure it |
| 63 // gets freed. |
| 64 Zone zone_; |
| 65 ZoneScope zone_scope_; |
| 66 |
| 67 int block_count_; |
| 68 |
| 69 // Largest number of local variables in any environment in the graph |
| 70 // (including inlined environments). |
| 71 int maximum_environment_size_; |
| 72 |
| 73 // Per-block data. All these lists are indexed by block_id. |
| 74 ZoneList<BitVector*>* live_at_block_start_; |
| 75 ZoneList<HSimulate*>* first_simulate_; |
| 76 ZoneList<BitVector*>* first_simulate_invalid_for_index_; |
| 77 |
| 78 // List of all HEnvironmentMarker instructions for quick iteration/deletion. |
| 79 // It is populated during the first pass over the graph, controlled by |
| 80 // |collect_markers_|. |
| 81 ZoneList<HEnvironmentMarker*>* markers_; |
| 82 bool collect_markers_; |
| 83 |
| 84 // Keeps track of the last simulate seen, as well as the environment slots |
| 85 // for which a new live range has started since (so they must not be zapped |
| 86 // in that simulate when the end of another live range of theirs is found). |
| 87 HSimulate* last_simulate_; |
| 88 BitVector* went_live_since_last_simulate_; |
| 89 }; |
| 90 |
| 91 |
| 92 } } // namespace v8::internal |
| 93 |
| 94 #endif /* V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ */ |
OLD | NEW |