| // 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 |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef V8_HYDROGEN_GVN_H_ |
| #define V8_HYDROGEN_GVN_H_ |
| |
| #include "hydrogen.h" |
| #include "hydrogen-instructions.h" |
| #include "compiler.h" |
| #include "zone.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| // Simple sparse set with O(1) add, contains, and clear. |
| class SparseSet { |
| public: |
| SparseSet(Zone* zone, int capacity) |
| : capacity_(capacity), |
| length_(0), |
| dense_(zone->NewArray<int>(capacity)), |
| sparse_(zone->NewArray<int>(capacity)) { |
| #ifndef NVALGRIND |
| // Initialize the sparse array to make valgrind happy. |
| memset(sparse_, 0, sizeof(sparse_[0]) * capacity); |
| #endif |
| } |
| |
| bool Contains(int n) const { |
| ASSERT(0 <= n && n < capacity_); |
| int d = sparse_[n]; |
| return 0 <= d && d < length_ && dense_[d] == n; |
| } |
| |
| bool Add(int n) { |
| if (Contains(n)) return false; |
| dense_[length_] = n; |
| sparse_[n] = length_; |
| ++length_; |
| return true; |
| } |
| |
| void Clear() { length_ = 0; } |
| |
| private: |
| int capacity_; |
| int length_; |
| int* dense_; |
| int* sparse_; |
| |
| DISALLOW_COPY_AND_ASSIGN(SparseSet); |
| }; |
| |
| |
| // Perform common subexpression elimination and loop-invariant code motion. |
| class HGlobalValueNumberingPhase : public HPhase { |
| public: |
| explicit HGlobalValueNumberingPhase(HGraph* graph); |
| |
| void Run() { |
| Analyze(); |
| // Trigger a second analysis pass to further eliminate duplicate values |
| // that could only be discovered by removing side-effect-generating |
| // instructions during the first pass. |
| if (FLAG_smi_only_arrays && removed_side_effects_) { |
| Analyze(); |
| ASSERT(!removed_side_effects_); |
| } |
| } |
| |
| private: |
| void Analyze(); |
| GVNFlagSet CollectSideEffectsOnPathsToDominatedBlock( |
| HBasicBlock* dominator, |
| HBasicBlock* dominated); |
| void AnalyzeGraph(); |
| void ComputeBlockSideEffects(); |
| void LoopInvariantCodeMotion(); |
| void ProcessLoopBlock(HBasicBlock* block, |
| HBasicBlock* before_loop, |
| GVNFlagSet loop_kills, |
| GVNFlagSet* accumulated_first_time_depends, |
| GVNFlagSet* accumulated_first_time_changes); |
| bool AllowCodeMotion(); |
| bool ShouldMove(HInstruction* instr, HBasicBlock* loop_header); |
| |
| bool removed_side_effects_; |
| |
| // A map of block IDs to their side effects. |
| ZoneList<GVNFlagSet> block_side_effects_; |
| |
| // A map of loop header block IDs to their loop's side effects. |
| ZoneList<GVNFlagSet> loop_side_effects_; |
| |
| // Used when collecting side effects on paths from dominator to |
| // dominated. |
| SparseSet visited_on_paths_; |
| |
| DISALLOW_COPY_AND_ASSIGN(HGlobalValueNumberingPhase); |
| }; |
| |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_HYDROGEN_GVN_H_ |