1 // Copyright (c) 2017 The Khronos Group Inc. 2 // Copyright (c) 2017 Valve Corporation 3 // Copyright (c) 2017 LunarG Inc. 4 // 5 // Licensed under the Apache License, Version 2.0 (the "License"); 6 // you may not use this file except in compliance with the License. 7 // You may obtain a copy of the License at 8 // 9 // http://www.apache.org/licenses/LICENSE-2.0 10 // 11 // Unless required by applicable law or agreed to in writing, software 12 // distributed under the License is distributed on an "AS IS" BASIS, 13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 // See the License for the specific language governing permissions and 15 // limitations under the License. 16 17 #ifndef SOURCE_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_ 18 #define SOURCE_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_ 19 20 #include <algorithm> 21 #include <map> 22 #include <queue> 23 #include <string> 24 #include <unordered_map> 25 #include <unordered_set> 26 #include <utility> 27 #include <vector> 28 29 #include "source/opt/basic_block.h" 30 #include "source/opt/def_use_manager.h" 31 #include "source/opt/mem_pass.h" 32 #include "source/opt/module.h" 33 34 namespace spvtools { 35 namespace opt { 36 37 // See optimizer.hpp for documentation. 38 class LocalSingleStoreElimPass : public Pass { 39 using cbb_ptr = const BasicBlock*; 40 41 public: 42 LocalSingleStoreElimPass(); 43 name()44 const char* name() const override { return "eliminate-local-single-store"; } 45 Status Process() override; 46 GetPreservedAnalyses()47 IRContext::Analysis GetPreservedAnalyses() override { 48 return IRContext::kAnalysisDefUse | 49 IRContext::kAnalysisInstrToBlockMapping | 50 IRContext::kAnalysisConstants | IRContext::kAnalysisTypes; 51 } 52 53 private: 54 // Do "single-store" optimization of function variables defined only 55 // with a single non-access-chain store in |func|. Replace all their 56 // non-access-chain loads with the value that is stored and eliminate 57 // any resulting dead code. 58 bool LocalSingleStoreElim(Function* func); 59 60 // Initialize extensions allowlist 61 void InitExtensionAllowList(); 62 63 // Return true if all extensions in this module are allowed by this pass. 64 bool AllExtensionsSupported() const; 65 66 Pass::Status ProcessImpl(); 67 68 // If there is a single store to |var_inst|, and it covers the entire 69 // variable, then replace all of the loads of the entire variable that are 70 // dominated by the store by the value that was stored. Returns true if the 71 // module was changed. 72 bool ProcessVariable(Instruction* var_inst); 73 74 // Collects all of the uses of |var_inst| into |uses|. This looks through 75 // OpObjectCopy's that copy the address of the variable, and collects those 76 // uses as well. 77 void FindUses(const Instruction* var_inst, 78 std::vector<Instruction*>* uses) const; 79 80 // Returns a store to |var_inst| if 81 // - it is a store to the entire variable, 82 // - and there are no other instructions that may modify |var_inst|. 83 Instruction* FindSingleStoreAndCheckUses( 84 Instruction* var_inst, const std::vector<Instruction*>& users) const; 85 86 // Returns true if the address that results from |inst| may be used as a base 87 // address in a store instruction or may be used to compute the base address 88 // of a store instruction. 89 bool FeedsAStore(Instruction* inst) const; 90 91 // Replaces all of the loads in |uses| by the value stored in |store_inst|. 92 // The load instructions are then killed. |all_rewritten| is true iff all 93 // uses have been rewritten. 94 bool RewriteLoads(Instruction* store_inst, 95 const std::vector<Instruction*>& uses, bool* all_rewritten); 96 97 // Replaces DebugDeclares of |var_id| with DebugValues using the value 98 // assignment of |store_inst|. 99 bool RewriteDebugDeclares(Instruction* store_inst, uint32_t var_id); 100 101 // Extensions supported by this pass. 102 std::unordered_set<std::string> extensions_allowlist_; 103 }; 104 105 } // namespace opt 106 } // namespace spvtools 107 108 #endif // SOURCE_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_ 109