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1 // Copyright (c) 2022 The Khronos Group Inc.
2 // Copyright (c) 2022 LunarG Inc.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 //     http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 
16 #ifndef SOURCE_OPT_ELIMINATE_DEAD_OUTPUT_STORES_H_
17 #define SOURCE_OPT_ELIMINATE_DEAD_OUTPUT_STORES_H_
18 
19 #include <unordered_set>
20 
21 #include "source/opt/ir_context.h"
22 #include "source/opt/module.h"
23 #include "source/opt/pass.h"
24 
25 namespace spvtools {
26 namespace opt {
27 
28 // See optimizer.hpp for documentation.
29 class EliminateDeadOutputStoresPass : public Pass {
30  public:
EliminateDeadOutputStoresPass(std::unordered_set<uint32_t> * live_locs,std::unordered_set<uint32_t> * live_builtins)31   explicit EliminateDeadOutputStoresPass(
32       std::unordered_set<uint32_t>* live_locs,
33       std::unordered_set<uint32_t>* live_builtins)
34       : live_locs_(live_locs), live_builtins_(live_builtins) {}
35 
name()36   const char* name() const override { return "eliminate-dead-output-stores"; }
37   Status Process() override;
38 
39   // Return the mask of preserved Analyses.
GetPreservedAnalyses()40   IRContext::Analysis GetPreservedAnalyses() override {
41     return IRContext::kAnalysisDefUse |
42            IRContext::kAnalysisInstrToBlockMapping |
43            IRContext::kAnalysisCombinators | IRContext::kAnalysisCFG |
44            IRContext::kAnalysisDominatorAnalysis |
45            IRContext::kAnalysisLoopAnalysis | IRContext::kAnalysisNameMap |
46            IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;
47   }
48 
49  private:
50   // Initialize elimination
51   void InitializeElimination();
52 
53   // Do dead output store analysis
54   Status DoDeadOutputStoreElimination();
55 
56   // Kill all stores resulting from |ref|.
57   void KillAllStoresOfRef(Instruction* ref);
58 
59   // Kill all dead stores resulting from |user| of loc-based |var|.
60   void KillAllDeadStoresOfLocRef(Instruction* user, Instruction* var);
61 
62   // Kill all dead stores resulting from |user| of builtin |var|.
63   void KillAllDeadStoresOfBuiltinRef(Instruction* user, Instruction* var);
64 
65   // Return true if any of |count| locations starting at location |start| are
66   // live.
67   bool AnyLocsAreLive(uint32_t start, uint32_t count);
68 
69   // Return true if builtin |bi| is live.
70   bool IsLiveBuiltin(uint32_t bi);
71 
72   std::unordered_set<uint32_t>* live_locs_;
73   std::unordered_set<uint32_t>* live_builtins_;
74 
75   std::vector<Instruction*> kill_list_;
76 };
77 
78 }  // namespace opt
79 }  // namespace spvtools
80 
81 #endif  // SOURCE_OPT_ELIMINATE_DEAD_OUTPUT_STORES_H_
82