1 // Copyright (c) 2018 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #ifndef SOURCE_OPT_REDUCE_LOAD_SIZE_H_
16 #define SOURCE_OPT_REDUCE_LOAD_SIZE_H_
17 
18 #include <unordered_map>
19 
20 #include "source/opt/ir_context.h"
21 #include "source/opt/module.h"
22 #include "source/opt/pass.h"
23 
24 namespace spvtools {
25 namespace opt {
26 
27 // See optimizer.hpp for documentation.
28 class ReduceLoadSize : public Pass {
29  public:
name()30   const char* name() const override { return "reduce-load-size"; }
31   Status Process() override;
32 
33   // Return the mask of preserved Analyses.
GetPreservedAnalyses()34   IRContext::Analysis GetPreservedAnalyses() override {
35     return IRContext::kAnalysisDefUse |
36            IRContext::kAnalysisInstrToBlockMapping |
37            IRContext::kAnalysisCombinators | IRContext::kAnalysisCFG |
38            IRContext::kAnalysisDominatorAnalysis |
39            IRContext::kAnalysisLoopAnalysis | IRContext::kAnalysisNameMap |
40            IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;
41   }
42 
43  private:
44   // Replaces |inst|, which must be an OpCompositeExtract instruction, with
45   // an OpAccessChain and a load if possible.  This happens only if it is a load
46   // feeding |inst|.  Returns true if the substitution happened.  The position
47   // of the new instructions will be in the same place as the load feeding the
48   // extract.
49   bool ReplaceExtract(Instruction* inst);
50 
51   // Returns true if the OpCompositeExtract instruction |inst| should be replace
52   // or not.  This is determined by looking at the load that feeds |inst| if
53   // it is a load.  |should_replace_cache_| is used to cache the results based
54   // on the load feeding |inst|.
55   bool ShouldReplaceExtract(Instruction* inst);
56 
57   // Maps the result id of an OpLoad instruction to the result of whether or
58   // not the OpCompositeExtract that use the id should be replaced.
59   std::unordered_map<uint32_t, bool> should_replace_cache_;
60 };
61 
62 }  // namespace opt
63 }  // namespace spvtools
64 
65 #endif  // SOURCE_OPT_REDUCE_LOAD_SIZE_H_
66