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// Copyright (c) 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SOURCE_OPT_REDUCE_LOAD_SIZE_H_
#define SOURCE_OPT_REDUCE_LOAD_SIZE_H_
#include <unordered_map>
#include "source/opt/ir_context.h"
#include "source/opt/module.h"
#include "source/opt/pass.h"
namespace spvtools {
namespace opt {
// See optimizer.hpp for documentation.
class ReduceLoadSize : public Pass {
public:
explicit ReduceLoadSize(double replacement_threshold)
: replacement_threshold_(replacement_threshold) {}
const char* name() const override { return "reduce-load-size"; }
Status Process() override;
// Return the mask of preserved Analyses.
IRContext::Analysis GetPreservedAnalyses() override {
return IRContext::kAnalysisDefUse |
IRContext::kAnalysisInstrToBlockMapping |
IRContext::kAnalysisCombinators | IRContext::kAnalysisCFG |
IRContext::kAnalysisDominatorAnalysis |
IRContext::kAnalysisLoopAnalysis | IRContext::kAnalysisNameMap |
IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;
}
private:
// Replaces |inst|, which must be an OpCompositeExtract instruction, with
// an OpAccessChain and a load if possible. This happens only if it is a load
// feeding |inst|. Returns true if the substitution happened. The position
// of the new instructions will be in the same place as the load feeding the
// extract.
bool ReplaceExtract(Instruction* inst);
// Returns true if the OpCompositeExtract instruction |inst| should be replace
// or not. This is determined by looking at the load that feeds |inst| if
// it is a load. |should_replace_cache_| is used to cache the results based
// on the load feeding |inst|.
bool ShouldReplaceExtract(Instruction* inst);
// Threshold to determine whether we have to replace the load or not. If the
// ratio of the used components of the load is less than the threshold, we
// replace the load.
double replacement_threshold_;
// Maps the result id of an OpLoad instruction to the result of whether or
// not the OpCompositeExtract that use the id should be replaced.
std::unordered_map<uint32_t, bool> should_replace_cache_;
};
} // namespace opt
} // namespace spvtools
#endif // SOURCE_OPT_REDUCE_LOAD_SIZE_H_