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// Copyright (c) 2017 The Khronos Group Inc.
// Copyright (c) 2017 Valve Corporation
// Copyright (c) 2017 LunarG Inc.
//
// 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 LIBSPIRV_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_
#define LIBSPIRV_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_
#include <algorithm>
#include <map>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include "basic_block.h"
#include "def_use_manager.h"
#include "mem_pass.h"
#include "module.h"
namespace spvtools {
namespace opt {
// See optimizer.hpp for documentation.
class LocalSingleStoreElimPass : public Pass {
using cbb_ptr = const BasicBlock*;
public:
LocalSingleStoreElimPass();
const char* name() const override { return "eliminate-local-single-store"; }
Status Process() override;
IRContext::Analysis GetPreservedAnalyses() override {
return IRContext::kAnalysisDefUse | IRContext::kAnalysisInstrToBlockMapping;
}
private:
// Do "single-store" optimization of function variables defined only
// with a single non-access-chain store in |func|. Replace all their
// non-access-chain loads with the value that is stored and eliminate
// any resulting dead code.
bool LocalSingleStoreElim(Function* func);
// Initialize extensions whitelist
void InitExtensionWhiteList();
// Return true if all extensions in this module are allowed by this pass.
bool AllExtensionsSupported() const;
Pass::Status ProcessImpl();
// If there is a single store to |var_inst|, and it covers the entire
// variable, then replace all of the loads of the entire variable that are
// dominated by the store by the value that was stored. Returns true if the
// module was changed.
bool ProcessVariable(Instruction* var_inst);
// Collects all of the uses of |var_inst| into |uses|. This looks through
// OpObjectCopy's that copy the address of the variable, and collects those
// uses as well.
void FindUses(const Instruction* var_inst,
std::vector<Instruction*>* uses) const;
// Returns a store to |var_inst| if
// - it is a store to the entire variable,
// - and there are no other instructions that may modify |var_inst|.
Instruction* FindSingleStoreAndCheckUses(
Instruction* var_inst, const std::vector<Instruction*>& users) const;
// Returns true if the address that results from |inst| may be used as a base
// address in a store instruction or may be used to compute the base address
// of a store instruction.
bool FeedsAStore(Instruction* inst) const;
// Replaces all of the loads in |uses| by the value stored in |store_inst|.
// The load instructions are then killed.
bool RewriteLoads(Instruction* store_inst,
const std::vector<Instruction*>& uses);
// Extensions supported by this pass.
std::unordered_set<std::string> extensions_whitelist_;
};
} // namespace opt
} // namespace spvtools
#endif // LIBSPIRV_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_
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