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https://github.com/KhronosGroup/SPIRV-Tools
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This pass basically follows the same process as ssa-rewrite: it adds a DebugValue after each Store and removes the DebugDeclare or DebugValue Deref. It only does this if all instructions that are dependent on the Store are Loads and are replaced.
105 lines
3.7 KiB
C++
105 lines
3.7 KiB
C++
// Copyright (c) 2017 The Khronos Group Inc.
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// Copyright (c) 2017 Valve Corporation
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// Copyright (c) 2017 LunarG Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef SOURCE_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_
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#define SOURCE_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_
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#include <algorithm>
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#include <map>
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#include <queue>
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#include <string>
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#include <unordered_map>
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#include <unordered_set>
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#include <utility>
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#include <vector>
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#include "source/opt/basic_block.h"
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#include "source/opt/def_use_manager.h"
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#include "source/opt/mem_pass.h"
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#include "source/opt/module.h"
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namespace spvtools {
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namespace opt {
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// See optimizer.hpp for documentation.
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class LocalSingleStoreElimPass : public Pass {
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using cbb_ptr = const BasicBlock*;
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public:
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LocalSingleStoreElimPass();
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const char* name() const override { return "eliminate-local-single-store"; }
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Status Process() override;
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IRContext::Analysis GetPreservedAnalyses() override {
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return IRContext::kAnalysisDefUse |
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IRContext::kAnalysisInstrToBlockMapping |
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IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;
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}
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private:
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// Do "single-store" optimization of function variables defined only
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// with a single non-access-chain store in |func|. Replace all their
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// non-access-chain loads with the value that is stored and eliminate
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// any resulting dead code.
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bool LocalSingleStoreElim(Function* func);
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// Initialize extensions allowlist
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void InitExtensionAllowList();
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// Return true if all extensions in this module are allowed by this pass.
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bool AllExtensionsSupported() const;
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Pass::Status ProcessImpl();
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// If there is a single store to |var_inst|, and it covers the entire
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// variable, then replace all of the loads of the entire variable that are
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// dominated by the store by the value that was stored. Returns true if the
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// module was changed.
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bool ProcessVariable(Instruction* var_inst);
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// Collects all of the uses of |var_inst| into |uses|. This looks through
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// OpObjectCopy's that copy the address of the variable, and collects those
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// uses as well.
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void FindUses(const Instruction* var_inst,
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std::vector<Instruction*>* uses) const;
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// Returns a store to |var_inst| if
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// - it is a store to the entire variable,
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// - and there are no other instructions that may modify |var_inst|.
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Instruction* FindSingleStoreAndCheckUses(
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Instruction* var_inst, const std::vector<Instruction*>& users) const;
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// Returns true if the address that results from |inst| may be used as a base
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// address in a store instruction or may be used to compute the base address
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// of a store instruction.
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bool FeedsAStore(Instruction* inst) const;
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// Replaces all of the loads in |uses| by the value stored in |store_inst|.
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// The load instructions are then killed. |all_rewritten| is true iff all
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// uses have been rewritten.
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bool RewriteLoads(Instruction* store_inst,
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const std::vector<Instruction*>& uses, bool* all_rewritten);
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// Extensions supported by this pass.
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std::unordered_set<std::string> extensions_allowlist_;
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};
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} // namespace opt
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} // namespace spvtools
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#endif // SOURCE_OPT_LOCAL_SINGLE_STORE_ELIM_PASS_H_
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