mirror of
https://github.com/KhronosGroup/SPIRV-Tools
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161 lines
6.7 KiB
C++
161 lines
6.7 KiB
C++
// Copyright (c) 2018 Google LLC.
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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_VECTOR_DCE_H_
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#define SOURCE_OPT_VECTOR_DCE_H_
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#include <unordered_map>
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#include <vector>
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#include "source/opt/mem_pass.h"
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#include "source/util/bit_vector.h"
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namespace spvtools {
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namespace opt {
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class VectorDCE : public MemPass {
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private:
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using LiveComponentMap = std::unordered_map<uint32_t, utils::BitVector>;
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// According to the SPEC the maximum size for a vector is 16. See the data
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// rules in the universal validation rules (section 2.16.1).
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enum { kMaxVectorSize = 16 };
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struct WorkListItem {
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WorkListItem() : instruction(nullptr), components(kMaxVectorSize) {}
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Instruction* instruction;
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utils::BitVector components;
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};
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public:
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VectorDCE() : all_components_live_(kMaxVectorSize) {
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for (uint32_t i = 0; i < kMaxVectorSize; i++) {
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all_components_live_.Set(i);
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}
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}
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const char* name() const override { return "vector-dce"; }
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Status Process() override;
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IRContext::Analysis GetPreservedAnalyses() override {
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return IRContext::kAnalysisDefUse | IRContext::kAnalysisCFG |
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IRContext::kAnalysisInstrToBlockMapping |
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IRContext::kAnalysisLoopAnalysis | IRContext::kAnalysisDecorations |
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IRContext::kAnalysisDominatorAnalysis | IRContext::kAnalysisNameMap |
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IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;
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}
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private:
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// Runs the vector dce pass on |function|. Returns true if |function| was
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// modified.
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bool VectorDCEFunction(Function* function);
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// Identifies the live components of the vectors that are results of
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// instructions in |function|. The results are stored in |live_components|.
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void FindLiveComponents(Function* function,
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LiveComponentMap* live_components);
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// Rewrites instructions in |function| that are dead or partially dead. If an
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// instruction does not have an entry in |live_components|, then it is not
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// changed. Returns true if |function| was modified.
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bool RewriteInstructions(Function* function,
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const LiveComponentMap& live_components);
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// Makes all DebugValue instructions that use |composite| for their values as
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// dead instructions by putting them into |dead_dbg_value|.
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void MarkDebugValueUsesAsDead(Instruction* composite,
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std::vector<Instruction*>* dead_dbg_value);
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// Rewrites the OpCompositeInsert instruction |current_inst| to avoid
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// unnecessary computes given that the only components of the result that are
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// live are |live_components|.
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//
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// If the value being inserted is not live, then the result of |current_inst|
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// is replaced by the composite input to |current_inst|.
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//
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// If the composite input to |current_inst| is not live, then it is replaced
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// by and OpUndef in |current_inst|.
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bool RewriteInsertInstruction(Instruction* current_inst,
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const utils::BitVector& live_components,
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std::vector<Instruction*>* dead_dbg_value);
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// Returns true if the result of |inst| is a vector or a scalar.
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bool HasVectorOrScalarResult(const Instruction* inst) const;
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// Returns true if the result of |inst| is a vector.
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bool HasVectorResult(const Instruction* inst) const;
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// Returns true if the result of |inst| is a scalar.
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bool HasScalarResult(const Instruction* inst) const;
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// Returns the number of elements in the vector type with id |type_id|.
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uint32_t GetVectorComponentCount(uint32_t type_id);
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// Adds |work_item| to |work_list| if it is not already live according to
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// |live_components|. |live_components| is updated to indicate that
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// |work_item| is now live.
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void AddItemToWorkListIfNeeded(WorkListItem work_item,
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LiveComponentMap* live_components,
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std::vector<WorkListItem>* work_list);
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// Marks the components |live_elements| of the uses in |current_inst| as live
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// according to |live_components|. If they were not live before, then they are
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// added to |work_list|.
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void MarkUsesAsLive(Instruction* current_inst,
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const utils::BitVector& live_elements,
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LiveComponentMap* live_components,
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std::vector<WorkListItem>* work_list);
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// Marks the uses in the OpVectorShuffle instruction in |current_item| as live
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// based on the live components in |current_item|. If anything becomes live
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// they are added to |work_list| and |live_components| is updated
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// accordingly.
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void MarkVectorShuffleUsesAsLive(const WorkListItem& current_item,
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VectorDCE::LiveComponentMap* live_components,
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std::vector<WorkListItem>* work_list);
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// Marks the uses in the OpCompositeInsert instruction in |current_item| as
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// live based on the live components in |current_item|. If anything becomes
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// live they are added to |work_list| and |live_components| is updated
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// accordingly.
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void MarkInsertUsesAsLive(const WorkListItem& current_item,
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LiveComponentMap* live_components,
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std::vector<WorkListItem>* work_list);
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// Marks the uses in the OpCompositeExtract instruction |current_inst| as
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// live. If anything becomes live they are added to |work_list| and
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// |live_components| is updated accordingly.
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void MarkExtractUseAsLive(const Instruction* current_inst,
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const utils::BitVector& live_elements,
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LiveComponentMap* live_components,
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std::vector<WorkListItem>* work_list);
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// Marks the uses in the OpCompositeConstruct instruction |current_inst| as
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// live. If anything becomes live they are added to |work_list| and
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// |live_components| is updated accordingly.
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void MarkCompositeContructUsesAsLive(WorkListItem work_item,
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LiveComponentMap* live_components,
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std::vector<WorkListItem>* work_list);
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// A BitVector that can always be used to say that all components of a vector
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// are live.
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utils::BitVector all_components_live_;
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};
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} // namespace opt
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} // namespace spvtools
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#endif // SOURCE_OPT_VECTOR_DCE_H_
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