| // Copyright (c) 2017 Google 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 SPIRV_TOOLS_DEAD_VARIABLE_ELIMINATION_H |
| #define SPIRV_TOOLS_DEAD_VARIABLE_ELIMINATION_H |
| |
| #include <climits> |
| #include <unordered_map> |
| |
| #include "decoration_manager.h" |
| #include "mem_pass.h" |
| |
| namespace spvtools { |
| namespace opt { |
| |
| class DeadVariableElimination : public MemPass { |
| public: |
| const char* name() const override { return "dead-variable-elimination"; } |
| Status Process(ir::IRContext* c) override; |
| |
| ir::IRContext::Analysis GetPreservedAnalyses() override { |
| return ir::IRContext::kAnalysisDefUse; |
| } |
| |
| private: |
| // Deletes the OpVariable instruction who result id is |result_id|. |
| void DeleteVariable(uint32_t result_id); |
| |
| // Keeps track of the number of references of an id. Once that value is 0, it |
| // is safe to remove the corresponding instruction. |
| // |
| // Note that the special value kMustKeep is used to indicate that the |
| // instruction cannot be deleted for reasons other that is being explicitly |
| // referenced. |
| std::unordered_map<uint32_t, size_t> reference_count_; |
| |
| // Special value used to indicate that an id cannot be safely deleted. |
| enum { kMustKeep = INT_MAX }; |
| }; |
| |
| } // namespace opt |
| } // namespace spvtools |
| |
| #endif // SPIRV_TOOLS_DEAD_VARIABLE_ELIMINATION_H |