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https://github.com/KhronosGroup/SPIRV-Tools
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efe12ff5a1
Originally the passes that extended from MemPass were those that are of the def-use manager. I am assuming they would be able to preserve it because of that. Added a check to verify consistency of the IRContext. The IRContext relies on the pass to tell it if something is invalidated. It is possible that the pass lied. To help identify those situations, we will check if the valid analyses are correct after each pass. This will be enabled by default for the debug build, and disabled in the production build. It can be disabled in the debug build by adding "-DSPIRV_CHECK_CONTEXT=OFF" to the cmake command.
56 lines
1.8 KiB
C++
56 lines
1.8 KiB
C++
// Copyright (c) 2017 Google 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 SPIRV_TOOLS_DEAD_VARIABLE_ELIMINATION_H
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#define SPIRV_TOOLS_DEAD_VARIABLE_ELIMINATION_H
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#include <climits>
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#include <unordered_map>
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#include "decoration_manager.h"
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#include "mem_pass.h"
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namespace spvtools {
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namespace opt {
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class DeadVariableElimination : public MemPass {
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public:
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const char* name() const override { return "dead-variable-elimination"; }
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Status Process(ir::IRContext* c) override;
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ir::IRContext::Analysis GetPreservedAnalyses() override {
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return ir::IRContext::kAnalysisDefUse;
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}
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private:
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// Deletes the OpVariable instruction who result id is |result_id|.
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void DeleteVariable(uint32_t result_id);
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// Keeps track of the number of references of an id. Once that value is 0, it
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// is safe to remove the corresponding instruction.
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//
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// Note that the special value kMustKeep is used to indicate that the
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// instruction cannot be deleted for reasons other that is being explicitly
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// referenced.
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std::unordered_map<uint32_t, size_t> reference_count_;
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// Special value used to indicate that an id cannot be safely deleted.
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enum { kMustKeep = INT_MAX };
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};
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} // namespace opt
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} // namespace spvtools
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#endif // SPIRV_TOOLS_DEAD_VARIABLE_ELIMINATION_H
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