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https://github.com/KhronosGroup/SPIRV-Tools
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54 lines
2.2 KiB
C
54 lines
2.2 KiB
C
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// 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 LIBSPIRV_OPT_LOCAL_REDUNDANCY_ELIMINATION_H_
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#define LIBSPIRV_OPT_LOCAL_REDUNDANCY_ELIMINATION_H_
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#include "ir_context.h"
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#include "pass.h"
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#include "value_number_table.h"
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namespace spvtools {
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namespace opt {
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// This pass implements local redundancy elimination. Its goal is to reduce the
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// number of times the same value is computed. It works on each basic block
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// independently, ie local. For each instruction in a basic block, it gets the
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// value number for the result id, |id|, of the instruction. If that value
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// number has already been computed in the basic block, it tries to replace the
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// uses of |id| by the id that already contains the same value. Then the
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// current instruction is deleted.
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class LocalRedundancyEliminationPass : public Pass {
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public:
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const char* name() const override { return "local-redundancy-elimination"; }
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Status Process(ir::IRContext*) override;
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private:
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// Deletes instructions in |block| whose value is in |vnTable| or is computed
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// earlier in |block|. The values computed in |block| are added to |vnTable|.
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// |value_to_ids| is a map from a value number to the result ids known to
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// contain those values. The definition of the ids in value_to_ids must
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// dominate |block|. One value needs to map to multiple ids because the ids
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// may contain the same value, but have different decorations. Returns true
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// if the module is changed.
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bool EliminateRedundanciesInBB(
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ir::BasicBlock* block, ValueNumberTable* vnTable,
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std::vector<std::vector<uint32_t>>* value_to_ids);
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};
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} // namespace opt
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} // namespace spvtools
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#endif // LIBSPIRV_OPT_LOCAL_REDUNDANCY_ELIMINATION_H_
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