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https://github.com/KhronosGroup/SPIRV-Tools
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e4c7d8e748
Create a new optimization pass, strength reduction, which will replace integer multiplication by a constant power of 2 with an equivalent bit shift. More changes could be added later. - Does not duplicate constants - Adds vector |Concat| utility function to a common test header.
76 lines
2.5 KiB
C++
76 lines
2.5 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 LIBSPIRV_OPT_STRENGTH_REDUCTION_PASS_H_
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#define LIBSPIRV_OPT_STRENGTH_REDUCTION_PASS_H_
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#include "def_use_manager.h"
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#include "module.h"
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#include "pass.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 StrengthReductionPass : public Pass {
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public:
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const char* name() const override { return "strength-reduction"; }
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Status Process(ir::Module*) override;
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private:
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// Replaces multiple by power of 2 with an equivalent bit shift.
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// Returns true if something changed.
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bool ReplaceMultiplyByPowerOf2(ir::BasicBlock::iterator*);
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// Scan the types and constants in the module looking for the the integer types that we are
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// interested in. The shift operation needs a small unsigned integer. We need to find
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// them or create them. We do not want duplicates.
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void FindIntTypesAndConstants();
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// Get the id for the given constant. If it does not exist, it will be
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// created. The parameter must be between 0 and 32 inclusive.
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uint32_t GetConstantId(uint32_t);
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// Replaces certain instructions in function bodies with presumably cheaper
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// ones. Returns true if something changed.
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bool ScanFunctions();
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// Will create the type for an unsigned 32-bit integer and return the id.
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// This functions assumes one does not already exist.
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uint32_t CreateUint32Type();
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// Def-Uses for the module we are processing
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std::unique_ptr<analysis::DefUseManager> def_use_mgr_;
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// Type ids for the types of interest, or 0 if they do not exist.
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uint32_t int32_type_id_;
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uint32_t uint32_type_id_;
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// constant_ids[i] is the id for unsigned integer constant i.
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// We set the limit at 32 because a bit shift of a 32-bit integer does not
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// need a value larger than 32.
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uint32_t constant_ids_[33];
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// Next unused ID
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uint32_t next_id_;
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// The module that the pass is being applied to.
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ir::Module* module_;
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};
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} // namespace opt
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} // namespace spvtools
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#endif // LIBSPIRV_OPT_STRENGTH_REDUCTION_PASS_H_
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