SPIRV-Tools/source/reduce/operand_to_dominating_id_reduction_pass.h
Paul Thomson 71aa48f91d spirv-reduce: add OperandToUndefReductionPass (#2200)
* Add OperandToUndefReductionPass.

Fixes #2115.

Also added some tests that are similar to those in OperandToConstantReductionPassTest.

In addition, refactor FindOrCreateGlobalUndef into reduction_util.cpp. Fixes #2184.

Removed many documentation comments that were identical or very similar to the overridden function's documentation comment.
2018-12-19 13:25:56 +00:00

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// Copyright (c) 2018 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 SOURCE_REDUCE_OPERAND_TO_DOMINATING_ID_REDUCTION_PASS_H_
#define SOURCE_REDUCE_OPERAND_TO_DOMINATING_ID_REDUCTION_PASS_H_
#include "reduction_pass.h"
namespace spvtools {
namespace reduce {
// A reduction pass that aims to bring to SPIR-V (and generalize) the idea from
// human-readable languages of e.g. replacing an expression with one of its
// arguments, (x + y) -> x, or with a reference to an identifier that was
// assigned to higher up in the program. The generalization of this is to
// replace an id with a different id of the same type defined in some
// dominating instruction.
//
// If id x is defined and then used several times, changing each use of x to
// some dominating definition may eventually allow the statement defining x
// to be eliminated by another pass.
class OperandToDominatingIdReductionPass : public ReductionPass {
public:
// Creates the reduction pass in the context of the given target environment
// |target_env|
explicit OperandToDominatingIdReductionPass(const spv_target_env target_env)
: ReductionPass(target_env) {}
~OperandToDominatingIdReductionPass() override = default;
std::string GetName() const final;
protected:
std::vector<std::unique_ptr<ReductionOpportunity>> GetAvailableOpportunities(
opt::IRContext* context) const final;
private:
void GetOpportunitiesForDominatingInst(
std::vector<std::unique_ptr<ReductionOpportunity>>* opportunities,
opt::Instruction* dominating_instruction,
opt::Function::iterator candidate_dominator_block,
opt::Function* function, opt::IRContext* context) const;
};
} // namespace reduce
} // namespace spvtools
#endif // SOURCE_REDUCE_OPERAND_TO_DOMINATING_ID_REDUCTION_PASS_H_