SPIRV-Tools/source/reduce/merge_blocks_reduction_opportunity.h

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// Copyright (c) 2019 Google LLC
//
// 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_MERGE_BLOCKS_REDUCTION_OPPORTUNITY_H_
#define SOURCE_REDUCE_MERGE_BLOCKS_REDUCTION_OPPORTUNITY_H_
#include "source/opt/basic_block.h"
#include "source/opt/function.h"
#include "source/reduce/reduction_opportunity.h"
namespace spvtools {
namespace reduce {
// An opportunity to merge two blocks into one.
class MergeBlocksReductionOpportunity : public ReductionOpportunity {
public:
// Creates the opportunity to merge |block| with its successor, where |block|
// is inside |function|, and |context| is the enclosing IR context.
MergeBlocksReductionOpportunity(opt::IRContext* context,
opt::Function* function,
opt::BasicBlock* block);
bool PreconditionHolds() override;
protected:
void Apply() override;
private:
opt::IRContext* context_;
opt::Function* function_;
// Rather than holding on to the block that can be merged with its successor,
// we hold on to its successor. This is because the predecessor block might
// get merged with *its* predecessor, and so will no longer exist, while the
// successor will continue to exist until this opportunity gets applied.
opt::BasicBlock* successor_block_;
};
} // namespace reduce
} // namespace spvtools
#endif // SOURCE_REDUCE_MERGE_BLOCKS_REDUCTION_OPPORTUNITY_H_