chromium/third_party/spirv-tools/src/source/opt/copy_prop_arrays.h

// Copyright (c) 2018 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_OPT_COPY_PROP_ARRAYS_H_
#define SOURCE_OPT_COPY_PROP_ARRAYS_H_

#include <memory>
#include <vector>

#include "source/opt/mem_pass.h"

namespace spvtools {
namespace opt {

// This pass implements a simple array copy propagation.  It does not do a full
// array data flow.  It looks for simple cases that meet the following
// conditions:
//
// 1) The source must never be stored to.
// 2) The target must be stored to exactly once.
// 3) The store to the target must be a store to the entire array, and be a
// copy of the entire source.
// 4) All loads of the target must be dominated by the store.
//
// The hard part is keeping all of the types correct.  We do not want to
// have to do too large a search to update everything, which may not be
// possible, so we give up if we see any instruction that might be hard to
// update.

class CopyPropagateArrays : public MemPass { … };

}  // namespace opt
}  // namespace spvtools

#endif  // SOURCE_OPT_COPY_PROP_ARRAYS_H_