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// Copyright 2021 The Tint Authors.
//
// 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 SRC_TRANSFORM_FOLD_TRIVIAL_SINGLE_USE_LETS_H_
#define SRC_TRANSFORM_FOLD_TRIVIAL_SINGLE_USE_LETS_H_
#include <string>
#include <unordered_map>
#include "src/transform/transform.h"
namespace tint {
namespace transform {
/// FoldTrivialSingleUseLets is an optimizer for folding away trivial `let`
/// statements into their single place of use. This transform is intended to
/// clean up the SSA `let`s produced by the SPIR-V reader.
/// `let`s can only be folded if:
/// * There is a single usage of the `let` value.
/// * The `let` is constructed with a ScalarConstructorExpression, or with an
/// IdentifierExpression.
/// * There are only other foldable `let`s between the `let` declaration and its
/// single usage.
/// These rules prevent any hoisting of the let that may affect execution
/// behaviour.
class FoldTrivialSingleUseLets
: public Castable<FoldTrivialSingleUseLets, Transform> {
public:
/// Constructor
FoldTrivialSingleUseLets();
/// Destructor
~FoldTrivialSingleUseLets() override;
protected:
/// Runs the transform using the CloneContext built for transforming a
/// program. Run() is responsible for calling Clone() on the CloneContext.
/// @param ctx the CloneContext primed with the input program and
/// ProgramBuilder
/// @param inputs optional extra transform-specific input data
/// @param outputs optional extra transform-specific output data
void Run(CloneContext& ctx,
const DataMap& inputs,
DataMap& outputs) const override;
};
} // namespace transform
} // namespace tint
#endif // SRC_TRANSFORM_FOLD_TRIVIAL_SINGLE_USE_LETS_H_