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

// Copyright (c) 2017 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_OPT_VALUE_NUMBER_TABLE_H_
#define SOURCE_OPT_VALUE_NUMBER_TABLE_H_

#include <cstdint>
#include <unordered_map>

#include "source/opt/instruction.h"

namespace spvtools {
namespace opt {

class IRContext;

// Returns true if the two instructions compute the same value.  Used by the
// value number table to compare two instructions.
class ComputeSameValue { … };

// The hash function used in the value number table.
class ValueTableHash { … };

// This class implements the value number analysis.  It is using a hash-based
// approach to value numbering.  It is essentially doing dominator-tree value
// numbering described in
//
//   Preston Briggs, Keith D. Cooper, and L. Taylor Simpson. 1997. Value
//   numbering. Softw. Pract. Exper. 27, 6 (June 1997), 701-724.
//   https://www.cs.rice.edu/~keith/Promo/CRPC-TR94517.pdf.gz
//
// The main difference is that because we do not perform redundancy elimination
// as we build the value number table, we do not have to deal with cleaning up
// the scope.
class ValueNumberTable { … };

}  // namespace opt
}  // namespace spvtools

#endif  // SOURCE_OPT_VALUE_NUMBER_TABLE_H_