Liveness.h

Go to the documentation of this file.

//===- Liveness.h - Liveness analysis for MLIR ------------------*- C++ -*-===//
//
// Part of the MLIR Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains an analysis for computing liveness information from a
// given top-level operation. The current version of the analysis uses a
// traditional algorithm to resolve detailed live-range information about all
// values within the specified regions. It is also possible to query liveness
// information on block level.
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_ANALYSIS_LIVENESS_H
#define MLIR_ANALYSIS_LIVENESS_H

#include <vector>

#include "mlir/Support/LLVM.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"

namespace mlir {

class Block;
class LivenessBlockInfo;
class Operation;
class Region;
class Value;

class Liveness {
public:
  using OperationListT = std::vector<Operation *>;
  using BlockMapT = DenseMap<Block *, LivenessBlockInfo>;
  using ValueSetT = SmallPtrSet<Value, 16>;

public:
  Liveness(Operation *op);

  Operation *getOperation() const { return operation; }

  OperationListT resolveLiveness(Value value) const;

  const LivenessBlockInfo *getLiveness(Block *block) const;

  const ValueSetT &getLiveIn(Block *block) const;

  const ValueSetT &getLiveOut(Block *block) const;

  bool isLastUse(Value value, Operation *operation) const;

  void dump() const;

  void print(raw_ostream &os) const;

private:
  void build(MutableArrayRef<Region> regions);

private:
  Operation *operation;

  BlockMapT blockMapping;
};

class LivenessBlockInfo {
public:
  using ValueSetT = Liveness::ValueSetT;

public:
  Block *getBlock() const { return block; }

  const ValueSetT &in() const { return inValues; }

  const ValueSetT &out() const { return outValues; }

  bool isLiveIn(Value value) const;

  bool isLiveOut(Value value) const;

  Operation *getStartOperation(Value value) const;

  Operation *getEndOperation(Value value, Operation *startOperation) const;

private:
  Block *block;

  ValueSetT inValues;

  ValueSetT outValues;

  friend class Liveness;
};

} // end namespace mlir

#endif // MLIR_ANALYSIS_LIVENESS_H