llvm/mlir/include/mlir/Transforms/CFGToSCF.h

//===- CFGToSCF.h - Control Flow Graph to Structured Control Flow *- C++ -*===//
//
// Part of the LLVM 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 header file defines a generic `transformCFGToSCF` function that can be
// used to lift any dialect operations implementing control flow graph
// operations to any dialect implementing structured control flow operations.
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_TRANSFORMS_CFGTOSCF_H
#define MLIR_TRANSFORMS_CFGTOSCF_H

#include "mlir/IR/Builders.h"
#include "mlir/IR/Dominance.h"
#include "mlir/IR/Operation.h"

namespace mlir {

/// Interface that should be implemented by any caller of `transformCFGToSCF`.
/// The transformation requires the caller to 1) create switch-like control
/// flow operations for intermediate transformations and 2) to create
/// the desired structured control flow ops.
class CFGToSCFInterface { … };

/// Transformation lifting any dialect implementing control flow graph
/// operations to a dialect implementing structured control flow operations.
/// `region` is the region that should be transformed.
/// The implementation of `interface` is responsible for the conversion of the
/// control flow operations to the structured control flow operations.
///
/// If the region contains only a single kind of return-like operation, all
/// control flow graph operations will be converted successfully.
/// Otherwise a single control flow graph operation branching to one block
/// per return-like operation kind remains.
///
/// The transformation currently requires that all control flow graph operations
/// have no side effects, implement the BranchOpInterface and does not have any
/// operation produced successor operands.
/// Returns failure if any of the preconditions are violated or if any of the
/// methods of `interface` failed. The IR is left in an unspecified state.
///
/// Otherwise, returns true or false if any changes to the IR have been made.
FailureOr<bool> transformCFGToSCF(Region &region, CFGToSCFInterface &interface,
                                  DominanceInfo &dominanceInfo);

} // namespace mlir

#endif // MLIR_TRANSFORMS_CFGTOSCF_H