llvm/llvm/include/llvm/Transforms/Utils/LoopConstrainer.h

//===- LoopConstrainer.h ----------------------------------------*- 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
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_TRANSFORMS_UTILS_LOOP_CONSTRAINER_H
#define LLVM_TRANSFORMS_UTILS_LOOP_CONSTRAINER_H

#include "llvm/Support/Casting.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <optional>

namespace llvm {

class BasicBlock;
class BranchInst;
class DominatorTree;
class IntegerType;
class Loop;
class LoopInfo;
class PHINode;
class ScalarEvolution;
class SCEV;
class Value;

// Keeps track of the structure of a loop.  This is similar to llvm::Loop,
// except that it is more lightweight and can track the state of a loop through
// changing and potentially invalid IR.  This structure also formalizes the
// kinds of loops we can deal with -- ones that have a single latch that is also
// an exiting block *and* have a canonical induction variable.
struct LoopStructure { … };

/// This class is used to constrain loops to run within a given iteration space.
/// The algorithm this class implements is given a Loop and a range [Begin,
/// End).  The algorithm then tries to break out a "main loop" out of the loop
/// it is given in a way that the "main loop" runs with the induction variable
/// in a subset of [Begin, End).  The algorithm emits appropriate pre and post
/// loops to run any remaining iterations.  The pre loop runs any iterations in
/// which the induction variable is < Begin, and the post loop runs any
/// iterations in which the induction variable is >= End.
class LoopConstrainer { … };
} // namespace llvm

#endif // LLVM_TRANSFORMS_UTILS_LOOP_CONSTRAINER_H