llvm/llvm/include/llvm/Analysis/IVDescriptors.h

//===- llvm/Analysis/IVDescriptors.h - IndVar Descriptors -------*- 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 file "describes" induction and recurrence variables.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_IVDESCRIPTORS_H
#define LLVM_ANALYSIS_IVDESCRIPTORS_H

#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/ValueHandle.h"

namespace llvm {

class AssumptionCache;
class DemandedBits;
class DominatorTree;
class Loop;
class PredicatedScalarEvolution;
class ScalarEvolution;
class SCEV;
class StoreInst;

/// These are the kinds of recurrences that we support.
enum class RecurKind { … };

/// The RecurrenceDescriptor is used to identify recurrences variables in a
/// loop. Reduction is a special case of recurrence that has uses of the
/// recurrence variable outside the loop. The method isReductionPHI identifies
/// reductions that are basic recurrences.
///
/// Basic recurrences are defined as the summation, product, OR, AND, XOR, min,
/// or max of a set of terms. For example: for(i=0; i<n; i++) { total +=
/// array[i]; } is a summation of array elements. Basic recurrences are a
/// special case of chains of recurrences (CR). See ScalarEvolution for CR
/// references.

/// This struct holds information about recurrence variables.
class RecurrenceDescriptor { … };

/// A struct for saving information about induction variables.
class InductionDescriptor { … };

} // end namespace llvm

#endif // LLVM_ANALYSIS_IVDESCRIPTORS_H