llvm/llvm/include/llvm/Analysis/DemandedBits.h

//===- llvm/Analysis/DemandedBits.h - Determine demanded bits ---*- 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 pass implements a demanded bits analysis. A demanded bit is one that
// contributes to a result; bits that are not demanded can be either zero or
// one without affecting control or data flow. For example in this sequence:
//
//   %1 = add i32 %x, %y
//   %2 = trunc i32 %1 to i16
//
// Only the lowest 16 bits of %1 are demanded; the rest are removed by the
// trunc.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_DEMANDEDBITS_H
#define LLVM_ANALYSIS_DEMANDEDBITS_H

#include "llvm/ADT/APInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/IR/PassManager.h"

namespace llvm {

class AssumptionCache;
class DominatorTree;
class Function;
class Instruction;
struct KnownBits;
class raw_ostream;
class Use;
class Value;

class DemandedBits { … };

/// An analysis that produces \c DemandedBits for a function.
class DemandedBitsAnalysis : public AnalysisInfoMixin<DemandedBitsAnalysis> { … };

/// Printer pass for DemandedBits
class DemandedBitsPrinterPass : public PassInfoMixin<DemandedBitsPrinterPass> { … };

} // end namespace llvm

#endif // LLVM_ANALYSIS_DEMANDEDBITS_H