ValueTracking.h

//===- llvm/Analysis/ValueTracking.h - Walk computations --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains routines that help analyze properties that chains of
// computations have.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_VALUETRACKING_H
#define LLVM_ANALYSIS_VALUETRACKING_H

#include "llvm/System/DataTypes.h"
#include <string>

namespace llvm {
  template <typename T> class SmallVectorImpl;
  class Value;
  class Instruction;
  class APInt;
  class TargetData;
  
  void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
                         APInt &KnownOne, const TargetData *TD = 0,
                         unsigned Depth = 0);
  
  bool MaskedValueIsZero(Value *V, const APInt &Mask, 
                         const TargetData *TD = 0, unsigned Depth = 0);

  
  unsigned ComputeNumSignBits(Value *Op, const TargetData *TD = 0,
                              unsigned Depth = 0);

  bool ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
                       bool LookThroughSExt = false,
                       unsigned Depth = 0);

  bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);

  const Value *DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
                 SmallVectorImpl<std::pair<const Value*, int64_t> > &VarIndices,
                                      const TargetData *TD);
    
  
  
  Value *FindInsertedValue(Value *V,
                           const unsigned *idx_begin,
                           const unsigned *idx_end,
                           Instruction *InsertBefore = 0);

  inline Value *FindInsertedValue(Value *V, const unsigned Idx,
                                  Instruction *InsertBefore = 0) {
    const unsigned Idxs[1] = { Idx };
    return FindInsertedValue(V, &Idxs[0], &Idxs[1], InsertBefore);
  }
  
  bool GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset = 0,
                             bool StopAtNul = true);
                        
  uint64_t GetStringLength(Value *V);
} // end namespace llvm

#endif

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