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//===- 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
namespace llvm {
class Value;
class Instruction;
class APInt;
class TargetData;
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
/// known to be either zero or one and return them in the KnownZero/KnownOne
/// bit sets. This code only analyzes bits in Mask, in order to short-circuit
/// processing.
void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
APInt &KnownOne, TargetData *TD = 0,
unsigned Depth = 0);
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
/// this predicate to simplify operations downstream. Mask is known to be
/// zero for bits that V cannot have.
bool MaskedValueIsZero(Value *V, const APInt &Mask,
TargetData *TD = 0, unsigned Depth = 0);
/// ComputeNumSignBits - Return the number of times the sign bit of the
/// register is replicated into the other bits. We know that at least 1 bit
/// is always equal to the sign bit (itself), but other cases can give us
/// information. For example, immediately after an "ashr X, 2", we know that
/// the top 3 bits are all equal to each other, so we return 3.
///
/// 'Op' must have a scalar integer type.
///
unsigned ComputeNumSignBits(Value *Op, TargetData *TD = 0,
unsigned Depth = 0);
/// CannotBeNegativeZero - Return true if we can prove that the specified FP
/// value is never equal to -0.0.
///
bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);
/// FindScalarValue - Given an aggregrate and an sequence of indices, see if the
/// scalar value indexed is already around as a register, for example if it were
/// inserted directly into the aggregrate.
///
/// If InsertBefore is not null, this function will duplicate (modified)
/// insertvalues when a part of a nested struct is extracted.
Value *FindInsertedValue(Value *V,
const unsigned *idx_begin,
const unsigned *idx_end,
Instruction *InsertBefore = 0);
} // end namespace llvm
#endif
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