1 //===- llvm/Analysis/ValueTracking.h - Walk computations --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains routines that help analyze properties that chains of
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ANALYSIS_VALUETRACKING_H
16 #define LLVM_ANALYSIS_VALUETRACKING_H
23 /// ComputeMaskedBits - Determine which of the bits specified in Mask are
24 /// known to be either zero or one and return them in the KnownZero/KnownOne
25 /// bit sets. This code only analyzes bits in Mask, in order to short-circuit
27 void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
28 APInt &KnownOne, TargetData *TD = 0,
31 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
32 /// this predicate to simplify operations downstream. Mask is known to be
33 /// zero for bits that V cannot have.
34 bool MaskedValueIsZero(Value *V, const APInt &Mask,
35 TargetData *TD = 0, unsigned Depth = 0);
38 /// ComputeNumSignBits - Return the number of times the sign bit of the
39 /// register is replicated into the other bits. We know that at least 1 bit
40 /// is always equal to the sign bit (itself), but other cases can give us
41 /// information. For example, immediately after an "ashr X, 2", we know that
42 /// the top 3 bits are all equal to each other, so we return 3.
44 /// 'Op' must have a scalar integer type.
46 unsigned ComputeNumSignBits(Value *Op, TargetData *TD = 0,
49 /// CannotBeNegativeZero - Return true if we can prove that the specified FP
50 /// value is never equal to -0.0.
52 bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);
53 } // end namespace llvm