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[ValueTracking] Clarify comments on CannotBeOrderedLessThanZero and SignBitMustBeZero. 

Reviewers: hfinkel, efriedma, sanjoy

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28926

llvm-svn: 292691
This commit is contained in:
Justin Lebar 2017-01-21 00:59:40 +00:00
parent 474a28563f
commit da57dbf8f7
1 changed files with 17 additions and 5 deletions
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22
llvm/include/llvm/Analysis/ValueTracking.h
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@ -167,13 +167,25 @@ template <typename T> class ArrayRef;
bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
unsigned Depth = 0);
/// Return true if we can prove that the specified FP value is either a NaN or
/// never less than 0.0.
/// If \p IncludeNeg0 is false, -0.0 is considered less than 0.0.
/// Return true if we can prove that the specified FP value is either NaN or
/// never less than -0.0.
///
/// NaN --> true
/// +0 --> true
/// -0 --> true
/// x > +0 --> true
/// x < -0 --> false
///
bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI);
/// \returns true if we can prove that the specified FP value has a 0 sign
/// bit.
/// Return true if we can prove that the specified FP value's sign bit is 0.
///
/// NaN --> true/false (depending on the NaN's sign bit)
/// +0 --> true
/// -0 --> false
/// x > +0 --> true
/// x < -0 --> false
///
bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI);
/// If the specified value can be set by repeating the same byte in memory,