[PATCH] D28925: [ValueTracking] Clarify comments on CannotBeOrderedLessThanZero and SignBitMustBeZero.
Justin Lebar via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 19 16:43:11 PST 2017
jlebar created this revision.
Reviewers: hfinkel,efreidma,sanjoy
https://reviews.llvm.org/D28925
Files:
llvm/include/llvm/Analysis/ValueTracking.h
Index: llvm/include/llvm/Analysis/ValueTracking.h
===================================================================
--- llvm/include/llvm/Analysis/ValueTracking.h
+++ llvm/include/llvm/Analysis/ValueTracking.h
@@ -167,13 +167,25 @@
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,
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