[PATCH] D148599: ValueTrackng: Handle sign bit for fptrunc

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: llvm/lib/Analysis/ValueTracking.cpp:4083
+  // Sign should be preserved
+  if (KnownSrc.cannotBeOrderedLessThanZero())
+    Known.knownNot(NegExcept0);
----------------
foad wrote:
> Writing this as `KnownSrc.isKnownNot(NegExcept0)` would make it clearer that the source and result classes are the same here.
> 
> Also why can't this logic be mirrored for PosExcept0?
It could be but it’s more cases to test and less useful 


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148599/new/

https://reviews.llvm.org/D148599