[PATCH] D143195: ValueTracking: Add start of computeKnownFPClass API

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/include/llvm/Analysis/ValueTracking.h:234
+    else if (SignBit)
+      *SignBit &= *RHS.SignBit;
+
----------------
I don't understand your logic here. If `&` is supposed to be (doc comments?) an intersection, then if one side knows the sign bit and the other doesn't, shouldn't we be using the known sign bit?

It doesn't look like `operator&=` or `commonBits()` is actually used though. It may be worthwhile to split out this class into a separate header (like KnownBits) and unit test it.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D143195/new/

https://reviews.llvm.org/D143195