[PATCH] D44043: [DAGCombine] Remove AND in SETCC if we can prove they are unneeded

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

In https://reviews.llvm.org/D44043#1031702, @dmgreen wrote:

> > I was asked not to add DemandedElts to individual cases in computeKnownBits until you have test coverage - this should probably be the same for AnyToZeroExtLoads.
>
> OK. Noted. By this you mean unit tests for computeKnownBits? Sounds like a sensible idea. I'm guessing the nature of ISel makes this difficult?


Most of my tests for these cases come from combines that make use of SelectionDAG::SignBitIsZero which uses computeKnownBits - converting uitofp to sitofp etc. in x86 combine-*.ll tests have some good examples.


https://reviews.llvm.org/D44043