[PATCH] D116616: [InstSimplify] use knownbits to fold more udiv/urem

Wed Jan 5 06:18:34 PST 2022

foad added a comment.

In D116616#3222181 <https://reviews.llvm.org/D116616#3222181>, @spatel wrote:

> In D116616#3221740 <https://reviews.llvm.org/D116616#3221740>, @foad wrote:
>
>> It seems like you're using knownbits information to derive range information. It would be good to do this more universally, and in both directions.
>
> Yes - we do have a combination analysis called "computeConstantRangeIncludingKnownBits", so that should be more powerful. 
> But that is currently a static helper function in ValueTracking, so it would have to be made visible, and it would be good to have more tests to show where the extra logic gives us a better result. Ok to make that a TODO item?

Sure. I don't object to the current patch. Just wanted to understand if there's a way of doing this more universally in future.

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