[PATCH] D111836: [indvars] Use fact loop must exit to canonicalize to unsigned conditions

Fri Oct 15 09:54:15 PDT 2021

reames added a comment.

In D111836#3067107 <https://reviews.llvm.org/D111836#3067107>, @lebedev.ri wrote:

> In D111836#3067101 <https://reviews.llvm.org/D111836#3067101>, @reames wrote:
>
>> In D111836#3066152 <https://reviews.llvm.org/D111836#3066152>, @lebedev.ri wrote:
>>
>>> Some time ago i addempted to do this in CVP via constant range reasoning:
>>> D90924 <https://reviews.llvm.org/D90924> (ignore the SCEV part)
>>> Would that be worthwhile? Should i pick that back up?
>>
>> Yes, I think a CVP based form would be useful.  We have the range information, we might as well use it.
>>
>> If you want to implement the CVP part, I'd be happy to review.  Alternatively, I can implement, and you can review.  Your preference.
>
> (CVP isn't the hard part, actually modelling it in ConstantRange is.)
> I guess i just need to rebase the patch then.

Why?  The "both are positive" check should be pretty trivial given the two constant ranges for the operands?  Are you looking to go much beyond that?  If so, maybe split the changes?

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https://reviews.llvm.org/D111836