[PATCH] D94014: [InstCombine] reduce icmp(ashr X, C1), C2 to sign-bit test

Mon Jan 11 08:00:22 PST 2021

nlopes added a comment.

In D94014#2490258 <https://reviews.llvm.org/D94014#2490258>, @spatel wrote:

> In D94014#2490113 <https://reviews.llvm.org/D94014#2490113>, @lebedev.ri wrote:
>
>> alive1 does not actually have a `countLeadingOnes()` precondition
>
> Weird - maybe @nlopes can tell us how this example parses at all then: https://rise4fun.com/Alive/juX1
>
>> (at least as per https://github.com/nunoplopes/alive/blob/master/constants.py),

Ah, the rise4fun.com version uses the newsema branch. `countLeadingOnes` seems to be implemented in newsema but not in master.
(the newsema has better support for undef & poison, which wasn't complete in the original/master version. I don't remember why this branch wasn't merged, but I think it broke some functionality)

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D94014/new/

https://reviews.llvm.org/D94014