[PATCH] D57243: GlobalISel: Allow bitcount ops to have different result type

Daniel Sanders via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue Feb 5 10:29:18 PST 2019


dsanders added a comment.

In D57243#1385543 <https://reviews.llvm.org/D57243#1385543>, @qcolombet wrote:

> > The legalizer is already done the way I'm talking about on the rule matching side and performance was marginally better on average than the old setAction() interface.
>
> Got it.
>  That said, to me the legalizer is no different than ISel or a sort of InstCombine, thus I would expect we eventually use the same engine/automaton for selecting/lowering what goes through. The same goes with the way we represent them, although admittedly legalization is a bit more complicated because we have to come up with a way of representing the constraints on the unbound input types.


I'd agree with that. Though it's worth pointing out that none of those currently build a description of what it wants to do like the legalizer currently does, they just make the change straightaway when the rules match. Removing in LegalizationAction in favour of just making the change brings the legalizer closer to the others.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57243/new/

https://reviews.llvm.org/D57243





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