[PATCH] D74484: [AggressiveInstCombine] Add support for ICmp instr that feeds a select intsr's condition operand.

Roman Lebedev via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Feb 12 23:56:07 PST 2020


lebedev.ri added a comment.

In D74484#1872137 <https://reviews.llvm.org/D74484#1872137>, @lebedev.ri wrote:

> This seems not generic enough to me, can't we not require the icmp operands to be constants/[sz]ext's,
>  but instead try to see if it can be evaluated in smaller bitwidth (what the rest of the code here does)?
>
> As long as the icmp can be shrunked to at least as small bitwidth as we need there to get rid of cast,
>  i think we can always pick the actual bitwidth we'll use, which might be wider than minimal?


After thinking about this, i'd be okay with not doing that straight away.
It should be doable, but would require substantial redesign to nicely model more than one dag and their connection/dependency.


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