[PATCH] D83964: GlobalISel: Augment addsat/subsat lowering with an optional type

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D83964#2199356 <https://reviews.llvm.org/D83964#2199356>, @foad wrote:

> Looks OK technically. As an alternative, would it be possible to widen, and then have the lowering spot that the operands are both extended from a smaller type, so they're known to have a small range, so we can use the more efficient lowering? That would avoid the need for this new "optional type" concept.

I tried this, but it complicates the heuristic for which lowering strategy to use. If we need to promote, the isLegalOrCustom check for min/max won't work for the narrower type


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