[PATCH] D85965: [GlobalISel] Add a combine for ashr(shl x, c), c --> sext_inreg x, c'

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In D85965#2218352 <https://reviews.llvm.org/D85965#2218352>, @aemerson wrote:

> In D85965#2218104 <https://reviews.llvm.org/D85965#2218104>, @arsenm wrote:
>
>> Seems like it's missing a legality check, although I'm unclear on what the overall strategy for those is supposed to be
>
> This is intended to run prelegalizer so I don't think we need it.

Combines should probably try to support both. There's fragments of half implemented support for this


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