[PATCH] D121147: [x86] try harder to use shift instead of test if it can save some immediate bytes

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D121147#3365414 <https://reviews.llvm.org/D121147#3365414>, @RKSimon wrote:

> I like this, but I don't know if any intel archs have slow shift-by-imm ops (slow eflags updates) like they do for non-immediate shift amounts?

I think it should be ok. The decoders can see the shift amount and do some tricks to make the flags efficient.


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