[PATCH] D130956: [X86][MC] Always emit `rep` prefix for `bsf`

[Phoebe Wang via Phabricator via llvm-commits]

pengfei added a comment.

In D130956#3692473 <https://reviews.llvm.org/D130956#3692473>, @pengfei wrote:

> In D130956#3692469 <https://reviews.llvm.org/D130956#3692469>, @craig.topper wrote:
>
>> Assembler should faithful to the original source. This needs to be done at codegen only I would think.
>
> I see, how about changing the assembly string to `"rep bsf{w}\t{$src, $dst|$dst, $src}"`?

Oh, we can't do it consider the decoding. I'll reconsider the solution. Thanks!

> Maybe you can consider implementing it in X86MCInstLower::Lower by using Flags of MCInst.

Thanks for the suggestion, let me have a try.


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https://reviews.llvm.org/D130956