x86: add_branch_prefix_frag_p() vs PadLock insns

[Jan Beulich]

On 26.09.2025 12:21, H.J. Lu wrote:
> On Fri, Sep 26, 2025, 6:16 PM Jan Beulich <jbeulich@suse.com> wrote:
>> why is it that add_branch_prefix_frag_p() special-cases PadLock insns?
>> They're by far not the only ones including prefixes in their opcodes.
>> IOW - I wonder if the conditional there is either insufficient or
>> excessive.
> 
> If I remember correctly, this is to mitigate
> an Intel processor issue.  No Intel processor
> support such instructions.

Yes. But then why was the PadLock check added there right when that code
was introduced? (It has meanwhile been extended, but if that's really
needed for some reason, it likely wasn't extended enough.)

Jan