On Mon, Mar 17 2025 at 09:53, Sean Christopherson wrote:
> On Mon, Mar 17, 2025, Thomas Gleixner wrote:
>> > - for (i = 0; i < 4; i++)
>> > + for (i = 0; i < 4; i++) {
>> > pir_copy[i] = READ_ONCE(pir[i]);
>> > + if (pir_copy[i])
>> > + found_irq = true;
>> > + }
>>
>> That's four extra conditional branches. You can avoid them completely. See
>> delta patch below.
>
> Huh. gcc elides the conditional branches when computing found_irq regardless of
> the approach; the JEs in the changelog are from skipping the XCHG.
>
> But clang-14 does not. I'll slot this in.
Neither does GCC 12. That's why I noticed.
