Re: [PATCH 2/2] x86/bitops: Fix false output register dependency of TZCNT insn

Borislav Petkov
2025-03-25T17:59:30Z

On Tue, Mar 25, 2025 at 06:52:02PM +0100, Uros Bizjak wrote:
> On Haswell and later Intel processors, the TZCNT instruction appears
> to have a false dependency on the destination register. Even though
> the instruction only writes to it, the instruction will wait until
> destination is ready before executing. This false dependency
> was fixed for Skylake (and later) processors.
>
> Fix false dependency by clearing the destination register first.

Same questions as about the POPCNT patch.

--
Regards/Gruss,
Boris.