Re: [PATCH 08/24] alpha: select ARCH_HAS_FAST_MULTIPLIER

[Magnus Lindholm]

Hi Matt,

On Tue, Sep 1, 2026 at 5:51 PM Matt Turner <mattst88@xxxxxxxxx> wrote:
>
> All Alpha CPUs have hardware integer multiply (MULL/MULQ). EV4 and EV5
> implement it in microcode; EV56 and later have fast single-cycle
> multiply. Since no EV4 system is likely to run a modern kernel, select
> this unconditionally to enable multiply-based fast paths in hweight and
> string routines.
>

I tested this on an AlphaServer ES40 (EV67). A test module exercised
the multiplication-based memchr_inv() path with offsets 0 through 7,
buffer lengths from 17 through 257 bytes, four fill values, and
mismatches at the beginning, middle, and end of each buffer. All
tests passed.

On EV67, hweight uses the native CTPOP instruction, so the generic
multiplication-based hweight path is not selected by this configuration.

Tested-by: Magnus Lindholm <linmag7@xxxxxxxxx>
Reviewed-by: Magnus Lindholm <linmag7@xxxxxxxxx>

Regards,
Magnus