Re: Linux 6.15-rc1

[Linus Torvalds]

On Mon, 7 Apr 2025 at 10:15, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> > Hmm. Why didn't that show up on x86-32? Or maybe it did and you're
> > just quoting the xtensa case.
>
> I didn't see the problem on x86. I didn't check others.
> Let's see.... openrisc and parisc are affected as well. I don't build
> allmodconfig for all architectures, so that may miss some.

I think what is going on is that gcc is smart enough to turn the
64-bit divide by a constant into a series of shifts and adds and a
32x32->64 multiply instruction.

Presumably on some other 32-bit architectures, that optimization
doesn't trigger - perhaps due to them not having the 32x32->64
multiply?

           Linus