[Bug target/99548] Help me! Lost the fight against the compiler.

[unlvsur at live dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99548

--- Comment #2 from cqwrteur <unlvsur at live dot com> ---
(In reply to Andrew Pinski from comment #1)
> For aarch64 we get:
>         ldp     x4, x3, [x1]
>         mov     x7, 38
>         ldp     x6, x5, [x2]
>         ldr     x8, [x1, 16]
>         add     x6, x4, x6
>         cmp     x4, x6
>         adc     x5, x3, x5
>         cmp     x3, x5
>         ldr     x3, [x1, 24]
>         ldp     x4, x1, [x2, 16]
>         adc     x4, x8, x4
>         cmp     x8, x4
>         adc     x1, x3, x1
>         cmp     x3, x1
>         csetm   x2, cs
>         and     x2, x2, x7
>         add     x2, x2, x6
>         cmp     x2, x6
>         cinc    x6, x5, ls
>         cmp     x6, x5
>         cinc    x5, x4, ls
>         cmp     x5, x4
>         cinc    x3, x1, ls
>         cmp     x3, x1
>         csetm   x1, ls
>         and     x1, x1, x7
>         add     x1, x1, x2
>         str     x1, [x0]
>         cmp     x1, x2
>         cinc    x1, x6, ls
>         str     x1, [x0, 8]
>         cmp     x1, x6
>         cinc    x1, x5, ls
>         cmp     x1, x5
>         cinc    x3, x3, ls
>         stp     x1, x3, [x0, 16]
>         ret
> There is only one missing optimization there really:
>         csetm   x1, ls
>         and     x1, x1, x7
> Should be turned into:
> csel x1, x7, xzw, ls
> Which is repeated a few times.
> 
> It looks like x86_64 has other issues.

my add carry implementation for none-x86_64 platforms is wrong on godbolt.