https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125905
--- Comment #3 from Drea Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Jeffrey A. Law from comment #2)
> Another example, this time derived from x264. I *think* this is
> representative of what's created by the vectorizer for selecting across two
> different loop variants. It's ultimately just a conditional add. It's a
> gimple test because I haven't managed to trip it directly in C.
>
>
> long __GIMPLE (ssa)
> f (long sa, long ua)
> {
> long ua15;
> long hi;
> _Bool neg;
>
> __BB(2):
> ua15_5 = ua_3(D) + 15l;
> neg_6 = sa_4(D) < 0l;
> hi_7 = neg_6 ? 15l : ua15_5;
> return hi_7;
> }
>
> Generates:
> srli a5,a0,63 # 10 [c=4 l=4] lshrdi3
> addi a1,a1,15 # 31 [c=4 l=4] *adddi3/1
> li a4,15 # 30 [c=4 l=4] *movdi_64bit/1
> czero.nez a0,a1,a5 # 33 [c=4 l=4] *czero.nez.didi
> czero.eqz t0,a4,a5 # 34 [c=4 l=4] *czero.eqz.didi
> add a0,t0,a0 # 22 [c=4 l=4] *adddi3/0
> ret # 47 [c=0 l=4] simple_return
>
> But really just one czero is needed. Select across 0/15 using that single
> czero, then unconditionall add that to a1.
Actually it is select between 0 and ua15_3(D) if I read the gimple correctly.
That is conditionally add ua15_3(D) to 15.
