[Bug target/83210] __builtin_mul_overflow() generates suboptimal code when exactly one argument is the constant 2

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83210

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> (res >> 3) != src;
> 
> Why not just (src>>(sizeof (res)*8-3))!=0.
> 
> Seems shorter and might be faster.

And for the original case
Src>>31!=0 Just becomes src>>31. :)