[Bug rtl-optimization/50088] movzbl is generated instead of movl

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50088

--- Comment #17 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-08-17 14:42:11 UTC ---
(In reply to comment #16)
> The testcase has ...
> 
>   int n8 = (arr[7] * 9 + 8) & 15;
> 
>   for (i = 0; i < len; i+=8)
>     {
>       n1 = (n1 + 1) & 15;
> 
>       s += arr[i] << n1;
> 
> The shift count is 32bit, which causes 32bit spill. Since shift/rotate
> instructions only take 8bit register (CL) as shift count, we load 8bit
> into CL. How do we solve this?

Well, always load from the spill slot with the mode the reg was spilled
if the arch says that is prefered.