Hi!
On Thu, Oct 15, 2020 at 09:59:24AM +0100, Alex Coplan wrote:
> This patch remedies this situation: after the patch, make_extraction()
> now also identifies RTXs such as:
>
> (mult:DI (subreg:DI (reg:SI r)) (const_int 2^n))
>
> and rewrites this as:
>
> (mult:DI (sign_extend:DI (reg:SI r)) (const_int 2^n))
>
> instead of using a sign_extract.
Do we do that in simplify-rtx already (w/ the proper SUBREG_PROMOTED_*
stuff set)? If not, we should; if so, why does that not work here?
(Just the subreg->{sign,zero}_extend that is, nothing with the mult.)
Segher
