On Mon, Jan 02, 2023 at 09:20:33AM -0700, Jeff Law wrote:
> > > In fact Raphael and I were about to submit a patch which takes advantage
> > > of
> > > that capability to improve the code slightly for risc-v.
> >
> > Just use a pattern with zero_extend or sign_extend around it or subreg of
> > it?
> If it were only that easy ;( In the bowels of the simplifications the
> zero_extension turns into either a pair of shifts or an AND with a mask (I
> forget which offhand). I'm sure we *can* work around this in the target,
> but it'll be ugly.
>
> The documentation definitely needs to be updated. I looked at the whole
> family a few weeks ago and my recollection was they all need to be fixed
> (ffs, clrsb, clz, ctz, popcount & parity) if the defined semantics are that
> the input and output operand modes must match.
When I look at the documentation of all the above, all of them have
"The mode of @var{x} must be @var{m} or @code{VOIDmode}."
Jakub
