https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110717
--- Comment #12 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #9)
> Wonder how many important targets provide double-word shift patterns vs.
> ones which expand it through generic code.
Very long ago rs6000 had special code for this. That was sub-optimal in
other ways, and the generic code generated almost ideal code (sometimes an
extra data movement insn).
> powerpc probably could be improved:
> foo:
> srwi 9,4,5
> mr 10,9
> rlwimi 4,9,5,0,31-5
> rlwimi 10,3,27,0,31-27
> srawi 3,10,27
> blr
This is hugely worse than what we used to do, it seems?
GCC 8 did
srdi 9,4,5
rldimi 9,3,59,0
rldimi 4,9,5,0
sradi 3,9,59
blr
GCC 9 started with the unnecessary move.
But we should get only one insert insn in any case!
