On Thu, Jun 15, 2023 at 2:41 PM Jan Beulich <jbeul...@suse.com> wrote: > > On 15.06.2023 07:23, Hongtao Liu wrote: > > On Wed, Jun 14, 2023 at 5:03 PM Jan Beulich <jbeul...@suse.com> wrote: > >> > >> On 14.06.2023 09:41, Hongtao Liu wrote: > >>> On Wed, Jun 14, 2023 at 1:58 PM Jan Beulich via Gcc-patches > >>> <gcc-patches@gcc.gnu.org> wrote: > >>>> > >>>> ... in vec_dupv4sf / *vec_dupv4si. The respective broadcast insns are > >>>> never longer (yet sometimes shorter) than the corresponding VSHUFPS / > >>>> VPSHUFD, due to the immediate operand of the shuffle insns balancing the > >>>> need for VEX3 in the broadcast ones. When EVEX encoding is required the > >>>> broadcast insns are always shorter. > >>>> > >>>> Add two new alternatives each, one covering the AVX2 case and one > >>>> covering AVX512. > >>> I think you can just change assemble output for this first alternative > >>> when TARGET_AVX2, use vbroadcastss, else use vshufps since > >>> vbroadcastss only accept register operand when TARGET_AVX2. And no > >>> need to support 2 extra alternatives which doesn't make sense just > >>> make RA more confused about the same meaning of different > >>> alternatives. > >> > >> You mean by switching from "@ ..." to C code using "switch > >> (which_alternative)"? I can do that, sure. Yet that'll make for a > >> more complicated "length_immediate" attribute then. Would be nice > > Yes, you can also do something like > > (set (attr "length_immediate") > > (cond [(eq_attr "alternative" "0") > > (if_then_else (match_test "TARGET_AVX2) > > (const_string "") > > (const_string "1")) > > ...] > > Yes, that's along the lines of what I was thinking of. I'm uncertain > about one aspect of what you spelled out above, though: What is the > meaning of the empty string in (const_string "")? Shouldn't this be > "0" or "*"? Yes, sorry for the typo, should be 0 or *. > > >> But that'll be for vec_dupv4sf only, as vec_dupv4si is subtly > >> different. > > Yes, but can we use vpbroadcastd for vec_dupv4si similarly? > > Well, the use there is similar, but the folding with the shuffle > alternative won't be possible, because of the new first alternative > also allowing m for the source, when the shuffle one allows for only > Yv. The extra m is pointless to have in vec_dupv4sf (because a later > alternative with a wider ISA [avx] has it already), while in > vec_dupv4si the similar later alternative resolves to vbroadcastss, > not vpbroadcastd. I should be able to fold the two vpbroadcastd > alternatives, along the lines of what I've done in the vec_dupv2di > patch just sent. (As I just realized the m in what are alternatives > 1 each in patch v1 is pointless, since already taken care of by > other alternatives.) > > Jan
-- BR, Hongtao
