On Fri, Oct 20, 2017 at 12:33 PM, Kirill Yukhin <kirill.yuk...@gmail.com> wrote: > Hello Jakub, Uroš, Jakub > On 04 Oct 21:35, Jakub Jelinek wrote: >> Hi! >> >> The following patch tweaks the TImode vector shifts similarly >> to the earlier vector shift patch, so that for shifts by immediate >> we can accept a memory input. Additionally, it removes the vec_shl_* >> expander, because the middle-end has dropped that a few years ago, >> and merges the left and right shift patterns using code iterators. >> Appart from the code/names that can be handled by mode attributes, >> the only difference was that one of the insns had >> (set_attr "atom_unit" "sishuf") >> and the other didn't. I hope that is just an error, I'd really expect >> both vpslldq and vpsrldq to use the same atom unit, isn't that the case? > This was introduced back in 2010. So, I have no info. > What I can see from config/atom.md: > ;; if palignr or psrldq > (define_insn_reservation "atom_sseishft_2" 1 > (and (eq_attr "cpu" "atom") > (and (eq_attr "type" "sseishft") > (and (eq_attr "atom_unit" "sishuf") > (match_operand 2 "immediate_operand")))) > "atom-simple-0") > > This leads back to initial commit of atom.md. > So, discrimination of psrldq and pslldq looks intentional. > > On the over hand, I see in Software Optimization Guide, Table 14-2 that > PSRLDQ and PSLLDQ occupy same line which directs both insns to port-0 (p > 14-18). > So, looking from that point, definition for PSLLDQ which allow either of > port-0 > and port-1 looks wrong (atom-simple-either reservation). > > In absence of other information, I'd play on safe side and leave things as > they > occur right now. >
I prefer to leave atom.md ASIS. As for (set_attr "atom_unit" "sishuf"), it was added for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44615 You can drop (set_attr "atom_unit" "sishuf") if gcc.target/i386/sse2-vec-2a.c still compiles. -- H.J.
