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From: "segher at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/106536] P9: gcc does not detect setb pattern Date: Tue, 13 Sep 2022 16:25:02 +0000 [thread overview] Message-ID: <bug-106536-4-QJvB8qsLYx@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-106536-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106536 Segher Boessenkool <segher at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Last reconfirmed| |2022-09-13 Status|UNCONFIRMED |NEW CC| |segher at gcc dot gnu.org --- Comment #1 from Segher Boessenkool <segher at gcc dot gnu.org> --- Confirmed. GCC uses conditional branches here in expand already. It is hard to optimise this over that. Using -mcpu=power10 we don't get conditional branches: cmpld 7,3,4 # 8 [c=4 l=4] *cmpdi_unsigned li 9,1 # 43 [c=4 l=4] *movsi_internal1/8 cmpld 0,3,4 # 45 [c=4 l=4] *cmpdi_unsigned setnbc 10,28 # 44 [c=4 l=4] *setnbc_unsigned_si isel 3,9,10,1 # 46 [c=4 l=4] isel_unsigned_si/1 extsw 3,3 # 24 [c=4 l=4] extendsidi2/1 blr # 51 [c=4 l=4] simple_return but this of course isn't ideal yet either. The branches aren't fully optimised away until ce2, which is *after* combine. ce1 didn't catch this, perhaps because the two conditional assignments are a bit intertwined there?
prev parent reply other threads:[~2022-09-13 16:25 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-05 10:17 [Bug target/106536] New: " jens.seifert at de dot ibm.com 2022-09-13 16:25 ` segher at gcc dot gnu.org [this message]
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