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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/94782] Simple multiplication-related arithmetic not optimized to direct multiplication Date: Fri, 17 Feb 2023 18:24:04 +0000 [thread overview] Message-ID: <bug-94782-4-VcbfQ49HBT@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-94782-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94782 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |TREE --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- It is fixed on the RTL level but not the gimple level. Combine does it for x86_64: Trying 7, 8 -> 9: 7: {r91:SI=r93:SI-0x1;clobber flags:CC;} REG_DEAD r93:SI REG_UNUSED flags:CC 8: {r92:SI=r91:SI*r94:SI;clobber flags:CC;} REG_UNUSED flags:CC REG_DEAD r91:SI 9: r90:SI=r92:SI+r94:SI REG_DEAD r94:SI REG_DEAD r92:SI Successfully matched this instruction: (set (reg:SI 90) (mult:SI (reg:SI 93) (reg:SI 94))) allowing combination of insns 7, 8 and 9 original costs 4 + 12 + 4 = 20 replacement cost 12 But it fails to do it on aarch64: Trying 7 -> 14: 7: r101:SI=r103:SI-0x1 REG_DEAD r103:SI 14: x0:SI=r101:SI*r104:SI+r104:SI REG_DEAD r101:SI REG_DEAD r104:SI
next prev parent reply other threads:[~2023-02-17 18:24 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-27 2:08 [Bug tree-optimization/94782] New: " gabravier at gmail dot com 2020-04-27 7:07 ` [Bug tree-optimization/94782] " rguenth at gcc dot gnu.org 2023-02-17 18:16 ` gabravier at gmail dot com 2023-02-17 18:24 ` pinskia at gcc dot gnu.org [this message] 2023-02-17 18:28 ` pinskia at gcc dot gnu.org
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