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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/43491] Unnecessary temporary for global register variable Date: Thu, 16 Feb 2012 14:55:00 -0000 [thread overview] Message-ID: <bug-43491-4-Wji8KDyCq4@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-43491-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43491 --- Comment #7 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-16 14:43:51 UTC --- With tree hoisting we generate <bb 2>: pretmp.5_19 = data_0; pretmp.5_20 = data_3; i_21 = pretmp.5_19 + pretmp.5_20; if (data_3(D) != 0) goto <bb 3>; else goto <bb 4>; <bb 3>: <bb 4>: # v_1 = PHI <v_7(D)(3), 2(2)> # i_2 = PHI <i_21(3), 5(2)> D.1719_14 = v_1 * i_21; D.1718_15 = i_2 * D.1719_14; return D.1718_15; instead of <bb 2>: if (data_3(D) != 0) goto <bb 4>; else goto <bb 3>; <bb 3>: pretmp.5_19 = data_0; pretmp.5_21 = data_3; i_23 = pretmp.5_19 + pretmp.5_21; goto <bb 5>; <bb 4>: data_0.0_4 = data_0; data_3.1_5 = data_3; i_6 = data_0.0_4 + data_3.1_5; <bb 5>: # v_1 = PHI <v_7(D)(4), 2(3)> # i_2 = PHI <i_6(4), 5(3)> # i_24 = PHI <i_6(4), i_23(3)> D.1719_14 = v_1 * i_24; D.1718_15 = i_2 * D.1719_14; return D.1718_15; } I suppose that's good enough? See that PRE still inserts loads from register variables, not sure if you'd want to disallow that as well.
next prev parent reply other threads:[~2012-02-16 14:49 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-43491-4@http.gcc.gnu.org/bugzilla/> 2011-11-23 8:35 ` [Bug rtl-optimization/43491] " amker.cheng at gmail dot com 2011-11-24 10:22 ` amker.cheng at gmail dot com 2011-12-21 4:35 ` amker.cheng at gmail dot com 2011-12-21 8:11 ` [Bug tree-optimization/43491] " ubizjak at gmail dot com 2011-12-23 6:32 ` jye2 at gcc dot gnu.org 2012-02-16 14:55 ` rguenth at gcc dot gnu.org [this message] 2012-02-17 4:48 ` amker.cheng at gmail dot com 2014-05-09 9:48 ` rguenth at gcc dot gnu.org
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