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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/109138] [10/11/12/13 Regression] wrong code at -O1 and above on x86_64-linux-gnu Date: Wed, 15 Mar 2023 09:39:59 +0000 [thread overview] Message-ID: <bug-109138-4-LDxAqS2yZ3@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-109138-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109138 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |INVALID Status|NEW |RESOLVED --- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I don't think this has anything to do with reassoc though. The testcase looks incorrect to me. Because d is defined in the scope of the outer loop's body, for b == 0 a is -1U and so the inner loop does nothing, d is set to 1, a is set to 0 and then d goes out of scope. Then for b = 1, a scope with d variable is entered but the variable is again uninitialized, a <= 0 is true, and we use the uninitialized variable. fixup_cfg1 dump shows this nicely with the clobber in there: <bb 2> : b = 0; goto <bb 6>; [INV] <bb 3> : d.0_1 = d; if (d.0_1 != 0) goto <bb 5>; [INV] else goto <bb 4>; [INV] <bb 4> : L: a.1_2 = a; if (a.1_2 == 0) goto <bb 3>; [INV] else goto <bb 5>; [INV] <bb 5> : d = 1; a.2_3 = a; _4 = a.2_3 + 1; a = _4; d = {CLOBBER(eol)}; b = b + 1; <bb 6> : if (b <= 1) goto <bb 4>; [INV] else goto <bb 7>; [INV] <bb 7> : D.2753 = 0; return D.2753;
next prev parent reply other threads:[~2023-03-15 9:40 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-03-15 5:20 [Bug tree-optimization/109138] New: " zhendong.su at inf dot ethz.ch 2023-03-15 6:07 ` [Bug tree-optimization/109138] " pinskia at gcc dot gnu.org 2023-03-15 8:40 ` rguenth at gcc dot gnu.org 2023-03-15 8:51 ` pinskia at gcc dot gnu.org 2023-03-15 9:26 ` [Bug tree-optimization/109138] [10/11/12/13 Regression] " jakub at gcc dot gnu.org 2023-03-15 9:39 ` jakub at gcc dot gnu.org [this message] 2023-03-15 10:54 ` zhendong.su at inf dot ethz.ch
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