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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/110361] [13/14 Regression] Missed Dead Code Elimination when using __builtin_unreachable since r13-2020-g16b013c9d9b Date: Mon, 07 Aug 2023 09:05:21 +0000 [thread overview] Message-ID: <bug-110361-4-yW0RJzOnf0@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-110361-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110361 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2023-08-07 Ever confirmed|0 |1 Status|UNCONFIRMED |NEW --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Confirmed. What is interesting is we have: ``` <bb 7> [local count: 525923045]: g = &p; f.0_18 = f; if (f.0_18 == 0) goto <bb 8>; [50.00%] else goto <bb 13>; [50.00%] <bb 9> [local count: 225485782]: g = &p; f.0_36 = f; if (f.0_36 == 0) goto <bb 8>; [50.00%] else goto <bb 13>; [50.00%] ``` Those bb's are exactly the same. Their pred bbs are: ``` <bb 3> [local count: 751619280]: if (e.4_19 == &a) goto <bb 9>; [30.00%] else goto <bb 4>; [70.00%] <bb 4> [local count: 526133498]: if (e.4_19 == &d) goto <bb 7>; [99.96%] else goto <bb 5>; [0.04%] ``` Their succ branch (that matters) is: ``` <bb 13> [local count: 375914866]: c = &m; m ={v} {CLOBBER(eol)}; _22 = e.4_19 == &d; _1 = e.4_19 == &a; _23 = _1 | _22; if (_23 != 0) goto <bb 12>; [25.16%] else goto <bb 10>; [74.84%] ``` So coming into bb13, we know that `(e.4_19 == &d) | (e.4_19 == &a)` is true. Removing the branch to bb 10 which was the call to foo: <bb 10> [local count: 281323581]: foo ();
next prev parent reply other threads:[~2023-08-07 9:05 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-22 11:40 [Bug tree-optimization/110361] New: " theodort at inf dot ethz.ch 2023-06-22 12:58 ` [Bug tree-optimization/110361] " rguenth at gcc dot gnu.org 2023-07-27 9:27 ` rguenth at gcc dot gnu.org 2023-08-07 9:05 ` pinskia at gcc dot gnu.org [this message] 2024-03-08 15:30 ` law at gcc dot gnu.org 2024-05-21 9:16 ` [Bug tree-optimization/110361] [13/14/15 " jakub at gcc dot gnu.org
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