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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/108358] [13 Regression] Dead Code Elimination Regression at -Os since r13-3378-gf6c168f8c06047
Date: Mon, 27 Mar 2023 11:56:32 +0000	[thread overview]
Message-ID: <bug-108358-4-eaje25CuIC@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108358-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108358

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Both -O2 and -O1 can optimize away the call to foo.  For -Os we end up with

  <bb 2> [local count: 118111600]:
  l = *.LC0;
  goto <bb 4>; [100.00%]

  <bb 3> [local count: 955630225]:
  bar31_ ();
  i.0_1 = i;
  _2 = i.0_1 + 1;
  i = _2;

  <bb 4> [local count: 1073741824]:
  i.1_3 = i;
  if (i.1_3 != 0)
    goto <bb 3>; [89.00%]
  else
    goto <bb 5>; [11.00%]

  <bb 5> [local count: 118111600]:
  j = l;
  m$h$b_18 = j.h.b;
  if (m$h$b_18 != 0)
    goto <bb 7>; [67.00%]
  else
    goto <bb 6>; [33.00%]

  <bb 6> [local count: 38976828]:
  foo ();

but FREs looking through the j = l copy causes us to fail disambiguating
against the cycle because of 'abort_on_visited' which I think is a bit
overeager here.

  parent reply	other threads:[~2023-03-27 11:56 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-10 13:03 [Bug tree-optimization/108358] New: Dead Code Elimination Regression at -Os (trunk vs. 12.2.0) yann at ywg dot ch
2023-01-10 14:47 ` [Bug tree-optimization/108358] [13 Regression] Dead Code Elimination Regression at -Os since r13-3378-gf6c168f8c06047 marxin at gcc dot gnu.org
2023-02-21 13:20 ` rguenth at gcc dot gnu.org
2023-03-27 11:56 ` rguenth at gcc dot gnu.org [this message]
2023-04-08 14:37 ` law at gcc dot gnu.org
2023-04-26  6:57 ` [Bug tree-optimization/108358] [13/14 " rguenth at gcc dot gnu.org
2023-07-27  9:25 ` rguenth at gcc dot gnu.org
2024-05-21  9:13 ` [Bug tree-optimization/108358] [13/14/15 " jakub at gcc dot gnu.org

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