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From: "marxin at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/105832] [13 Regression] Dead Code Elimination
 Regression at -O3 (trunk vs. 12.1.0)
Date: Thu, 22 Dec 2022 12:03:12 +0000
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X-Bugzilla-Component: tree-optimization
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X-Bugzilla-Keywords: missed-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105832

Martin Li=C5=A1ka <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-bisection             |

--- Comment #5 from Martin Li=C5=A1ka <marxin at gcc dot gnu.org> ---
With r13-3897-gbe2c74fdcd0e8d66 get:
gcc pr105832.c -c -O3 -fdump-tree-optimized=3D/dev/stdout --param
max-jump-thread-duplication-stmts=3D17


;; Function main (main, funcdef_no=3D0, decl_uid=3D2741, cgraph_uid=3D1,
symbol_order=3D2) (executed once)

int main ()
{
  <bb 2> [local count: 178992760]:
  c.a =3D 0;
  return 0;

}

before the revision I was:

;; Function main (main, funcdef_no=3D0, decl_uid=3D2741, cgraph_uid=3D1,
symbol_order=3D2) (executed once)

Removing basic block 5
int main ()
{
  char _1;
  unsigned char _2;
  char iftmp.0_11;

  <bb 2> [local count: 178992758]:
  _1 =3D c.b;
  _2 =3D (unsigned char) _1;
  if (_2 > 4)
    goto <bb 4>; [50.00%]
  else
    goto <bb 3>; [50.00%]

  <bb 3> [local count: 89496379]:
  iftmp.0_11 =3D _1 << 2;

  <bb 4> [local count: 178992760]:
  c.a =3D 0;
  return 0;

}=