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From: "kristerw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/112738] New: forwprop4 introduces invalid
 wide signed Boolean values
Date: Mon, 27 Nov 2023 23:21:09 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: kristerw at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112738

            Bug ID: 112738
           Summary: forwprop4 introduces invalid wide signed Boolean
                    values
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kristerw at gcc dot gnu.org
  Target Milestone: ---

The forwprop4 pass introduces an invalid wide Boolean when compiling the
following function with -O3 for X86_64:

  int *a, b, c, d;
  void
  foo (void)
  {
    for (; d <=3D 0; d++)
      b &=3D ((a || d) ^ c) =3D=3D 1;
  }

What is happening is that forwprop4 changes the IR

  _38 =3D (signed int) _16;
  _59 =3D -_38;
  _65 =3D (<signed-boolean:32>) _59;

to the incorrect

  _55 =3D (<signed-boolean:32>) _16;
  _65 =3D -_55;=