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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/103399] [12 Regression] Wrong code with -O2
Date: Wed, 24 Nov 2021 02:00:05 +0000	[thread overview]
Message-ID: <bug-103399-4-S3wCFtoyv3@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103399-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103399

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-11-24

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed reduced testcase:
int t1 = -2;
int e(int) __attribute__((noipa));
int e(int f) {
    int t = 0;
  for (int d = 0; d < f; d ++) {
    for (int c = 0; c < ((f ? t1 : 0) ^ t1) + 1; c++)
      t= 42;
  }
 return t;
}
int main() {
  unsigned a = e(1);
  printf("%u\n", a);
  if (a != 42)
    __builtin_abort ();
}

Note the t1 being negative is important. t1 being global is also important, if
you do a load of t1 before either loop, you end up with working code.

THis is another bswap issue ...

  parent reply	other threads:[~2021-11-24  2:00 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-23 22:34 [Bug tree-optimization/103399] New: " vsevolod.livinskij at frtk dot ru
2021-11-24  1:38 ` [Bug tree-optimization/103399] " pinskia at gcc dot gnu.org
2021-11-24  2:00 ` pinskia at gcc dot gnu.org [this message]
2021-11-24  2:00 ` pinskia at gcc dot gnu.org
2021-11-24  2:02 ` pinskia at gcc dot gnu.org

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