[Bug c/53160] New: likely wrong code bug

[Bug c/53160] New: likely wrong code bug

[regehr at cs dot utah.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53160

             Bug #: 53160
           Summary: likely wrong code bug
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: regehr@cs.utah.edu
                CC: chenyang@cs.utah.edu


regehr@regehr-System-Product-Name:~$ current-gcc -O1 small.c ; ./a.out 
0
regehr@regehr-System-Product-Name:~$ current-gcc -O2 small.c ; ./a.out 
1466236928
regehr@regehr-System-Product-Name:~$ cat small.c 
int printf (const char *, ...);
int a, c = 1, d, e, g;
volatile int b;
volatile char f;
long h;
short i;
void
fn1 (p1)
{
    e = 0;
    for (; e; ++e)
        ;
}
int
main ()
{
    fn1 (g && b);
    d = 0;
    for (; d >= 0; d--)
    {
        short j = f;
        int k = 0;
        i = j ? j : j << k;
    }
    h = c == 0 ? 0 : i;
    a = h;
    printf ("%d\n", a);
    return 0;
}
regehr@regehr-System-Product-Name:~$ current-gcc -v
Using built-in specs.
COLLECT_GCC=current-gcc
COLLECT_LTO_WRAPPER=/home/regehr/z/compiler-install/gcc-r186920-install/libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --with-libelf=/usr/local --enable-lto
--prefix=/home/regehr/z/compiler-install/gcc-r186920-install
--program-prefix=r186920- --enable-languages=c,c++
Thread model: posix
gcc version 4.8.0 20120427 (experimental) (GCC)

[Bug rtl-optimization/53160] [4.8 Regression] likely wrong code bug

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53160

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |x86_64-*-* i?86-*-*
          Component|c                           |rtl-optimization
   Target Milestone|---                         |4.8.0
            Summary|likely wrong code bug       |[4.8 Regression] likely
                   |                            |wrong code bug

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-04-29 20:01:37 UTC ---
It works correctly on mips64-linux-gnu but fails on x86_64-linux-gnu.  The tree
level looks exactly the same on both targets

[Bug rtl-optimization/53160] [4.7/4.8 Regression] likely wrong code bug

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53160

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-04-30
                 CC|                            |jakub at gcc dot gnu.org
         AssignedTo|unassigned at gcc dot       |jakub at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|4.8.0                       |4.7.1
            Summary|[4.8 Regression] likely     |[4.7/4.8 Regression] likely
                   |wrong code bug              |wrong code bug
     Ever Confirmed|0                           |1

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-30 07:17:31 UTC ---
Caused by my http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183416
Will have a look.

[Bug rtl-optimization/53160] [4.7/4.8 Regression] likely wrong code bug

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53160

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-30 09:45:34 UTC ---
Created attachment 27265
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27265
gcc48-pr53160.patch

Untested fix.

[Bug rtl-optimization/53160] [4.7/4.8 Regression] likely wrong code bug

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53160

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-05-02 07:13:54 UTC ---
Author: jakub
Date: Wed May  2 07:13:49 2012
New Revision: 187035

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187035
Log:
    PR rtl-optimization/53160
    * ree.c (combine_reaching_defs): Handle the case where cand->insn
    has been modified by ree pass already.

    * gcc.c-torture/execute/pr53160.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr53160.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/ree.c
    trunk/gcc/testsuite/ChangeLog

[Bug rtl-optimization/53160] [4.7/4.8 Regression] likely wrong code bug

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53160

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-05-02 07:19:46 UTC ---
Author: jakub
Date: Wed May  2 07:19:41 2012
New Revision: 187036

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187036
Log:
    PR rtl-optimization/53160
    * ree.c (combine_reaching_defs): Handle the case where cand->insn
    has been modified by ree pass already.

    * gcc.c-torture/execute/pr53160.c: New test.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/gcc.c-torture/execute/pr53160.c
Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/ree.c
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog

[Bug rtl-optimization/53160] [4.7/4.8 Regression] likely wrong code bug

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53160

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-05-02 07:21:45 UTC ---
Fixed.