[Bug c/37125] New: possible integer codegen bug

[Bug c/37125] New: possible integer codegen bug

[regehr at cs dot utah dot edu]

This is seen using r139123 on Ubuntu Hardy on ia32.

regehr@john-home:~/volatile/tmp6$ current-gcc -fwrapv -O0 small.c -o small 
regehr@john-home:~/volatile/tmp6$ ./small
regehr@john-home:~/volatile/tmp6$ current-gcc -fwrapv -O1 small.c -o small 
regehr@john-home:~/volatile/tmp6$ ./small
Aborted
regehr@john-home:~/volatile/tmp6$ current-gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../configure --program-prefix=current-
--enable-languages=c,c++ --prefix=/home/regehr
Thread model: posix
gcc version 4.4.0 20080815 (experimental) (GCC) 
regehr@john-home:~/volatile/tmp6$ cat small.c

extern void abort (void);

static inline unsigned long int
mod_rhs(const long int rhs)
{
    if (rhs == 0) return 1;
    return rhs;
}

void func_44 (unsigned int p_45);
void func_44 (unsigned int p_45)
{
  if (!((p_45 * -9) % mod_rhs (-9))) {
    abort();
  }
}

int main (void)
{
  func_44 (2);
  return 0;
}


-- 
           Summary: possible integer codegen bug
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: regehr at cs dot utah dot edu
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug c/37125] possible integer codegen bug

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2008-08-15 14:32 -------
This somehow looks familiar.  Also happens on the 4.3 branch.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2008-08-15 14:37 -------
Probably a dup of PR36548.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|c                           |middle-end
     Ever Confirmed|0                           |1
           Keywords|                            |wrong-code
      Known to fail|                            |4.3.1
      Known to work|                            |4.2.4
   Last reconfirmed|0000-00-00 00:00:00         |2008-08-15 14:37:41
               date|                            |
            Summary|possible integer codegen bug|[4.3/4.4 Regression]
                   |                            |possible integer codegen bug
   Target Milestone|---                         |4.3.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[regehr at cs dot utah dot edu]

------- Comment #3 from regehr at cs dot utah dot edu  2008-08-15 17:20 -------
(In reply to comment #2)
> Probably a dup of PR36548.
> 

But PR36548 seemed to be about overflow whereas this one doesn't appear to have
any overflows.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[jsm28 at gcc dot gnu dot org]

-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[cnstar9988 at gmail dot com]

------- Comment #4 from cnstar9988 at gmail dot com  2008-08-22 00:31 -------
works well on 4.2.4, 4.3.0, 4.3.2-RC1.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2008-08-22 09:01 -------
It only fails for 32bit targets.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[cnstar9988 at gmail dot com]

------- Comment #6 from cnstar9988 at gmail dot com  2008-08-22 09:28 -------
sorry, I use 64bit linux for testing.
I tested again.

works well on all 64bit 4.2.4, 4.3.0, 4.3.2-RC1.
works well on 4.2.4 32bit.
works failed on gcc 4.3.0 32bit.
wokrs failed on gcc 4.3.2 RC1 32bit.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2008-08-22 10:34 -------
Same issue as PR36548.

*** This bug has been marked as a duplicate of 36548 ***


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[rguenth at gcc dot gnu dot org]

------- Comment #8 from rguenth at gcc dot gnu dot org  2008-08-22 12:45 -------
Subject: Bug 37125

Author: rguenth
Date: Fri Aug 22 12:43:49 2008
New Revision: 139450

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=139450
Log:
2008-08-22  Richard Guenther  <rguenther@suse.de>

        PR middle-end/36548
        PR middle-end/37125
        * fold-const.c (extract_muldiv_1): Optimize (X * C1) % C2 only
        if the multiplication does not overflow.

        * gcc.c-torture/execute/pr37125.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr37125.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c
    trunk/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125

[Bug middle-end/37125] [4.3/4.4 Regression] possible integer codegen bug

[rguenth at gcc dot gnu dot org]

------- Comment #9 from rguenth at gcc dot gnu dot org  2008-08-28 14:19 -------
Subject: Bug 37125

Author: rguenth
Date: Thu Aug 28 14:18:23 2008
New Revision: 139709

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=139709
Log:
2008-08-28  Richard Guenther  <rguenther@suse.de>

        PR middle-end/36548
        PR middle-end/37125
        * fold-const.c (extract_muldiv_1): Optimize (X * C1) % C2 only
        if the multiplication does not overflow.

        * gcc.c-torture/execute/pr37125.c: New testcase.

Added:
    branches/gcc-4_3-branch/gcc/testsuite/gcc.c-torture/execute/pr37125.c
Modified:
    branches/gcc-4_3-branch/gcc/ChangeLog
    branches/gcc-4_3-branch/gcc/fold-const.c
    branches/gcc-4_3-branch/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37125