[Bug tree-optimization/67953] New: [6 Regression] match.pd: X - (X / Y) * Y wrong on change of sign

[Bug tree-optimization/67953] New: [6 Regression] match.pd: X - (X / Y) * Y wrong on change of sign

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67953

            Bug ID: 67953
           Summary: [6 Regression] match.pd: X - (X / Y) * Y wrong on
                    change of sign
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glisse at gcc dot gnu.org
                CC: mpolacek at gcc dot gnu.org
  Target Milestone: ---

$ cat z.c
#include <stdio.h>
unsigned f(signed a){
  return (unsigned)a-((a/3)*3);
}
unsigned g(signed a){
  return a-((a/3)*3);
}
int main(){
  printf("%d %d\n", f(-5), g(-5));
}
$ gcc-5 z.c && ./a.out
-2 -2
$ clang z.c && ./a.out       
-2 -2
$ gcc-snapshot z.c && ./a.out 
2 -2

[Bug tree-optimization/67953] [6 Regression] match.pd: X - (X / Y) * Y wrong on change of sign

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67953

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-10-13
   Target Milestone|---                         |6.0
     Ever confirmed|0                           |1

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r225195 :(.

[Bug tree-optimization/67953] [6 Regression] match.pd: X - (X / Y) * Y wrong on change of sign

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67953

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
So mine.

[Bug tree-optimization/67953] [6 Regression] match.pd: X - (X / Y) * Y wrong on change of sign

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67953

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Thu Oct 15 09:39:35 2015
New Revision: 228839

URL: https://gcc.gnu.org/viewcvs?rev=228839&root=gcc&view=rev
Log:
        PR tree-optimization/67953
        * match.pd (X - (X / Y) * Y): Don't change signedness of @0.

        * gcc.dg/fold-minus-6.c (fn4): Change the type of A to
        unsigned.
        * gcc.dg/torture/pr67953.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr67953.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/match.pd
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/fold-minus-6.c

[Bug tree-optimization/67953] [6 Regression] match.pd: X - (X / Y) * Y wrong on change of sign

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67953

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

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

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.