[Bug sanitizer/64906] New: -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[Bug sanitizer/64906] New: -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[sirl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64906

            Bug ID: 64906
           Summary: -fsanitize=integer-divide-by-zero creates false
                    -Wmaybe-uninitialized warning
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sirl at gcc dot gnu.org
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org

This testcase produces a false warning when compiled with -O2
-fsanitize=integer-divide-by-zero -Wmaybe-uninitialized:

struct s {
    __SIZE_TYPE__ size;
    unsigned int flags;
};

int testf(struct s * source)
{
    __SIZE_TYPE__ msize = 0;
    if ((source->flags & 88) ? (__SIZE_TYPE__) 43 * 8 : 0)
        msize = source->size / ((source->flags & 88) ? (__SIZE_TYPE__) 43 * 8:
0);
    return msize;
}

test.c: In function 'testf':
test.c:11:8: warning: 'iftmp.1' may be used uninitialized in this function
[-Wmaybe-uninitialized]
  msize = source->size / ((source->flags & 88) ? (__SIZE_TYPE__) 43 * 8: 0);
        ^

[Bug sanitizer/64906] -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64906

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-09-21
                 CC|                            |mpolacek at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |5.3
     Ever confirmed|0                           |1

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I'll have a look.

[Bug sanitizer/64906] -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64906

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
int
testf (int f, int s)
{
  int ret = 0;
  if (f)
    ret = s / (f ? (unsigned long) 8 : 0);
  return ret;
}

[Bug sanitizer/64906] -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64906

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I'm testing a fix.

[Bug sanitizer/64906] -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64906

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Fri Sep 25 09:50:29 2015
New Revision: 228112

URL: https://gcc.gnu.org/viewcvs?rev=228112&root=gcc&view=rev
Log:
        PR sanitizer/64906
        * c-ubsan.c (ubsan_instrument_division): Also pre-evaluate OP1.

        * c-c++-common/ubsan/pr64906.c: New test.

Added:
    trunk/gcc/testsuite/c-c++-common/ubsan/pr64906.c
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-ubsan.c
    trunk/gcc/testsuite/ChangeLog

[Bug sanitizer/64906] -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64906

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Fri Sep 25 10:46:03 2015
New Revision: 228113

URL: https://gcc.gnu.org/viewcvs?rev=228113&root=gcc&view=rev
Log:
        PR sanitizer/64906
        * c-ubsan.c (ubsan_instrument_division): Also pre-evaluate OP1.

        * c-c++-common/ubsan/pr64906.c: New test.

Added:
    branches/gcc-5-branch/gcc/testsuite/c-c++-common/ubsan/pr64906.c
Modified:
    branches/gcc-5-branch/gcc/c-family/ChangeLog
    branches/gcc-5-branch/gcc/c-family/c-ubsan.c
    branches/gcc-5-branch/gcc/testsuite/ChangeLog

[Bug sanitizer/64906] -fsanitize=integer-divide-by-zero creates false -Wmaybe-uninitialized warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64906

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

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

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.