[Bug middle-end/33779] New: [4.3 Regression] folds unsigned multiplication == 0 to true

["rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

int foo(int i)
{
  if (((unsigned)(i + 1)) * 4 == 0)
    return 1;
  return 0;
}

extern void abort(void);
int main()
{
  if (foo(0x3fffffff) == 0)
    abort ();
  return 0;
}


This goes wrong in extract_muldiv and is exposed by folding X * C CMP 0 to
X CMP 0 for undefined overflow.


-- 
           Summary: [4.3 Regression] folds unsigned multiplication == 0 to
                    true
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33779