[Bug middle-end/37103] [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  2008-08-13 09:16 -------
The C standard specifies that the comparison is done in type int which means
that for both signed and unsigned char

  (char)-1 != (unsigned short)-1

should evaluate to false.  Testcase:

extern void abort (void);

void func_1 (unsigned short p_65)
{
  signed char g_99 = -1;
  if (p_65 == g_99)
    abort ();
}

void func_2 (unsigned short p_65)
{
  unsigned char g_99 = -1;
  if (p_65 == g_99)
    abort ();
}

int main (void)
{
  func_1 (-1);
  func_2 (-1);
  return 0;
}

This looks like yet another folding bug as we end up with the comparison
narrowed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|c                           |middle-end
     Ever Confirmed|0                           |1
           Keywords|                            |wrong-code
      Known to fail|                            |4.3.1 4.4.0
      Known to work|                            |4.2.4
   Last reconfirmed|0000-00-00 00:00:00         |2008-08-13 09:16:17
               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=37103