------- 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
