I believe that the program below is well-formed and that it is miscompiled by
r148318 at -Os.
reg...@john-home:~$ cat foo.c
#include <stdio.h>
int foo(int y)
{
return (((unsigned short)y*(unsigned short)-2)>=(y?0:y));
}
int main (void)
{
printf ("%d\n", foo(-2));
return 0;
}
reg...@john-home:~$ current-gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../configure --prefix=/home/regehr/z/tmp/gcc-r148318-install
--program-prefix=r148318- --enable-languages=c,c++
Thread model: posix
gcc version 4.5.0 20090609 (experimental) (GCC)
reg...@john-home:~$ current-gcc -Os foo.c -o foo
reg...@john-home:~$ ./foo
1
reg...@john-home:~$ current-gcc -O0 foo.c -o foo
reg...@john-home:~$ ./foo
0
reg...@john-home:~$ gcc-4.1 -Os foo.c -o foo
reg...@john-home:~$ ./foo
0
reg...@john-home:~$ gcc-4.2 -Os foo.c -o foo
reg...@john-home:~$ ./foo
0
reg...@john-home:~$ icc -Os foo.c -o foo
reg...@john-home:~$ ./foo
0
--
Summary: possible integer wrong code bug
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: regehr at cs dot utah dot edu
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40390
