https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68835
--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Testcase that is miscompiled starting with r210113 at -O2:
__attribute__((noinline, noclone)) unsigned __int128
foo (void)
{
unsigned __int128 x = (unsigned __int128) 0xffffffffffffffffULL;
struct { unsigned __int128 a:65; } w;
w.a = x;
w.a += x;
return w.a;
}
int
main ()
{
unsigned __int128 x = foo ();
if ((unsigned long long) x != 0xfffffffffffffffeULL
|| (unsigned long long) (x >> 64) != 1)
__builtin_abort ();
return 0;
}
The function foo returns 0xfffffffffffffffffffffffffffffffe instead of
0x1fffffffffffffffe. So, how do we want to represent such large unsigned
values? Force in that case get_len () > 1 representation, or tweak all
consumers including tree-pretty-print.c and other spots that if the
representation is negative number and the type is unsigned non-power of two
precision > HOST_BITS_PER_WIDE_INT, treat negative values differently?
