https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126503
Bug ID: 126503
Summary: Wrong code with signed bitint
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: ktkachov at gcc dot gnu.org
CC: jakub at redhat dot com
Target Milestone: ---
__attribute__((noipa)) unsigned _BitInt(400)
neg (_BitInt(257) a)
{
return (unsigned _BitInt(400)) (-a);
}
__attribute__((noipa)) unsigned _BitInt(300)
addm1 (_BitInt(7) a, unsigned _BitInt(17) b)
{
_BitInt(257) x = (_BitInt(257)) a + -1;
return ~((unsigned _BitInt(300)) x ^ (unsigned _BitInt(300)) b);
}
int
main (void)
{
/* -(-1) == 1, so bits 257..399 of the widened result must be 0. */
unsigned _BitInt(400) r = neg (-1wb);
if ((unsigned long long) r != 1
|| (unsigned long long) (r >> 256) != 0
|| (unsigned long long) (r >> 320) != 0)
__builtin_abort ();
/* x == 0, so ~(0 ^ 3) has bits 256..299 all set. */
unsigned _BitInt(300) s = addm1 (1wb, 3uwb);
if ((unsigned long long) (s >> 256) != 0xfffffffffffULL)
__builtin_abort ();
return 0;
}
on aarch64 aborts with optimisation, but doesn't with -O0
