https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97386
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The actual bug is much older though, as shown e.g. on
__attribute__((noipa)) unsigned
foo (int x)
{
unsigned long long a = (0x800000000000ccccULL << x) | (0x800000000000ccccULL
>> (64 - x));
unsigned int b = a;
return (b << 24) | (b >> 8);
}
int
main ()
{
if (__CHAR_BIT__ != 8 || __SIZEOF_INT__ != 4 || __SIZEOF_LONG_LONG__ != 8)
return 0;
if (foo (1) != 0x99000199U)
__builtin_abort ();
return 0;
}
with the first if commented out and -O1 -fno-inline this is miscompiled e.g.
even with r105000.
For rotates, I guess we can swap them only if they have the same modes, or at
least we shouldn't if the outer one is narrower than the inner one.
