trofi, 9 months ago

Today's gcc bug is https://gcc.gnu.org/PR111048 where gcc generated wrong code for highway-1.0.6 library in -mavx2 mode.

When handling the following loop:

u8 in_lanes[32];
for (unsigned i = 0; i < 32; i += 2) {
in_lanes[i + 0] = 0;
in_lanes[i + 1] = ((u8)0xff) >> (i & 7);
}

gcc broke i =12 iteration and instead of i[13] = 0xf; (0xff >> 4) stored something like i[13] = 0xef; there.

#gcc #bug