https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114080
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- You could have checked this very easily using -fsanitize=undefined just like it asks you to at https://gcc.gnu.org/bugs/ and at the top of the page when you created this bug. dst is 512-bit aligned (0x10112c0) src is 32-bit aligned (0x10112e4) buf is 64-bit aligned (0x1011308) al.c:41:72: runtime error: load of misaligned address 0x0000010112e4 for type '__int128 unsigned', which requires 16 byte alignment 0x0000010112e4: note: pointer points here 00 00 00 00 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 00 00 00 00 21 00 00 00 00 00 00 00 ^ al.c:41:46: runtime error: load of misaligned address 0x0000010112e4 for type '__int128 unsigned', which requires 16 byte alignment 0x0000010112e4: note: pointer points here 00 00 00 00 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 00 00 00 00 21 00 00 00 00 00 00 00 ^ src: 0x10101010101010101010101010101010 al.c:42:72: runtime error: load of misaligned address 0x000001011308 for type '__int128 unsigned', which requires 16 byte alignment 0x000001011308: note: pointer points here 00 00 00 00 00 08 10 18 20 28 30 38 40 48 50 58 60 68 70 78 11 04 00 00 00 00 00 00 73 72 63 3a ^ al.c:42:46: runtime error: load of misaligned address 0x000001011308 for type '__int128 unsigned', which requires 16 byte alignment 0x000001011308: note: pointer points here 00 00 00 00 00 08 10 18 20 28 30 38 40 48 50 58 60 68 70 78 11 04 00 00 00 00 00 00 73 72 63 3a ^ buf: 0x78706860585048403830282018100800 dst: 0x00000000000000000000000000000000 xoring... al.c:47:10: runtime error: load of misaligned address 0x0000010112e4 for type '__int128 unsigned', which requires 16 byte alignment 0x0000010112e4: note: pointer points here 00 00 00 00 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 00 00 00 00 21 00 00 00 00 00 00 00 ^ al.c:47:18: runtime error: load of misaligned address 0x000001011308 for type '__int128 unsigned', which requires 16 byte alignment 0x000001011308: note: pointer points here 00 00 00 00 00 08 10 18 20 28 30 38 40 48 50 58 60 68 70 78 11 04 00 00 00 00 00 00 78 6f 72 69 ^ success! dst: 0x68607870484058502820383008001810
