https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66804
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to Fei Yang from comment #4) > (In reply to Markus Trippelsdorf from comment #2) > > You're invoking undefined behavior: > > test.c:34:12: runtime error: store to > > misaligned address 0x000000401c8c for type 'unsigned char *', which requires > > 8 byte alignment > 0x000000401c8c: note: pointer points here > 00 00 00 00 00 > > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > 00 00 00 > ^ > > So your testcase is invalid. > > Any reference? The testcase works fine without vectorization. thanks It works fine without vectorization because on x86 unaligned non-vector accesses do not trap. Still the C standard says that pointers have to be suitably aligned.
