https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78782 --- Comment #1 from Jeffrey Walton <noloader at gmail dot com> --- Also documented in the Intel Intrinsics Guide at https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_loadu_si64. According to the guide, the intrinsic is the movq instruction.