gcc/config/arm/arm-builtins.c:arm_expand_builtin contains numerous lines of the form: if (fcode == ARM_BUILTIN_WRORHI) error ("the range of count should be in 0 to 32. please check the intrinsic _mm_rori_pi16 in code."); else if (fcode == ARM_BUILTIN_WRORWI) See https://gcc.gnu.org/ml/gcc-patches/2017-03/msg00511.html for a discussion of how they could be improved.
Confirmed.