Function dr_set_vector_length 

pub unsafe extern "C" fn dr_set_vector_length(vl: c_int) -> bool_

• AArch64 Scalable Vector Extension’s vector length in bits is one of: 128 256 384 512 640 768 896 1024 1152 1280 1408 1536 1664 1792 1920 2048
• RISC-V Vector Extension’s vector length in bit is from 64 to 65536 in the power of 2. Returns whether successful. TODO i#3044: This function will only allow setting vector length if not running on SVE or RVV.