I'm not able to compile a program that uses `rdrand` and a word64 due to "Error: operand size mismatch for `rdrand'". If I try to explicitly use `rdrandq` and the word64, then it results in "Error: invalid instruction suffix for `rdrand'" According to the Intel manual [1], RDRAND operates on 32-bit operands even in 64-bit mode. The manual goes onto to say we should use the REX prefix to operate on 64-bit operands. How do I set REX prefix when using RDRAND and the inline assembler? Thanks in advance. [1] Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 2, page 4-298 (https://www-ssl.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf)
