Hello, With gcc 4.7, on Intel 64 I have trouble using avx register global variables: register unsigned int something __asm__("xmm2") __attribute__ ((__vector_size__ (16))); works fine, but register unsigned int something __asm__("ymm2") __attribute__ ((__vector_size__ (32))); results in "error: invalid register name for something" Is it at all possible to use the YMM registers as variables? If yes, how? ps the ralated builtin functions are recognized, -mavx argument used. - Gabor