syntax_data: {"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"Self::xmm_reg"}]}
source_snippet:             Self::xmm_reg => Some(('x', "xmm0", 128).into()),
context_before:             Self::reg_byte => None,
context_after:             Self::ymm_reg => Some(('y', "ymm0", 256).into()),