{"ast_node_type":"other","tokens":[{"end":94,"kind":"keyword","start":0,"text":"//"}]}
        // https://github.com/gcc-mirror/gcc/blob/master/gcc/config/nvptx/nvptx.md -> look for
        InlineAsmRegClass::Msp430(Msp430InlineAsmRegClass::reg) => "r",
        // "define_constraint".