"Bharati Bhole" <bharati.bhole@xxxxxxxxx> writes: > I am not able to understand the structure of rtx_def fully its too complicated. > Could anybody please guide me. Its defined in rtl.h. > struct rtx_def GTY((chain_next ("RTX_NEXT (&%h)"), > chain_prev ("RTX_PREV (&%h)"))) > { > ENUM_BITFIELD(rtx_code) code: 16; > ENUM_BITFIELD(machine_mode) mode : 8; > unsigned int jump : 1; > unsigned int call : 1; > unsigned int unchanging : 1; > unsigned int volatil : 1; > unsigned int in_struct : 1; > unsigned int used : 1; > unsigned frame_related : 1; > unsigned return_val : 1; > union u { > rtunion fld[1]; > HOST_WIDE_INT hwint[1]; > } GTY ((special ("rtx_def"), desc ("GET_CODE (&%0)"))) u; > }; What is your specific question? The GTY construct is documented in gcc/doc/gty.texi. Everything else is pretty standard. You can find the definition of ENUM_BITFIELD by using grep. Ian