bug in gcc?

It seems that gcc not always put COMPONENT_REF when access fields of structures passed by reference. For example I add today simple static function append_name(aux_type_clutch &clutch, const char *name)

It has reference to field txt of structure aux_type_clutch but RTL looks like:

(insn 20 19 21 4 (set (reg/f:DI 0 ax [89])
        (mem/f/c:DI (plus:DI (reg/f:DI 6 bp)
                (const_int -8 [0xfffffffffffffff8])) [258 clutch+0 S8 A64])) "gptest.cpp":1364:24 80 {*movdi_internal}
     (nil))
(insn 21 20 22 4 (parallel [
            (set (reg/f:DI 0 ax [orig:83 _2 ] [83])
                (plus:DI (reg/f:DI 0 ax [89])
                    (const_int 8 [0x8])))
            (clobber (reg:CC 17 flags))
        ]) "gptest.cpp":1364:24 230 {*adddi_1}
     (expr_list:REG_EQUAL (plus:DI (mem/f/c:DI (plus:DI (reg/f:DI 19 frame)
                    (const_int -8 [0xfffffffffffffff8])) [258 clutch+0 S8 A64])
            (const_int 8 [0x8]))
        (nil)))

First instruction just loads in register RAX parm_decl (of type aux_type_clutch) like

mov     rax, [rbp+clutch]

and second add to RAX just some const 0x8 (offset to field txt):

add     rax, 8

it's impossible from RTL to track back this constant to offset in COMPONENT_REF

What is more even strange - for methods you can track fields access for parameters passed by reference (like this) - for example in constructor of the same aux_type_clutch:

(insn 12 11 13 2 (set (mem:SI (plus:DI (reg/f:DI 0 ax [94])
                (const_int 40 [0x28])) [4 this_12(D)->level+0 S4 A64])
        (const_int 0 [0])) "gptest.cpp":465:4 81 {*movsi_internal}
     (nil))