[gcc plugin] get member offset in struct just like offsetof

[Eric Botcazou]

> I am writing a gcc plugin for parsing the structure fields. But I have the
> problem how to get the offset of each field in the struct? Just like the
> offsetof macro in gcc.
> 
> I see DECL_FIELD_OFFSET in tree.h, but the result seems not right.

The offset in bits/bytes is given by tree.c:bit_position/byte_position.

-- 
Eric Botcazou