[BE] How to query attributes of a function being called?

[Georg-Johann Lay]

Hi, suppose this test case of C code:

typedef void (*cb_t)(void) __attribute__((callback));

void caller (cb_t cb)
{
     cb();
}

What I need in the backend is a way to query for the attributs that are 
attaches to callees like 'cb'.

./config/i386/winnt.c uses TARGET_MANGLE_DECL_ASSEMBLER_NAME in order to 
encode some information in the callee's name, but in my case the call 
may be indirect as indicated above.

FYI, the attribute indicates that upon calling cb the program will cross 
a security barrier, so that the caller must take some actions before and 
after issuing the call to establish some kind of "wall" against the 
callback.

Thanks, Georg-Johann