Re: frame.c assertion failure

[Andrew Cagney <ac131313@redhat.com>]

> (unless you're trying to get code to use the new unwinder that is, or its some sort of inner most frame edge case?).

Nope, the backtrace tells all ...

> #0  internal_error (file=0x82acccd "../../src/gdb/frame.c", line=2083, 
>     string=0x82accb2 "%s%sAssertion `%s' failed.") at ../../src/gdb/utils.c:800
> #1  0x08141d9f in get_frame_type (frame=0x87af19c) at ../../src/gdb/frame.c:2083
> #2  0x080f39d6 in mips_init_extra_frame_info (fromleaf=0, fci=0x87af19c)
>     at ../../src/gdb/mips-tdep.c:2504

The legacy mips target is calling get_frame_type() on a frame that 
hasn't yet had it's type initialized.  I can think of:

-- Tweaking the below if to also test !legacy_frame_p().

> enum frame_type
> get_frame_type (struct frame_info *frame)
...
>   if (frame->unwind == NULL)

-- Tweaking the assignment to also check !legacy_frame_p().

>       /* FIXME: cagney/2003-04-02: Rather than storing the frame's
>          type in the frame, the unwinder's type should be returned
>          directly.  Unfortunatly, legacy code, called by
>          legacy_get_prev_frame, explicitly set the frames type using
>          the method deprecated_set_frame_type().  */
>       gdb_assert (frame->unwind->type != UNKNOWN_FRAME);

-- explicitly setting ->unwind to legacy_... in legacy_get_prev_frame.

I think the first is best:

- the second causes a get_frame_pc() call when, quite possibly, the 
legacy code isn't ready for this (see comments in legacy_get_prev_frame).

- the third leaves things open to gdb unintentionally calling a legacy 
unwind method.

Andrew