Re: [RFC] Use address_from_register in dwarf2-frame.c:read_addr_from_reg

[Joel Brobecker <brobecker@adacore.com>]

> ChangeLog:
> 
> 	* gdbarch.sh (value_from_register): Make class "m" instead of "f".
> 	Replace FRAME argument with FRAME_ID.
> 	* gdbarch.c, gdbarch.h: Regenerate.
> 	* findvar.c (default_value_from_register): Add GDBARCH argument;
> 	replace FRAME by FRAME_ID.  No longer call get_frame_id.
> 	(value_from_register): Update call to gdbarch_value_from_register.
> 	* value.h (default_value_from_register): Update prototype.
> 	* s390-linux-tdep.c (s390_value_from_register): Update interface
> 	and call to default_value_from_register.
> 	* spu-tdep.c (spu_value_from_register): Likewise.
> 
> 	* findvar.c (address_from_register): Remove TYPE argument.
> 	Do not call value_from_register; use gdbarch_value_from_register
> 	with null_frame_id instead.
> 	* value.h (address_from_register): Update prototype.
> 	* dwarf2-frame.c (read_addr_from_reg): Use address_from_register.
> 	* dwarf2loc.c (dwarf_expr_read_addr_from_reg): Update for
> 	address_from_register interface change.

FWIW, I am not a specialist here, but it seemed reasonable to me.

It took me a minute or two to figure out that you needed to make
value_from_register a class "m" because you don't have access to
the gdbarch via the frame anymore, so you have to have it passed
directly. Perhaps it's worth a sentence in the revision log when
you commit the patch?

Thanks for the detailed comment explaining why we use a null_frame_id
in address_from_register, and why it's OK to do so. Very helpful!

-- 
Joel