Re: [rfc] [02/05] Get rid of current_gdbarch in hppa-linux-nat.c

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Wed, 07 Nov 2007 12:49:22 +0100
> From: Markus Deuling <deuling@de.ibm.com>
> CC: gdb-patches@sourceware.org, uweigand@de.ibm.com
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> Mark Kettenis schrieb:
> >> Date: Wed, 07 Nov 2007 12:11:02 +0100
> >> From: Markus Deuling <deuling@de.ibm.com>
> >>
> >> Hi,
> >>
> >> this patch adds gdbarch as a parameter to hppa_linux_register_addr. 
> >>
> >> Tested with gdb_mbuild. Ok to commit ?
> > 
> > Actually, this is getting a bit silly.  That gdbarch is only needed
> > for a sanaity check, and obviously the gdbarch_num_regs call can just
> > be replaced with an appropriate bounds check on the u_offsets array.
> > 
> >    if (regno < 0 || regno >= ARRAY_SIZE(u_offsets))
> > 
> > should do the trick.
> 
> Sure it would. But what for do we have gdbarch_num_regs? I dont think its a good idea
> to either use gdbarch_num_regs or ARRAY_SIZE(whatever) at will. This is redundant and error-prone.
> Btw, there are two further uses of gdbarch_num_regs in that file.
> 
> For my opinion gdbarch should be used to describe an architecture.

Indeed, and the check in hppa_linux_register_addr is not checking the
architecture.  It's there to check whether that function is being
called for a register that's outside the range covered by u_offsets.
Using gdb_num_regs for that purpose is error-prone, since someone
might increase the number of registers for the hppa architecture, but
forget to update the u_offsets array.  The whole check should probably
be converted into a gdb_assert(), since this function should not be
called with a register number not covered by u_offsets in the first
place.

The other uses of gdbarch_num_regs() in this file are fine, since
there they are used as the number of registers defined by the
architecture.

Mark