Register Groups (again)

[Andrew Cagney <ac131313 at ges dot redhat dot com>]

See: http://sources.redhat.com/ml/gdb/2001-02/msg00268.html for the 
origins of this idea.


I'd like to propose a new object ``struct reggroup'' and a number of 
methods:


struct reggroup; // the opaque object

// Some predefined register groups
struct reggroup *general_reggroup;
struct reggroup *float_reggroup;
struct reggroup *system_reggroup;
struct reggroup *vector_reggroup;
struct reggroup *all_reggroup;

// architecture method indicating membership of a register group
int register_reggroup_p (gdbarch, regnum, reggroup);

// The reggroup's attributes
const char *reggroup_name (reggroup);

// Null terminated list of the architectures reggroups
struct reggroup **reggroups (gdbarch);

// Add a custom register group to an architecture
struct reggroup *reggroup_add (gdbarch, name, other attributes?);


A default register group function could look something like:

	if all group
	  return 1
	if float group and register's type is float
	  return 1;
	if vector group and register's type is vector
	  return 1;
	if general group and register's type isn't float or vector
	  return 1
	return 0

And the ``info registers', ``info float'', ``info all-registers'' and 
``info vector'' (``info system''?) commands would then use it.


The big gapeing holes in this proposal are:


- an MI/GUI interface.

The above interface provides:

	for (regnum = 0; regnum < NUM_REGS+NUM_PSEUDO_REGS; regnum++)
	  if (register_reggroup_p (arch, regnum, XXXX_group)
	    ....

I guess that would be abstracted somehow.  Somebody elses problem though :-)


- how it relates to frames

It currently assumes that the register groups are identical between 
frames :-/


comments, thoughts?
Andrew


PS: I guess this gets written up and goes into the ``Registers'' chapter.