Hello,

This patch pulls the reggroup framework in from my sysregs branch and 
adds it to GDB.  The reggroups framework makes it possible for an 
architecture to group the ISAs registers into a number of different 
categories.  Some groups are user-level, some are internal.  For instance:

User:
vector - vector registers
float - floating-point registers

Internal:
restore - registers to restore after performing an inferior function call

It makes the following changes:

- adds maintenance commands for displaying the register / groups and 
includes documentation.

(gdb) maint print register-groups
  Name         Nr  Rel Offset    Size  Type            Groups
  eax           0    0      0       4  int 
general,all,save,restore
  ecx           1    1      4       4  int 
general,all,save,restore
  edx           2    2      8       4  int 
general,all,save,restore
  ebx           3    3     12       4  int 
general,all,save,restore
  esp           4    4     16       4  *1 
general,all,save,restore
  ebp           5    5     20       4  *1 
general,all,save,restore
  esi           6    6     24       4  int 
general,all,save,restore
...
(gdb) maint print reggroups
  Group      Type
  general    user
  float      user
  system     user
  vector     user
  all        user
  save       internal
  restore    internal

- adds the files reggroups.[hc] which implement the `struct reggroup' 
object and reggroups() method.

- adds the architecture method:
	register_reggroup_p(gdbarch, regnum, reggroup)
to identify a register's group membership (provides a default).

Follow-on patches will modify varios parts of core GDB so that the 
mechanism is used vis:

- modify the default ``info registers'', ``info vector'' and ``info 
float'' and ``info all-registers'' commands so that reggroups are used 
to determine which registers should be displayed.

- modify the i386 to better specify the register groups (so that ``info 
vector'' displays all the SSE/MMX registers for instance.

- modify the regcache save/restore code so that it uses reggroups when 
determining which registers should be saved/restored across an inferior 
function call

Comments.

Eli, now does the revised doco look?  You've seen ``maint print 
reggroups'' before, but ``maint print register-groups'' is new.

I'll look to commit it next week.

The full internals doco is still work-in-progress :-(

Andrew