Re: [PATCH 3/3] tdesc: handle arbitrary strings in tdesc_register_in_reggroup_p

Stafford Horne
2017-06-09T11:45:48Z

On Thu, Jun 08, 2017 at 10:52:01PM +0200, Simon Marchi wrote:
> Hi Stafford,
>
> On 2017-06-08 00:15, Stafford Horne wrote:
> > @@ -1081,17 +1080,13 @@ tdesc_remote_register_number (struct gdbarch
> > *gdbarch, int regno)
> > }
> >
> > /* Check whether REGNUM is a member of REGGROUP. Registers from the
> > - target description may be classified as general, float, or vector.
> > - Unlike a gdbarch register_reggroup_p method, this function will
> > - return -1 if it does not know; the caller should handle registers
> > - with no specified group.
> > -
> > - Arbitrary strings (other than "general", "float", and "vector")
> > - from the description are not used; they cause the register to be
> > - displayed in "info all-registers" but excluded from "info
> > - registers" et al. The names of containing features are also not
> > - used. This might be extended to display registers in some more
> > - useful groupings.
> > + target description may be classified as general, float, vector or
> > other
> > + register groups registerd with reggroup_add(). Unlike a gdbarch
>
> s/registerd/registered/

Doh, I seem to never be able to spell register.

> > @@ -1231,6 +1209,27 @@ tdesc_use_registers (struct gdbarch *gdbarch,
> > void **slot = htab_find_slot (reg_hash, reg, INSERT);
> >
> > *slot = reg;
> > + /* Add reggroup if its new. */
> > + if (reg->group != NULL)
> > + {
> > + struct reggroup *group;
> > + bool group_exists = false;
> > +
> > + for (group = reggroup_next (gdbarch, NULL);
> > + group != NULL;
> > + group = reggroup_next (gdbarch, group))
> > + {
> > + if (strcmp (reg->group, reggroup_name (group)) == 0)
> > + {
> > + group_exists = true;
> > + break;
> > + }
> > + }
> > +
> > + if (!group_exists)
> > + reggroup_add (gdbarch, reggroup_new (reg->group,
> > + USER_REGGROUP));
>
> Is the memory allocated by reggroup_new ever freed?

It is not, and its a bit tricky. I looked through gdb, it seems the
reggroup objects are never freed, anywhere. The list itself and list
elements (reggroup_el) are all allocated on obstack, but not reggroup.

It could get a bit messy to try to do something about it like refcounts or
tracking reggroups per target description.

Any suggestions?

-Stafford