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Subject: RE: [PATCH:MI] Return a subset of a variable object's children
Date: Wed, 30 Apr 2008 16:29:00 -0000
Message-ID: <6D19CA8D71C89C43A057926FE0D4ADAA042910B7@ecamlmw720.eamcs.ericsson.se>
In-Reply-To: <200804301109.20906.vladimir@codesourcery.com>
From: "Marc Khouzam" <marc.khouzam@ericsson.com>
To: "Vladimir Prus" <vladimir@codesourcery.com>,         "Nick Roberts" <nickrob@snap.net.nz>
Cc: <gdb-patches@sources.redhat.com>
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> > > > > but only actually create the children that have been requested by=
 the
> > > > > user.  I'm not sure how much efficiency there is by allocating the
> > > > > memory before hand?  Also, is there no way to grow the vector by =
more
> > > > > than a single point at a time?
> > > >=20
> > > > Like resize with STL vectors?  I'm not aware of one.
> > >=20
> > > VEC_safe_grow
> >=20
> > OK, I didn't know about that.  Why not use it instead of VEC_safe_push =
in the
> > construct above?
>=20
> Well, it happens not to initialize the data, so some changes in further l=
ogic will
> be required. Until now, it was not a performance issue.

My concern about

  while (VEC_length (varobj_p, var->children) < var->num_children)
    VEC_safe_push (varobj_p, var->children, NULL);

is that the vector may be reallocated multiple times.
How about something like this (assuming quick_push does what I think it doe=
s)

  var->children =3D VEC_alloc(varobj_p, var->num_children);
  for (i=3D0; i<var->num_children; i++)
    VEC_quick_push (varobj_p, var->children, NULL);

Same loop, but it avoids having to reallocate the vector.

Just a thought, not related to Nick's patch.

Marc