Re: variable objects and registers

[Vladimir Prus <ghost@cs.msu.su>]

On Thursday 21 December 2006 04:29, Nick Roberts wrote:
>  >  > I think that we need more higher-level notification -- namely "new locals
>  >  > appeared" and either:
>  >  >         - "varobj now refers to different object"
>  >  >         - or have a command that creates varobjs for all variables
>  >  >         in a function.
>  > 
>  > The latter is "-stack-list-locals --make-varobjs" isn't it?  Or are you
>  > talking about variables declared within compound statements?
> 
> I see now that Insight has two commands:
> 
>     /* This implements the tcl command gdb_get_blocks
>      *
>      * Returns the start and end addresses for all blocks in
>      * the selected frame.
>      *
>      * Arguments:
>      *    None
>      * Tcl Result:
>      *    A list of all valid blocks in the selected_frame.
>      */
>     static int
>     gdb_get_blocks (ClientData clientData, Tcl_Interp *interp,
>     		    int objc, Tcl_Obj *CONST objv[])
> 
> 
> and
> 
> 
>     /* This implements the tcl command gdb_block_vars.
>      *
>      * Returns all variables valid in the specified block.
>      *
>      * Arguments:
>      *    The start and end addresses which identify the block.
>      * Tcl Result:
>      *    All variables defined in the given block.
>      */
>     static int
>     gdb_block_vars (ClientData clientData, Tcl_Interp *interp,
> 		    int objc, Tcl_Obj *CONST objv[])
> 
> 
> gdb_block_vars only gets called if gdb_get_blocks finds a new block which
> then finds any variabes local to it.  That way new variable objects can be
> added (and old ones deleted if a block has disappeared) while keeping
> the variable objects which are still in scope.  I think we should implement
> these functions in MI (perhaps Apple already have).

Again, I think we need more automated approach. Frontend should have a
single command  that:

	1. Reports which local variables are really dead now
	2. Creates and reports variable object for new locals 
	3. Reports which varobjs are out of scope

For example:

    -var-update --locals
    ^done,varobjs=[{name="v1",in_scope="false"....}{"name="v2",in_scope="true"....}]
               created=[{name="v3"....],
               gone-forever=[{name="v0"...}]


Apple creates varobjs for all variables in all blocks in a function, and use "in_scope" to
track their scope. That might be good approach too. IIRC, you've posted a patch
to consider block boundaries when computing "in_scope"? That's exactly what's
needed for this approach to work.

- Volodya