[PATCH] Step over Objective-C dispatch function
Andrew Cagney
ac131313@redhat.com
Thu Mar 20 21:08:00 GMT 2003
> + /* Determine if we are currently in the Objective-C dispatch
> + function. If so, get the address of the method function that
> + the dispatcher would call and use that as the function to
> + step into instead. Also skip over the trampoline for the
> + function (if any). This is better for the user since they
> + are only interested in stepping into the method function
> + anyway. */
> + {
> + CORE_ADDR method_stop_pc;
> +
> + if (real_stop_pc)
> + find_objc_msgcall (real_stop_pc, &method_stop_pc);
> + else
> + find_objc_msgcall (stop_pc, &method_stop_pc);
> +
> + if (method_stop_pc)
> + ecs->stop_func_start = method_stop_pc;
> +
> + if (method_stop_pc)
> + {
> + real_stop_pc = SKIP_TRAMPOLINE_CODE (method_stop_pc);
> + if (real_stop_pc != 0)
> + ecs->stop_func_start = real_stop_pc;
> + }
> + }
> +
Adam,
Seems you were waiting on me here :-(
I've looked at what the underlying code is trying to do and,
unfortunatly, the original objc-lang.c botched its portability(1), sigh!
The file is currently native only so infrun.c can't directly refer to
objc-lang.c, and hence, will need to go via a dispatch table. Going via
a dispatch table wouldn't hurt anyway.
Can you please do things as sketched out below.
- append to "language.h":struct language_defn the method:
/* If PC is possibly an unknown languages trampoline.
If that PC falls in a trampoline belonging to this language,
return the address of the first pc in the real function, or 0
if it isn't a language tramp for this language. */
CORE_ADDR (*skip_trampoline) (CORE_ADDR pc);
- add to "language.h" the global method:
CORE_ADDR skip_language_trampoline (CORE_ADDR pc);
the implementation iterates through all registered languages looking for
and calling any non-NULL struct language_defn.skip_trampoline()
functions. Returning the result from the first that returns non-zero,
or 0 if all `fail'.
- add to objc-lang.c, a language specific objc_skip_trampoline() that
implements the above
- just confirm that the objc_skip_trampoline() only does target side
accesses (memory/register read/write) after it's confirmed that there is
a valid objc symbol. No valid objc symbol, no target access.
- for infrun.c, before the existing SKIP_TRAMPOLINE() call, make a call
to skip_language_trampoline() and then, only if that `fails', try the
SKIP_TRAMPOLINE() method.
The intent of all this is to make it possible to at leat enable objc on
selective natives, and then over time make it more portable.
Andrew
(1) I noticed that the parameter extract methods assume host=target.
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