Slightly tweak and clarify target_resume's interface

The current target_resume interface is a bit odd & non-intuitive.
I've found myself explaining it a couple times the recent past, while
reviewing patches that assumed STEP/SIGNAL always applied to the
passed in PTID.  It goes like this today:

  - if the passed in PTID is a thread, then the step/signal request is
    for that thread.

  - otherwise, if PTID is a wildcard (all threads or all threads of
    process), the step/signal request is for inferior_ptid, and PTID
    indicates which set of threads run free.

Because GDB always switches the current thread to "leader" thread
being resumed/stepped/signalled, we can simplify this a bit to:

  - step/signal are always for inferior_ptid.

  - PTID indicates the set of threads that run free.

Still not ideal, but it's a minimal change and at least there are no
special cases this way.

That's what this patch does.  It renames the PTID parameter to
SCOPE_PTID, adds some assertions to target_resume, and tweaks
target_resume's description.  In addition, it also renames PTID to
SCOPE_PTID in the remote and linux-nat targets, and simplifies their
implementation a little bit.  Other targets could do the same, but
they don't have to.

Change-Id: I02a2ec2ab3a3e9b191de1e9a84f55c17cab7daaf

1 files changed, 8 insertions, 5 deletions

diff --git a/gdb/target.c b/gdb/target.c
index 7d291fd4d0..1063f8086b 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -2655,21 +2655,24 @@ target_thread_info_to_thread_handle (struct thread_info *tip)
 }
 
 void
-target_resume (ptid_t ptid, int step, enum gdb_signal signal)
+target_resume (ptid_t scope_ptid, int step, enum gdb_signal signal)
 {
   process_stratum_target *curr_target = current_inferior ()->process_target ();
   gdb_assert (!curr_target->commit_resumed_state);
 
+  gdb_assert (inferior_ptid != null_ptid);
+  gdb_assert (inferior_ptid.matches (scope_ptid));
+
   target_dcache_invalidate ();
 
-  current_inferior ()->top_target ()->resume (ptid, step, signal);
+  current_inferior ()->top_target ()->resume (scope_ptid, step, signal);
 
-  registers_changed_ptid (curr_target, ptid);
+  registers_changed_ptid (curr_target, scope_ptid);
   /* We only set the internal executing state here.  The user/frontend
      running state is set at a higher level.  This also clears the
      thread's stop_pc as side effect.  */
-  set_executing (curr_target, ptid, true);
-  clear_inline_frame_state (curr_target, ptid);
+  set_executing (curr_target, scope_ptid, true);
+  clear_inline_frame_state (curr_target, scope_ptid);
 
   if (target_can_async_p ())
     target_async (1);