gdb: introduce 'all_non_exited_process_targets' and 'switch_to_target_no_thread'

Introduce two new convenience functions:

1. all_non_exited_process_targets: returns a collection of all process
stratum targets that have non-exited inferiors on them.  Useful for
iterating targets.

2. switch_to_target_no_thread: switch the context to the first
inferior of the given target, and to no selected thread.

gdb/ChangeLog:
2020-05-14  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* process-stratum-target.h: Include <set>.
	(all_non_exited_process_targets, switch_to_target_no_thread): New
	function declarations.
	* process-stratum-target.c (all_non_exited_process_targets)
	(switch_to_target_no_thread): New function implementations.

1 files changed, 25 insertions, 0 deletions

diff --git a/gdb/process-stratum-target.c b/gdb/process-stratum-target.c
index f3fd9ee..9eff5ab 100644
--- a/gdb/process-stratum-target.c
+++ b/gdb/process-stratum-target.c
@@ -83,3 +83,28 @@ process_stratum_target::has_execution (inferior *inf)
      through hoops.  */
   return inf->pid != 0;
 }
+
+/* See process-stratum-target.h.  */
+
+std::set<process_stratum_target *>
+all_non_exited_process_targets ()
+{
+  /* Inferiors may share targets.  To eliminate duplicates, use a set.  */
+  std::set<process_stratum_target *> targets;
+  for (inferior *inf : all_non_exited_inferiors ())
+    targets.insert (inf->process_target ());
+
+  return targets;
+}
+
+/* See process-stratum-target.h.  */
+
+void
+switch_to_target_no_thread (process_stratum_target *target)
+{
+  for (inferior *inf : all_inferiors (target))
+    {
+      switch_to_inferior_no_thread (inf);
+      break;
+    }
+}