Add multiple-CPU support in ravenscar-thread.c

This patch reworks the ravenscar-thread layer to remove the
assumption that the target only has 1 CPU. In particular,
when connected to a QEMU target over the remote protocol,
QEMU reports each CPU as one thread. This patch adapts
the ravenscar-thread layer to this, and adds a large comment
explaining the general design of this unit.

gdb/ChangeLog:

        * ada-lang.h (ada_get_task_info_from_ptid): Add declaration.
        * ada-tasks.c (ada_get_task_info_from_ptid): New function.
        * ravenscar-thread.c: Add into comment.
        (base_magic_null_ptid): Delete.
        (base_ptid): Change documentation.
        (ravenscar_active_task): Renames ravenscar_running_thread.
        All callers updated throughout.
        (is_ravenscar_task, ravenscar_get_thread_base_cpu): New function.
        (ravenscar_task_is_currently_active): Likewise.
        (get_base_thread_from_ravenscar_task): Ditto.
        (ravenscar_update_inferior_ptid): Adjust to handle multiple CPUs.
        (ravenscar_runtime_initialized): Likewise.
        (get_running_thread_id): Add new parameter "cpu".  Adjust
        implementation to handle this new parameter.
        (ravenscar_fetch_registers): Small adjustment to use
        is_ravenscar_task and ravenscar_task_is_currently_active in
        order to decide whether to use the target beneath or this
        module's arch_ops.
        (ravenscar_store_registers, ravenscar_prepare_to_store): Likewise.
        (ravenscar_stopped_by_sw_breakpoint): Use
        get_base_thread_from_ravenscar_task to get the underlying
        thread, rather than using base_ptid.
        (ravenscar_stopped_by_hw_breakpoint, ravenscar_stopped_by_watchpoint)
        (ravenscar_stopped_data_address, ravenscar_core_of_thread):
        Likewise.
        (ravenscar_inferior_created): Do not set base_magic_null_ptid.

1 files changed, 24 insertions, 0 deletions

diff --git a/gdb/ada-tasks.c b/gdb/ada-tasks.c
index e29b563..16cee35 100644
--- a/gdb/ada-tasks.c
+++ b/gdb/ada-tasks.c
@@ -353,6 +353,30 @@ ada_task_is_alive (struct ada_task_info *task_info)
   return (task_info->state != Terminated);
 }
 
+/* Search through the list of known tasks for the one whose ptid is
+   PTID, and return it.  Return NULL if the task was not found.  */
+
+struct ada_task_info *
+ada_get_task_info_from_ptid (ptid_t ptid)
+{
+  int i, nb_tasks;
+  struct ada_task_info *task;
+  struct ada_tasks_inferior_data *data;
+
+  ada_build_task_list ();
+  data = get_ada_tasks_inferior_data (current_inferior ());
+  nb_tasks = VEC_length (ada_task_info_s, data->task_list);
+
+  for (i = 0; i < nb_tasks; i++)
+    {
+      task = VEC_index (ada_task_info_s, data->task_list, i);
+      if (ptid_equal (task->ptid, ptid))
+	return task;
+    }
+
+  return NULL;
+}
+
 /* Call the ITERATOR function once for each Ada task that hasn't been
    terminated yet.  */