Simplify thread initialization and GC

* src/lisp.h (PVECHEADERSIZE): New macro.
(XSETPVECTYPESIZE): Use it.
* src/search.c (syms_of_search): No need to initialize or
staticpro last_thing_searched or saved_last_thing_searched, as
the thread code arranges for initialization and GC.
* src/thread.c (main_thread): Initialize statically.
(Fmake_mutex, Fmake_condition_variable, Fmake_thread):
Use ALLOCATE_ZEROED_PSEUDOVECTOR rather than zeroing by hand.
(mark_one_thread): No need to mark Lisp_Object members.
(init_main_thread, init_threads_once): Remove.  All uses removed.

1 files changed, 30 insertions, 62 deletions

diff --git a/src/thread.c b/src/thread.c
index 670680f2b0d..e2deadd7a83 100644
--- a/src/thread.c
+++ b/src/thread.c
@@ -35,7 +35,21 @@ union aligned_thread_state
 };
 verify (GCALIGNED (union aligned_thread_state));
 
-static union aligned_thread_state main_thread;
+static union aligned_thread_state main_thread
+  = {{
+      .header.size = PVECHEADERSIZE (PVEC_THREAD,
+                                     PSEUDOVECSIZE (struct thread_state,
+                                                    event_object),
+                                     VECSIZE (struct thread_state)),
+      .m_last_thing_searched = LISPSYM_INITIALLY (Qnil),
+      .m_saved_last_thing_searched = LISPSYM_INITIALLY (Qnil),
+      .name = LISPSYM_INITIALLY (Qnil),
+      .function = LISPSYM_INITIALLY (Qnil),
+      .result = LISPSYM_INITIALLY (Qnil),
+      .error_symbol = LISPSYM_INITIALLY (Qnil),
+      .error_data = LISPSYM_INITIALLY (Qnil),
+      .event_object = LISPSYM_INITIALLY (Qnil),
+    }};
 
 struct thread_state *current_thread = &main_thread.s;
 
@@ -261,19 +275,15 @@ NAME, if given, is used as the name of the mutex.  The name is
 informational only.  */)
   (Lisp_Object name)
 {
-  struct Lisp_Mutex *mutex;
-  Lisp_Object result;
-
   if (!NILP (name))
     CHECK_STRING (name);
 
-  mutex = ALLOCATE_PSEUDOVECTOR (struct Lisp_Mutex, name, PVEC_MUTEX);
-  memset ((char *) mutex + offsetof (struct Lisp_Mutex, mutex),
-          0, sizeof (struct Lisp_Mutex) - offsetof (struct Lisp_Mutex,
-                                                    mutex));
+  struct Lisp_Mutex *mutex
+    = ALLOCATE_ZEROED_PSEUDOVECTOR (struct Lisp_Mutex, name, PVEC_MUTEX);
   mutex->name = name;
   lisp_mutex_init (&mutex->mutex);
 
+  Lisp_Object result;
   XSETMUTEX (result, mutex);
   return result;
 }
@@ -379,21 +389,17 @@ NAME, if given, is the name of this condition variable.  The name is
 informational only.  */)
   (Lisp_Object mutex, Lisp_Object name)
 {
-  struct Lisp_CondVar *condvar;
-  Lisp_Object result;
-
   CHECK_MUTEX (mutex);
   if (!NILP (name))
     CHECK_STRING (name);
 
-  condvar = ALLOCATE_PSEUDOVECTOR (struct Lisp_CondVar, name, PVEC_CONDVAR);
-  memset ((char *) condvar + offsetof (struct Lisp_CondVar, cond),
-          0, sizeof (struct Lisp_CondVar) - offsetof (struct Lisp_CondVar,
-                                                      cond));
+  struct Lisp_CondVar *condvar
+    = ALLOCATE_ZEROED_PSEUDOVECTOR (struct Lisp_CondVar, name, PVEC_CONDVAR);
   condvar->mutex = mutex;
   condvar->name = name;
   sys_cond_init (&condvar->cond);
 
+  Lisp_Object result;
   XSETCONDVAR (result, condvar);
   return result;
 }
@@ -637,10 +643,8 @@ mark_one_thread (struct thread_state *thread)
       mark_object (tem);
     }
 
-  mark_object (thread->m_last_thing_searched);
-
-  if (!NILP (thread->m_saved_last_thing_searched))
-    mark_object (thread->m_saved_last_thing_searched);
+  /* No need to mark Lisp_Object members like m_last_thing_searched,
+     as mark_threads_callback does that by calling mark_object.  */
 }
 
 static void
@@ -792,12 +796,6 @@ When the function exits, the thread dies.
 If NAME is given, it must be a string; it names the new thread.  */)
   (Lisp_Object function, Lisp_Object name)
 {
-  sys_thread_t thr;
-  struct thread_state *new_thread;
-  Lisp_Object result;
-  const char *c_name = NULL;
-  size_t offset = offsetof (struct thread_state, m_stack_bottom);
-
   /* Can't start a thread in temacs.  */
   if (!initialized)
     emacs_abort ();
@@ -805,20 +803,13 @@ If NAME is given, it must be a string; it names the new thread.  */)
   if (!NILP (name))
     CHECK_STRING (name);
 
-  new_thread = ALLOCATE_PSEUDOVECTOR (struct thread_state, event_object,
-                                      PVEC_THREAD);
-  memset ((char *) new_thread + offset, 0,
-          sizeof (struct thread_state) - offset);
-
+  struct thread_state *new_thread
+    = ALLOCATE_ZEROED_PSEUDOVECTOR (struct thread_state, event_object,
+                                    PVEC_THREAD);
   new_thread->function = function;
   new_thread->name = name;
-  new_thread->m_last_thing_searched = Qnil; /* copy from parent? */
-  new_thread->m_saved_last_thing_searched = Qnil;
+  /* Perhaps copy m_last_thing_searched from parent?  */
   new_thread->m_current_buffer = current_thread->m_current_buffer;
-  new_thread->result = Qnil;
-  new_thread->error_symbol = Qnil;
-  new_thread->error_data = Qnil;
-  new_thread->event_object = Qnil;
 
   new_thread->m_specpdl_size = 50;
   new_thread->m_specpdl = xmalloc ((1 + new_thread->m_specpdl_size)
@@ -833,9 +824,8 @@ If NAME is given, it must be a string; it names the new thread.  */)
   new_thread->next_thread = all_threads;
   all_threads = new_thread;
 
-  if (!NILP (name))
-    c_name = SSDATA (ENCODE_UTF_8 (name));
-
+  char const *c_name = !NILP (name) ? SSDATA (ENCODE_UTF_8 (name)) : NULL;
+  sys_thread_t thr;
   if (! sys_thread_create (&thr, c_name, run_thread, new_thread))
     {
       /* Restore the previous situation.  */
@@ -848,6 +838,7 @@ If NAME is given, it must be a string; it names the new thread.  */)
     }
 
   /* FIXME: race here where new thread might not be filled in?  */
+  Lisp_Object result;
   XSETTHREAD (result, new_thread);
   return result;
 }
@@ -1060,22 +1051,6 @@ thread_check_current_buffer (struct buffer *buffer)
 
 
 
-static void
-init_main_thread (void)
-{
-  main_thread.s.header.size
-    = PSEUDOVECSIZE (struct thread_state, event_object);
-  XSETPVECTYPE (&main_thread.s, PVEC_THREAD);
-  main_thread.s.m_last_thing_searched = Qnil;
-  main_thread.s.m_saved_last_thing_searched = Qnil;
-  main_thread.s.name = Qnil;
-  main_thread.s.function = Qnil;
-  main_thread.s.result = Qnil;
-  main_thread.s.error_symbol = Qnil;
-  main_thread.s.error_data = Qnil;
-  main_thread.s.event_object = Qnil;
-}
-
 bool
 main_thread_p (const void *ptr)
 {
@@ -1091,15 +1066,8 @@ in_current_thread (void)
 }
 
 void
-init_threads_once (void)
-{
-  init_main_thread ();
-}
-
-void
 init_threads (void)
 {
-  init_main_thread ();
   sys_cond_init (&main_thread.s.thread_condvar);
   sys_mutex_init (&global_lock);
   sys_mutex_lock (&global_lock);