[MPS] Use xmalloc to allocate 'bc_thread_state' struct

This struct cannot live in MPS-managed memory because it's required
for scanning the bytecode stack.

* src/bytecode.c (free_bc_thread) [MPS]: Free bytecode structure.
(Finternal_stack_stats, exec_byte_code):
* src/igc.c (scan_bc): Adjust.
(root_create_bc): Save 'bc' pointer.
* src/lisp.h (get_act_rec, set_act_rec):
* src/thread.c (mark_one_thread, finalize_one_thread): Adjust.
(Fmake_thread) [MPS]:
(init_threads) [MPS]: Allocate bytecode structure.
* src/thread.h (struct thread_state): Turn 'bc' member into a
pointer (MPS) or single-member array.

src/bytecode.c

@@ -399,6 +399,9 @@ void
 free_bc_thread (struct bc_thread_state *bc)
 {
   xfree (bc->stack);
+#ifdef HAVE_MPS
+  xfree (bc);
+#endif
 }
 
 #ifndef HAVE_MPS
@@ -439,7 +442,7 @@ DEFUN ("internal-stack-stats", Finternal_stack_stats, Sinternal_stack_stats,
        doc: /* internal */)
   (void)
 {
-  struct bc_thread_state *bc = &current_thread->bc;
+  struct bc_thread_state *bc = current_thread->bc;
   int nframes = 0;
   int nruns = 0;
   for (struct bc_frame *fp = bc->fp; fp; fp = fp->saved_fp)
@@ -474,7 +477,7 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template,
   int volatile this_op = 0;
 #endif
   unsigned char quitcounter = 1;
-  struct bc_thread_state *bc = &current_thread->bc;
+  struct bc_thread_state *bc = current_thread->bc;
 
   /* Values used for the first stack record when called from C.  */
   Lisp_Object *top = NULL;
@@ -983,7 +986,7 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template,
 		handlerlist = c->next;
 		top = c->bytecode_top;
 		op = c->bytecode_dest;
-		bc = &current_thread->bc;
+		bc = current_thread->bc;
 		struct bc_frame *fp = bc->fp;
 
 		Lisp_Object fun = fp->fun;

src/igc.c

@@ -163,7 +163,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. */
 # ifndef HASH_Lisp_User_Ptr_7DC5544B44
 #  error "struct Lisp_User_Ptr changed"
 # endif
-# ifndef HASH_thread_state_67C02A2EF0
+# ifndef HASH_thread_state_6DAE3DDD15
 #  error "struct thread_state changed"
 # endif
 # ifndef HASH_Lisp_Mutex_744F44A86D
@@ -923,6 +923,7 @@ struct igc_thread
   /* Back pointer to Emacs' thread object.  Allocated so that it doesn't
      move in memory.  */
   struct thread_state *ts;
+  struct bc_thread_state *bc;
 };
 
 typedef struct igc_thread igc_thread;
@@ -1732,7 +1733,7 @@ scan_bc (mps_ss_t ss, void *start, void *end, void *closure)
   MPS_SCAN_BEGIN (ss)
   {
     struct igc_thread_list *t = closure;
-    struct bc_thread_state *bc = &t->d.ts->bc;
+    struct bc_thread_state *bc = t->d.bc;
     igc_assert (start == (void *) bc->stack);
     igc_assert (end == (void *) bc->stack_end);
     /* FIXME/igc: AFAIU the current top frame starts at
@@ -3135,7 +3136,8 @@ static void
 root_create_bc (struct igc_thread_list *t)
 {
   struct igc *gc = t->d.gc;
-  struct bc_thread_state *bc = &t->d.ts->bc;
+  struct bc_thread_state *bc = t->d.ts->bc;
+  t->d.bc = bc;
   igc_assert (bc->stack != NULL);
   mps_root_t root;
   mps_res_t res = mps_root_create_area (&root, gc->arena, mps_rank_ambig (), 0,

src/lisp.h

@@ -5640,13 +5640,13 @@ extern void *bc_next_frame (struct bc_frame *bc);
 INLINE struct bc_frame *
 get_act_rec (struct thread_state *th)
 {
-  return th->bc.fp;
+  return th->bc->fp;
 }
 
 INLINE void
 set_act_rec (struct thread_state *th, struct bc_frame *act_rec)
 {
-  th->bc.fp = act_rec;
+  th->bc->fp = act_rec;
 }
 
 /* Defined in macros.c.  */

src/thread.c

@@ -687,7 +687,7 @@ mark_one_thread (struct thread_state *thread)
       mark_object (tem);
     }
 
-  mark_bytecode (&thread->bc);
+  mark_bytecode (thread->bc);
 
   /* No need to mark Lisp_Object members like m_last_thing_searched,
      as mark_threads_callback does that by calling mark_object.  */
@@ -895,7 +895,7 @@ finalize_one_thread (struct thread_state *state)
   free_search_regs (&state->m_search_regs);
   free_search_regs (&state->m_saved_search_regs);
   sys_cond_destroy (&state->thread_condvar);
-  free_bc_thread (&state->bc);
+  free_bc_thread (state->bc);
 }
 
 DEFUN ("make-thread", Fmake_thread, Smake_thread, 1, 3, 0,
@@ -925,6 +925,7 @@ will be signaled.  */)
   new_thread->name = name;
 #ifdef HAVE_MPS
   new_thread->m_getcjmp = igc_xzalloc_ambig (sizeof (*new_thread->m_getcjmp));
+  new_thread->bc = xzalloc (sizeof (*new_thread->bc));
 #endif
   /* Perhaps copy m_last_thing_searched from parent?  */
   new_thread->m_current_buffer = current_thread->m_current_buffer;
@@ -935,7 +936,7 @@ will be signaled.  */)
   new_thread->m_specpdl_end = new_thread->m_specpdl + size;
   new_thread->m_specpdl_ptr = new_thread->m_specpdl;
 
-  init_bc_thread (&new_thread->bc);
+  init_bc_thread (new_thread->bc);
   sys_cond_init (&new_thread->thread_condvar);
 
   /* We'll need locking here eventually.  */
@@ -1273,7 +1274,10 @@ init_threads (void)
 
   main_thread.s.thread_id = sys_thread_self ();
   main_thread.s.buffer_disposition = Qnil;
-  init_bc_thread (&main_thread.s.bc);
+#ifdef HAVE_MPS
+  main_thread.s.bc = xzalloc (sizeof (*main_thread.s.bc));
+#endif
+  init_bc_thread (main_thread.s.bc);
 #ifdef HAVE_MPS
   igc_on_alloc_main_thread_bc ();
 #endif

src/thread.h

@@ -224,12 +224,13 @@ struct thread_state
   /* Threads are kept on a linked list.  */
   struct thread_state *next_thread;
 
-  struct bc_thread_state bc;
-
-# ifdef HAVE_MPS
+#ifndef HAVE_MPS
+  struct bc_thread_state bc[1];
+#else
+  struct bc_thread_state *bc;
   void *gc_info;
   ptrdiff_t pin_index;
-# endif
+#endif
 
 } GCALIGNED_STRUCT;