Don't GC-scan stack data redundantly.

* src/alloc.c (Fgarbage_collect): When using stack scanning, don't
redundantly scan byte-code stacks, catchlist, and handlerlist.
* src/bytecode.c (BYTE_MAINTAIN_TOP): New macros.
(struct byte_stack): Only define `top' and `bottom' if used.
(mark_byte_stack): Only define if used.
(BEFORE_POTENTIAL_GC, AFTER_POTENTIAL_GC): Nullify if BYTE_MAINTAIN_TOP
is not set.
(Fbyte_code): Don't set `bottom' unless BYTE_MAINTAIN_TOP is set.
* src/lisp.h (BYTE_MARK_STACK): New macro.
(mark_byte_stack): Only declare if BYTE_MARK_STACK is set.
* src/term.c (OUTPUT_IF): Use OUTPUT.

1 files changed, 6 insertions, 4 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 566c6fe00b9..e8b8f45e9b1 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -4842,8 +4842,6 @@ returns nil, because real GC can't be done.  */)
   (void)
 {
   register struct specbinding *bind;
-  struct catchtag *catch;
-  struct handler *handler;
   char stack_top_variable;
   register int i;
   int message_p;
@@ -4972,9 +4970,11 @@ returns nil, because real GC can't be done.  */)
       for (i = 0; i < tail->nvars; i++)
         mark_object (tail->var[i]);
   }
-#endif
-
   mark_byte_stack ();
+  {
+    struct catchtag *catch;
+    struct handler *handler;
+
   for (catch = catchlist; catch; catch = catch->next)
     {
       mark_object (catch->tag);
@@ -4985,7 +4985,9 @@ returns nil, because real GC can't be done.  */)
       mark_object (handler->handler);
       mark_object (handler->var);
     }
+  }
   mark_backtrace ();
+#endif
 
 #ifdef HAVE_WINDOW_SYSTEM
   mark_fringe_data ();