Cleanup basic buffer management.

* buffer.h (struct buffer): Change layout to use generic vector
marking code.  Fix some comments.  Change type of 'clip_changed'
to bitfield.  Remove unused #ifndef old.
(FIRST_FIELD_PER_BUFFER, LAST_FIELD_PER_BUFFER): Remove.
(GET_OVERLAYS_AT): Fix indentation.
(for_each_per_buffer_object_at): New macro.
* buffer.c (clone_per_buffer_values, reset_buffer_local_variables)
(Fbuffer_local_variables): Use it.
(init_buffer_once, syms_of_buffer): Remove unused #ifndef old.
* alloc.c (allocate_buffer): Adjust to match new layout of
struct buffer.  Fix comment.
(mark_overlay): New function.
(mark_buffer): Use it.  Use mark_vectorlike to mark normal
Lisp area of struct buffer.
(mark_object): Use it.  Adjust marking of misc objects
and related comments.

1 files changed, 54 insertions, 77 deletions

diff --git a/src/alloc.c b/src/alloc.c
index b0945aa30de..b329f89d15b 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1186,21 +1186,6 @@ lisp_align_free (void *block)
   MALLOC_UNBLOCK_INPUT;
 }
 
-/* Return a new buffer structure allocated from the heap with
-   a call to lisp_malloc.  */
-
-struct buffer *
-allocate_buffer (void)
-{
-  struct buffer *b
-    = (struct buffer *) lisp_malloc (sizeof (struct buffer),
-                                     MEM_TYPE_BUFFER);
-  XSETPVECTYPESIZE (b, PVEC_BUFFER,
-                    ((sizeof (struct buffer) + sizeof (EMACS_INT) - 1)
-                     / sizeof (EMACS_INT)));
-  return b;
-}
-
 
 #ifndef SYSTEM_MALLOC
 
@@ -3258,6 +3243,17 @@ allocate_pseudovector (int memlen, int lisplen, int tag)
   return v;
 }
 
+struct buffer *
+allocate_buffer (void)
+{
+  struct buffer *b = lisp_malloc (sizeof (struct buffer), MEM_TYPE_BUFFER);
+
+  XSETPVECTYPESIZE (b, PVEC_BUFFER, (offsetof (struct buffer, own_text)
+                                     - header_size) / word_size);
+  /* Note that the fields of B are not initialized.  */
+  return b;
+}
+
 struct Lisp_Hash_Table *
 allocate_hash_table (void)
 {
@@ -5786,15 +5782,29 @@ mark_char_table (struct Lisp_Vector *ptr)
     }
 }
 
-/* Mark the pointers in a buffer structure.  */
+/* Mark the chain of overlays starting at PTR.  */
+
+static void
+mark_overlay (struct Lisp_Overlay *ptr)
+{
+  for (; ptr && !ptr->gcmarkbit; ptr = ptr->next)
+    {
+      ptr->gcmarkbit = 1;
+      mark_object (ptr->start);
+      mark_object (ptr->end);
+      mark_object (ptr->plist);
+    }
+}
+
+/* Mark Lisp_Objects and special pointers in BUFFER.  */
 
 static void
 mark_buffer (struct buffer *buffer)
 {
-  register Lisp_Object *ptr, tmp;
+  /* This is handled much like other pseudovectors...  */
+  mark_vectorlike ((struct Lisp_Vector *) buffer);
 
-  eassert (!VECTOR_MARKED_P (buffer));
-  VECTOR_MARK (buffer);
+  /* ...but there are some buffer-specific things.  */
 
   MARK_INTERVAL_TREE (BUF_INTERVALS (buffer));
 
@@ -5802,24 +5812,8 @@ mark_buffer (struct buffer *buffer)
      a special way just before the sweep phase, and after stripping
      some of its elements that are not needed any more.  */
 
-  if (buffer->overlays_before)
-    {
-      XSETMISC (tmp, buffer->overlays_before);
-      mark_object (tmp);
-    }
-  if (buffer->overlays_after)
-    {
-      XSETMISC (tmp, buffer->overlays_after);
-      mark_object (tmp);
-    }
-
-  /* buffer-local Lisp variables start at `undo_list',
-     tho only the ones from `name' on are GC'd normally.  */
-  for (ptr = &buffer->BUFFER_INTERNAL_FIELD (name);
-       ptr <= &PER_BUFFER_VALUE (buffer,
-                                 PER_BUFFER_VAR_OFFSET (LAST_FIELD_PER_BUFFER));
-       ptr++)
-    mark_object (*ptr);
+  mark_overlay (buffer->overlays_before);
+  mark_overlay (buffer->overlays_after);
 
   /* If this is an indirect buffer, mark its base buffer.  */
   if (buffer->base_buffer && !VECTOR_MARKED_P (buffer->base_buffer))
@@ -6061,52 +6055,35 @@ mark_object (Lisp_Object arg)
 
     case Lisp_Misc:
       CHECK_ALLOCATED_AND_LIVE (live_misc_p);
-      if (XMISCANY (obj)->gcmarkbit)
-        break;
-      XMISCANY (obj)->gcmarkbit = 1;
 
-      switch (XMISCTYPE (obj))
+      if (XMISCTYPE (obj) == Lisp_Misc_Overlay)
+        mark_overlay (XOVERLAY (obj));
+      else
         {
+          if (XMISCANY (obj)->gcmarkbit)
+            break;
+          XMISCANY (obj)->gcmarkbit = 1;
 
-        case Lisp_Misc_Marker:
-          /* DO NOT mark thru the marker's chain.
-             The buffer's markers chain does not preserve markers from gc;
-             instead, markers are removed from the chain when freed by gc.  */
-          break;
+          /* Note that we don't mark thru the marker's
+             chain.  The buffer's markers chain does not
+             preserve markers from GC; instead, markers
+             are removed from the chain when freed by GC.  */
 
-        case Lisp_Misc_Save_Value:
 #if GC_MARK_STACK
-          {
-            register struct Lisp_Save_Value *ptr = XSAVE_VALUE (obj);
-            /* If DOGC is set, POINTER is the address of a memory
-               area containing INTEGER potential Lisp_Objects.  */
-            if (ptr->dogc)
-              {
-                Lisp_Object *p = (Lisp_Object *) ptr->pointer;
-                ptrdiff_t nelt;
-                for (nelt = ptr->integer; nelt > 0; nelt--, p++)
-                  mark_maybe_object (*p);
-              }
-          }
+          if (XMISCTYPE (obj) == Lisp_Misc_Save_Value)
+            {
+              register struct Lisp_Save_Value *ptr = XSAVE_VALUE (obj);
+              /* If DOGC is set, POINTER is the address of a memory
+                 area containing INTEGER potential Lisp_Objects.  */
+              if (ptr->dogc)
+                {
+                  Lisp_Object *p = (Lisp_Object *) ptr->pointer;
+                  ptrdiff_t nelt;
+                  for (nelt = ptr->integer; nelt > 0; nelt--, p++)
+                    mark_maybe_object (*p);
+                }
+            }
 #endif
-          break;
-
-        case Lisp_Misc_Overlay:
-          {
-            struct Lisp_Overlay *ptr = XOVERLAY (obj);
-            mark_object (ptr->start);
-            mark_object (ptr->end);
-            mark_object (ptr->plist);
-            if (ptr->next)
-              {
-                XSETMISC (obj, ptr->next);
-                goto loop;
-              }
-          }
-          break;
-
-        default:
-          abort ();
         }
       break;