Shrink struct vectorlike_header to the only size field.

* lisp.h (enum pvec_type): Avoid explicit enum member values.
Adjust comment.
(enum More_Lisp_Bits): Change PSEUDOVECTOR_SIZE_BITS and
PVEC_TYPE_MASK to arrange new bitfield in the vector header.
(PSEUDOVECTOR_REST_BITS, PSEUDOVECTOR_REST_MASK): New members.
(PSEUDOVECTOR_AREA_BITS): New member used to extract subtype
information from the vector header.  Adjust comment.
(XSETPVECTYPE, XSETPVECTYPESIZE, XSETTYPED_PSEUDOVECTOR)
(PSEUDOVECTOR_TYPEP, DEFUN): Adjust to match new vector header
layout.
(XSETSUBR, SUBRP): Adjust to match new Lisp_Subr layout.
(struct vectorlike_header): Remove next member.  Adjust comment.
(struct Lisp_Subr): Add convenient header.  Adjust comment.
(allocate_pseudovector): Adjust prototype.
* alloc.c (mark_glyph_matrix, mark_face_cache, allocate_string)
(sweep_string, lisp_malloc): Remove useless prototypes.
(enum mem_type): Adjust comment.
(NEXT_IN_FREE_LIST): New macro.
(SETUP_ON_FREE_LIST): Adjust XSETPVECTYPESIZE usage.
(Fmake_bool_vector): Likewise.
(struct large_vector): New type to represent allocation unit for
the vectors with the memory footprint more than VBLOOCK_BYTES_MAX.
(large_vectors): Change type to struct large_vector.
(allocate_vector_from_block): Simplify.
(PSEUDOVECTOR_NBYTES): Replace with...
(vector_nbytes): ...new function.  Adjust users.
(sweep_vectors): Adjust processing of large vectors.
(allocate_vectorlike): Likewise.
(allocate_pseudovector): Change type of 3rd arg to enum pvec_type.
Add easserts.  Adjust XSETPVECTYPESIZE usage.
(allocate_buffer): Use BUFFER_PVEC_INIT.
(live_vector_p): Adjust to match large vector.
* buffer.c (init_buffer_once): Use BUFFER_PVEC_INIT.
* buffer.h (struct buffer): Add next member.
(BUFFER_LISP_SIZE, BUFFER_REST_SIZE, BUFFER_PVEC_INIT):
New macros.
(FOR_EACH_BUFFER): Adjust to match struct buffer change.
* fns.c (internal_equal): Adjust to match enum pvec_type change.
(copy_hash_table): Adjust to match vector header change.
* lread.c (defsubr): Use XSETPVECTYPE.
* .gdbinit (xpr, xbacktrace): Adjust to match vector header change.
(xvectype): Likewise.  Print PVEC_NORMAL_VECTOR for regular vectors.
(xvecsize): New command.

1 files changed, 25 insertions, 6 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 9e0e9eef0b1..fbbbf1b8434 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -482,11 +482,6 @@ struct buffer_text
 
 struct buffer
 {
-  /* HEADER.NEXT is the next buffer, in chain of all buffers, including killed
-     buffers.  This chain, starting from all_buffers, is used only for garbage
-     collection, in order to collect killed buffers properly.  Note that large
-     vectors and large pseudo-vector objects are all on another chain starting
-     from large_vectors.  */
   struct vectorlike_header header;
 
   /* The name of this buffer.  */
@@ -750,6 +745,9 @@ struct buffer
      In an indirect buffer, this is the own_text field of another buffer.  */
   struct buffer_text *text;
 
+  /* Next buffer, in chain of all buffers, including killed ones.  */
+  struct buffer *next;
+
   /* Char position of point in buffer.  */
   ptrdiff_t pt;
 
@@ -959,6 +957,27 @@ bset_width_table (struct buffer *b, Lisp_Object val)
   b->INTERNAL_FIELD (width_table) = val;
 }
 
+/* Number of Lisp_Objects at the beginning of struct buffer.
+   If you add, remove, or reorder Lisp_Objects within buffer
+   structure, make sure that this is still correct.  */
+
+#define BUFFER_LISP_SIZE                                                \
+  ((offsetof (struct buffer, own_text) - header_size) / word_size)
+
+/* Size of the struct buffer part beyond leading Lisp_Objects, in word_size
+   units.  Rounding is needed for --with-wide-int configuration.  */
+
+#define BUFFER_REST_SIZE                                                \
+  ((((sizeof (struct buffer) - offsetof (struct buffer, own_text))      \
+     + (word_size - 1)) & ~(word_size - 1)) / word_size)
+
+/* Initialize the pseudovector header of buffer object.  BUFFER_LISP_SIZE
+   is required for GC, but BUFFER_REST_SIZE is set up just to be consistent
+   with other pseudovectors.  */
+
+#define BUFFER_PVEC_INIT(b)                                    \
+  XSETPVECTYPESIZE (b, PVEC_BUFFER, BUFFER_LISP_SIZE, BUFFER_REST_SIZE)
+
 /* Convenient check whether buffer B is live.  */
 
 #define BUFFER_LIVE_P(b) (!NILP (BVAR (b, name)))
@@ -986,7 +1005,7 @@ extern struct buffer *all_buffers;
 /* Used to iterate over the chain above.  */
 
 #define FOR_EACH_BUFFER(b) \
-  for ((b) = all_buffers; (b); (b) = (b)->header.next.buffer)
+  for ((b) = all_buffers; (b); (b) = (b)->next)
 
 /* This points to the current buffer.  */