Backport revisions 2011-04-24T05:30:24Z!eggert@cs.ucla.edu..2011-04-25T19:40:22Z!eggert@cs.ucla.edu (inclusive) from trunk (bug#8623)

	The next log entry shows the actual changes by Paul Eggert.

 Fix a problem with aliasing and vector headers.
 GCC 4.6.0 optimizes based on type-based alias analysis.  For
 example, if b is of type struct buffer * and v of type struct
 Lisp_Vector *, then gcc -O2 was incorrectly assuming that &b->size
 != &v->size, and therefore "v->size = 1; b->size = 2; return
 v->size;" must therefore return 1.  This assumption is incorrect
 for Emacs, since it type-puns struct Lisp_Vector * with many other
 types.  To fix this problem, this patch adds a new type struct
 vector_header that documents the constraints on layout of vectors
 and pseudovectors, and helps optimizing compilers not get fooled
 by Emacs's type punning.  It also adds the macros XSETTYPED_PVECTYPE
 XSETTYPED_PSEUDOVECTOR, TYPED_PSEUDOVECTORP, for similar reasons.
 src/lisp.h (XVECTOR_SIZE): New convenience macro.  All previous uses of
 XVECTOR (foo)->size replaced to use this macro, to avoid the hassle
 of writing XVECTOR (foo)->header.size.
 src/lisp.h: Say "vectorlike header" rather than "vector header.
 (struct vectorlike_header): Rename from struct vector_header.
 (XVECTORLIKE_HEADER_SIZE): Renamed from XVECTOR_HEADER_SIZE.
 All uses changed.
 (XVECTOR_HEADER_SIZE): New macro, for use in XSETPSEUDOVECTOR.
 (XSETTYPED_PVECTYPE): New macro, specifying the name of the size
 member.
 (XSETPVECTYPE): Rewrite in terms of new macro.
 (XSETPVECTYPESIZE): New macro, specifying both type and size.
 This is a bit clearer, and further avoids the possibility of
 undesirable aliasing.
 (XSETTYPED_PSEUDOVECTOR): New macro, specifying the size.
 (XSETPSEUDOVECTOR): Rewrite in terms of XSETTYPED_PSEUDOVECTOR
 and XVECTOR_HEADER_SIZE.
 (XSETSUBR): Rewrite in terms of XSETTYPED_PSEUDOVECTOR and XSIZE,
 since Lisp_Subr is a special case (no "next" field).
 (ASIZE): Rewrite in terms of XVECTOR_SIZE.
 (struct vector_header): New type.
 (TYPED_PSEUDOVECTORP): New macro, also specifying the C type of the
 object, to help avoid aliasing.
 (PSEUDOVECTORP): Rewrite in terms of TYPED_PSEUDOVECTORP.
 (SUBRP): Likewise, since Lisp_Subr is a special case.
 src/lisp.h (struct Lisp_Vector, struct Lisp_Char_Table):
 (struct Lisp_Sub_Char_Table, struct Lisp_Bool_Vector):
 (struct Lisp_Hash_Table): Combine first two members into a single
 struct vector_header member.  All uses of "size" and "next" members
 changed to be "header.size" and "header.next".
 src/buffer.h (struct buffer): Likewise.
 src/font.h (struct font_spec, struct font_entity, struct font): Likewise.
 src/frame.h (struct frame): Likewise.
 src/process.h (struct Lisp_Process): Likewise.
 src/termhooks.h (struct terminal): Likewise.
 src/window.c (struct save_window_data, struct saved_window): Likewise.
 src/window.h (struct window): Likewise.
 src/alloc.c (allocate_buffer, Fmake_bool_vector, allocate_pseudovector):
 Use XSETPVECTYPESIZE, not XSETPVECTYPE, to avoid aliasing problems.
 src/buffer.c (init_buffer_once): Likewise.
 src/lread.c (defsubr): Use XSETTYPED_PVECTYPE, since Lisp_Subr is a
 special case.
 src/process.c (Fformat_network_address): Use local var for size,
 for brevity.
 src/fns.c (vector): Remove; this old hack is no longer needed.
 src/bytecode.c (exec_byte_code): Don't use XVECTOR before CHECK_VECTOR.

40 files changed, 299 insertions, 219 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 42d9185e0dd..2a051a9e27b 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,71 @@
+2011-05-09  Eli Zaretskii  <eliz@gnu.org>
+
+        Backport revisions 103939.1.41..103939.1.44 (inclusive) from trunk.
+        (bug#8623)
+        The next log entry shows the actual changes by Paul Eggert.
+
+2011-05-08  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Fix a problem with aliasing and vector headers.
+        GCC 4.6.0 optimizes based on type-based alias analysis.  For
+        example, if b is of type struct buffer * and v of type struct
+        Lisp_Vector *, then gcc -O2 was incorrectly assuming that &b->size
+        != &v->size, and therefore "v->size = 1; b->size = 2; return
+        v->size;" must therefore return 1.  This assumption is incorrect
+        for Emacs, since it type-puns struct Lisp_Vector * with many other
+        types.  To fix this problem, this patch adds a new type struct
+        vector_header that documents the constraints on layout of vectors
+        and pseudovectors, and helps optimizing compilers not get fooled
+        by Emacs's type punning.  It also adds the macros XSETTYPED_PVECTYPE
+        XSETTYPED_PSEUDOVECTOR, TYPED_PSEUDOVECTORP, for similar reasons.
+        * lisp.h (XVECTOR_SIZE): New convenience macro.  All previous uses of
+        XVECTOR (foo)->size replaced to use this macro, to avoid the hassle
+        of writing XVECTOR (foo)->header.size.
+        * lisp.h: Say "vectorlike header" rather than "vector header.
+        (struct vectorlike_header): Rename from struct vector_header.
+        (XVECTORLIKE_HEADER_SIZE): Renamed from XVECTOR_HEADER_SIZE.
+        All uses changed.
+        (XVECTOR_HEADER_SIZE): New macro, for use in XSETPSEUDOVECTOR.
+        (XSETTYPED_PVECTYPE): New macro, specifying the name of the size
+        member.
+        (XSETPVECTYPE): Rewrite in terms of new macro.
+        (XSETPVECTYPESIZE): New macro, specifying both type and size.
+        This is a bit clearer, and further avoids the possibility of
+        undesirable aliasing.
+        (XSETTYPED_PSEUDOVECTOR): New macro, specifying the size.
+        (XSETPSEUDOVECTOR): Rewrite in terms of XSETTYPED_PSEUDOVECTOR
+        and XVECTOR_HEADER_SIZE.
+        (XSETSUBR): Rewrite in terms of XSETTYPED_PSEUDOVECTOR and XSIZE,
+        since Lisp_Subr is a special case (no "next" field).
+        (ASIZE): Rewrite in terms of XVECTOR_SIZE.
+        (struct vector_header): New type.
+        (TYPED_PSEUDOVECTORP): New macro, also specifying the C type of the
+        object, to help avoid aliasing.
+        (PSEUDOVECTORP): Rewrite in terms of TYPED_PSEUDOVECTORP.
+        (SUBRP): Likewise, since Lisp_Subr is a special case.
+
+        * lisp.h (struct Lisp_Vector, struct Lisp_Char_Table):
+        (struct Lisp_Sub_Char_Table, struct Lisp_Bool_Vector):
+        (struct Lisp_Hash_Table): Combine first two members into a single
+        struct vector_header member.  All uses of "size" and "next" members
+        changed to be "header.size" and "header.next".
+        * buffer.h (struct buffer): Likewise.
+        * font.h (struct font_spec, struct font_entity, struct font): Likewise.
+        * frame.h (struct frame): Likewise.
+        * process.h (struct Lisp_Process): Likewise.
+        * termhooks.h (struct terminal): Likewise.
+        * window.c (struct save_window_data, struct saved_window): Likewise.
+        * window.h (struct window): Likewise.
+        * alloc.c (allocate_buffer, Fmake_bool_vector, allocate_pseudovector):
+        Use XSETPVECTYPESIZE, not XSETPVECTYPE, to avoid aliasing problems.
+        * buffer.c (init_buffer_once): Likewise.
+        * lread.c (defsubr): Use XSETTYPED_PVECTYPE, since Lisp_Subr is a
+        special case.
+        * process.c (Fformat_network_address): Use local var for size,
+        for brevity.
+        * fns.c (vector): Remove; this old hack is no longer needed.
+        * bytecode.c (exec_byte_code): Don't use XVECTOR before CHECK_VECTOR.
+
 2011-04-29  Eli Zaretskii  <eliz@gnu.org>
 
         * w32heap.c (allocate_heap) [USE_LISP_UNION_TYPE || USE_LSB_TAG]:
diff --git a/src/alloc.c b/src/alloc.c
index ad11e215da7..77b870f4754 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -163,9 +163,9 @@ static __malloc_size_t bytes_used_when_reconsidered;
 #define UNMARK_STRING(S)        ((S)->size &= ~ARRAY_MARK_FLAG)
 #define STRING_MARKED_P(S)      (((S)->size & ARRAY_MARK_FLAG) != 0)
 
-#define VECTOR_MARK(V)          ((V)->size |= ARRAY_MARK_FLAG)
-#define VECTOR_UNMARK(V)        ((V)->size &= ~ARRAY_MARK_FLAG)
-#define VECTOR_MARKED_P(V)      (((V)->size & ARRAY_MARK_FLAG) != 0)
+#define VECTOR_MARK(V)          ((V)->header.size |= ARRAY_MARK_FLAG)
+#define VECTOR_UNMARK(V)        ((V)->header.size &= ~ARRAY_MARK_FLAG)
+#define VECTOR_MARKED_P(V)      (((V)->header.size & ARRAY_MARK_FLAG) != 0)
 
 /* Value is the number of bytes/chars of S, a pointer to a struct
    Lisp_String.  This must be used instead of STRING_BYTES (S) or
@@ -1151,8 +1151,9 @@ allocate_buffer ()
   struct buffer *b
     = (struct buffer *) lisp_malloc (sizeof (struct buffer),
                                      MEM_TYPE_BUFFER);
-  b->size = sizeof (struct buffer) / sizeof (EMACS_INT);
-  XSETPVECTYPE (b, PVEC_BUFFER);
+  XSETPVECTYPESIZE (b, PVEC_BUFFER,
+                    ((sizeof (struct buffer) + sizeof (EMACS_INT) - 1)
+                     / sizeof (EMACS_INT)));
   return b;
 }
 
@@ -2341,10 +2342,8 @@ LENGTH must be a number.  INIT matters only in whether it is t or nil.  */)
      slot `size' of the struct Lisp_Bool_Vector.  */
   val = Fmake_vector (make_number (length_in_elts + 1), Qnil);
 
-  /* Get rid of any bits that would cause confusion.  */
-  XVECTOR (val)->size = 0;      /* No Lisp_Object to trace in there.  */
-  /* Use  XVECTOR (val) rather than `p' because p->size is not TRT. */
-  XSETPVECTYPE (XVECTOR (val), PVEC_BOOL_VECTOR);
+  /* No Lisp_Object to trace in there.  */
+  XSETPVECTYPESIZE (XVECTOR (val), PVEC_BOOL_VECTOR, 0);
 
   p = XBOOL_VECTOR (val);
   p->size = XFASTINT (length);
@@ -2943,7 +2942,7 @@ allocate_vectorlike (len)
   consing_since_gc += nbytes;
   vector_cells_consed += len;
 
-  p->next = all_vectors;
+  p->header.next.vector = all_vectors;
   all_vectors = p;
 
   MALLOC_UNBLOCK_INPUT;
@@ -2960,7 +2959,7 @@ allocate_vector (nslots)
      EMACS_INT nslots;
 {
   struct Lisp_Vector *v = allocate_vectorlike (nslots);
-  v->size = nslots;
+  v->header.size = nslots;
   return v;
 }
 
@@ -2976,11 +2975,10 @@ allocate_pseudovector (memlen, lisplen, tag)
   EMACS_INT i;
 
   /* Only the first lisplen slots will be traced normally by the GC.  */
-  v->size = lisplen;
   for (i = 0; i < lisplen; ++i)
     v->contents[i] = Qnil;
 
-  XSETPVECTYPE (v, tag);        /* Add the appropriate tag.  */
+  XSETPVECTYPESIZE (v, tag, lisplen);
   return v;
 }
 
@@ -4884,7 +4882,7 @@ make_pure_vector (len)
 
   p = (struct Lisp_Vector *) pure_alloc (size, Lisp_Vectorlike);
   XSETVECTOR (new, p);
-  XVECTOR (new)->size = len;
+  XVECTOR (new)->header.size = len;
   return new;
 }
 
@@ -4916,7 +4914,7 @@ Does not copy symbols.  Copies strings without text properties.  */)
       register int i;
       EMACS_INT size;
 
-      size = XVECTOR (obj)->size;
+      size = XVECTOR_SIZE (obj);
       if (size & PSEUDOVECTOR_FLAG)
         size &= PSEUDOVECTOR_SIZE_MASK;
       vec = XVECTOR (make_pure_vector (size));
@@ -5038,7 +5036,7 @@ returns nil, because real GC can't be done.  */)
               }
           }
 
-        nextb = nextb->next;
+        nextb = nextb->header.next.buffer;
       }
   }
 
@@ -5184,7 +5182,7 @@ returns nil, because real GC can't be done.  */)
            undo_list any more, we can finally mark the list.  */
         mark_object (nextb->undo_list);
 
-        nextb = nextb->next;
+        nextb = nextb->header.next.buffer;
       }
   }
 
@@ -5361,7 +5359,7 @@ static void
 mark_vectorlike (ptr)
      struct Lisp_Vector *ptr;
 {
-  register EMACS_INT size = ptr->size;
+  register EMACS_UINT size = ptr->header.size;
   register int i;
 
   eassert (!VECTOR_MARKED_P (ptr));
@@ -5385,7 +5383,7 @@ static void
 mark_char_table (ptr)
      struct Lisp_Vector *ptr;
 {
-  register EMACS_INT size = ptr->size & PSEUDOVECTOR_SIZE_MASK;
+  register EMACS_UINT size = ptr->header.size & PSEUDOVECTOR_SIZE_MASK;
   register int i;
 
   eassert (!VECTOR_MARKED_P (ptr));
@@ -5500,7 +5498,7 @@ mark_object (arg)
           if (po != &buffer_defaults && po != &buffer_local_symbols)
             {
               struct buffer *b;
-              for (b = all_buffers; b && b != po; b = b->next)
+              for (b = all_buffers; b && b != po; b = b->header.next.buffer)
                 ;
               if (b == NULL)
                 abort ();
@@ -5516,7 +5514,7 @@ mark_object (arg)
            recursion there.  */
         {
           register struct Lisp_Vector *ptr = XVECTOR (obj);
-          register EMACS_INT size = ptr->size;
+          register EMACS_UINT size = ptr->header.size;
           register int i;
 
           CHECK_LIVE (live_vector_p);
@@ -6150,10 +6148,10 @@ gc_sweep ()
       if (!VECTOR_MARKED_P (buffer))
         {
           if (prev)
-            prev->next = buffer->next;
+            prev->header.next = buffer->header.next;
           else
-            all_buffers = buffer->next;
-          next = buffer->next;
+            all_buffers = buffer->header.next.buffer;
+          next = buffer->header.next.buffer;
           lisp_free (buffer);
           buffer = next;
         }
@@ -6161,7 +6159,7 @@ gc_sweep ()
         {
           VECTOR_UNMARK (buffer);
           UNMARK_BALANCE_INTERVALS (BUF_INTERVALS (buffer));
-          prev = buffer, buffer = buffer->next;
+          prev = buffer, buffer = buffer->header.next.buffer;
         }
   }
 
@@ -6174,10 +6172,10 @@ gc_sweep ()
       if (!VECTOR_MARKED_P (vector))
         {
           if (prev)
-            prev->next = vector->next;
+            prev->header.next = vector->header.next;
           else
-            all_vectors = vector->next;
-          next = vector->next;
+            all_vectors = vector->header.next.vector;
+          next = vector->header.next.vector;
           lisp_free (vector);
           n_vectors--;
           vector = next;
@@ -6186,11 +6184,11 @@ gc_sweep ()
       else
         {
           VECTOR_UNMARK (vector);
-          if (vector->size & PSEUDOVECTOR_FLAG)
-            total_vector_size += (PSEUDOVECTOR_SIZE_MASK & vector->size);
+          if (vector->header.size & PSEUDOVECTOR_FLAG)
+            total_vector_size += PSEUDOVECTOR_SIZE_MASK & vector->header.size;
           else
-            total_vector_size += vector->size;
-          prev = vector, vector = vector->next;
+            total_vector_size += vector->header.size;
+          prev = vector, vector = vector->header.next.vector;
         }
   }
 
diff --git a/src/buffer.c b/src/buffer.c
index 076495cfc64..70d7d00edfe 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -53,7 +53,7 @@ extern int errno;
 struct buffer *current_buffer;          /* the current buffer */
 
 /* First buffer in chain of all buffers (in reverse order of creation).
-   Threaded through ->next.  */
+   Threaded through ->header.next.buffer.  */
 
 struct buffer *all_buffers;
 
@@ -400,7 +400,7 @@ even if it is dead.  The return value is never nil.  */)
   b->prevent_redisplay_optimizations_p = 1;
 
   /* Put this on the chain of all buffers including killed ones.  */
-  b->next = all_buffers;
+  b->header.next.buffer = all_buffers;
   all_buffers = b;
 
   /* An ordinary buffer normally doesn't need markers
@@ -633,7 +633,7 @@ CLONE nil means the indirect buffer's state is reset to default values.  */)
   b->width_table = Qnil;
 
   /* Put this on the chain of all buffers including killed ones.  */
-  b->next = all_buffers;
+  b->header.next.buffer = all_buffers;
   all_buffers = b;
 
   name = Fcopy_sequence (name);
@@ -1544,7 +1544,7 @@ with SIGHUP.  */)
 
       GCPRO1 (buffer);
 
-      for (other = all_buffers; other; other = other->next)
+      for (other = all_buffers; other; other = other->header.next.buffer)
         /* all_buffers contains dead buffers too;
            don't re-kill them.  */
         if (other->base_buffer == b && !NILP (other->name))
@@ -2214,7 +2214,7 @@ DEFUN ("buffer-swap-text", Fbuffer_swap_text, Sbuffer_swap_text,
 
   { /* This is probably harder to make work.  */
     struct buffer *other;
-    for (other = all_buffers; other; other = other->next)
+    for (other = all_buffers; other; other = other->header.next.buffer)
       if (other->base_buffer == other_buffer
           || other->base_buffer == current_buffer)
         error ("One of the buffers to swap has indirect buffers");
@@ -2585,7 +2585,7 @@ current buffer is cleared.  */)
 
   /* Copy this buffer's new multibyte status
      into all of its indirect buffers.  */
-  for (other = all_buffers; other; other = other->next)
+  for (other = all_buffers; other; other = other->header.next.buffer)
     if (other->base_buffer == current_buffer && !NILP (other->name))
       {
         other->enable_multibyte_characters
@@ -4346,7 +4346,7 @@ static void
 add_overlay_mod_hooklist (functionlist, overlay)
      Lisp_Object functionlist, overlay;
 {
-  int oldsize = XVECTOR (last_overlay_modification_hooks)->size;
+  int oldsize = XVECTOR_SIZE (last_overlay_modification_hooks);
 
   if (last_overlay_modification_hooks_used == oldsize)
     last_overlay_modification_hooks = larger_vector 
@@ -5150,9 +5150,9 @@ init_buffer_once ()
   buffer_local_symbols.text = &buffer_local_symbols.own_text;
   BUF_INTERVALS (&buffer_defaults) = 0;
   BUF_INTERVALS (&buffer_local_symbols) = 0;
-  XSETPVECTYPE (&buffer_defaults, PVEC_BUFFER);
+  XSETPVECTYPESIZE (&buffer_defaults, PVEC_BUFFER, 0);
   XSETBUFFER (Vbuffer_defaults, &buffer_defaults);
-  XSETPVECTYPE (&buffer_local_symbols, PVEC_BUFFER);
+  XSETPVECTYPESIZE (&buffer_local_symbols, PVEC_BUFFER, 0);
   XSETBUFFER (Vbuffer_local_symbols, &buffer_local_symbols);
 
   /* Set up the default values of various buffer slots.  */
diff --git a/src/buffer.h b/src/buffer.h
index 56d0422b7e3..a9240546427 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -487,14 +487,13 @@ struct buffer
 
      Check out mark_buffer (alloc.c) to see why.  */
 
-  EMACS_UINT size;
-
-  /* Next buffer, in chain of all buffers including killed buffers.
+  /* HEADER.NEXT is the next buffer, in chain of all buffers,
+     including killed buffers.
      This chain is used only for garbage collection, in order to
      collect killed buffers properly.
      Note that vectors and most pseudovectors are all on one chain,
      but buffers are on a separate chain of their own.  */
-  struct buffer *next;
+  struct vectorlike_header header;
 
   /* This structure holds the coordinates of the buffer contents
      in ordinary buffers.  In indirect buffers, this is not used.  */
diff --git a/src/bytecode.c b/src/bytecode.c
index db80f5b1a9c..fd119c58e19 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -415,7 +415,7 @@ If the third argument is incorrect, Emacs may crash.  */)
   /* Lisp_Object v1, v2; */
   Lisp_Object *vectorp;
 #ifdef BYTE_CODE_SAFE
-  int const_length = XVECTOR (vector)->size;
+  int const_length;
   Lisp_Object *stacke;
 #endif
   int bytestr_length;
@@ -437,6 +437,9 @@ If the third argument is incorrect, Emacs may crash.  */)
   CHECK_VECTOR (vector);
   CHECK_NUMBER (maxdepth);
 
+#ifdef BYTE_CODE_SAFE
+  const_length = XVECTOR_SIZE (vector);
+#endif
   if (STRING_MULTIBYTE (bytestr))
     /* BYTESTR must have been produced by Emacs 20.2 or the earlier
        because they produced a raw 8-bit string for byte-code and now
diff --git a/src/callint.c b/src/callint.c
index 8fd04bb00de..f4bdf40dfa3 100644
--- a/src/callint.c
+++ b/src/callint.c
@@ -313,7 +313,7 @@ invoke it.  If KEYS is omitted or nil, the return value of
   else
     {
       CHECK_VECTOR (keys);
-      key_count = XVECTOR (keys)->size;
+      key_count = XVECTOR_SIZE (keys);
     }
 
   /* Save this now, since use of minibuffer will clobber it. */
diff --git a/src/ccl.c b/src/ccl.c
index d1ac29778a8..bebf15e496e 100644
--- a/src/ccl.c
+++ b/src/ccl.c
@@ -1924,7 +1924,7 @@ setup_ccl_program (ccl, ccl_prog)
       if (! VECTORP (ccl_prog))
         return -1;
       vp = XVECTOR (ccl_prog);
-      ccl->size = vp->size;
+      ccl->size = vp->header.size;
       ccl->prog = vp->contents;
       ccl->eof_ic = XINT (vp->contents[CCL_HEADER_EOF]);
       ccl->buf_magnification = XINT (vp->contents[CCL_HEADER_BUF_MAG]);
diff --git a/src/character.c b/src/character.c
index b9ba15d1b0f..ba6fb4ff098 100644
--- a/src/character.c
+++ b/src/character.c
@@ -411,7 +411,7 @@ c_string_width (const unsigned char *str, int len, int precision, int *nchars, i
         {
           val = DISP_CHAR_VECTOR (dp, c);
           if (VECTORP (val))
-            thiswidth = XVECTOR (val)->size;
+            thiswidth = XVECTOR_SIZE (val);
           else
             thiswidth = CHAR_WIDTH (c);
         }
@@ -503,7 +503,7 @@ lisp_string_width (string, precision, nchars, nbytes)
             {
               val = DISP_CHAR_VECTOR (dp, c);
               if (VECTORP (val))
-                thiswidth = XVECTOR (val)->size;
+                thiswidth = XVECTOR_SIZE (val);
               else
                 thiswidth = CHAR_WIDTH (c);
             }
diff --git a/src/chartab.c b/src/chartab.c
index 978c4b8b678..c4cf6253a8b 100644
--- a/src/chartab.c
+++ b/src/chartab.c
@@ -152,7 +152,7 @@ copy_char_table (table)
      Lisp_Object table;
 {
   Lisp_Object copy;
-  int size = XCHAR_TABLE (table)->size & PSEUDOVECTOR_SIZE_MASK;
+  int size = XCHAR_TABLE (table)->header.size & PSEUDOVECTOR_SIZE_MASK;
   int i;
 
   copy = Fmake_vector (make_number (size), Qnil);
diff --git a/src/coding.c b/src/coding.c
index b20a72ca678..555e6623383 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -7339,7 +7339,7 @@ handle_composition_annotation (pos, limit, coding, buf, stop)
               components = COMPOSITION_COMPONENTS (prop);
               if (VECTORP (components))
                 {
-                  len = XVECTOR (components)->size;
+                  len = XVECTOR_SIZE (components);
                   for (i = 0; i < len; i++)
                     *buf++ = XINT (AREF (components, i));
                 }
diff --git a/src/composite.c b/src/composite.c
index a9376c0ec2d..ec2595813aa 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -300,7 +300,7 @@ get_composition_id (charpos, bytepos, nchars, prop, string)
     }
   else if (VECTORP (components) || CONSP (components))
     {
-      int len = XVECTOR (key)->size;
+      EMACS_UINT len = XVECTOR_SIZE (key);
 
       /* The number of elements should be odd.  */
       if ((len % 2) == 0)
@@ -333,8 +333,8 @@ get_composition_id (charpos, bytepos, nchars, prop, string)
                     : COMPOSITION_WITH_RULE_ALTCHARS));
   cmp->hash_index = hash_index;
   glyph_len = (cmp->method == COMPOSITION_WITH_RULE_ALTCHARS
-               ? (XVECTOR (key)->size + 1) / 2
-               : XVECTOR (key)->size);
+               ? (XVECTOR_SIZE (key) + 1) / 2
+               : XVECTOR_SIZE (key));
   cmp->glyph_len = glyph_len;
   cmp->offsets = (short *) xmalloc (sizeof (short) * glyph_len * 2);
   cmp->font = NULL;
diff --git a/src/data.c b/src/data.c
index 0c7cb241568..79ae01f26f4 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1402,7 +1402,7 @@ for this variable.  */)
         {
           struct buffer *b;
 
-          for (b = all_buffers; b; b = b->next)
+          for (b = all_buffers; b; b = b->header.next.buffer)
             if (!PER_BUFFER_VALUE_P (b, idx))
               PER_BUFFER_VALUE (b, offset) = value;
         }
@@ -2029,9 +2029,9 @@ or a byte-code object.  IDX starts at 0.  */)
     {
       int size = 0;
       if (VECTORP (array))
-        size = XVECTOR (array)->size;
+        size = XVECTOR_SIZE (array);
       else if (COMPILEDP (array))
-        size = XVECTOR (array)->size & PSEUDOVECTOR_SIZE_MASK;
+        size = XVECTOR_SIZE (array) & PSEUDOVECTOR_SIZE_MASK;
       else
         wrong_type_argument (Qarrayp, array);
 
@@ -2058,7 +2058,7 @@ bool-vector.  IDX starts at 0.  */)
 
   if (VECTORP (array))
     {
-      if (idxval < 0 || idxval >= XVECTOR (array)->size)
+      if (idxval < 0 || idxval >= XVECTOR_SIZE (array))
         args_out_of_range (array, idx);
       XVECTOR (array)->contents[idxval] = newelt;
     }
diff --git a/src/dispnew.c b/src/dispnew.c
index 6062f40f598..60ce149da1c 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -6729,7 +6729,7 @@ pass nil for VARIABLE.  */)
     state = frame_and_buffer_state;
 
   vecp = XVECTOR (state)->contents;
-  end = vecp + XVECTOR (state)->size;
+  end = vecp + XVECTOR_SIZE (state);
 
   FOR_EACH_FRAME (tail, frame)
     {
@@ -6780,8 +6780,8 @@ pass nil for VARIABLE.  */)
   /* Reallocate the vector if data has grown to need it,
      or if it has shrunk a lot.  */
   if (! VECTORP (state)
-      || n > XVECTOR (state)->size
-      || n + 20 < XVECTOR (state)->size / 2)
+      || n > XVECTOR_SIZE (state)
+      || n + 20 < XVECTOR_SIZE (state) / 2)
     /* Add 20 extra so we grow it less often.  */
     {
       state = Fmake_vector (make_number (n + 20), Qlambda);
@@ -6811,11 +6811,11 @@ pass nil for VARIABLE.  */)
   /* Fill up the vector with lambdas (always at least one).  */
   *vecp++ = Qlambda;
   while (vecp - XVECTOR (state)->contents
-         < XVECTOR (state)->size)
+         < XVECTOR_SIZE (state))
     *vecp++ = Qlambda;
   /* Make sure we didn't overflow the vector.  */
   if (vecp - XVECTOR (state)->contents
-      > XVECTOR (state)->size)
+      > XVECTOR_SIZE (state))
     abort ();
   return Qt;
 }
diff --git a/src/disptab.h b/src/disptab.h
index 92a42702187..0e9978a7bdb 100644
--- a/src/disptab.h
+++ b/src/disptab.h
@@ -62,7 +62,7 @@ extern Lisp_Object Vglyph_table;
 /* Return the current length of the GLYPH table,
    or 0 if the table isn't currently valid.  */
 #define GLYPH_TABLE_LENGTH  \
-  ((VECTORP (Vglyph_table)) ? XVECTOR (Vglyph_table)->size : 0)
+  ((VECTORP (Vglyph_table)) ? XVECTOR_SIZE (Vglyph_table) : 0)
 
 /* Return the current base (for indexing) of the GLYPH table,
    or 0 if the table isn't currently valid.  */
diff --git a/src/doc.c b/src/doc.c
index 9b72b17cffa..d22c3bf872b 100644
--- a/src/doc.c
+++ b/src/doc.c
@@ -809,7 +809,7 @@ a new string, without any text properties, is returned.  */)
         do_remap:
           tem = Fwhere_is_internal (name, keymap, Qt, Qnil, Qnil);
 
-          if (VECTORP (tem) && XVECTOR (tem)->size > 1
+          if (VECTORP (tem) && XVECTOR_SIZE (tem) > 1
               && EQ (AREF (tem, 0), Qremap) && SYMBOLP (AREF (tem, 1))
               && follow_remap)
             {
diff --git a/src/fns.c b/src/fns.c
index 064c4d270e9..0bf38fd472a 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -27,11 +27,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <time.h>
 #include <setjmp.h>
 
-/* Note on some machines this defines `vector' as a typedef,
-   so make sure we don't use that name in this file.  */
-#undef vector
-#define vector *****
-
 #include "lisp.h"
 #include "commands.h"
 #include "character.h"
@@ -4022,9 +4017,9 @@ copy_hash_table (h1)
   struct Lisp_Vector *next;
 
   h2 = allocate_hash_table ();
-  next = h2->vec_next;
+  next = h2->header.next.vector;
   bcopy (h1, h2, sizeof *h2);
-  h2->vec_next = next;
+  h2->header.next.vector = next;
   h2->key_and_value = Fcopy_sequence (h1->key_and_value);
   h2->hash = Fcopy_sequence (h1->hash);
   h2->next = Fcopy_sequence (h1->next);
@@ -4379,7 +4374,7 @@ sweep_weak_hash_tables ()
       marked = 0;
       for (h = weak_hash_tables; h; h = h->next_weak)
         {
-          if (h->size & ARRAY_MARK_FLAG)
+          if (h->header.size & ARRAY_MARK_FLAG)
             marked |= sweep_weak_table (h, 0);
         }
     }
@@ -4390,7 +4385,7 @@ sweep_weak_hash_tables ()
     {
       next = h->next_weak;
 
-      if (h->size & ARRAY_MARK_FLAG)
+      if (h->header.size & ARRAY_MARK_FLAG)
         {
           /* TABLE is marked as used.  Sweep its contents.  */
           if (h->count > 0)
@@ -4513,7 +4508,7 @@ sxhash_bool_vector (vec)
   unsigned hash = XBOOL_VECTOR (vec)->size;
   int i, n;
 
-  n = min (SXHASH_MAX_LEN, XBOOL_VECTOR (vec)->vector_size);
+  n = min (SXHASH_MAX_LEN, XBOOL_VECTOR (vec)->header.size);
   for (i = 0; i < n; ++i)
     hash = SXHASH_COMBINE (hash, XBOOL_VECTOR (vec)->data[i]);
 
diff --git a/src/font.c b/src/font.c
index 08309d3697b..ed2999b8923 100644
--- a/src/font.c
+++ b/src/font.c
@@ -269,7 +269,7 @@ font_intern_prop (str, len, force_symbol)
   /* The following code is copied from the function intern (in
      lread.c), and modified to suite our purpose.  */
   obarray = Vobarray;
-  if (!VECTORP (obarray) || XVECTOR (obarray)->size == 0)
+  if (!VECTORP (obarray) || XVECTOR_SIZE (obarray) == 0)
     obarray = check_obarray (obarray);
   parse_str_as_multibyte ((unsigned char *) str, len, &nchars, &nbytes);
   if (len == nchars || len != nbytes)
diff --git a/src/font.h b/src/font.h
index 208c42617e9..7471464bb9b 100644
--- a/src/font.h
+++ b/src/font.h
@@ -247,8 +247,7 @@ extern Lisp_Object Qja, Qko;
 
 struct font_spec
 {
-  EMACS_UINT size;
-  struct Lisp_Vector *next;
+  struct vectorlike_header header;
   Lisp_Object props[FONT_SPEC_MAX];
 };
 
@@ -256,8 +255,7 @@ struct font_spec
 
 struct font_entity
 {
-  EMACS_UINT size;
-  struct Lisp_Vector *next;
+  struct vectorlike_header header;
   Lisp_Object props[FONT_ENTITY_MAX];
 };
 
@@ -270,8 +268,7 @@ struct font_entity
 
 struct font
 {
-  EMACS_UINT size;
-  struct Lisp_Vector *next;
+  struct vectorlike_header header;
 
   /* All Lisp_Object components must come first.
      That ensures they are all aligned normally.  */
diff --git a/src/frame.h b/src/frame.h
index c236304937b..194c4410fa8 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -93,8 +93,7 @@ struct font_driver_list;
 
 struct frame
 {
-  EMACS_UINT size;
-  struct Lisp_Vector *next;
+  struct vectorlike_header header;
 
   /* All Lisp_Object components must come first.
      That ensures they are all aligned normally.  */
diff --git a/src/fringe.c b/src/fringe.c
index 861aa6e9487..880fe2c6e42 100644
--- a/src/fringe.c
+++ b/src/fringe.c
@@ -1569,7 +1569,7 @@ If BITMAP already exists, the existing definition is replaced.  */)
   if (STRINGP (bits))
     h = SCHARS (bits);
   else if (VECTORP (bits))
-    h = XVECTOR (bits)->size;
+    h = XVECTOR_SIZE (bits);
   else
     wrong_type_argument (Qsequencep, bits);
 
diff --git a/src/image.c b/src/image.c
index b814b795fab..5a1be6e4747 100644
--- a/src/image.c
+++ b/src/image.c
@@ -2459,7 +2459,7 @@ xbm_image_p (object)
           int i;
 
           /* Number of elements of the vector must be >= height.  */
-          if (XVECTOR (data)->size < height)
+          if (XVECTOR_SIZE (data) < height)
             return 0;
 
           /* Each string or bool-vector in data must be large enough
@@ -8083,7 +8083,7 @@ gs_image_p (object)
     }
   else if (VECTORP (tem))
     {
-      if (XVECTOR (tem)->size != 4)
+      if (XVECTOR_SIZE (tem) != 4)
         return 0;
       for (i = 0; i < 4; ++i)
         if (!INTEGERP (XVECTOR (tem)->contents[i]))
diff --git a/src/indent.c b/src/indent.c
index e92e6b2776c..e965daf08c8 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -101,7 +101,7 @@ character_width (c, dp)
   /* Everything can be handled by the display table, if it's
      present and the element is right.  */
   if (dp && (elt = DISP_CHAR_VECTOR (dp, c), VECTORP (elt)))
-    return XVECTOR (elt)->size;
+    return XVECTOR_SIZE (elt);
 
   /* Some characters are special.  */
   if (c == '\n' || c == '\t' || c == '\015')
@@ -131,7 +131,7 @@ disptab_matches_widthtab (disptab, widthtab)
 {
   int i;
 
-  if (widthtab->size != 256)
+  if (widthtab->header.size != 256)
     abort ();
 
   for (i = 0; i < 256; i++)
@@ -155,7 +155,7 @@ recompute_width_table (buf, disptab)
   if (!VECTORP (buf->width_table))
     buf->width_table = Fmake_vector (make_number (256), make_number (0));
   widthtab = XVECTOR (buf->width_table);
-  if (widthtab->size != 256)
+  if (widthtab->header.size != 256)
     abort ();
 
   for (i = 0; i < 256; i++)
@@ -301,7 +301,7 @@ skip_invisible (pos, next_boundary_p, to, window)
     else                                                                \
       {                                                                 \
         if (dp != 0 && VECTORP (DISP_CHAR_VECTOR (dp, c)))              \
-          width = XVECTOR (DISP_CHAR_VECTOR (dp, c))->size;             \
+          width = XVECTOR_SIZE (DISP_CHAR_VECTOR (dp, c));              \
         else                                                            \
           width = CHAR_WIDTH (c);                                       \
         if (width > 1)                                                  \
@@ -786,7 +786,7 @@ string_display_width (string, beg, end)
 
       c = *--ptr;
       if (dp != 0 && VECTORP (DISP_CHAR_VECTOR (dp, c)))
-        col += XVECTOR (DISP_CHAR_VECTOR (dp, c))->size;
+        col += XVECTOR_SIZE (DISP_CHAR_VECTOR (dp, c));
       else if (c >= 040 && c < 0177)
         col++;
       else if (c == '\n')
@@ -1159,7 +1159,7 @@ compute_motion (from, fromvpos, fromhpos, did_motion, to, tovpos, tohpos, width,
        : !NILP (current_buffer->selective_display) ? -1 : 0);
   int selective_rlen
     = (selective && dp && VECTORP (DISP_INVIS_VECTOR (dp))
-       ? XVECTOR (DISP_INVIS_VECTOR (dp))->size : 0);
+       ? XVECTOR_SIZE (DISP_INVIS_VECTOR (dp)) : 0);
   /* The next location where the `invisible' property changes, or an
      overlay starts or ends.  */
   EMACS_INT next_boundary = from;
diff --git a/src/keyboard.c b/src/keyboard.c
index 6a63caa15d3..09564418ddf 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -137,7 +137,7 @@ int raw_keybuf_count;
 Lisp_Object Vthis_command_keys_shift_translated;
 
 #define GROW_RAW_KEYBUF                                                 \
- if (raw_keybuf_count == XVECTOR (raw_keybuf)->size)                    \
+ if (raw_keybuf_count == XVECTOR_SIZE (raw_keybuf))                     \
    raw_keybuf = larger_vector (raw_keybuf, raw_keybuf_count * 2, Qnil)  \
 
 /* Number of elements of this_command_keys
@@ -1774,7 +1774,7 @@ command_loop_1 ()
                   if (PT == last_point_position + 1
                       && (dp
                           ? (VECTORP (DISP_CHAR_VECTOR (dp, lose))
-                             ? XVECTOR (DISP_CHAR_VECTOR (dp, lose))->size == 1
+                             ? XVECTOR_SIZE (DISP_CHAR_VECTOR (dp, lose)) == 1
                              : (NILP (DISP_CHAR_VECTOR (dp, lose))
                                 && (lose >= 0x20 && lose < 0x7f)))
                           : (lose >= 0x20 && lose < 0x7f))
@@ -1814,7 +1814,7 @@ command_loop_1 ()
                   if (PT == last_point_position - 1
                       && (dp
                           ? (VECTORP (DISP_CHAR_VECTOR (dp, lose))
-                             ? XVECTOR (DISP_CHAR_VECTOR (dp, lose))->size == 1
+                             ? XVECTOR_SIZE (DISP_CHAR_VECTOR (dp, lose)) == 1
                              : (NILP (DISP_CHAR_VECTOR (dp, lose))
                                 && (lose >= 0x20 && lose < 0x7f)))
                           : (lose >= 0x20 && lose < 0x7f))
@@ -3203,7 +3203,7 @@ read_char (commandflag, nmaps, maps, prev_event, used_mouse_menu, end_time)
       if ((STRINGP (current_kboard->Vkeyboard_translate_table)
            && SCHARS (current_kboard->Vkeyboard_translate_table) > (unsigned) XFASTINT (c))
           || (VECTORP (current_kboard->Vkeyboard_translate_table)
-              && XVECTOR (current_kboard->Vkeyboard_translate_table)->size > (unsigned) XFASTINT (c))
+              && XVECTOR_SIZE (current_kboard->Vkeyboard_translate_table) > (unsigned) XFASTINT (c))
           || (CHAR_TABLE_P (current_kboard->Vkeyboard_translate_table)
               && CHARACTERP (c)))
         {
@@ -4552,7 +4552,7 @@ timer_start_idle ()
 
       timer = XCAR (timers);
 
-      if (!VECTORP (timer) || XVECTOR (timer)->size != 8)
+      if (!VECTORP (timer) || XVECTOR_SIZE (timer) != 8)
         continue;
       XVECTOR (timer)->contents[0] = Qnil;
     }
@@ -4646,7 +4646,7 @@ timer_check_2 ()
       if (!NILP (timers))
         {
           timer = XCAR (timers);
-          if (!VECTORP (timer) || XVECTOR (timer)->size != 8)
+          if (!VECTORP (timer) || XVECTOR_SIZE (timer) != 8)
             {
               timers = XCDR (timers);
               continue;
@@ -4664,7 +4664,7 @@ timer_check_2 ()
       if (!NILP (idle_timers))
         {
           timer = XCAR (idle_timers);
-          if (!VECTORP (timer) || XVECTOR (timer)->size != 8)
+          if (!VECTORP (timer) || XVECTOR_SIZE (timer) != 8)
             {
               idle_timers = XCDR (idle_timers);
               continue;
@@ -5830,7 +5830,7 @@ make_lispy_event (event)
                 /* Find the menu bar item under `column'.  */
                 item = Qnil;
                 items = FRAME_MENU_BAR_ITEMS (f);
-                for (i = 0; i < XVECTOR (items)->size; i += 4)
+                for (i = 0; i < XVECTOR_SIZE (items); i += 4)
                   {
                     Lisp_Object pos, string;
                     string = AREF (items, i + 1);
@@ -6025,7 +6025,7 @@ make_lispy_event (event)
                                       Qmouse_click, Vlispy_mouse_stem,
                                       NULL,
                                       &mouse_syms,
-                                      XVECTOR (mouse_syms)->size);
+                                      XVECTOR_SIZE (mouse_syms));
           if (event->modifiers & drag_modifier)
             return Fcons (head,
                           Fcons (start_pos,
@@ -6198,7 +6198,7 @@ make_lispy_event (event)
                                     Qmouse_click,
                                     Vlispy_mouse_stem,
                                     NULL, &mouse_syms,
-                                    XVECTOR (mouse_syms)->size);
+                                    XVECTOR_SIZE (mouse_syms));
         return Fcons (head, Fcons (position, Qnil));
       }
 
@@ -6318,7 +6318,7 @@ make_lispy_event (event)
                                     Qmouse_click, Vlispy_mouse_stem,
                                     NULL,
                                     &mouse_syms,
-                                    XVECTOR (mouse_syms)->size);
+                                    XVECTOR_SIZE (mouse_syms));
 
         if (event->modifiers & drag_modifier)
           return Fcons (head,
@@ -6825,7 +6825,7 @@ modify_event_symbol (symbol_num, modifiers, symbol_kind, name_alist_or_stem,
   else
     {
       if (! VECTORP (*symbol_table)
-          || XVECTOR (*symbol_table)->size != table_size)
+          || XVECTOR_SIZE (*symbol_table) != table_size)
         {
           Lisp_Object size;
 
@@ -7865,7 +7865,7 @@ menu_bar_items (old)
 
   /* Add nil, nil, nil, nil at the end.  */
   i = menu_bar_items_index;
-  if (i + 4 > XVECTOR (menu_bar_items_vector)->size)
+  if (i + 4 > XVECTOR_SIZE (menu_bar_items_vector))
     menu_bar_items_vector = larger_vector (menu_bar_items_vector, 2 * i, Qnil);
   /* Add this item.  */
   XVECTOR (menu_bar_items_vector)->contents[i++] = Qnil;
@@ -7937,7 +7937,7 @@ menu_bar_item (key, item, dummy1, dummy2)
   if (i == menu_bar_items_index)
     {
       /* If vector is too small, get a bigger one.  */
-      if (i + 4 > XVECTOR (menu_bar_items_vector)->size)
+      if (i + 4 > XVECTOR_SIZE (menu_bar_items_vector))
         menu_bar_items_vector = larger_vector (menu_bar_items_vector, 2 * i, Qnil);
       /* Add this item.  */
       XVECTOR (menu_bar_items_vector)->contents[i++] = key;
@@ -8573,7 +8573,7 @@ parse_tool_bar_item (key, item)
         }
       else if (EQ (key, QCimage)
                && (CONSP (value)
-                   || (VECTORP (value) && XVECTOR (value)->size == 4)))
+                   || (VECTORP (value) && XVECTOR_SIZE (value) == 4)))
         /* Value is either a single image specification or a vector
            of 4 such specifications for the different button states.  */
         PROP (TOOL_BAR_ITEM_IMAGES) = value;
@@ -8634,10 +8634,10 @@ append_tool_bar_item ()
 
   /* Enlarge tool_bar_items_vector if necessary.  */
   if (ntool_bar_items + TOOL_BAR_ITEM_NSLOTS
-      >= XVECTOR (tool_bar_items_vector)->size)
+      >= XVECTOR_SIZE (tool_bar_items_vector))
     tool_bar_items_vector
       = larger_vector (tool_bar_items_vector,
-                       2 * XVECTOR (tool_bar_items_vector)->size, Qnil);
+                       2 * XVECTOR_SIZE (tool_bar_items_vector), Qnil);
 
   /* Append entries from tool_bar_item_properties to the end of
      tool_bar_items_vector.  */
@@ -8966,7 +8966,7 @@ read_char_minibuf_menu_prompt (commandflag, nmaps, maps)
                 }
 
               /* Move past this element.  */
-              if (idx >= 0 && idx + 1 >= XVECTOR (vector)->size)
+              if (idx >= 0 && idx + 1 >= XVECTOR_SIZE (vector))
                 /* Handle reaching end of dense table.  */
                 idx = -1;
               if (idx >= 0)
@@ -10244,7 +10244,7 @@ read_key_sequence (keybuf, bufsize, prompt, dont_downcase_last,
               /* Treat uppercase keys as shifted.  */
               || (INTEGERP (key)
                   && (KEY_TO_CHAR (key)
-                      < XCHAR_TABLE (current_buffer->downcase_table)->size)
+                      < XCHAR_TABLE (current_buffer->downcase_table)->header.size)
                   && UPPERCASEP (KEY_TO_CHAR (key))))
             {
               Lisp_Object new_key
@@ -10642,7 +10642,7 @@ give to the command you invoke, if it asks for an argument.  */)
     this_single_command_key_start = 0;
 
     keys = XVECTOR (saved_keys)->contents;
-    for (i = 0; i < XVECTOR (saved_keys)->size; i++)
+    for (i = 0; i < XVECTOR_SIZE (saved_keys); i++)
       add_command_key (keys[i]);
 
     for (i = 0; i < SCHARS (function); i++)
@@ -10939,7 +10939,7 @@ KEEP-RECORD is non-nil.  */)
 
   if (NILP (keep_record))
     {
-      for (i = 0; i < XVECTOR (recent_keys)->size; ++i)
+      for (i = 0; i < XVECTOR_SIZE (recent_keys); ++i)
         XVECTOR (recent_keys)->contents[i] = Qnil;
       total_keys = 0;
       recent_keys_index = 0;
diff --git a/src/keymap.c b/src/keymap.c
index b3c1400a64c..dec53cbd8e1 100644
--- a/src/keymap.c
+++ b/src/keymap.c
@@ -421,7 +421,7 @@ Return PARENT.  PARENT should be nil or another keymap.  */)
                                 XCDR (XCAR (list)));
 
       if (VECTORP (XCAR (list)))
-        for (i = 0; i < XVECTOR (XCAR (list))->size; i++)
+        for (i = 0; i < XVECTOR_SIZE (XCAR (list)); i++)
           if (CONSP (XVECTOR (XCAR (list))->contents[i]))
             fix_submap_inheritance (keymap, make_number (i),
                                     XVECTOR (XCAR (list))->contents[i]);
@@ -2337,7 +2337,7 @@ spaces are put between sequence elements, etc.  */)
   if (STRINGP (list))
     size = SCHARS (list);
   else if (VECTORP (list))
-    size = XVECTOR (list)->size;
+    size = XVECTOR_SIZE (list);
   else if (CONSP (list))
     size = XINT (Flength (list));
   else
@@ -3257,7 +3257,7 @@ key             binding\n\
 
           elt = XCAR (list);
           prefix = Fcar (elt);
-          if (XVECTOR (prefix)->size >= 1)
+          if (XVECTOR_SIZE (prefix) >= 1)
             {
               tem = Faref (prefix, make_number (0));
               if (EQ (tem, Qmenu_bar))
@@ -3300,7 +3300,7 @@ key             binding\n\
           /* If the sequence by which we reach this keymap is zero-length,
              then the shadow map for this keymap is just SHADOW.  */
           if ((STRINGP (prefix) && SCHARS (prefix) == 0)
-              || (VECTORP (prefix) && XVECTOR (prefix)->size == 0))
+              || (VECTORP (prefix) && XVECTOR_SIZE (prefix) == 0))
             ;
           /* If the sequence by which we reach this keymap actually has
              some elements, then the sequence's definition in SHADOW is
@@ -3748,7 +3748,7 @@ describe_vector (vector, prefix, args, elt_describer,
   if (CHAR_TABLE_P (vector))
     stop = MAX_5_BYTE_CHAR + 1, to = MAX_CHAR + 1;
   else
-    stop = to = XVECTOR (vector)->size;
+    stop = to = XVECTOR_SIZE (vector);
 
   for (i = from; ; i++)
     {
diff --git a/src/lisp.h b/src/lisp.h
index 34330b0e6c6..adda5455390 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -550,6 +550,12 @@ extern Lisp_Object make_number P_ ((EMACS_INT));
 #define XSYMBOL(a) (eassert (SYMBOLP(a)),(struct Lisp_Symbol *) XPNTR(a))
 #define XFLOAT(a) (eassert (FLOATP(a)),(struct Lisp_Float *) XPNTR(a))
 
+/* Extract the size field of a vector or vector-like object.  */
+
+#define XVECTOR_SIZE(a) (XVECTOR (a)->header.size + 0)
+#define XVECTORLIKE_HEADER_SIZE(a) \
+  (((struct vectorlike_header *) XPNTR (a))->size + 0)
+
 /* Misc types.  */
 
 #define XMISC(a)   ((union Lisp_Misc *) XPNTR(a))
@@ -595,17 +601,24 @@ extern Lisp_Object make_number P_ ((EMACS_INT));
 
 /* Pseudovector types.  */
 
-#define XSETPVECTYPE(v,code) ((v)->size |= PSEUDOVECTOR_FLAG | (code))
+#define XSETPVECTYPE(v, code) XSETTYPED_PVECTYPE(v, header.size, code)
+#define XSETTYPED_PVECTYPE(v, size_member, code) \
+  ((v)->size_member |= PSEUDOVECTOR_FLAG | (code))
+#define XSETPVECTYPESIZE(v, code, sizeval) \
+  ((v)->header.size = PSEUDOVECTOR_FLAG | (code) | (sizeval))
 #define XSETPSEUDOVECTOR(a, b, code) \
+  XSETTYPED_PSEUDOVECTOR(a, b, XVECTORLIKE_HEADER_SIZE (a), code)
+#define XSETTYPED_PSEUDOVECTOR(a, b, size, code)                        \
   (XSETVECTOR (a, b),                                                   \
-   eassert ((XVECTOR (a)->size & (PSEUDOVECTOR_FLAG | PVEC_TYPE_MASK))  \
+   eassert ((size & (PSEUDOVECTOR_FLAG | PVEC_TYPE_MASK))               \
             == (PSEUDOVECTOR_FLAG | (code))))
 #define XSETWINDOW_CONFIGURATION(a, b) \
   (XSETPSEUDOVECTOR (a, b, PVEC_WINDOW_CONFIGURATION))
 #define XSETPROCESS(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_PROCESS))
 #define XSETWINDOW(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_WINDOW))
 #define XSETTERMINAL(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_TERMINAL))
-#define XSETSUBR(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_SUBR))
+#define XSETSUBR(a, b) \
+  XSETTYPED_PSEUDOVECTOR (a, b, XSUBR (a)->size, PVEC_SUBR)
 #define XSETCOMPILED(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_COMPILED))
 #define XSETBUFFER(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_BUFFER))
 #define XSETCHAR_TABLE(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_CHAR_TABLE))
@@ -615,7 +628,7 @@ extern Lisp_Object make_number P_ ((EMACS_INT));
 /* Convenience macros for dealing with Lisp arrays.  */
 
 #define AREF(ARRAY, IDX)        XVECTOR ((ARRAY))->contents[IDX]
-#define ASIZE(ARRAY)            XVECTOR ((ARRAY))->size
+#define ASIZE(ARRAY)            XVECTOR_SIZE (ARRAY)
 /* The IDX==IDX tries to detect when the macro argument is side-effecting.  */
 #define ASET(ARRAY, IDX, VAL)   \
   (eassert ((IDX) == (IDX)),                            \
@@ -780,11 +793,21 @@ struct Lisp_String
 #define OFFSETOF(type,field) \
   ((int)((char*)&((type*)0)->field - (char*)0))
 #endif
+/* Header of vector-like objects.  This type documents the constraints on
+   layout of vectors and pseudovectors, and helps optimizing compilers not get
+   fooled by Emacs's type punning.  */
+struct vectorlike_header
+  {
+    EMACS_UINT size;
+    union {
+      struct buffer *buffer;
+      struct Lisp_Vector *vector;
+    } next;
+  };
 
 struct Lisp_Vector
   {
-    EMACS_UINT size;
-    struct Lisp_Vector *next;
+    struct vectorlike_header header;
     Lisp_Object contents[1];
   };
 
@@ -820,7 +843,7 @@ struct Lisp_Vector
 /* Return the number of "extra" slots in the char table CT.  */
 
 #define CHAR_TABLE_EXTRA_SLOTS(CT)      \
-  (((CT)->size & PSEUDOVECTOR_SIZE_MASK) - CHAR_TABLE_STANDARD_SLOTS)
+  (((CT)->header.size & PSEUDOVECTOR_SIZE_MASK) - CHAR_TABLE_STANDARD_SLOTS)
 
 #ifdef __GNUC__
 
@@ -882,12 +905,11 @@ struct Lisp_Sub_Char_Table;
 
 struct Lisp_Char_Table
   {
-    /* This is the vector's size field, which also holds the
+    /* HEADER.SIZE is the vector's size field, which also holds the
        pseudovector type information.  It holds the size, too.
        The size counts the defalt, parent, purpose, ascii,
        contents, and extras slots.  */
-    EMACS_UINT size;
-    struct Lisp_Vector *next;
+    struct vectorlike_header header;
 
     /* This holds a default value,
        which is used whenever the value for a specific character is nil.  */
@@ -914,10 +936,9 @@ struct Lisp_Char_Table
 
 struct Lisp_Sub_Char_Table
   {
-    /* This is the vector's size field, which also holds the
+    /* HEADER.SIZE is the vector's size field, which also holds the
        pseudovector type information.  It holds the size, too.  */
-    EMACS_INT size;
-    struct Lisp_Vector *next;
+    struct vectorlike_header header;
 
     /* Depth of this sub char-table.  It should be 1, 2, or 3.  A sub
        char-table of depth 1 contains 16 elements, and each element
@@ -936,10 +957,9 @@ struct Lisp_Sub_Char_Table
 /* A boolvector is a kind of vectorlike, with contents are like a string.  */
 struct Lisp_Bool_Vector
   {
-    /* This is the vector's size field.  It doesn't have the real size,
+    /* HEADER.SIZE is the vector's size field.  It doesn't have the real size,
        just the subtype information.  */
-    EMACS_UINT vector_size;
-    struct Lisp_Vector *next;
+    struct vectorlike_header header;
     /* This is the size in bits.  */
     EMACS_UINT size;
     /* This contains the actual bits, packed into bytes.  */
@@ -952,7 +972,7 @@ struct Lisp_Bool_Vector
 
    This type is treated in most respects as a pseudovector,
    but since we never dynamically allocate or free them,
-   we don't need a next-vector field.  */
+   we don't need a struct vectorlike_header and its 'next' field.  */
 
 struct Lisp_Subr
   {
@@ -1066,9 +1086,8 @@ struct Lisp_Symbol
 
 struct Lisp_Hash_Table
 {
-  /* Vector fields.  The hash table code doesn't refer to these.  */
-  EMACS_UINT size;
-  struct Lisp_Vector *vec_next;
+  /* This is for Lisp; the hash table code does not refer to it.  */
+  struct vectorlike_header header;
 
   /* Function used to compare keys.  */
   Lisp_Object test;
@@ -1169,7 +1188,7 @@ struct Lisp_Hash_Table
 
 /* Value is the size of hash table H.  */
 
-#define HASH_TABLE_SIZE(H) XVECTOR ((H)->next)->size
+#define HASH_TABLE_SIZE(H) XVECTOR_SIZE ((H)->next)
 
 /* Default size for hash tables if not specified.  */
 
@@ -1551,7 +1570,7 @@ typedef struct {
 #define CONSP(x) (XTYPE ((x)) == Lisp_Cons)
 
 #define FLOATP(x) (XTYPE ((x)) == Lisp_Float)
-#define VECTORP(x)    (VECTORLIKEP (x) && !(XVECTOR (x)->size & PSEUDOVECTOR_FLAG))
+#define VECTORP(x)    (VECTORLIKEP (x) && !(XVECTOR_SIZE (x) & PSEUDOVECTOR_FLAG))
 #define OVERLAYP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Overlay)
 #define MARKERP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Marker)
 #define INTFWDP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Intfwd)
@@ -1566,8 +1585,14 @@ typedef struct {
 
 /* True if object X is a pseudovector whose code is CODE.  */
 #define PSEUDOVECTORP(x, code)                                  \
+  TYPED_PSEUDOVECTORP(x, vectorlike_header, code)
+
+/* True if object X, with internal type struct T *, is a pseudovector whose
+   code is CODE.  */
+#define TYPED_PSEUDOVECTORP(x, t, code)                         \
   (VECTORLIKEP (x)                                              \
-   && (((XVECTOR (x)->size & (PSEUDOVECTOR_FLAG | (code))))     \
+   && (((((struct t *) XPNTR (x))->size                         \
+         & (PSEUDOVECTOR_FLAG | (code))))                       \
        == (PSEUDOVECTOR_FLAG | (code))))
 
 /* Test for specific pseudovector types.  */
@@ -1575,7 +1600,7 @@ typedef struct {
 #define PROCESSP(x) PSEUDOVECTORP (x, PVEC_PROCESS)
 #define WINDOWP(x) PSEUDOVECTORP (x, PVEC_WINDOW)
 #define TERMINALP(x) PSEUDOVECTORP (x, PVEC_TERMINAL)
-#define SUBRP(x) PSEUDOVECTORP (x, PVEC_SUBR)
+#define SUBRP(x) TYPED_PSEUDOVECTORP (x, Lisp_Subr, PVEC_SUBR)
 #define COMPILEDP(x) PSEUDOVECTORP (x, PVEC_COMPILED)
 #define BUFFERP(x) PSEUDOVECTORP (x, PVEC_BUFFER)
 #define CHAR_TABLE_P(x) PSEUDOVECTORP (x, PVEC_CHAR_TABLE)
diff --git a/src/lread.c b/src/lread.c
index 2da64632417..3d954ac282b 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -2433,7 +2433,7 @@ read1 (readcharfun, pch, first_in_list)
             {
               Lisp_Object tmp;
               tmp = read_vector (readcharfun, 0);
-              if (XVECTOR (tmp)->size < CHAR_TABLE_STANDARD_SLOTS)
+              if (XVECTOR_SIZE (tmp) < CHAR_TABLE_STANDARD_SLOTS)
                 error ("Invalid size char-table");
               XSETPVECTYPE (XVECTOR (tmp), PVEC_CHAR_TABLE);
               return tmp;
@@ -2452,7 +2452,7 @@ read1 (readcharfun, pch, first_in_list)
                   depth = XINT (AREF (tmp, 0));
                   if (depth < 1 || depth > 3)
                     error ("Invalid depth in char-table");
-                  size = XVECTOR (tmp)->size - 2;
+                  size = XVECTOR_SIZE (tmp) - 2;
                   if (chartab_size [depth] != size)
                     error ("Invalid size char-table");
                   XSETPVECTYPE (XVECTOR (tmp), PVEC_SUB_CHAR_TABLE);
@@ -2503,7 +2503,7 @@ read1 (readcharfun, pch, first_in_list)
              build them using function calls.  */
           Lisp_Object tmp;
           tmp = read_vector (readcharfun, 1);
-          return Fmake_byte_code (XVECTOR (tmp)->size,
+          return Fmake_byte_code (XVECTOR_SIZE (tmp),
                                   XVECTOR (tmp)->contents);
         }
       if (c == '(')
@@ -3332,7 +3332,7 @@ read_vector (readcharfun, bytecodeflag)
   len = Flength (tem);
   vector = (read_pure ? make_pure_vector (XINT (len)) : Fmake_vector (len, Qnil));
 
-  size = XVECTOR (vector)->size;
+  size = XVECTOR_SIZE (vector);
   ptr = XVECTOR (vector)->contents;
   for (i = 0; i < size; i++)
     {
@@ -3601,7 +3601,7 @@ Lisp_Object
 check_obarray (obarray)
      Lisp_Object obarray;
 {
-  if (!VECTORP (obarray) || XVECTOR (obarray)->size == 0)
+  if (!VECTORP (obarray) || XVECTOR_SIZE (obarray) == 0)
     {
       /* If Vobarray is now invalid, force it to be valid.  */
       if (EQ (Vobarray, obarray)) Vobarray = initial_obarray;
@@ -3622,7 +3622,7 @@ intern (str)
   Lisp_Object obarray;
 
   obarray = Vobarray;
-  if (!VECTORP (obarray) || XVECTOR (obarray)->size == 0)
+  if (!VECTORP (obarray) || XVECTOR_SIZE (obarray) == 0)
     obarray = check_obarray (obarray);
   tem = oblookup (obarray, str, len, len);
   if (SYMBOLP (tem))
@@ -3638,7 +3638,7 @@ intern_c_string (const char *str)
   Lisp_Object obarray;
 
   obarray = Vobarray;
-  if (!VECTORP (obarray) || XVECTOR (obarray)->size == 0)
+  if (!VECTORP (obarray) || XVECTOR_SIZE (obarray) == 0)
     obarray = check_obarray (obarray);
   tem = oblookup (obarray, str, len, len);
   if (SYMBOLP (tem))
@@ -3831,10 +3831,10 @@ oblookup (obarray, ptr, size, size_byte)
   Lisp_Object bucket, tem;
 
   if (!VECTORP (obarray)
-      || (obsize = XVECTOR (obarray)->size) == 0)
+      || (obsize = XVECTOR_SIZE (obarray)) == 0)
     {
       obarray = check_obarray (obarray);
-      obsize = XVECTOR (obarray)->size;
+      obsize = XVECTOR_SIZE (obarray);
     }
   /* This is sometimes needed in the middle of GC.  */
   obsize &= ~ARRAY_MARK_FLAG;
@@ -3887,7 +3887,7 @@ map_obarray (obarray, fn, arg)
   register int i;
   register Lisp_Object tail;
   CHECK_VECTOR (obarray);
-  for (i = XVECTOR (obarray)->size - 1; i >= 0; i--)
+  for (i = XVECTOR_SIZE (obarray) - 1; i >= 0; i--)
     {
       tail = XVECTOR (obarray)->contents[i];
       if (SYMBOLP (tail))
@@ -3974,7 +3974,7 @@ defsubr (sname)
 {
   Lisp_Object sym;
   sym = intern_c_string (sname->symbol_name);
-  XSETPVECTYPE (sname, PVEC_SUBR);
+  XSETTYPED_PVECTYPE (sname, size, PVEC_SUBR);
   XSETSUBR (XSYMBOL (sym)->function, sname);
 }
 
diff --git a/src/minibuf.c b/src/minibuf.c
index 90df137411c..2b2d8dc81fb 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -1326,7 +1326,7 @@ is used to further constrain the set of candidates.  */)
   if (type == obarray_table)
     {
       collection = check_obarray (collection);
-      obsize = XVECTOR (collection)->size;
+      obsize = XVECTOR_SIZE (collection);
       bucket = XVECTOR (collection)->contents[index];
     }
 
@@ -1590,7 +1590,7 @@ with a space are ignored unless STRING itself starts with a space.  */)
   if (type == 2)
     {
       collection = check_obarray (collection);
-      obsize = XVECTOR (collection)->size;
+      obsize = XVECTOR_SIZE (collection);
       bucket = XVECTOR (collection)->contents[index];
     }
 
@@ -1889,7 +1889,7 @@ the values STRING, PREDICATE and `lambda'.  */)
 
       if (completion_ignore_case && !SYMBOLP (tem))
         {
-          for (i = XVECTOR (collection)->size - 1; i >= 0; i--)
+          for (i = XVECTOR_SIZE (collection) - 1; i >= 0; i--)
             {
               tail = XVECTOR (collection)->contents[i];
               if (SYMBOLP (tail))
diff --git a/src/print.c b/src/print.c
index 682212d5e39..8ffe7b544b0 100644
--- a/src/print.c
+++ b/src/print.c
@@ -1365,7 +1365,7 @@ print_preprocess (obj)
               /* Initialize the table.  */
               Vprint_number_table = Fmake_vector (make_number (40), Qnil);
             }
-          else if (XVECTOR (Vprint_number_table)->size == print_number_index * 2)
+          else if (XVECTOR_SIZE (Vprint_number_table) == print_number_index * 2)
             {
               /* Reallocate the table.  */
               int i = print_number_index * 4;
@@ -1411,7 +1411,7 @@ print_preprocess (obj)
           goto loop;
 
         case Lisp_Vectorlike:
-          size = XVECTOR (obj)->size;
+          size = XVECTOR_SIZE (obj);
           if (size & PSEUDOVECTOR_FLAG)
             size &= PSEUDOVECTOR_SIZE_MASK;
           for (i = 0; i < size; i++)
@@ -2051,7 +2051,7 @@ print_object (obj, printcharfun, escapeflag)
               strout (SDATA (SYMBOL_NAME (h->weak)), -1, -1, printcharfun, 0);
               PRINTCHAR (' ');
               sprintf (buf, "%ld/%ld", (long) h->count,
-                       (long) XVECTOR (h->next)->size);
+                       (long) XVECTOR_SIZE (h->next));
               strout (buf, -1, -1, printcharfun, 0);
             }
           sprintf (buf, " 0x%lx", (unsigned long) h);
@@ -2062,7 +2062,7 @@ print_object (obj, printcharfun, escapeflag)
             #s(hash-table size 2 test equal data (k1 v1 k2 v2)) */
           /* Always print the size. */
           sprintf (buf, "#s(hash-table size %ld",
-                   (long) XVECTOR (h->next)->size);
+                   (long) XVECTOR_SIZE (h->next));
           strout (buf, -1, -1, printcharfun, 0);
 
           if (!NILP (h->test))
@@ -2174,7 +2174,7 @@ print_object (obj, printcharfun, escapeflag)
         }
       else
         {
-          EMACS_INT size = XVECTOR (obj)->size;
+          EMACS_INT size = XVECTOR_SIZE (obj);
           if (COMPILEDP (obj))
             {
               PRINTCHAR ('#');
@@ -2354,7 +2354,7 @@ print_object (obj, printcharfun, escapeflag)
         if (MISCP (obj))
           sprintf (buf, "(MISC 0x%04x)", (int) XMISCTYPE (obj));
         else if (VECTORLIKEP (obj))
-          sprintf (buf, "(PVEC 0x%08x)", (int) XVECTOR (obj)->size);
+          sprintf (buf, "(PVEC 0x%08lx)", (unsigned long) XVECTOR_SIZE (obj));
         else
           sprintf (buf, "(0x%02x)", (int) XTYPE (obj));
         strout (buf, -1, -1, printcharfun, 0);
diff --git a/src/process.c b/src/process.c
index 9a33500dc4e..d4371fb8f32 100644
--- a/src/process.c
+++ b/src/process.c
@@ -1277,25 +1277,26 @@ Returns nil if format of ADDRESS is invalid.  */)
   if (VECTORP (address))  /* AF_INET or AF_INET6 */
     {
       register struct Lisp_Vector *p = XVECTOR (address);
+      EMACS_UINT size = p->header.size;
       Lisp_Object args[10];
       int nargs, i;
 
-      if (p->size == 4 || (p->size == 5 && !NILP (omit_port)))
+      if (size == 4 || (size == 5 && !NILP (omit_port)))
         {
           args[0] = build_string ("%d.%d.%d.%d");
           nargs = 4;
         }
-      else if (p->size == 5)
+      else if (size == 5)
         {
           args[0] = build_string ("%d.%d.%d.%d:%d");
           nargs = 5;
         }
-      else if (p->size == 8 || (p->size == 9 && !NILP (omit_port)))
+      else if (size == 8 || (size == 9 && !NILP (omit_port)))
         {
           args[0] = build_string ("%x:%x:%x:%x:%x:%x:%x:%x");
           nargs = 8;
         }
-      else if (p->size == 9)
+      else if (size == 9)
         {
           args[0] = build_string ("[%x:%x:%x:%x:%x:%x:%x:%x]:%d");
           nargs = 9;
@@ -2477,13 +2478,13 @@ get_lisp_to_sockaddr_size (address, familyp)
   if (VECTORP (address))
     {
       p = XVECTOR (address);
-      if (p->size == 5)
+      if (p->header.size == 5)
         {
           *familyp = AF_INET;
           return sizeof (struct sockaddr_in);
         }
 #ifdef AF_INET6
-      else if (p->size == 9)
+      else if (p->header.size == 9)
         {
           *familyp = AF_INET6;
           return sizeof (struct sockaddr_in6);
@@ -2502,7 +2503,7 @@ get_lisp_to_sockaddr_size (address, familyp)
       struct sockaddr *sa;
       *familyp = XINT (XCAR (address));
       p = XVECTOR (XCDR (address));
-      return p->size + sizeof (sa->sa_family);
+      return p->header.size + sizeof (sa->sa_family);
     }
   return 0;
 }
diff --git a/src/process.h b/src/process.h
index 72e8af70262..0ff374ee47f 100644
--- a/src/process.h
+++ b/src/process.h
@@ -27,13 +27,13 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 /* This structure records information about a subprocess
    or network connection.
 
-   Every field in this structure except for the first two
+   Every field in this structure except for the header
    must be a Lisp_Object, for GC's sake.  */
 
 struct Lisp_Process
   {
-    EMACS_UINT size;
-    struct Lisp_Vector *v_next;
+    struct vectorlike_header header;
+
     /* Name of subprocess terminal.  */
     Lisp_Object tty_name;
     /* Name of this process */
diff --git a/src/syntax.c b/src/syntax.c
index 97c67c955b1..bfdf0e5ee6d 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -956,7 +956,7 @@ text property.  */)
         break;
       }
 
-  if (val < XVECTOR (Vsyntax_code_object)->size && NILP (match))
+  if (val < XVECTOR_SIZE (Vsyntax_code_object) && NILP (match))
     return XVECTOR (Vsyntax_code_object)->contents[val];
   else
     /* Since we can't use a shared object, let's make a new one.  */
@@ -3348,7 +3348,7 @@ init_syntax_once ()
 
   /* Create objects which can be shared among syntax tables.  */
   Vsyntax_code_object = Fmake_vector (make_number (Smax), Qnil);
-  for (i = 0; i < XVECTOR (Vsyntax_code_object)->size; i++)
+  for (i = 0; i < XVECTOR_SIZE (Vsyntax_code_object); i++)
     XVECTOR (Vsyntax_code_object)->contents[i]
       = Fcons (make_number (i), Qnil);
 
diff --git a/src/termhooks.h b/src/termhooks.h
index f8c26b0a54c..a318087e846 100644
--- a/src/termhooks.h
+++ b/src/termhooks.h
@@ -325,10 +325,8 @@ struct w32_display_info;
 /* Terminal-local parameters. */
 struct terminal
 {
-  /* The first two fields are really the header of a vector */
-  /* The terminal code does not refer to them.  */
-  EMACS_UINT size;
-  struct Lisp_Vector *vec_next;
+  /* This is for Lisp; the terminal code does not refer to it.  */
+  struct vectorlike_header header;
 
   /* Parameter alist of this terminal.  */
   Lisp_Object param_alist;
diff --git a/src/w32font.c b/src/w32font.c
index 0f01cebefc0..b467122b5fd 100644
--- a/src/w32font.c
+++ b/src/w32font.c
@@ -173,7 +173,7 @@ intern_font_name (string)
 
   /* The following code is copied from the function intern (in lread.c).  */
   obarray = Vobarray;
-  if (!VECTORP (obarray) || XVECTOR (obarray)->size == 0)
+  if (!VECTORP (obarray) || XVECTOR_SIZE (obarray) == 0)
     obarray = check_obarray (obarray);
   tem = oblookup (obarray, SDATA (str), len, len);
   if (SYMBOLP (tem))
diff --git a/src/w32menu.c b/src/w32menu.c
index d85a17e5b85..f29ca9e2ef1 100644
--- a/src/w32menu.c
+++ b/src/w32menu.c
@@ -464,11 +464,11 @@ set_frame_menubar (f, first_time, deep_p)
 
       menu_items = f->menu_bar_vector;
       menu_items_allocated = VECTORP (menu_items) ? ASIZE (menu_items) : 0;
-      submenu_start = (int *) alloca (XVECTOR (items)->size * sizeof (int *));
-      submenu_end = (int *) alloca (XVECTOR (items)->size * sizeof (int *));
-      submenu_n_panes = (int *) alloca (XVECTOR (items)->size * sizeof (int));
+      submenu_start = (int *) alloca (XVECTOR_SIZE (items) * sizeof (int *));
+      submenu_end = (int *) alloca (XVECTOR_SIZE (items) * sizeof (int *));
+      submenu_n_panes = (int *) alloca (XVECTOR_SIZE (items) * sizeof (int));
       submenu_top_level_items
-        = (int *) alloca (XVECTOR (items)->size * sizeof (int *));
+        = (int *) alloca (XVECTOR_SIZE (items) * sizeof (int *));
       init_menu_items ();
       for (i = 0; i < ASIZE (items); i += 4)
         {
diff --git a/src/window.c b/src/window.c
index 3e6062a7153..894ff65b600 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5931,8 +5931,7 @@ zero means top of window, negative means relative to bottom of window.  */)
 
 struct save_window_data
   {
-    EMACS_UINT size;
-    struct Lisp_Vector *next_from_Lisp_Vector_struct;
+    struct vectorlike_header header;
     Lisp_Object selected_frame;
     Lisp_Object current_window;
     Lisp_Object current_buffer;
@@ -5954,10 +5953,7 @@ struct save_window_data
 /* This is saved as a Lisp_Vector  */
 struct saved_window
 {
-  /* these first two must agree with struct Lisp_Vector in lisp.h */
-  EMACS_UINT size;
-  struct Lisp_Vector *next_from_Lisp_Vector_struct;
-
+  struct vectorlike_header header;
   Lisp_Object window;
   Lisp_Object buffer, start, pointm, mark;
   Lisp_Object left_col, top_line, total_cols, total_lines;
@@ -6141,7 +6137,7 @@ the return value is nil.  Otherwise the value is t.  */)
          dead.  */
       delete_all_subwindows (XWINDOW (FRAME_ROOT_WINDOW (f)));
 
-      for (k = 0; k < saved_windows->size; k++)
+      for (k = 0; k < saved_windows->header.size; k++)
         {
           p = SAVED_WINDOW_N (saved_windows, k);
           w = XWINDOW (p->window);
@@ -7078,10 +7074,10 @@ compare_window_configurations (c1, c2, ignore_positions)
     return 0;
 
   /* Verify that the two confis have the same number of windows.  */
-  if (sw1->size != sw2->size)
+  if (sw1->header.size != sw2->header.size)
     return 0;
 
-  for (i = 0; i < sw1->size; i++)
+  for (i = 0; i < sw1->header.size; i++)
     {
       struct saved_window *p1, *p2;
       int w1_is_current, w2_is_current;
diff --git a/src/window.h b/src/window.h
index 99259b7f3a2..f7759467d0d 100644
--- a/src/window.h
+++ b/src/window.h
@@ -89,10 +89,9 @@ struct cursor_pos
 
 struct window
   {
-    /* The first two fields are really the header of a vector */
-    /* The window code does not refer to them.  */
-    EMACS_UINT size;
-    struct Lisp_Vector *vec_next;
+    /* This is for Lisp; the terminal code does not refer to it.  */
+    struct vectorlike_header header;
+
     /* The frame this window is on.  */
     Lisp_Object frame;
     /* t if this window is a minibuffer window.  */
diff --git a/src/xdisp.c b/src/xdisp.c
index c42410b9f9f..1f4c829ce94 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -3865,7 +3865,7 @@ setup_for_ellipsis (it, len)
     {
       struct Lisp_Vector *v = XVECTOR (DISP_INVIS_VECTOR (it->dp));
       it->dpvec = v->contents;
-      it->dpend = v->contents + v->size;
+      it->dpend = v->contents + v->header.size;
     }
   else
     {
@@ -5697,11 +5697,11 @@ get_next_display_element (it)
               /* Return the first character from the display table
                  entry, if not empty.  If empty, don't display the
                  current character.  */
-              if (v->size)
+              if (v->header.size)
                 {
                   it->dpvec_char_len = it->len;
                   it->dpvec = v->contents;
-                  it->dpend = v->contents + v->size;
+                  it->dpend = v->contents + v->header.size;
                   it->current.dpvec_index = 0;
                   it->dpvec_face_id = -1;
                   it->saved_face_id = it->face_id;
@@ -17087,7 +17087,7 @@ display_menu_bar (w)
 
   /* Display all items of the menu bar.  */
   items = FRAME_MENU_BAR_ITEMS (it.f);
-  for (i = 0; i < XVECTOR (items)->size; i += 4)
+  for (i = 0; i < XVECTOR_SIZE (items); i += 4)
     {
       Lisp_Object string;
 
@@ -23086,7 +23086,7 @@ on_hot_spot_p (hot_spot, x, y)
         {
           struct Lisp_Vector *v = XVECTOR (XCDR (hot_spot));
           Lisp_Object *poly = v->contents;
-          int n = v->size;
+          int n = v->header.size;
           int i;
           int inside = 0;
           Lisp_Object lx, ly;
diff --git a/src/xfaces.c b/src/xfaces.c
index 9956ef55842..1606113596d 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -1966,7 +1966,7 @@ the WIDTH times as wide as FACE on FRAME.  */)
 
 #define LFACEP(LFACE)                                   \
      (VECTORP (LFACE)                                   \
-      && XVECTOR (LFACE)->size == LFACE_VECTOR_SIZE     \
+      && XVECTOR_SIZE (LFACE) == LFACE_VECTOR_SIZE      \
       && EQ (AREF (LFACE, 0), Qface))
 
 
diff --git a/src/xmenu.c b/src/xmenu.c
index c2e70e13bf9..2a05c52ee34 100644
--- a/src/xmenu.c
+++ b/src/xmenu.c
@@ -1012,6 +1012,7 @@ set_frame_menubar (f, first_time, deep_p)
       Lisp_Object *previous_items
         = (Lisp_Object *) alloca (previous_menu_items_used
                                   * sizeof (Lisp_Object));
+      EMACS_UINT subitems;
 
       /* If we are making a new widget, its contents are empty,
          do always reinitialize them.  */
@@ -1056,13 +1057,14 @@ set_frame_menubar (f, first_time, deep_p)
 
       menu_items = f->menu_bar_vector;
       menu_items_allocated = VECTORP (menu_items) ? ASIZE (menu_items) : 0;
-      submenu_start = (int *) alloca (XVECTOR (items)->size * sizeof (int *));
-      submenu_end = (int *) alloca (XVECTOR (items)->size * sizeof (int *));
-      submenu_n_panes = (int *) alloca (XVECTOR (items)->size * sizeof (int));
+      subitems = XVECTOR_SIZE (items) / 4;
+      submenu_start = (int *) alloca (subitems * sizeof (int *));
+      submenu_end = (int *) alloca (subitems * sizeof (int *));
+      submenu_n_panes = (int *) alloca (subitems * sizeof (int));
       submenu_top_level_items
-        = (int *) alloca (XVECTOR (items)->size * sizeof (int *));
+        = (int *) alloca (subitems * sizeof (int *));
       init_menu_items ();
-      for (i = 0; i < XVECTOR (items)->size; i += 4)
+      for (i = 0; i < subitems; i += 4)
         {
           Lisp_Object key, string, maps;
 
@@ -1142,7 +1144,7 @@ set_frame_menubar (f, first_time, deep_p)
       /* Now GC cannot happen during the lifetime of the widget_value,
          so it's safe to store data from a Lisp_String.  */
       wv = first_wv->contents;
-      for (i = 0; i < XVECTOR (items)->size; i += 4)
+      for (i = 0; i < XVECTOR_SIZE (items); i += 4)
         {
           Lisp_Object string;
           string = XVECTOR (items)->contents[i + 1];
@@ -1168,7 +1170,7 @@ set_frame_menubar (f, first_time, deep_p)
       first_wv = wv;
 
       items = FRAME_MENU_BAR_ITEMS (f);
-      for (i = 0; i < XVECTOR (items)->size; i += 4)
+      for (i = 0; i < XVECTOR_SIZE (items); i += 4)
         {
           Lisp_Object string;
 
diff --git a/src/xselect.c b/src/xselect.c
index 023d2eee8c3..00099ec6f0c 100644
--- a/src/xselect.c
+++ b/src/xselect.c
@@ -486,7 +486,7 @@ x_get_local_selection (selection_symbol, target_type, local_request)
       int size;
       int i;
       pairs = XCDR (target_type);
-      size = XVECTOR (pairs)->size;
+      size = XVECTOR_SIZE (pairs);
       /* If the target is MULTIPLE, then target_type looks like
           (MULTIPLE . [[SELECTION1 TARGET1] [SELECTION2 TARGET2] ... ])
          We modify the second element of each pair in the vector and
@@ -1351,12 +1351,12 @@ copy_multiple_data (obj)
     return Fcons (XCAR (obj), copy_multiple_data (XCDR (obj)));
 
   CHECK_VECTOR (obj);
-  vec = Fmake_vector (size = XVECTOR (obj)->size, Qnil);
+  vec = Fmake_vector (size = XVECTOR_SIZE (obj), Qnil);
   for (i = 0; i < size; i++)
     {
       Lisp_Object vec2 = XVECTOR (obj)->contents [i];
       CHECK_VECTOR (vec2);
-      if (XVECTOR (vec2)->size != 2)
+      if (XVECTOR_SIZE (vec2) != 2)
         /* ??? Confusing error message */
         signal_error ("Vectors must be of length 2", vec2);
       XVECTOR (vec)->contents [i] = Fmake_vector (2, Qnil);
@@ -1996,7 +1996,7 @@ lisp_data_to_selection_data (display, obj,
         /* This vector is an ATOM set */
         {
           if (NILP (type)) type = QATOM;
-          *size_ret = XVECTOR (obj)->size;
+          *size_ret = XVECTOR_SIZE (obj);
           *format_ret = 32;
           *data_ret = (unsigned char *) xmalloc ((*size_ret) * sizeof (Atom));
           for (i = 0; i < *size_ret; i++)
@@ -2011,7 +2011,7 @@ lisp_data_to_selection_data (display, obj,
         /* This vector is an ATOM_PAIR set */
         {
           if (NILP (type)) type = QATOM_PAIR;
-          *size_ret = XVECTOR (obj)->size;
+          *size_ret = XVECTOR_SIZE (obj);
           *format_ret = 32;
           *data_ret = (unsigned char *)
             xmalloc ((*size_ret) * sizeof (Atom) * 2);
@@ -2019,7 +2019,7 @@ lisp_data_to_selection_data (display, obj,
             if (VECTORP (XVECTOR (obj)->contents [i]))
               {
                 Lisp_Object pair = XVECTOR (obj)->contents [i];
-                if (XVECTOR (pair)->size != 2)
+                if (XVECTOR_SIZE (pair) != 2)
                   signal_error (
         "Elements of the vector must be vectors of exactly two elements",
                                 pair);
@@ -2041,7 +2041,7 @@ lisp_data_to_selection_data (display, obj,
         /* This vector is an INTEGER set, or something like it */
         {
           int data_size = 2;
-          *size_ret = XVECTOR (obj)->size;
+          *size_ret = XVECTOR_SIZE (obj);
           if (NILP (type)) type = QINTEGER;
           *format_ret = 16;
           for (i = 0; i < *size_ret; i++)
@@ -2095,7 +2095,7 @@ clean_local_selection_data (obj)
   if (VECTORP (obj))
     {
       int i;
-      int size = XVECTOR (obj)->size;
+      int size = XVECTOR_SIZE (obj);
       Lisp_Object copy;
       if (size == 1)
         return clean_local_selection_data (XVECTOR (obj)->contents [0]);