Simplify enforcement of object address alignment

* lisp.h (struct Lisp_Symbol): Remove explicit padding.
(struct Lisp_Misc_Any): Likewise.
(struct Lisp_Free): Likewise.
* alloc.c (union aligned_Lisp_Symbol): Define.
(SYMBOL_BLOCK_SIZE, struct symbol_block): Use union
aligned_Lisp_Symbol instead of struct Lisp_Symbol.
(union aligned_Lisp_Misc): Define.
(MARKER_BLOCK_SIZE, struct marker_block): Use union
aligned_Lisp_Misc instead of union Lisp_Misc.
(Fmake_symbol, allocate_misc, gc_sweep): Adjust

1 files changed, 9 insertions, 20 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 81d17f4b922..d1e2cc8715d 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1134,8 +1134,6 @@ struct Lisp_Symbol
      special (with `defvar' etc), and shouldn't be lexically bound.  */
   unsigned declared_special : 1;
 
-  unsigned spacer : 23;
-
   /* The symbol's name, as a Lisp string.
      The name "xname" is used to intentionally break code referring to
      the old field "name" of type pointer to struct Lisp_String.  */
@@ -1337,8 +1335,6 @@ struct Lisp_Misc_Any		/* Supertype of all Misc types.  */
   ENUM_BF (Lisp_Misc_Type) type : 16;           /* = Lisp_Misc_??? */
   unsigned gcmarkbit : 1;
   int spacer : 15;
-  /* Make it as long as "Lisp_Free without padding".  */
-  void *fill;
 };
 
 struct Lisp_Marker
@@ -1530,13 +1526,6 @@ struct Lisp_Free
     unsigned gcmarkbit : 1;
     int spacer : 15;
     union Lisp_Misc *chain;
-#ifdef USE_LSB_TAG
-    /* Try to make sure that sizeof(Lisp_Misc) preserves TYPEBITS-alignment.
-       This assumes that Lisp_Marker is the largest of the alternatives and
-       that Lisp_Misc_Any has the same size as "Lisp_Free w/o padding".  */
-    char padding[((((sizeof (struct Lisp_Marker) - 1) >> GCTYPEBITS) + 1)
-                  << GCTYPEBITS) - sizeof (struct Lisp_Misc_Any)];
-#endif
   };
 
 /* To get the type field of a union Lisp_Misc, use XMISCTYPE.
@@ -1545,19 +1534,19 @@ struct Lisp_Free
 union Lisp_Misc
   {
     struct Lisp_Misc_Any u_any;    /* Supertype of all Misc types.  */
-    struct Lisp_Free u_free;       /* Includes padding to force alignment.  */
-    struct Lisp_Marker u_marker;                         /* 5 */
-    struct Lisp_Overlay u_overlay;                       /* 5 */
-    struct Lisp_Save_Value u_save_value;                 /* 3 */
+    struct Lisp_Free u_free;
+    struct Lisp_Marker u_marker;
+    struct Lisp_Overlay u_overlay;
+    struct Lisp_Save_Value u_save_value;
   };
 
 union Lisp_Fwd
   {
-    struct Lisp_Intfwd u_intfwd;                         /* 2 */
-    struct Lisp_Boolfwd u_boolfwd;                       /* 2 */
-    struct Lisp_Objfwd u_objfwd;                         /* 2 */
-    struct Lisp_Buffer_Objfwd u_buffer_objfwd;           /* 2 */
-    struct Lisp_Kboard_Objfwd u_kboard_objfwd;           /* 2 */
+    struct Lisp_Intfwd u_intfwd;
+    struct Lisp_Boolfwd u_boolfwd;
+    struct Lisp_Objfwd u_objfwd;
+    struct Lisp_Buffer_Objfwd u_buffer_objfwd;
+    struct Lisp_Kboard_Objfwd u_kboard_objfwd;
   };
 
 /* Lisp floating point type */