[Emacs-diffs] /srv/bzr/emacs/trunk r106018: * alloc.c: Add comment.

[Paul Eggert]

------------------------------------------------------------
revno: 106018
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Fri 2011-10-07 09:42:32 -0700
message:
  * alloc.c: Add comment.
modified:
  src/alloc.c

=== modified file 'src/alloc.c'
--- a/src/alloc.c       2011-10-07 07:23:44 +0000
+++ b/src/alloc.c       2011-10-07 16:42:32 +0000
@@ -4235,6 +4235,11 @@
 }
 
 
+/* Alignment of Lisp_Object and pointer values.  Use offsetof, as it
+   sometimes returns a smaller alignment than GCC's __alignof__ and
+   mark_memory might miss objects if __alignof__ were used.  For
+   example, on x86 with WIDE_EMACS_INT, __alignof__ (Lisp_Object) is 8
+   but GC_LISP_OBJECT_ALIGNMENT should be 4.  */
 #ifndef GC_LISP_OBJECT_ALIGNMENT
 # define GC_LISP_OBJECT_ALIGNMENT offsetof (struct {char a; Lisp_Object b;}, b)
 #endif