Stack marking and Lisp objects alignment

Stack marking and Lisp objects alignment

[Dmitry Antipov]

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Is that correct ? If yes, this is a tiny speedup for stack marking code...



Dmitry


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Index: alloc.c
===================================================================
RCS file: /sources/emacs/emacs/src/alloc.c,v
retrieving revision 1.410
diff -u -r1.410 alloc.c
--- alloc.c	8 Jun 2007 19:59:46 -0000	1.410
+++ alloc.c	7 Jul 2007 19:03:23 -0000
@@ -4263,9 +4263,14 @@
 {
   struct mem_node *m;
 
-  /* Quickly rule out some values which can't point to Lisp data.  We
-     assume that Lisp data is aligned on even addresses.  */
+  /* Quickly rule out some values which can't point to Lisp data.  We assume
+     that Lisp data is aligned on 8-byte boundaries if LSB tagging scheme is
+     used, or at least at even addresses otherwise.  */
+#ifdef USE_LSB_TAG
+  if ((EMACS_INT) p & 7)
+#else
   if ((EMACS_INT) p & 1)
+#endif
     return;
 
   m = mem_find (p);

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Re: Stack marking and Lisp objects alignment

[Stefan Monnier]

> Is that correct ? If yes, this is a tiny speedup for stack marking code...

Looks correct.  I've installed a similar patch.  But we will need you
to sign copyright papers for the rest of your changes,


        Stefan