admin/notes/tags small update

[bpt/emacs.git] / src / lisp.h

diff --git a/src/lisp.h b/src/lisp.h
index 366d24a..bd19da5 100644 (file)
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -168,6 +168,10 @@ extern int suppress_checking EXTERNALLY_VISIBLE;
 #define GCTYPEBITS 3
 #endif
 
+#ifndef VALBITS
+#define VALBITS (BITS_PER_EMACS_INT - GCTYPEBITS)
+#endif
+
 #ifndef NO_DECL_ALIGN
 # ifndef DECL_ALIGN
 #  if HAVE_ATTRIBUTE_ALIGNED
@@ -191,7 +195,14 @@ extern int suppress_checking EXTERNALLY_VISIBLE;
      || defined DARWIN_OS || defined __sun)
 /* We also need to be able to specify mult-of-8 alignment on static vars.  */
 # if defined DECL_ALIGN
-#  define USE_LSB_TAG
+/* On hosts where VALBITS is greater than the pointer width in bits,
+   USE_LSB_TAG is:
+    a. unnecessary, because the top bits of an EMACS_INT are unused, and
+    b. slower, because it typically requires extra masking.
+   So, define USE_LSB_TAG only on hosts where it might be useful.  */
+#  if UINTPTR_MAX >> VALBITS != 0
+#   define USE_LSB_TAG
+#  endif
 # endif
 #endif
 
@@ -309,11 +320,6 @@ enum Lisp_Fwd_Type
     Lisp_Fwd_Kboard_Obj,       /* Fwd to a Lisp_Object field of kboards.  */
   };
 
-/* These values are overridden by the m- file on some machines.  */
-#ifndef VALBITS
-#define VALBITS (BITS_PER_EMACS_INT - GCTYPEBITS)
-#endif
-
 #ifdef USE_LISP_UNION_TYPE
 
 #ifndef WORDS_BIGENDIAN
@@ -2931,6 +2937,7 @@ extern Lisp_Object Qinhibit_quit, Qclosure;
 extern Lisp_Object Qand_rest;
 extern Lisp_Object Vautoload_queue;
 extern Lisp_Object Vsignaling_function;
+extern Lisp_Object inhibit_lisp_code;
 extern int handling_signal;
 #if BYTE_MARK_STACK
 extern struct catchtag *catchlist;