X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fgeneric%2Fearly-objdef.lisp;h=eb6927509bbb286d175cbaa4b3ef4e7c1c410c53;hb=74cf7a4d01664fbf72a662ba093ad67ca243b524;hp=6967fe41d2ec1868b928df310da9d01b6a7d6337;hpb=dd04bd449535e9016b5652a708a3cac2ca24c87d;p=sbcl.git

diff --git a/src/compiler/generic/early-objdef.lisp b/src/compiler/generic/early-objdef.lisp
index 6967fe4..eb69275 100644
--- a/src/compiler/generic/early-objdef.lisp
+++ b/src/compiler/generic/early-objdef.lisp
@@ -33,6 +33,25 @@
 ;;; might easily be more, since these values have stayed highly
 ;;; constrained for more than a decade, an inviting target for
 ;;; inventive abstraction-phobic maintainers.:-)
+;;;
+;;; Another way to look at lowtags is that there is no one lowtag
+;;; length.  On 32-bit platforms, fixnums and other-immediates have a
+;;; lowtag length of two bits, and pointers have a lowtag length of
+;;; three bits.  On 64-bit platforms, fixnums and pointers gain an
+;;; extra bit, and six "pad" lowtags waste the extra encoding space so
+;;; obtained.
+;;;
+;;;  x00 -- fixnum
+;;;  x10 -- other-immediate
+;;;  001 -- instance-pointer
+;;;  011 -- list-pointer
+;;;  101 -- fun-pointer
+;;;  111 -- other-pointer
+;;;
+;;; If you change the tag layout, check the various functions in
+;;; src/runtime/runtime.h to see if they need to be updated, along
+;;; with print_obj() in src/runtime/print.c, possibly gc_init_tables()
+;;; in src/runtime/gc-common-c and possibly the code in src/code/room.
 (eval-when (:compile-toplevel :load-toplevel :execute)
   ;; The EVAL-WHEN is necessary (at least for Lispworks), because the
   ;; second DEFENUM uses the value of OTHER-IMMEDIATE-0-LOWTAG, which is
@@ -40,19 +59,20 @@
   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
   (defenum ()
     even-fixnum-lowtag
-    instance-pointer-lowtag
     other-immediate-0-lowtag
     pad0-lowtag
-    pad1-lowtag pad2-lowtag
+    instance-pointer-lowtag
+    pad1-lowtag
     other-immediate-1-lowtag
+    pad2-lowtag
     list-pointer-lowtag
     odd-fixnum-lowtag
-    fun-pointer-lowtag
     other-immediate-2-lowtag
     pad3-lowtag
+    fun-pointer-lowtag
     pad4-lowtag
-    pad5-lowtag
     other-immediate-3-lowtag
+    pad5-lowtag
     other-pointer-lowtag)
   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
   (defenum ()
@@ -79,7 +99,7 @@
                        (string= name "-LOWTAG" :start1 (- len 7))
                        (zerop (logand (symbol-value sym) fixnum-tag-mask)))
               (push sym fixtags))))
-        `',fixtags)
+        `',(sort fixtags #'string< :key #'symbol-name))
   #'equal)
 
 ;;; the heap types, stored in 8 bits of the header of an object on the
@@ -154,10 +174,10 @@
   fdefn-widetag                             ; 01010110
 
   no-tls-value-marker-widetag               ; 01011010
-  #!-(and sb-lutex sb-thread)
+  #!-sb-simd-pack
   unused01-widetag
-  #!+(and sb-lutex sb-thread)
-  lutex-widetag                             ; 01011110
+  #!+sb-simd-pack
+  simd-pack-widetag                          ; 01011110
   unused02-widetag                          ; 01100010
   unused03-widetag                          ; 01100110
   unused04-widetag                          ; 01101010