X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;ds=inline;f=src%2Fcompiler%2Fgeneric%2Fearly-vm.lisp;h=304637d53fb390fe70418b6f410c83be6341cf7e;hb=HEAD;hp=57c2d9d55b34388add8551a170cfe66885b2b1fc;hpb=672b2f6cb751566526c7f3bb3de6b7d8424760e2;p=sbcl.git

diff --git a/src/compiler/generic/early-vm.lisp b/src/compiler/generic/early-vm.lisp
index 57c2d9d..304637d 100644
--- a/src/compiler/generic/early-vm.lisp
+++ b/src/compiler/generic/early-vm.lisp
@@ -19,11 +19,30 @@
 ;;; pointer
 (def!constant lowtag-limit (ash 1 n-lowtag-bits))
 ;;; the number of tag bits used for a fixnum
-(def!constant n-fixnum-tag-bits (1- n-lowtag-bits))
+(def!constant n-fixnum-tag-bits
+    (if (= 64 sb!vm:n-word-bits)
+        ;; On 64-bit targets, this may be as low as 1 (for 63-bit
+        ;; fixnums) and as high as 3 (for 61-bit fixnums).  The
+        ;; constraint on the low end is that we need at least one bit
+        ;; to determine if a value is a fixnum or not, and the
+        ;; constraint on the high end is that it must not exceed
+        ;; WORD-SHIFT (defined below) due to the use of unboxed
+        ;; word-aligned byte pointers as boxed values in various
+        ;; places.  FIXME: This should possibly be exposed for
+        ;; configuration via customize-target-features.
+        1
+        ;; On 32-bit targets, this may be as low as 2 (for 30-bit
+        ;; fixnums) and as high as 2 (for 30-bit fixnums).  The
+        ;; constraint on the low end is simple overcrowding of the
+        ;; lowtag space, and the constraint on the high end is that it
+        ;; must not exceed WORD-SHIFT.
+        (1- n-lowtag-bits)))
 ;;; the fixnum tag mask
 (def!constant fixnum-tag-mask (1- (ash 1 n-fixnum-tag-bits)))
+;;; the bit width of fixnums
+(def!constant n-fixnum-bits (- n-word-bits n-fixnum-tag-bits))
 ;;; the bit width of positive fixnums
-(def!constant n-positive-fixnum-bits (- n-word-bits n-fixnum-tag-bits 1))
+(def!constant n-positive-fixnum-bits (1- n-fixnum-bits))
 
 ;;; the number of bits to shift between word addresses and byte addresses
 (def!constant word-shift (1- (integer-length (/ n-word-bits n-byte-bits))))
@@ -38,19 +57,33 @@
 (def!constant widetag-mask (1- (ash 1 n-widetag-bits)))
 
 (def!constant sb!xc:most-positive-fixnum
-    (1- (ash 1 (- n-word-bits n-lowtag-bits)))
+    (1- (ash 1 n-positive-fixnum-bits))
   #!+sb-doc
   "the fixnum closest in value to positive infinity")
 (def!constant sb!xc:most-negative-fixnum
-    (ash -1 (- n-word-bits n-lowtag-bits))
+    (ash -1 n-positive-fixnum-bits)
   #!+sb-doc
   "the fixnum closest in value to negative infinity")
 
+(def!constant most-positive-word (1- (expt 2 n-word-bits))
+  "The most positive integer that is of type SB-EXT:WORD.")
+
 (def!constant most-positive-exactly-single-float-fixnum
-  (min #xffffff most-positive-fixnum))
+  (min #xffffff sb!xc:most-positive-fixnum))
 (def!constant most-negative-exactly-single-float-fixnum
-  (max #x-ffffff most-negative-fixnum))
+  (max #x-ffffff sb!xc:most-negative-fixnum))
 (def!constant most-positive-exactly-double-float-fixnum
-  (min #x1fffffffffffff most-positive-fixnum))
+  (min #x1fffffffffffff sb!xc:most-positive-fixnum))
 (def!constant most-negative-exactly-double-float-fixnum
-  (max #x-1fffffffffffff most-negative-fixnum))
+  (max #x-1fffffffffffff sb!xc:most-negative-fixnum))
+
+;;;; Point where continuous area starting at dynamic-space-start bumps into
+;;;; next space.
+#!+gencgc
+(def!constant max-dynamic-space-end
+    (let ((stop (1- (ash 1 n-word-bits)))
+          (start dynamic-space-start))
+      (dolist (other-start (list read-only-space-start static-space-start linkage-table-space-start))
+        (when (< start other-start)
+          (setf stop (min stop other-start))))
+      stop))