X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fcompiler%2Fgeneric%2Fearly-vm.lisp;h=304637d53fb390fe70418b6f410c83be6341cf7e;hb=HEAD;hp=9654ac4a135c62e44c4b610a1b8582843a2e4142;hpb=a530bbe337109d898d5b4a001fc8f1afa3b5dc39;p=sbcl.git

diff --git a/src/compiler/generic/early-vm.lisp b/src/compiler/generic/early-vm.lisp
index 9654ac4..304637d 100644
--- a/src/compiler/generic/early-vm.lisp
+++ b/src/compiler/generic/early-vm.lisp
@@ -9,37 +9,81 @@
 
 (in-package "SB!VM")
 
-(file-comment
-  "$Header$")
+;;; the number of bits at the low end of a pointer used for type
+;;; information
+(def!constant n-lowtag-bits
+  (integer-length (1- (/ (* 2 n-word-bits) n-byte-bits))))
+;;; a mask to extract the low tag bits from a pointer
+(def!constant lowtag-mask (1- (ash 1 n-lowtag-bits)))
+;;; the exclusive upper bound on the value of the low tag bits from a
+;;; 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
+    (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 (1- n-fixnum-bits))
 
-(eval-when (:compile-toplevel :execute :load-toplevel)
+;;; 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))))
 
-(defconstant lowtag-bits 3
-  #!+sb-doc
-  "Number of bits at the low end of a pointer used for type information.")
+;;; the number of bytes in a word
+(def!constant n-word-bytes (/ n-word-bits n-byte-bits))
 
-(defconstant lowtag-mask (1- (ash 1 lowtag-bits))
-  #!+sb-doc
-  "Mask to extract the low tag bits from a pointer.")
+;;; the number of bits used in the header word of a data block to store
+;;; the type
+(def!constant n-widetag-bits 8)
+;;; a mask to extract the type from a data block header word
+(def!constant widetag-mask (1- (ash 1 n-widetag-bits)))
 
-(defconstant lowtag-limit (ash 1 lowtag-bits)
+(def!constant sb!xc:most-positive-fixnum
+    (1- (ash 1 n-positive-fixnum-bits))
   #!+sb-doc
-  "Exclusive upper bound on the value of the low tag bits from a pointer.")
-
-(defconstant type-bits 8
+  "the fixnum closest in value to positive infinity")
+(def!constant sb!xc:most-negative-fixnum
+    (ash -1 n-positive-fixnum-bits)
   #!+sb-doc
-  "Number of bits used in the header word of a data block to store the type.")
+  "the fixnum closest in value to negative infinity")
 
-(defconstant type-mask (1- (ash 1 type-bits))
-  #!+sb-doc
-  "Mask to extract the type from a header word.")
+(def!constant most-positive-word (1- (expt 2 n-word-bits))
+  "The most positive integer that is of type SB-EXT:WORD.")
 
-); eval-when
+(def!constant most-positive-exactly-single-float-fixnum
+  (min #xffffff sb!xc:most-positive-fixnum))
+(def!constant most-negative-exactly-single-float-fixnum
+  (max #x-ffffff sb!xc:most-negative-fixnum))
+(def!constant most-positive-exactly-double-float-fixnum
+  (min #x1fffffffffffff sb!xc:most-positive-fixnum))
+(def!constant most-negative-exactly-double-float-fixnum
+  (max #x-1fffffffffffff sb!xc:most-negative-fixnum))
 
-;;; FIXME: Couldn't/shouldn't these be DEFCONSTANT instead of DEFPARAMETER?
-(defparameter *target-most-positive-fixnum* (1- (ash 1 29))
-  #!+sb-doc
-  "most-positive-fixnum in the target architecture.")
-(defparameter *target-most-negative-fixnum* (ash -1 29)
-  #!+sb-doc
-  "most-negative-fixnum in the target architecture.")
+;;;; 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))