1.0.18.2: more conservative interval artihmetic

[sbcl.git] / src / compiler / generic / early-vm.lisp

diff --git a/src/compiler/generic/early-vm.lisp b/src/compiler/generic/early-vm.lisp
index 51ddc04..57c2d9d 100644 (file)
--- a/src/compiler/generic/early-vm.lisp
+++ b/src/compiler/generic/early-vm.lisp
@@ -11,28 +11,46 @@
 
 ;;; the number of bits at the low end of a pointer used for type
 ;;; information
-(defconstant lowtag-bits 3)
+(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
-(defconstant lowtag-mask (1- (ash 1 lowtag-bits)))
+(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
-(defconstant lowtag-limit (ash 1 lowtag-bits))
+(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))
+;;; the fixnum tag mask
+(def!constant fixnum-tag-mask (1- (ash 1 n-fixnum-tag-bits)))
+;;; the bit width of positive fixnums
+(def!constant n-positive-fixnum-bits (- n-word-bits n-fixnum-tag-bits 1))
+
+;;; 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))))
+
+;;; the number of bytes in a word
+(def!constant n-word-bytes (/ n-word-bits n-byte-bits))
 
 ;;; the number of bits used in the header word of a data block to store
 ;;; the type
-(defconstant type-bits 8)
+(def!constant n-widetag-bits 8)
 ;;; a mask to extract the type from a data block header word
-(defconstant type-mask (1- (ash 1 type-bits)))
+(def!constant widetag-mask (1- (ash 1 n-widetag-bits)))
 
-;;; FIXME: Couldn't/shouldn't these be DEFCONSTANT instead of
-;;; DEFPARAMETER? (It might seem even more tempting to make them
-;;; SB!XC:MOST-POSITIVE-FIXNUM and SB!XC:MOST-NEGATIVE-FIXNUM,
-;;; but that's probably not a good idea, since then we'd need
-;;; to worry about the effect of UNCROSS in expressions like
-;;; (DEFTYPE INDX3 () `(INTEGER 3 ,SB!XC:MOST-POSITIVE-FIXNUM)).)
-(defparameter *target-most-positive-fixnum* (1- (ash 1 29))
+(def!constant sb!xc:most-positive-fixnum
+    (1- (ash 1 (- n-word-bits n-lowtag-bits)))
   #!+sb-doc
-  "most-positive-fixnum in the target architecture")
-(defparameter *target-most-negative-fixnum* (ash -1 29)
+  "the fixnum closest in value to positive infinity")
+(def!constant sb!xc:most-negative-fixnum
+    (ash -1 (- n-word-bits n-lowtag-bits))
   #!+sb-doc
-  "most-negative-fixnum in the target architecture")
+  "the fixnum closest in value to negative infinity")
+
+(def!constant most-positive-exactly-single-float-fixnum
+  (min #xffffff most-positive-fixnum))
+(def!constant most-negative-exactly-single-float-fixnum
+  (max #x-ffffff most-negative-fixnum))
+(def!constant most-positive-exactly-double-float-fixnum
+  (min #x1fffffffffffff most-positive-fixnum))
+(def!constant most-negative-exactly-double-float-fixnum
+  (max #x-1fffffffffffff most-negative-fixnum))