X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fearly-extensions.lisp;h=c3f2474359ca59d915547548e5ffde8871901417;hb=b7f3ef098847a4cc680f6304cec735b63bb70a0a;hp=01bfd6f680c2fc96d2c02c592f23074f61187c79;hpb=a682f4c392bc874a6a898632889319ebdd8821fc;p=sbcl.git

diff --git a/src/code/early-extensions.lisp b/src/code/early-extensions.lisp
index 01bfd6f..c3f2474 100644
--- a/src/code/early-extensions.lisp
+++ b/src/code/early-extensions.lisp
@@ -30,6 +30,10 @@
 ;;; bound because ANSI specifies it as an exclusive bound.)
 (def!type index () `(integer 0 (,sb!xc:array-dimension-limit)))
 
+;;; like INDEX, but only up to half the maximum. Used by hash-table
+;;; code that does plenty to (aref v (* 2 i)) and (aref v (1+ (* 2 i))).
+(def!type index/2 () `(integer 0 (,(floor sb!xc:array-dimension-limit 2))))
+
 ;;; like INDEX, but augmented with -1 (useful when using the index
 ;;; to count downwards to 0, e.g. LOOP FOR I FROM N DOWNTO 0, with
 ;;; an implementation which terminates the loop by testing for the
@@ -65,6 +69,30 @@
                           (* max-offset sb!vm:n-word-bytes))
                        scale)))
 
+#!+(or x86 x86-64)
+(defun displacement-bounds (lowtag element-size data-offset)
+  (let* ((adjustment (- (* data-offset sb!vm:n-word-bytes) lowtag))
+         (bytes-per-element (ceiling element-size sb!vm:n-byte-bits))
+         (min (truncate (+ sb!vm::minimum-immediate-offset adjustment)
+                        bytes-per-element))
+         (max (truncate (+ sb!vm::maximum-immediate-offset adjustment)
+                        bytes-per-element)))
+    (values min max)))
+
+#!+(or x86 x86-64)
+(def!type constant-displacement (lowtag element-size data-offset)
+  (flet ((integerify (x)
+           (etypecase x
+             (integer x)
+             (symbol (symbol-value x)))))
+    (let ((lowtag (integerify lowtag))
+          (element-size (integerify element-size))
+          (data-offset (integerify data-offset)))
+      (multiple-value-bind (min max) (displacement-bounds lowtag
+                                                          element-size
+                                                          data-offset)
+        `(integer ,min ,max)))))
+
 ;;; Similar to FUNCTION, but the result type is "exactly" specified:
 ;;; if it is an object type, then the function returns exactly one
 ;;; value, if it is a short form of VALUES, then this short form