0.7.13.28:

[sbcl.git] / src / code / target-sxhash.lisp

diff --git a/src/code/target-sxhash.lisp b/src/code/target-sxhash.lisp
index 5fb9762..0b65801 100644 (file)
--- a/src/code/target-sxhash.lisp
+++ b/src/code/target-sxhash.lisp
@@ -26,9 +26,9 @@
 ;;; desiderata:
 ;;;   * Non-commutativity keeps us from hashing e.g. #(1 5) to the
 ;;;     same value as #(5 1), and ending up in real trouble in some
-;;;     special cases like bit vectors the way that CMUCL SXHASH 18b
+;;;     special cases like bit vectors the way that CMUCL 18b SXHASH 
 ;;;     does. (Under CMUCL 18b, SXHASH of any bit vector is 1..)
-;;;   * We'd like to scatter our hash values the entire possible range
+;;;   * We'd like to scatter our hash values over the entire possible range
 ;;;     of values instead of hashing small or common key values (like
 ;;;     2 and NIL and #\a) to small FIXNUMs the way that the CMUCL 18b
 ;;;     SXHASH function does, again helping to avoid pathologies like
@@ -115,6 +115,9 @@
 ;;;; the SXHASH function
 
 (defun sxhash (x)
+  ;; profiling SXHASH is hard, but we might as well try to make it go
+  ;; fast, in case it is the bottleneck somwhere.  -- CSR, 2003-03-14
+  (declare (optimize speed))
   (labels ((sxhash-number (x)
             (etypecase x
               (fixnum (sxhash x))      ; through DEFTRANSFORM
@@ -135,7 +138,7 @@
           (sxhash-recurse (x &optional (depthoid +max-hash-depthoid+))
             (declare (type index depthoid))
             (typecase x
-              (list
+              (cons
                (if (plusp depthoid)
                    (mix (sxhash-recurse (car x) (1- depthoid))
                         (sxhash-recurse (cdr x) (1- depthoid)))
@@ -145,30 +148,28 @@
                    (logxor 422371266
                            (sxhash ; through DEFTRANSFORM
                             (class-name (layout-class (%instance-layout x)))))
-                   ;; Nice though it might be to return a nontrivial
-                   ;; hash value for other instances (especially
-                   ;; STANDARD-OBJECTs) there seems to be no good way
-                   ;; to do so. We can't even do the CLASS-NAME trick
-                   ;; (as used above for STRUCTURE-OBJECT) because
-                   ;; then CHANGE-CLASS would cause SXHASH values to
-                   ;; change, ouch! -- WHN recording wisdom of CSR
-                   309518995))
+                   (sxhash-instance x)))
               (symbol (sxhash x)) ; through DEFTRANSFORM
               (array
                (typecase x
                  (simple-string (sxhash x)) ; through DEFTRANSFORM
                  (string (%sxhash-substring x))
-                 (bit-vector (let ((result 410823708))
-                               (declare (type fixnum result))
-                               (dotimes (i (min depthoid (length x)))
-                                 (mixf result (aref x i)))
-                               result))
+                 (simple-bit-vector (sxhash x)) ; through DEFTRANSFORM
+                 (bit-vector
+                  ;; FIXME: It must surely be possible to do better
+                  ;; than this.  The problem is that a non-SIMPLE
+                  ;; BIT-VECTOR could be displaced to another, with a
+                  ;; non-zero offset -- so that significantly more
+                  ;; work needs to be done using the %RAW-BITS
+                  ;; approach.  This will probably do for now.
+                  (sxhash-recurse (copy-seq x) depthoid))
                  (t (logxor 191020317 (sxhash (array-rank x))))))
               (character
                (logxor 72185131
                        (sxhash (char-code x)))) ; through DEFTRANSFORM
               ;; general, inefficient case of NUMBER
               (number (sxhash-number x))
+              (generic-function (sxhash-instance x))
               (t 42))))
     (sxhash-recurse x)))
 \f
@@ -193,7 +194,7 @@
     (array (array-psxhash key depthoid))
     (hash-table (hash-table-psxhash key))
     (structure-object (structure-object-psxhash key depthoid))
-    (list (list-psxhash key depthoid))
+    (cons (list-psxhash key depthoid))
     (number (number-psxhash key))
     (character (sxhash (char-upcase key)))
     (t (sxhash key))))