X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fearly-extensions.lisp;h=451405790bc9e8eb3107221fd57f90ab9aadeaca;hb=35bfc07cbd9aa8029e9cc42f1a3fab27f1a673f4;hp=df396b38308c02024ead6293c07394c68a694a7d;hpb=0aecc2b20142e08068c3434273500131cb13fe2d;p=sbcl.git

diff --git a/src/code/early-extensions.lisp b/src/code/early-extensions.lisp
index df396b3..4514057 100644
--- a/src/code/early-extensions.lisp
+++ b/src/code/early-extensions.lisp
@@ -127,16 +127,39 @@
 
 ;;;; type-ish predicates
 
-;;; Is X a list containing a cycle?
-(defun cyclic-list-p (x)
+;;; X may contain cycles -- a conservative approximation. This
+;;; occupies a somewhat uncomfortable niche between being fast for
+;;; common cases (we don't want to allocate a hash-table), and not
+;;; falling down to exponential behaviour for large trees (so we set
+;;; an arbitrady depth limit beyond which we punt).
+(defun maybe-cyclic-p (x &optional (depth-limit 12))
   (and (listp x)
-       (labels ((safe-cddr (x) (if (listp (cdr x)) (cddr x))))
-         (do ((y x (safe-cddr y))
-              (started-p nil t)
-              (z x (cdr z)))
-             ((not (and (consp z) (consp y))) nil)
-           (when (and started-p (eq y z))
-             (return t))))))
+       (labels ((safe-cddr (cons)
+                  (let ((cdr (cdr cons)))
+                    (when (consp cdr)
+                      (cdr cdr))))
+                (check-cycle (object seen depth)
+                  (when (and (consp object)
+                             (or (> depth depth-limit)
+                                 (member object seen)
+                                 (circularp object seen depth)))
+                    (return-from maybe-cyclic-p t)))
+                (circularp (list seen depth)
+                  ;; Almost regular circular list detection, with a twist:
+                  ;; we also check each element of the list for upward
+                  ;; references using CHECK-CYCLE.
+                  (do ((fast (cons (car list) (cdr list)) (safe-cddr fast))
+                       (slow list (cdr slow)))
+                      ((not (consp fast))
+                       ;; Not CDR-circular, need to check remaining CARs yet
+                       (do ((tail slow (and (cdr tail))))
+                           ((not (consp tail))
+                            nil)
+                         (check-cycle (car tail) (cons tail seen) (1+ depth))))
+                    (check-cycle (car slow) (cons slow seen) (1+ depth))
+                    (when (eq fast slow)
+                      (return t)))))
+         (circularp x (list x) 0))))
 
 ;;; Is X a (possibly-improper) list of at least N elements?
 (declaim (ftype (function (t index)) list-of-length-at-least-p))
@@ -400,6 +423,17 @@
 ;;; its first arg, but need not return any particular value.
 ;;; TEST-FUNCTION may be any thing that can be placed in CAR position.
 ;;;
+;;; This code used to store all the arguments / return values directly
+;;; in the cache vector. This was both interrupt- and thread-unsafe, since
+;;; it was possible that *-CACHE-ENTER would scribble over a region of the
+;;; cache vector which *-CACHE-LOOKUP had only partially processed. Instead
+;;; we now store the contents of each cache bucket as a separate array, which
+;;; is stored in the appropriate cell in the cache vector. A new bucket array
+;;; is created every time *-CACHE-ENTER is called, and the old ones are never
+;;; modified. This means that *-CACHE-LOOKUP will always work with a set
+;;; of consistent data. The overhead caused by consing new buckets seems to
+;;; be insignificant on the grand scale of things. -- JES, 2006-11-02
+;;;
 ;;; NAME is used to define these functions:
 ;;; <name>-CACHE-LOOKUP Arg*
 ;;;   See whether there is an entry for the specified ARGs in the
@@ -429,12 +463,12 @@
                                   (values 1))
   (let* ((var-name (symbolicate "*" name "-CACHE-VECTOR*"))
          (nargs (length args))
-         (entry-size (+ nargs values))
          (size (ash 1 hash-bits))
-         (total-size (* entry-size size))
          (default-values (if (and (consp default) (eq (car default) 'values))
                              (cdr default)
                              (list default)))
+         (args-and-values (gensym))
+         (args-and-values-size (+ nargs values))
          (n-index (gensym))
          (n-cache (gensym)))
 
@@ -445,14 +479,16 @@
     (collect ((inlines)
               (forms)
               (inits)
-              (tests)
               (sets)
+              (tests)
               (arg-vars)
-              (values-indices)
+              (values-refs)
               (values-names))
       (dotimes (i values)
-        (values-indices `(+ ,n-index ,(+ nargs i)))
-        (values-names (gensym)))
+        (let ((name (gensym)))
+          (values-names name)
+          (values-refs `(svref ,args-and-values (+ ,nargs ,i)))
+          (sets `(setf (svref ,args-and-values (+ ,nargs ,i)) ,name))))
       (let ((n 0))
         (dolist (arg args)
           (unless (= (length arg) 2)
@@ -460,8 +496,8 @@
           (let ((arg-name (first arg))
                 (test (second arg)))
             (arg-vars arg-name)
-            (tests `(,test (svref ,n-cache (+ ,n-index ,n)) ,arg-name))
-            (sets `(setf (svref ,n-cache (+ ,n-index ,n)) ,arg-name)))
+            (tests `(,test (svref ,args-and-values ,n) ,arg-name))
+            (sets `(setf (svref ,args-and-values ,n) ,arg-name)))
           (incf n)))
 
       (when *profile-hash-cache*
@@ -479,12 +515,12 @@
          `(defun ,fun-name ,(arg-vars)
             ,@(when *profile-hash-cache*
                 `((incf ,(symbolicate  "*" name "-CACHE-PROBES*"))))
-            (let ((,n-index (* (,hash-function ,@(arg-vars)) ,entry-size))
-                  (,n-cache ,var-name))
-              (declare (type fixnum ,n-index))
-              (cond ((and ,@(tests))
-                     (values ,@(mapcar (lambda (x) `(svref ,n-cache ,x))
-                                       (values-indices))))
+            (let* ((,n-index (,hash-function ,@(arg-vars)))
+                   (,n-cache ,var-name)
+                   (,args-and-values (svref ,n-cache ,n-index)))
+              (cond ((and ,args-and-values
+                          ,@(tests))
+                     (values ,@(values-refs)))
                     (t
                      ,@(when *profile-hash-cache*
                          `((incf ,(symbolicate  "*" name "-CACHE-MISSES*"))))
@@ -494,41 +530,26 @@
         (inlines fun-name)
         (forms
          `(defun ,fun-name (,@(arg-vars) ,@(values-names))
-            (let ((,n-index (* (,hash-function ,@(arg-vars)) ,entry-size))
-                  (,n-cache ,var-name))
-              (declare (type fixnum ,n-index))
+            (let ((,n-index (,hash-function ,@(arg-vars)))
+                  (,n-cache ,var-name)
+                  (,args-and-values (make-array ,args-and-values-size)))
               ,@(sets)
-              ,@(mapcar (lambda (i val)
-                          `(setf (svref ,n-cache ,i) ,val))
-                        (values-indices)
-                        (values-names))
-              (values)))))
+              (setf (svref ,n-cache ,n-index) ,args-and-values))
+            (values))))
 
       (let ((fun-name (symbolicate name "-CACHE-CLEAR")))
         (forms
          `(defun ,fun-name ()
-            (do ((,n-index ,(- total-size entry-size) (- ,n-index ,entry-size))
-                 (,n-cache ,var-name))
-                ((minusp ,n-index))
-              (declare (type fixnum ,n-index))
-              ,@(collect ((arg-sets))
-                  (dotimes (i nargs)
-                    (arg-sets `(setf (svref ,n-cache (+ ,n-index ,i)) nil)))
-                  (arg-sets))
-              ,@(mapcar (lambda (i val)
-                          `(setf (svref ,n-cache ,i) ,val))
-                        (values-indices)
-                        default-values))
-            (values)))
+            (fill ,var-name nil)))
         (forms `(,fun-name)))
 
       (inits `(unless (boundp ',var-name)
-                (setq ,var-name (make-array ,total-size))))
+                (setq ,var-name (make-array ,size :initial-element nil))))
       #!+sb-show (inits `(setq *hash-caches-initialized-p* t))
 
       `(progn
          (defvar ,var-name)
-         (declaim (type (simple-vector ,total-size) ,var-name))
+         (declaim (type (simple-vector ,size) ,var-name))
          #!-sb-fluid (declaim (inline ,@(inlines)))
          (,init-wrapper ,@(inits))
          ,@(forms)
@@ -1184,3 +1205,13 @@
           (*print-level* (or (true *print-level*) 6))
           (*print-length* (or (true *print-length*) 12)))
       (funcall function))))
+
+;;; Default evaluator mode (interpeter / compiler)
+
+(declaim (type (member :compile #!+sb-eval :interpret) *evaluator-mode*))
+(defparameter *evaluator-mode* :compile
+  #!+sb-doc
+  "Toggle between different evaluator implementations. If set to :COMPILE,
+an implementation of EVAL that calls the compiler will be used. If set
+to :INTERPRET, an interpreter will be used.")
+