X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=OPTIMIZATIONS;h=d8d018f3f164a5a9d57343e495ce1b445627ca77;hb=d04b59670ab69405c4115ea3caac99fd62a4b7ab;hp=7c51f473ac7e0301e123fa41db6094598db835d1;hpb=8f4ef01b8c9930d7dd0a56a96845a6d84ca5774d;p=sbcl.git

diff --git a/OPTIMIZATIONS b/OPTIMIZATIONS
index 7c51f47..d8d018f 100644
--- a/OPTIMIZATIONS
+++ b/OPTIMIZATIONS
@@ -62,34 +62,6 @@ VOP DATA-VECTOR-SET/SIMPLE-STRING V2!14[EDI] t32[EAX] t30[S2]>t33[CL]
 
 * And why two moves?
 --------------------------------------------------------------------------------
-#6
-09:49:05 <jtra> I have found a case in those where suboptimal code is
-  generate with nested loops, it might be moderately easy to fix that
-09:49:28 <jtra> see
-  http://www.bagley.org/~doug/shootout/bench/nestedloop/nestedloop.cmucl
-09:50:30 <jtra> if you add declarations to dotimes, generated code is
-  almost optimal, but most inner loops run out of registers and use
-  memory location for iteration variable
-
-;;; -*- mode: lisp -*-
-;;; http://www.bagley.org/~doug/shootout/
-;;; from Friedrich Dominicus
-
-(defun main ()
-  (let ((n (parse-integer (or (car (last extensions:*command-line-strings*)) "1")))
-        (x 0))
-    (declare (fixnum n)
-             (fixnum x)
-             (optimize (speed 3) (debug 0) (safety 0)))
-    (dotimes (a n)
-      (dotimes (b n)
-        (dotimes (c n)
-          (dotimes (d n)
-            (dotimes (e n)
-              (dotimes (f n)
-                (incf x)))))))
-   (format t "~A~%" x)))
---------------------------------------------------------------------------------
 #8
 (defun foo (d)
   (declare (optimize (speed 3) (safety 0) (debug 0)))
@@ -169,3 +141,80 @@ then cons up a bignum for it:
     ((89 125 16) (ASH A (MIN 18 -706)))
     (T (DPB -3 (BYTE 30 30) -1))))
 --------------------------------------------------------------------------------
+#16
+(do ((i 0 (1+ i)))
+    ((= i (the (integer 0 100) n)))
+  ...)
+
+It is commonly expected for Python to derive (FIXNUMP I). (If ``='' is
+replaced with ``>='', Python will do.)
+--------------------------------------------------------------------------------
+#17 
+Type tests for (ARRAY BIT), (ARRAY T) and similar go through full
+%TYPEP, even though it is relatively simple to establish the arrayness
+of an object and also to obtain the element type of an array.  As of
+sbcl-0.8.12.30, this affects at least DUMP-OBJECT through
+COMPOUND-OBJECT-P, and (LABELS MAYBE-EMIT-MAKE-LOAD-FORMS GROVEL)
+through TYPEP UNBOXED-ARRAY, within the compiler itself.
+--------------------------------------------------------------------------------
+#18
+(lambda (x) (declare (null x)) (sxhash x)) goes through SYMBOL-HASH
+rather than either constant-folding or manipulating NIL-VALUE or
+NULL-TN directly.
+--------------------------------------------------------------------------------
+#19
+  (let ((dx (if (foo)
+                (list x)
+                (list y z))))
+    (declare (dynamic-extent dx))
+    ...)
+
+DX is not allocated on stack.
+--------------------------------------------------------------------------------
+#20
+(defun-with-dx foo (x)
+  (flet ((make (x)
+           (let ((l (list nil nil)))
+             (setf (first l) x)
+             (setf (second l) (1- x))
+             l)))
+    (let ((l (make x)))
+      (declare (dynamic-extent l))
+      (mapc #'print l))))
+
+Result of MAKE is not stack allocated, which means that
+stack-allocation of structures is impossible.
+--------------------------------------------------------------------------------
+#21
+(defun-with-dx foo ()
+  (let ((dx (list (list 1 2) (list 3 4))))
+    (declare (dynamic-extent dx))
+    ...))
+
+External list in DX is allocated on stack, but internal are not.
+--------------------------------------------------------------------------------
+#22
+IR2 does not perform unused code flushing.
+--------------------------------------------------------------------------------
+#23
+Python does not know that &REST lists are LISTs (and cannot derive it).
+--------------------------------------------------------------------------------
+#24
+a. Iterations on &REST lists, returning them as VALUES could be
+   rewritten with &MORE vectors.
+b. Implement local unknown-values mv-call (useful for fast type checking).
+--------------------------------------------------------------------------------
+#26
+SBCL cannot derive upper bound for I and uses generic arithmetic here:
+
+(defun foo (l)
+  (declare (vector l))
+  (dotimes (i (length l))
+    (if (block nil
+          (map-foo (lambda (x) (if x (return t)))
+                   l))
+        t
+        nil)))
+
+(So the constraint propagator or a possible future SSA-convertor
+should know the connection between an NLE and its CLEANUP.)