X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=OPTIMIZATIONS;h=1f8746f14400565d7246281ee0710e2f5721de78;hb=80f222325e1f677e5cf8de01c6990906fa47f65d;hp=51fcb32f0e2a426469ae07f97796e3b2d1685a19;hpb=51c5280a4b41f8c51d434643cde3e18af4113473;p=sbcl.git

diff --git a/OPTIMIZATIONS b/OPTIMIZATIONS
index 51fcb32..1f8746f 100644
--- a/OPTIMIZATIONS
+++ b/OPTIMIZATIONS
@@ -154,5 +154,39 @@ of representation selection. Problem: inter-TN dependencies.
 #14
 The derived type of (/ (THE (DOUBLE-FLOAT (0D0)) X) (THE (DOUBLE-FLOAT
 1D0) Y)) is (DOUBLE-FLOAT 0.0d0). While it might be reasonable, it is
-better to derive (DOUBLE-FLOAT (-0.0d0)).
+better to derive (OR (MEMBER 0.0d0) (DOUBLE-FLOAT (0.0d0))).
+--------------------------------------------------------------------------------
+#15
+On the alpha, the system is reluctant to refer directly to a constant bignum,
+preferring to load a large constant through a slow sequence of instructions,
+then cons up a bignum for it:
+
+(LAMBDA (A)
+  (DECLARE (OPTIMIZE (SAFETY 1) (SPEED 3) (DEBUG 1))
+           (TYPE (INTEGER -10000 10000) A)
+           (IGNORABLE A))
+  (CASE A
+    ((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.
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