From: Paul F. Dietz <pfdietz@users.sourceforge.net>
Date: Wed, 9 Feb 2005 23:48:45 +0000 (+0000)
Subject: Added optimization opportunity #25: improved type-based optimization
X-Git-Url: http://repo.macrolet.net/gitweb/?a=commitdiff_plain;h=9afd3958cf7b5ad829c61a4a85956cf783e500f5;p=sbcl.git

Added optimization opportunity #25: improved type-based optimization
of EQL forms.
---

diff --git a/OPTIMIZATIONS b/OPTIMIZATIONS
index 5474bd2..50d3417 100644
--- a/OPTIMIZATIONS
+++ b/OPTIMIZATIONS
@@ -203,3 +203,17 @@ Python does not know that &REST lists are LISTs (and cannot derive it).
 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).
+--------------------------------------------------------------------------------
+#25
+EQL is implemented generically in situations where this isn't necessary.
+
+(defun f (x y)
+  (declare (type (or symbol fixnum) x)
+	   (optimize speed (safety 0) (debug 0)))
+  (eql x y))
+
+SUBTYPEP is smart enough to determine that this type is a subtype
+of (and (or (not number) fixnum) (not character))
+
+This sitation where the type is (OR NULL FIXNUM) comes up
+in cl-bench, for example in the value returned by POSITION.