From: Chris Hanson <org/chris-hanson/cph>
Date: Mon, 29 Aug 1988 23:19:44 +0000 (+0000)
Subject: Redefine expression-cost computation to be mostly machine independent.
X-Git-Tag: 20090517-FFI~12564
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=ce9f9b4a98268be8ef2b54c3665886741e9dc884;p=mit-scheme.git

Redefine expression-cost computation to be mostly machine independent.
---

diff --git a/v7/src/compiler/rtlopt/rcseht.scm b/v7/src/compiler/rtlopt/rcseht.scm
index 24cd6c30e..b0cd5a082 100644
--- a/v7/src/compiler/rtlopt/rcseht.scm
+++ b/v7/src/compiler/rtlopt/rcseht.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/compiler/rtlopt/rcseht.scm,v 4.5 1988/08/11 20:11:06 cph Exp $
+$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/compiler/rtlopt/rcseht.scm,v 4.6 1988/08/29 23:19:44 cph Exp $
 
 Copyright (c) 1988 Massachusetts Institute of Technology
 
@@ -119,6 +119,19 @@ MIT in each case. |#
 		   (else
 		    (loop next (element-next-value next)))))))
     element))
+
+(define (rtl:expression-cost expression)
+  (case (rtl:expression-type expression)
+    ((REGISTER) 1)
+    ((CONSTANT) (rtl:constant-cost (rtl:constant-value expression)))
+    (else
+     (let loop ((parts (cdr expression)) (cost 2))
+       (if (null? parts)
+	   cost
+	   (loop (cdr parts)
+		 (if (pair? (car parts))
+		     (+ cost (rtl:expression-cost (car parts)))
+		     cost)))))))
 
 (define (hash-table-delete! hash element)
   (if element