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diff --git a/v7/src/compiler/fgopt/blktyp.scm b/v7/src/compiler/fgopt/blktyp.scm
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+#| -*-Scheme-*-
+
+$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/compiler/fgopt/blktyp.scm,v 4.1 1987/12/04 19:23:42 cph Exp $
+
+Copyright (c) 1987 Massachusetts Institute of Technology
+
+This material was developed by the Scheme project at the Massachusetts
+Institute of Technology, Department of Electrical Engineering and
+Computer Science.  Permission to copy this software, to redistribute
+it, and to use it for any purpose is granted, subject to the following
+restrictions and understandings.
+
+1. Any copy made of this software must include this copyright notice
+in full.
+
+2. Users of this software agree to make their best efforts (a) to
+return to the MIT Scheme project any improvements or extensions that
+they make, so that these may be included in future releases; and (b)
+to inform MIT of noteworthy uses of this software.
+
+3. All materials developed as a consequence of the use of this
+software shall duly acknowledge such use, in accordance with the usual
+standards of acknowledging credit in academic research.
+
+4. MIT has made no warrantee or representation that the operation of
+this software will be error-free, and MIT is under no obligation to
+provide any services, by way of maintenance, update, or otherwise.
+
+5. In conjunction with products arising from the use of this material,
+there shall be no use of the name of the Massachusetts Institute of
+Technology nor of any adaptation thereof in any advertising,
+promotional, or sales literature without prior written consent from
+MIT in each case. |#
+
+;;;; Environment Type Assignment
+
+(declare (usual-integrations))
+\f
+(package (setup-block-types!)
+
+(define-export (setup-block-types! root-block)
+  (define (loop block)
+    ;; **** Why is this here?  Leave comment.
+    (set-block-applications! block '())
+    (enumeration-case block-type (block-type block)
+      ((PROCEDURE)
+       (if (block-passed-out? block)
+          (block-type! block block-type/ic)
+          (begin
+            (block-type! block block-type/stack)
+            (maybe-close-procedure! block))))
+      ((CONTINUATION)
+       (for-each loop (block-children block)))
+      ((EXPRESSION)
+       (if (not (block-passed-out? block))
+          (error "Expression block not passed out" block))
+       (block-type! block block-type/ic))
+      (else
+       (error "Illegal block type" block))))
+
+  (define (block-type! block type)
+    (set-block-type! block type)
+    (for-each loop (block-children block)))
+
+  (loop root-block))
+
+(define (maybe-close-procedure! block)
+  (let ((procedure (block-procedure block)))
+    (if (close-procedure? procedure)
+       (let ((parent (block-parent block)))
+         (set-procedure-closure-block! procedure parent)
+         (set-block-parent!
+          block
+          ((find-closure-bindings parent)
+           (list-transform-negative (block-free-variables block)
+             (lambda (lvalue)
+               (eq? (lvalue-known-value lvalue) procedure)))
+           '()))
+         (set-block-children! parent (delq! block (block-children parent)))
+         (set-block-disowned-children!
+          parent
+          (cons block (block-disowned-children parent)))))))
+\f
+(define (find-closure-bindings block)
+  (lambda (free-variables bound-variables)
+    (if (or (not block) (ic-block? block))
+       (let ((grandparent (and (not (null? free-variables)) block)))
+         (if (null? bound-variables)
+             grandparent
+             (make-closure-block grandparent
+                                 free-variables
+                                 bound-variables
+                                 (and block (block-procedure block)))))
+       (transmit-values
+           (filter-bound-variables (block-bound-variables block)
+                                   free-variables
+                                   bound-variables)
+         (find-closure-bindings (block-parent block))))))
+
+(define (filter-bound-variables bindings free-variables bound-variables)
+  (cond ((null? bindings)
+        (return-2 free-variables bound-variables))
+       ((memq (car bindings) free-variables)
+        (filter-bound-variables (cdr bindings)
+                                (delq! (car bindings) free-variables)
+                                (cons (car bindings) bound-variables)))
+       (else
+        (filter-bound-variables (cdr bindings)
+                                free-variables
+                                bound-variables))))
+
+(define (make-closure-block parent free-variables bound-variables frame)
+  (let ((block (make-block parent 'CLOSURE)))
+    (set-block-free-variables! block free-variables)
+    (set-block-bound-variables! block bound-variables)
+    (set-block-frame! block
+                     (and frame
+                          (rvalue/procedure? frame)
+                          (procedure-name frame)))
+    (set-block-closure-offsets!
+     block
+     (let loop
+        ((variables (block-bound-variables block))
+         (offset (if (and parent (ic-block/use-lookup? parent)) 2 1)))
+       (cond ((null? variables) '())
+            ((lvalue-integrated? (car variables))
+             (loop (cdr variables) offset))
+            (else
+             (cons (cons (car variables) offset)
+                   (loop (cdr variables) (1+ offset)))))))
+    block))
+
+)
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