continuation benchmark patch

[Lynn Winebarger]

     I've added a use of continuations where the scheme program
actually uses some stack space, and returns from the same
continuation multiple times.  Possibly should change use-stack
to use + instead of cons.
     The code is pretty ham-handed.

Lynn  

Index: continuations.bm
===================================================================
RCS file: 
/cvsroot/guile/guile/guile-core/benchmark-suite/benchmarks/continuations.bm,v
retrieving revision 1.1
diff -c -r1.1 continuations.bm
*** continuations.bm    20 Jul 2002 01:21:36 -0000      1.1
--- continuations.bm    24 Aug 2002 15:08:59 -0000
***************
*** 1,5 ****
  (define (callee continuation)
    (continuation #t))
  
! (benchmark "call/cc" 300
    (call-with-current-continuation callee))
--- 1,53 ----
  (define (callee continuation)
    (continuation #t))
  
! (define call/cc call-with-current-continuation)
! 
! (define use-stack
!   (lambda (c escape)
!     (if (<= c 0)
!       (let ((deja-vu #f))
!         (let ((tmp (call/cc (lambda (k) k))))
!           (if deja-vu
!               '()
!               (begin
!                 (set! deja-vu tmp)
!                 (escape tmp)))))
!       (cons c (use-stack (- c 1) escape)))))
! 
! (benchmark "call/cc" 100
    (call-with-current-continuation callee))
+ 
+ (benchmark "call/cc with stack - creation only" 100
+   (let ((k1 #f)
+       (k2 #f)
+       (i 100)
+       (a '()))
+     (let ((v (call/cc (lambda (k) k))))
+       (if (and k1 (not k2))         ;;; the second return to v should be with 
a continuation from use-stack
+         (set! k2 v))
+       (if (not k1)                  ;;; this is the basic continuation that 
sets v
+         (set! k1 v))
+       (if k2
+         v     ;;; should never return here
+         (let ((v (use-stack 250 k1)))
+           v)))))
+ 
+ 
+ (benchmark "call/cc with stack creation + 100 calls" 100
+   (let ((k1 #f)
+       (k2 #f)
+       (i 100)
+       (a '()))
+     (let ((v (call/cc (lambda (k) k))))
+       (if (and k1 (not k2))         ;;; the second return to v should be with 
a continuation from use-stack
+           (set! k2 v))
+       (if (not k1)                  ;;; this is the basic continuation that 
sets v
+         (set! k1 v))
+       (if k2 (k2 #f))     ;;; should never return here
+       (let ((v (use-stack 250 k1)))
+       (set! a (cons v a))
+       (set! i (- i 1))
+       (if (<= i 0)
+           a
+           (k2 #f))))))