SICP/ex-5_31-xx.scm

(load "util.scm")

(display "\nex-5.31 - save-and-restore-for-apply\n")

; 1. save and restore env around operator
; 2. save and restore env around each operand (except last)
; 3. save and restore argl around each operand
; 4. save and restore proc around operand sequence

; (f 'x 'y)
; 1-4 are superfluous

; ((f) 'x 'y)
; 1-4 are superfluous
; no need to save env because compound-apply without args does
; not change env

; (f (g 'x) y)
; 1 is superfluous
; we need 2 because (g 'x) changes the env for y
; we need 3 because (g 'x) changes argl
; we need 4 because (g 'x) changes proc

; (f (g 'x) 'y) ; 1 is superfluous
; 1-2 are superfluous
; (g 'x) changes the env but we don't need it later (better save it anyway)
; 3-4 are still needed

(display "[answered]\n")

(display "\nex-5.32 - optimize-eceval-application\n")

'(
ev-application
  (save continue)
  (assign unev (op operands) (reg exp))
  (assign exp (op operator) (reg exp))
  (assign continue (label ev-appl-did-operator-no-restore))
  (test (op variable?) (reg exp))
  (branch (label ev-variable))
  (save env)
  (save unev)
  (assign continue (label ev-appl-did-operator))
  (goto (label eval-dispatch))
ev-appl-did-operator
  (restore unev)
  (restore env)
ev-appl-did-operator-no-restore
  (assign argl (op empty-arglist))
  (assign proc (reg val))
  (test (op no-operands?) (reg unev))
  (branch (label apply-dispatch))
  (save proc)
  )

(display "[ok]\n")

; b. Applying all the optimizations make sense, but the compiled code will
; still run faster because the interpreter has to analyze the code every time
; it executes and the analysis itself adds overhead that the compiler can do
; before runtime
(display "[answered]\n")

(display "\nex-5.33\n")

(display "CONTINUE at 5.5.3\n")

(display "\nex-5.34\n")
;(display "\nex-5.35\n")