Serendip

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問題5.34

こちらの反復的手続きの factorial では末尾再帰になっている。
一方こちらは再帰的手続きの factorial のコンパイル済みコード。

(env)
(val)
  (assign val (op make-compiled-procedure) (label entry1) (reg env))
  (goto (label after-lambda2))
entry1
  (assign env (op compiled-procedure-env) (reg proc))
  (assign env (op extend-environment) (const (n)) (reg argl) (reg env))
  (assign val (op make-compiled-procedure) (label entry3) (reg env))
  (goto (label after-lambda4))
entry3
  (assign env (op compiled-procedure-env) (reg proc))
  (assign env (op extend-environment) (const (product counter)) (reg argl) (reg env))
  (save continue)
  (save env)
  (assign proc (op lookup-variable-value) (const >) (reg env))
  (assign val (op lookup-variable-value) (const n) (reg env))
  (assign argl (op list) (reg val))
  (assign val (op lookup-variable-value) (const counter) (reg env))
  (assign argl (op cons) (reg val) (reg argl))
  (test (op primitive-procedure?) (reg proc))
  (branch (label primitive-branch8))
compiled-branch9
  (assign continue (label after-call10))
  (assign val (op compiled-procedure-entry) (reg proc))
  (goto (reg val))
primitive-branch8
  (assign val (op apply-primitive-procedure) (reg proc) (reg argl))
after-call10
  (restore env)
  (restore continue)
  (test (op false?) (reg val))
  (branch (label false-branch6))
true-branch5
  (assign val (op lookup-variable-value) (const product) (reg env))
  (goto (reg continue))
false-branch6
  (assign proc (op lookup-variable-value) (const iter) (reg env))
  (save continue)
  (save proc)
  (save env)
  (assign proc (op lookup-variable-value) (const +) (reg env))
  (assign val (const 1))
  (assign argl (op list) (reg val))
  (assign val (op lookup-variable-value) (const counter) (reg env))
  (assign argl (op cons) (reg val) (reg argl))
  (test (op primitive-procedure?) (reg proc))
  (branch (label primitive-branch14))
compiled-branch15
  (assign continue (label after-call16))
  (assign val (op compiled-procedure-entry) (reg proc))
  (goto (reg val))
primitive-branch14
  (assign val (op apply-primitive-procedure) (reg proc) (reg argl))
after-call16
  (assign argl (op list) (reg val))
  (restore env)
  (save argl)
  (assign proc (op lookup-variable-value) (const *) (reg env))
  (assign val (op lookup-variable-value) (const product) (reg env))
  (assign argl (op list) (reg val))
  (assign val (op lookup-variable-value) (const counter) (reg env))
  (assign argl (op cons) (reg val) (reg argl))
  (test (op primitive-procedure?) (reg proc))
  (branch (label primitive-branch11))
compiled-branch12
  (assign continue (label after-call13))
  (assign val (op compiled-procedure-entry) (reg proc))
  (goto (reg val))
primitive-branch11
  (assign val (op apply-primitive-procedure) (reg proc) (reg argl))
after-call13
  (restore argl)
  (assign argl (op cons) (reg val) (reg argl))
  (restore proc)
  (restore continue)
  (test (op primitive-procedure?) (reg proc))
  (branch (label primitive-branch17))
compiled-branch18
  (assign val (op compiled-procedure-entry) (reg proc))
  (goto (reg val))
primitive-branch17
  (assign val (op apply-primitive-procedure) (reg proc) (reg argl))
  (goto (reg continue))
after-call19
after-if7
after-lambda4
  (perform (op define-variable!) (const iter) (reg val) (reg env))
  (assign val (const ok))
  (assign proc (op lookup-variable-value) (const iter) (reg env))
  (assign val (const 1))
  (assign argl (op list) (reg val))
  (assign val (const 1))
  (assign argl (op cons) (reg val) (reg argl))
  (test (op primitive-procedure?) (reg proc))
  (branch (label primitive-branch20))
compiled-branch21
  (assign val (op compiled-procedure-entry) (reg proc))
  (goto (reg val))
primitive-branch20
  (assign val (op apply-primitive-procedure) (reg proc) (reg argl))
  (goto (reg continue))
after-call22
after-lambda2
  (perform (op define-variable!) (const factorial) (reg val) (reg env))
  (assign val (const ok))

計算機プログラムの構造と解釈

posted with amazlet at 08.11.07

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