300 lines
8.2 KiB
Scheme
300 lines
8.2 KiB
Scheme
; Copyright (c) 1993-1999 by Richard Kelsey and Jonathan Rees. See file COPYING.
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; Simple code analysis to determine whether it's a good idea to
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; in-line calls to a given procedure.
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; Hook into the byte code compiler.
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(set-optimizer! 'auto-integrate
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(lambda (forms package)
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(let ((out (current-noise-port)))
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(newline out)
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(display "Analyzing... " out) (force-output out)
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(let* ((forms (find-usages (map force-node forms) package))
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(names (analyze-forms forms package)))
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(cond ((not (null? names))
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(newline out)
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(display "Calls will be compiled in line: " out)
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(write (reverse names) out))
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(else
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(display "no in-line procedures" out)))
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(newline out)
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forms))))
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(define (analyze-forms scanned-nodes package)
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(let ((inlines '()))
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(for-each (lambda (node)
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(let ((lhs (analyze-form node package)))
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(if lhs
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(set! inlines (cons lhs inlines)))))
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scanned-nodes)
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inlines))
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(define (analyze-form node package) ;Return LHS iff calls will be inlined.
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(if (define-node? node)
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(let ((form (node-form node)))
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(let ((lhs (node-form (cadr form)))
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(rhs (caddr form)))
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(let ((type (package-lookup-type package lhs)))
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(if (variable-type? type)
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(require "not assigned" lhs #f)
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(let ((method (inlinable-rhs? rhs type package lhs)))
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(if method
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(begin (package-add-static! package lhs method)
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(if (transform? method)
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lhs
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#f))
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#f))))))
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#f))
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(define (inlinable-rhs? node type package lhs)
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(cond ((lambda-node? node)
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(if (simple-lambda? node lhs package)
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(make-inline-transform node type package lhs)
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#f))
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((name-node? node)
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(let ((name (node-form node)))
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(if (and (require "symbol rhs" (list lhs name)
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(symbol? name))
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(require "rhs bound" (list lhs name)
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(binding? (package-lookup-type package name)))
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(require "rhs unassigned" (list lhs name)
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(not (variable-type? (package-lookup-type package name))))
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(require "definitely procedure" (list lhs name)
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(procedure-type? (package-lookup-type package name))))
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(make-inline-transform node type package lhs)
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#f)))
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((loophole-node? node)
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(inlinable-rhs? (caddr (node-form node)) type package lhs))
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;These should already be taken care of.
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; ((primitive-procedure-node? node)
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; (get-operator (cadr (node-form node))))
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(else
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#f)))
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; We elect to integrate a procedure definition when
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; 1. The procedure in not n-ary,
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; 2. Every parameter is used exactly once and not assigned, and
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; 3. The analysis phase says that the body is acceptable (see below).
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(define (simple-lambda? node id package)
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(let* ((exp (node-form node))
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(formals (cadr exp))
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(body (caddr exp))
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(var-nodes (normalize-formals formals)))
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(and (require "not n-ary" id
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(not (n-ary? formals)))
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(require "unique references" id
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(every (lambda (var-node)
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(let ((usage (node-ref var-node 'usage)))
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(and (= (usage-reference-count usage) 1)
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(= (usage-assignment-count usage) 0))))
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var-nodes))
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(require "good analysis" id
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(simple? (caddr exp) ret)))))
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(define operator/name (get-operator 'name 'leaf))
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; --------------------
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; SIMPLE? takes an alpha-converted expression and returns either
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; - #f, meaning that the procedure in which the expression occurs
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; has no chance of being fully inlinable, so we might as well give up,
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; - #t, if there's no problem, or
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; - 'empty, if there's no problem AND there are no lexical variable
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; references at or below this node.
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; Foul situations are:
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; - complex quotations (we don't want to make multiple copies of them)
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; - a LAMBDA occurs (too much overhead, presumably)
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; - a call that is not to a primitive and not a tail call
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; Main dispatch for analyzer
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; The name node analyzer needs the node; all others can get by with the
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; expression.
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(define (simple? node ret?)
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((operator-table-ref analyzers (node-operator-id node))
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(if (name-node? node)
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node
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(node-form node))
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ret?))
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(define (simple-list? exp-list)
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(if (null? exp-list)
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'empty
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(let ((s1 (simple? (car exp-list) no-ret)))
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(cond ((eq? s1 'empty)
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(simple-list? (cdr exp-list)))
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((and s1
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(simple-list? (cdr exp-list)))
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#t)
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(else
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#f)))))
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; Particular operators
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(define analyzers
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(make-operator-table (lambda (exp ret?)
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(simple-list? (cdr exp)))))
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(define (define-analyzer name proc)
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(operator-define! analyzers name #f proc))
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(define-analyzer 'literal
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(lambda (exp ret?)
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(if (require "repeatable literal" #f
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(simple-literal? exp))
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'empty
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#f)))
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(define-analyzer 'unspecific
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(lambda (exp ret?)
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#t))
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; It's too awkward to try to inline references to unbound variables.
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; By special dispensation, this one analyzer receives the node instead of the
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; expression. It needs the node to look up the binding record.
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(define-analyzer 'name
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(lambda (node ret?)
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;; (if (node-ref node 'usage) #t 'empty)
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;; ... (not (generated? exp)) ugh ...
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(not (eq? (node-ref node 'binding)
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'unbound))))
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(define-analyzer 'quote
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(lambda (exp ret?)
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(if (require "repeatable quotation" #f
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(simple-literal? (cadr exp)))
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'empty
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#f)))
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(define-analyzer 'lambda
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(lambda (exp ret?) #f))
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(define-analyzer 'letrec
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(lambda (exp ret?) #f))
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(define-analyzer 'lap
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(lambda (exp ret?) #f))
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; SET! loses because we might move a variable reference past a SET! on the
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; variable. This can't happen if the SET! is the last thing done.
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; It's too awkward to try to inline references to unbound variables.
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(define-analyzer 'set!
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(lambda (exp ret?)
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(and ret?
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(not (eq? (node-ref (cadr exp) 'binding)
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'unbound))
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(simple? (caddr exp) no-ret))))
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(define-analyzer 'loophole
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(lambda (exp ret?)
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(simple? (caddr exp) ret?)))
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; Can't always fully in-line things like (lambda (a b c) (if a b c))
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(define-analyzer 'if
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(lambda (exp ret?)
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(and (eq? (simple? (caddr exp) ret?) 'empty)
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(eq? (simple? (cadddr exp) ret?) 'empty)
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(simple? (cadr exp) no-ret))))
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(define-analyzer 'begin
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(lambda (exp ret?)
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(let loop ((exps (cdr exp)))
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(if (null? (cdr exps))
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(if (simple? (car exps) ret?) #t #f)
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(and (simple? (car exps) no-ret)
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(loop (cdr exps)))))))
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(define-analyzer 'call
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(lambda (exp ret?)
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(let ((static (static-value (car exp))))
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(if (transform? static)
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(let* ((node (make-node (get-operator 'call) exp))
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(new-node (apply-inline-transform static
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(node-form node)
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(node-form (car exp)))))
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(if (eq? new-node node)
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(really-simple-call? exp ret?)
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(simple? new-node ret?)))
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(really-simple-call? exp ret?)))))
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; Return the static value of FORM, if any.
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(define (static-value form)
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(if (and (node? form)
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(name-node? form))
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(let ((probe (node-ref form 'binding)))
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(if (binding? probe)
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(binding-static probe)
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#f))
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#f))
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(define (really-simple-call? exp ret?)
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(let ((proc (car exp)))
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(and (require "non-local non-tail call" proc
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(or (and ret? (simple? proc no-ret)) ;tail calls are ok
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(lexical-node? proc))) ;so are calls to arguments
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(simple-list? exp))))
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(define (lexical-node? node)
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(not (node-ref node 'binding)))
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(define no-ret #f)
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(define ret #t)
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(define (simple-literal? x) ;Things that TRANSPORT won't copy.
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(or (integer? x)
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(boolean? x)
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(null? x)
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(char? x)
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(symbol? x)))
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; --------------------
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; debugging hack
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(define (require reason id x)
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(if (and *debug?* (not x))
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(begin (write id)
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(display " lost because ")
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(display reason)
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(display " failed")
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(newline)))
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x)
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(define *debug?* #f)
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; utility
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(define (package-lookup-type p name)
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(let ((probe (package-lookup p name)))
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(if (binding? probe)
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(binding-type probe)
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#f)))
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; --------------------
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(define lambda-node? (node-predicate 'lambda))
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(define name-node? (node-predicate 'name))
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(define loophole-node? (node-predicate 'loophole))
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(define define-node? (node-predicate 'define syntax-type))
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;----------------
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;(define (foo f p)
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; (analyze-forms (alpha-forms (scan-file f p) p)))
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;
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;
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;(define (tst e p)
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; (inlinable-rhs? (alpha e p) #f))
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;
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;(define b (make-compiler-base))
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;
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;(define p (make-simple-package (list b) eval #f))
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;
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;; (define b-stuff (alpha-structure b))
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;
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