Commit e856a453 authored by Stefan Monnier's avatar Stefan Monnier
Browse files

(byte-compile-log-lap, byte-compile-inline-expand): Use backquote.

(byte-optimize-pure-func): Rename from byte-optimize-concat.
(symbol-name, regexp-opt, regexp-quote): Mark as pure.
parent 1de9630d
;;; byte-opt.el --- the optimization passes of the emacs-lisp byte compiler
;;; Copyright (c) 1991, 1994, 2000, 2001, 2002 Free Software Foundation, Inc.
;; Copyright (c) 1991,1994,2000,01,02,2004 Free Software Foundation, Inc.
;; Author: Jamie Zawinski <jwz@lucid.com>
;; Hallvard Furuseth <hbf@ulrik.uio.no>
......@@ -148,37 +148,37 @@
;; Other things to consider:
;;;;; Associative math should recognize subcalls to identical function:
;;;(disassemble (lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
;;;;; This should generate the same as (1+ x) and (1- x)
;;;(disassemble (lambda (x) (cons (+ x 1) (- x 1))))
;;;;; An awful lot of functions always return a non-nil value. If they're
;;;;; error free also they may act as true-constants.
;;;(disassemble (lambda (x) (and (point) (foo))))
;;;;; When
;;;;; - all but one arguments to a function are constant
;;;;; - the non-constant argument is an if-expression (cond-expression?)
;;;;; then the outer function can be distributed. If the guarding
;;;;; condition is side-effect-free [assignment-free] then the other
;;;;; arguments may be any expressions. Since, however, the code size
;;;;; can increase this way they should be "simple". Compare:
;;;(disassemble (lambda (x) (eq (if (point) 'a 'b) 'c)))
;;;(disassemble (lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
;;;;; (car (cons A B)) -> (progn B A)
;;;(disassemble (lambda (x) (car (cons (foo) 42))))
;;;;; (cdr (cons A B)) -> (progn A B)
;;;(disassemble (lambda (x) (cdr (cons 42 (foo)))))
;;;;; (car (list A B ...)) -> (progn B ... A)
;;;(disassemble (lambda (x) (car (list (foo) 42 (bar)))))
;;;;; (cdr (list A B ...)) -> (progn A (list B ...))
;;;(disassemble (lambda (x) (cdr (list 42 (foo) (bar)))))
;; ;; Associative math should recognize subcalls to identical function:
;; (disassemble (lambda (x) (+ (+ (foo) 1) (+ (bar) 2))))
;; ;; This should generate the same as (1+ x) and (1- x)
;; (disassemble (lambda (x) (cons (+ x 1) (- x 1))))
;; ;; An awful lot of functions always return a non-nil value. If they're
;; ;; error free also they may act as true-constants.
;; (disassemble (lambda (x) (and (point) (foo))))
;; ;; When
;; ;; - all but one arguments to a function are constant
;; ;; - the non-constant argument is an if-expression (cond-expression?)
;; ;; then the outer function can be distributed. If the guarding
;; ;; condition is side-effect-free [assignment-free] then the other
;; ;; arguments may be any expressions. Since, however, the code size
;; ;; can increase this way they should be "simple". Compare:
;; (disassemble (lambda (x) (eq (if (point) 'a 'b) 'c)))
;; (disassemble (lambda (x) (if (point) (eq 'a 'c) (eq 'b 'c))))
;; ;; (car (cons A B)) -> (prog1 A B)
;; (disassemble (lambda (x) (car (cons (foo) 42))))
;; ;; (cdr (cons A B)) -> (progn A B)
;; (disassemble (lambda (x) (cdr (cons 42 (foo)))))
;; ;; (car (list A B ...)) -> (prog1 A B ...)
;; (disassemble (lambda (x) (car (list (foo) 42 (bar)))))
;; ;; (cdr (list A B ...)) -> (progn A (list B ...))
;; (disassemble (lambda (x) (cdr (list 42 (foo) (bar)))))
;;; Code:
......@@ -217,10 +217,8 @@
args)))))
(defmacro byte-compile-log-lap (format-string &rest args)
(list 'and
'(memq byte-optimize-log '(t byte))
(cons 'byte-compile-log-lap-1
(cons format-string args))))
`(and (memq byte-optimize-log '(t byte))
(byte-compile-log-lap-1 ,format-string ,@args)))
;;; byte-compile optimizers to support inlining
......@@ -274,18 +272,18 @@
(let (string)
(fetch-bytecode fn)
(setq string (aref fn 1))
;; Isn't it an error for `string' not to be unibyte?? --stef
(if (fboundp 'string-as-unibyte)
(setq string (string-as-unibyte string)))
(cons (list 'lambda (aref fn 0)
(list 'byte-code string (aref fn 2) (aref fn 3)))
(cons `(lambda ,(aref fn 0)
(byte-code ,string ,(aref fn 2) ,(aref fn 3)))
(cdr form)))
(if (eq (car-safe fn) 'lambda)
(cons fn (cdr form))
;; Give up on inlining.
form))))))
;;; ((lambda ...) ...)
;;;
;; ((lambda ...) ...)
(defun byte-compile-unfold-lambda (form &optional name)
(or name (setq name "anonymous lambda"))
(let ((lambda (car form))
......@@ -604,14 +602,14 @@
(nreverse result)))
;;; some source-level optimizers
;;;
;;; when writing optimizers, be VERY careful that the optimizer returns
;;; something not EQ to its argument if and ONLY if it has made a change.
;;; This implies that you cannot simply destructively modify the list;
;;; you must return something not EQ to it if you make an optimization.
;;;
;;; It is now safe to optimize code such that it introduces new bindings.
;; some source-level optimizers
;;
;; when writing optimizers, be VERY careful that the optimizer returns
;; something not EQ to its argument if and ONLY if it has made a change.
;; This implies that you cannot simply destructively modify the list;
;; you must return something not EQ to it if you make an optimization.
;;
;; It is now safe to optimize code such that it introduces new bindings.
;; I'd like this to be a defsubst, but let's not be self-referential...
(defmacro byte-compile-trueconstp (form)
......@@ -721,10 +719,10 @@
(condition-case ()
(eval form)
(error form)))
;;; It is not safe to delete the function entirely
;;; (actually, it would be safe if we know the sole arg
;;; is not a marker).
;; ((null (cdr (cdr form))) (nth 1 form))
;;; It is not safe to delete the function entirely
;;; (actually, it would be safe if we know the sole arg
;;; is not a marker).
;;; ((null (cdr (cdr form))) (nth 1 form))
((null (cddr form))
(if (numberp (nth 1 form))
(nth 1 form)
......@@ -763,9 +761,9 @@
(numberp last))
(setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form))
(delq last (copy-sequence (nthcdr 3 form))))))))
;;; It is not safe to delete the function entirely
;;; (actually, it would be safe if we know the sole arg
;;; is not a marker).
;;; It is not safe to delete the function entirely
;;; (actually, it would be safe if we know the sole arg
;;; is not a marker).
;;; (if (eq (nth 2 form) 0)
;;; (nth 1 form) ; (- x 0) --> x
(byte-optimize-predicate
......@@ -780,9 +778,9 @@
(setq form (byte-optimize-delay-constants-math form 1 '*))
;; If there is a constant in FORM, it is now the last element.
(cond ((null (cdr form)) 1)
;;; It is not safe to delete the function entirely
;;; (actually, it would be safe if we know the sole arg
;;; is not a marker or if it appears in other arithmetic).
;;; It is not safe to delete the function entirely
;;; (actually, it would be safe if we know the sole arg
;;; is not a marker or if it appears in other arithmetic).
;;; ((null (cdr (cdr form))) (nth 1 form))
((let ((last (car (reverse form))))
(cond ((eq 0 last) (cons 'progn (cdr form)))
......@@ -1117,8 +1115,16 @@
(byte-optimize-predicate form))
form))
(put 'concat 'byte-optimizer 'byte-optimize-concat)
(defun byte-optimize-concat (form)
(put 'concat 'byte-optimizer 'byte-optimize-pure-func)
(put 'symbol-name 'byte-optimizer 'byte-optimize-pure-func)
(put 'regexp-opt 'byte-optimizer 'byte-optimize-pure-func)
(put 'regexp-quote 'byte-optimizer 'byte-optimize-pure-func)
(defun byte-optimize-pure-func (form)
"Do constant folding for pure functions.
This assumes that the function will not have any side-effects and that
its return value depends solely on its arguments.
If the function can signal an error, this might change the semantics
of FORM by signalling the error at compile-time."
(let ((args (cdr form))
(constant t))
(while (and args constant)
......@@ -1181,28 +1187,28 @@
`(progn ,(cadr form) (setq ,(cadr var) ,@(cddr form))))
(t form))))
;;; enumerating those functions which need not be called if the returned
;;; value is not used. That is, something like
;;; (progn (list (something-with-side-effects) (yow))
;;; (foo))
;;; may safely be turned into
;;; (progn (progn (something-with-side-effects) (yow))
;;; (foo))
;;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
;;; Some of these functions have the side effect of allocating memory
;;; and it would be incorrect to replace two calls with one.
;;; But we don't try to do those kinds of optimizations,
;;; so it is safe to list such functions here.
;;; Some of these functions return values that depend on environment
;;; state, so that constant folding them would be wrong,
;;; but we don't do constant folding based on this list.
;;; However, at present the only optimization we normally do
;;; is delete calls that need not occur, and we only do that
;;; with the error-free functions.
;;; I wonder if I missed any :-\)
;; enumerating those functions which need not be called if the returned
;; value is not used. That is, something like
;; (progn (list (something-with-side-effects) (yow))
;; (foo))
;; may safely be turned into
;; (progn (progn (something-with-side-effects) (yow))
;; (foo))
;; Further optimizations will turn (progn (list 1 2 3) 'foo) into 'foo.
;; Some of these functions have the side effect of allocating memory
;; and it would be incorrect to replace two calls with one.
;; But we don't try to do those kinds of optimizations,
;; so it is safe to list such functions here.
;; Some of these functions return values that depend on environment
;; state, so that constant folding them would be wrong,
;; but we don't do constant folding based on this list.
;; However, at present the only optimization we normally do
;; is delete calls that need not occur, and we only do that
;; with the error-free functions.
;; I wonder if I missed any :-\)
(let ((side-effect-free-fns
'(% * + - / /= 1+ 1- < <= = > >= abs acos append aref ash asin atan
assoc assq
......@@ -1298,8 +1304,8 @@
(defconst byte-constref-ops
'(byte-constant byte-constant2 byte-varref byte-varset byte-varbind))
;;; This function extracts the bitfields from variable-length opcodes.
;;; Originally defined in disass.el (which no longer uses it.)
;; This function extracts the bitfields from variable-length opcodes.
;; Originally defined in disass.el (which no longer uses it.)
(defun disassemble-offset ()
"Don't call this!"
......@@ -1336,11 +1342,11 @@
(aref bytes ptr))))
;;; This de-compiler is used for inline expansion of compiled functions,
;;; and by the disassembler.
;;;
;;; This list contains numbers, which are pc values,
;;; before each instruction.
;; This de-compiler is used for inline expansion of compiled functions,
;; and by the disassembler.
;;
;; This list contains numbers, which are pc values,
;; before each instruction.
(defun byte-decompile-bytecode (bytes constvec)
"Turns BYTECODE into lapcode, referring to CONSTVEC."
(let ((byte-compile-constants nil)
......@@ -1461,38 +1467,39 @@
byte-member byte-assq byte-quo byte-rem)
byte-compile-side-effect-and-error-free-ops))
;;; This crock is because of the way DEFVAR_BOOL variables work.
;;; Consider the code
;;;
;;; (defun foo (flag)
;;; (let ((old-pop-ups pop-up-windows)
;;; (pop-up-windows flag))
;;; (cond ((not (eq pop-up-windows old-pop-ups))
;;; (setq old-pop-ups pop-up-windows)
;;; ...))))
;;;
;;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
;;; something else. But if we optimize
;;;
;;; varref flag
;;; varbind pop-up-windows
;;; varref pop-up-windows
;;; not
;;; to
;;; varref flag
;;; dup
;;; varbind pop-up-windows
;;; not
;;;
;;; we break the program, because it will appear that pop-up-windows and
;;; old-pop-ups are not EQ when really they are. So we have to know what
;;; the BOOL variables are, and not perform this optimization on them.
;;; The variable `byte-boolean-vars' is now primitive and updated
;;; automatically by DEFVAR_BOOL.
;; This crock is because of the way DEFVAR_BOOL variables work.
;; Consider the code
;;
;; (defun foo (flag)
;; (let ((old-pop-ups pop-up-windows)
;; (pop-up-windows flag))
;; (cond ((not (eq pop-up-windows old-pop-ups))
;; (setq old-pop-ups pop-up-windows)
;; ...))))
;;
;; Uncompiled, old-pop-ups will always be set to nil or t, even if FLAG is
;; something else. But if we optimize
;;
;; varref flag
;; varbind pop-up-windows
;; varref pop-up-windows
;; not
;; to
;; varref flag
;; dup
;; varbind pop-up-windows
;; not
;;
;; we break the program, because it will appear that pop-up-windows and
;; old-pop-ups are not EQ when really they are. So we have to know what
;; the BOOL variables are, and not perform this optimization on them.
;; The variable `byte-boolean-vars' is now primitive and updated
;; automatically by DEFVAR_BOOL.
(defun byte-optimize-lapcode (lap &optional for-effect)
"Simple peephole optimizer. LAP is both modified and returned."
"Simple peephole optimizer. LAP is both modified and returned.
If FOR-EFFECT is non-nil, the return value is assumed to be of no importance."
(let (lap0
lap1
lap2
......
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