X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fsrctran.lisp;h=f6369e6977cb25b5d81fd5f165ddaaa0ab1b2a78;hb=ccd2a1d4ab60a9539472df45fc4f9ec7b7fdc7b7;hp=ce1ac5a6099d757a2603f26a9b8916eef7b41896;hpb=4cd96b3be366d23b972a147965e40ea022329259;p=sbcl.git diff --git a/src/compiler/srctran.lisp b/src/compiler/srctran.lisp index ce1ac5a..f6369e6 100644 --- a/src/compiler/srctran.lisp +++ b/src/compiler/srctran.lisp @@ -13,23 +13,12 @@ (in-package "SB!C") -;;; Convert into an IF so that IF optimizations will eliminate redundant -;;; negations. -(define-source-transform not (x) `(if ,x nil t)) -(define-source-transform null (x) `(if ,x nil t)) - -;;; ENDP is just NULL with a LIST assertion. The assertion will be -;;; optimized away when SAFETY optimization is low; hopefully that -;;; is consistent with ANSI's "should return an error". -(define-source-transform endp (x) `(null (the list ,x))) - ;;; We turn IDENTITY into PROG1 so that it is obvious that it just ;;; returns the first value of its argument. Ditto for VALUES with one ;;; arg. (define-source-transform identity (x) `(prog1 ,x)) (define-source-transform values (x) `(prog1 ,x)) - ;;; CONSTANTLY is pretty much never worth transforming, but it's good to get the type. (defoptimizer (constantly derive-type) ((value)) (specifier-type @@ -99,6 +88,9 @@ ;;; Make source transforms to turn CxR forms into combinations of CAR ;;; and CDR. ANSI specifies that everything up to 4 A/D operations is ;;; defined. +;;; Don't transform CAD*R, they are treated specially for &more args +;;; optimizations + (/show0 "about to set CxR source transforms") (loop for i of-type index from 2 upto 4 do ;; Iterate over BUF = all names CxR where x = an I-element @@ -112,16 +104,18 @@ (declare (type index k)) (setf (aref buf (1+ k)) (if (logbitp k j) #\A #\D))) - (setf (info :function :source-transform (intern buf)) - #'source-transform-cxr)))) + (unless (member buf '("CADR" "CADDR" "CADDDR") + :test #'equal) + (setf (info :function :source-transform (intern buf)) + #'source-transform-cxr))))) (/show0 "done setting CxR source transforms") ;;; Turn FIRST..FOURTH and REST into the obvious synonym, assuming ;;; whatever is right for them is right for us. FIFTH..TENTH turn into ;;; Nth, which can be expanded into a CAR/CDR later on if policy ;;; favors it. -(define-source-transform first (x) `(car ,x)) (define-source-transform rest (x) `(cdr ,x)) +(define-source-transform first (x) `(car ,x)) (define-source-transform second (x) `(cadr ,x)) (define-source-transform third (x) `(caddr ,x)) (define-source-transform fourth (x) `(cadddr ,x)) @@ -163,8 +157,6 @@ (setf (cdr ,n-x) ,y) ,n-x))) -(define-source-transform nth (n l) `(car (nthcdr ,n ,l))) - (deftransform last ((list &optional n) (t &optional t)) (let ((c (constant-lvar-p n))) (cond ((or (not n) @@ -345,20 +337,26 @@ (defun set-bound (x open-p) (if (and x open-p) (list x) x)) -;;; Apply the function F to a bound X. If X is an open bound, then -;;; the result will be open. IF X is NIL, the result is NIL. -(defun bound-func (f x) +;;; Apply the function F to a bound X. If X is an open bound and the +;;; function is declared strictly monotonic, then the result will be +;;; open. IF X is NIL, the result is NIL. +(defun bound-func (f x strict) (declare (type function f)) (and x - (with-float-traps-masked (:underflow :overflow :inexact :divide-by-zero) - ;; With these traps masked, we might get things like infinity - ;; or negative infinity returned. Check for this and return - ;; NIL to indicate unbounded. - (let ((y (funcall f (type-bound-number x)))) - (if (and (floatp y) - (float-infinity-p y)) - nil - (set-bound y (consp x))))))) + (handler-case + (with-float-traps-masked (:underflow :overflow :inexact :divide-by-zero) + ;; With these traps masked, we might get things like infinity + ;; or negative infinity returned. Check for this and return + ;; NIL to indicate unbounded. + (let ((y (funcall f (type-bound-number x)))) + (if (and (floatp y) + (float-infinity-p y)) + nil + (set-bound y (and strict (consp x)))))) + ;; Some numerical operations will signal SIMPLE-TYPE-ERROR, e.g. + ;; in the course of converting a bignum to a float. Default to + ;; NIL in that case. + (simple-type-error ())))) (defun safe-double-coercion-p (x) (or (typep x 'double-float) @@ -366,30 +364,37 @@ (defun safe-single-coercion-p (x) (or (typep x 'single-float) - ;; Fix for bug 420, and related issues: during type derivation we often - ;; end up deriving types for both - ;; - ;; (some-op ) - ;; and - ;; (some-op (coerce 'single-float) ) - ;; - ;; or other equivalent transformed forms. The problem with this is that - ;; on some platforms like x86 (+ ) is on the machine level - ;; equivalent of - ;; - ;; (coerce (+ (coerce 'double-float) - ;; (coerce 'double-float)) - ;; 'single-float) - ;; - ;; so if the result of (coerce 'single-float) is not exact, the - ;; derived types for the transformed forms will have an empty - ;; intersection -- which in turn means that the compiler will conclude - ;; that the call never returns, and all hell breaks lose when it *does* - ;; return at runtime. (This affects not just +, but other operators are - ;; well.) - (and (not (typep x `(or (integer * (,most-negative-exactly-single-float-fixnum)) - (integer (,most-positive-exactly-single-float-fixnum) *)))) - (<= most-negative-single-float x most-positive-single-float)))) + (and + ;; Fix for bug 420, and related issues: during type derivation we often + ;; end up deriving types for both + ;; + ;; (some-op ) + ;; and + ;; (some-op (coerce 'single-float) ) + ;; + ;; or other equivalent transformed forms. The problem with this + ;; is that on x86 (+ ) is on the machine level + ;; equivalent of + ;; + ;; (coerce (+ (coerce 'double-float) + ;; (coerce 'double-float)) + ;; 'single-float) + ;; + ;; so if the result of (coerce 'single-float) is not exact, the + ;; derived types for the transformed forms will have an empty + ;; intersection -- which in turn means that the compiler will conclude + ;; that the call never returns, and all hell breaks lose when it *does* + ;; return at runtime. (This affects not just +, but other operators are + ;; well.) + ;; + ;; See also: SAFE-CTYPE-FOR-SINGLE-COERCION-P + ;; + ;; FIXME: If we ever add SSE-support for x86, this conditional needs to + ;; change. + #!+x86 + (not (typep x `(or (integer * (,most-negative-exactly-single-float-fixnum)) + (integer (,most-positive-exactly-single-float-fixnum) *)))) + (<= most-negative-single-float x most-positive-single-float)))) ;;; Apply a binary operator OP to two bounds X and Y. The result is ;;; NIL if either is NIL. Otherwise bound is computed and the result @@ -452,9 +457,19 @@ `(and (not (fp-zero-p ,xb)) (not (fp-zero-p ,yb)))))))))))) +(defun coercion-loses-precision-p (val type) + (typecase val + (single-float) + (double-float (subtypep type 'single-float)) + (rational (subtypep type 'float)) + (t (bug "Unexpected arguments to bounds coercion: ~S ~S" val type)))) + (defun coerce-for-bound (val type) (if (consp val) - (list (coerce-for-bound (car val) type)) + (let ((xbound (coerce-for-bound (car val) type))) + (if (coercion-loses-precision-p (car val) type) + xbound + (list xbound))) (cond ((subtypep type 'double-float) (if (<= most-negative-double-float val most-positive-double-float) @@ -468,7 +483,10 @@ (defun coerce-and-truncate-floats (val type) (when val (if (consp val) - (list (coerce-and-truncate-floats (car val) type)) + (let ((xbound (coerce-for-bound (car val) type))) + (if (coercion-loses-precision-p (car val) type) + xbound + (list xbound))) (cond ((subtypep type 'double-float) (if (<= most-negative-double-float val most-positive-double-float) @@ -517,7 +535,7 @@ :high (copy-interval-limit (interval-high x)))) ;;; Given a point P contained in the interval X, split X into two -;;; interval at the point P. If CLOSE-LOWER is T, then the left +;;; intervals at the point P. If CLOSE-LOWER is T, then the left ;;; interval contains P. If CLOSE-UPPER is T, the right interval ;;; contains P. You can specify both to be T or NIL. (defun interval-split (p x &optional close-lower close-upper) @@ -769,8 +787,8 @@ ;;; the negative of an interval (defun interval-neg (x) (declare (type interval x)) - (make-interval :low (bound-func #'- (interval-high x)) - :high (bound-func #'- (interval-low x)))) + (make-interval :low (bound-func #'- (interval-high x) t) + :high (bound-func #'- (interval-low x) t))) ;;; Add two intervals. (defun interval-add (x y) @@ -848,9 +866,6 @@ ((zerop (type-bound-number y)) ;; Divide by zero means result is infinity nil) - ((and (numberp x) (zerop x)) - ;; Zero divided by anything is zero. - x) (t (bound-binop / x y))))) (let ((top-range (interval-range-info top)) @@ -882,13 +897,17 @@ ;;; Apply the function F to the interval X. If X = [a, b], then the ;;; result is [f(a), f(b)]. It is up to the user to make sure the -;;; result makes sense. It will if F is monotonic increasing (or -;;; non-decreasing). -(defun interval-func (f x) +;;; result makes sense. It will if F is monotonic increasing (or, if +;;; the interval is closed, non-decreasing). +;;; +;;; (Actually most uses of INTERVAL-FUNC are coercions to float types, +;;; which are not monotonic increasing, so default to calling +;;; BOUND-FUNC with a non-strict argument). +(defun interval-func (f x &optional increasing) (declare (type function f) (type interval x)) - (let ((lo (bound-func f (interval-low x))) - (hi (bound-func f (interval-high x)))) + (let ((lo (bound-func f (interval-low x) increasing)) + (hi (bound-func f (interval-high x) increasing))) (make-interval :low lo :high hi))) ;;; Return T if X < Y. That is every number in the interval X is @@ -960,14 +979,13 @@ ;;; Compute the square of an interval. (defun interval-sqr (x) (declare (type interval x)) - (interval-func (lambda (x) (* x x)) - (interval-abs x))) + (interval-func (lambda (x) (* x x)) (interval-abs x))) ;;;; numeric DERIVE-TYPE methods ;;; a utility for defining derive-type methods of integer operations. If ;;; the types of both X and Y are integer types, then we compute a new -;;; integer type with bounds determined Fun when applied to X and Y. +;;; integer type with bounds determined by FUN when applied to X and Y. ;;; Otherwise, we use NUMERIC-CONTAGION. (defun derive-integer-type-aux (x y fun) (declare (type function fun)) @@ -2317,7 +2335,7 @@ (if (and divisor-low divisor-high) ;; We know the range of the divisor, and the remainder must be ;; smaller than the divisor. We can tell the sign of the - ;; remainer if we know the sign of the number. + ;; remainder if we know the sign of the number. (let ((divisor-max (1- (max (abs divisor-low) (abs divisor-high))))) `(integer ,(if (or (null number-low) (minusp number-low)) @@ -2328,7 +2346,7 @@ divisor-max 0))) ;; The divisor is potentially either very positive or very - ;; negative. Therefore, the remainer is unbounded, but we might + ;; negative. Therefore, the remainder is unbounded, but we might ;; be able to tell something about the sign from the number. `(integer ,(if (and number-low (not (minusp number-low))) ;; The number we are dividing is positive. @@ -3034,6 +3052,22 @@ (reoptimize-component (node-component node) :maybe)) (cut-node (node &aux did-something) (when (and (not (block-delete-p (node-block node))) + (ref-p node) + (constant-p (ref-leaf node))) + (let* ((constant-value (constant-value (ref-leaf node))) + (new-value (if signedp + (mask-signed-field width constant-value) + (ldb (byte width 0) constant-value)))) + (unless (= constant-value new-value) + (change-ref-leaf node (make-constant new-value)) + (let ((lvar (node-lvar node))) + (setf (lvar-%derived-type lvar) + (and (lvar-has-single-use-p lvar) + (make-values-type :required (list (ctype-of new-value)))))) + (setf (block-reoptimize (node-block node)) t) + (reoptimize-component (node-component node) :maybe) + (return-from cut-node t)))) + (when (and (not (block-delete-p (node-block node))) (combination-p node) (eq (basic-combination-kind node) :known)) (let* ((fun-ref (lvar-use (combination-fun node))) @@ -3108,9 +3142,23 @@ (best-modular-version width nil) (when w ;; FIXME: This should be (CUT-TO-WIDTH NODE KIND WIDTH SIGNEDP). - (cut-to-width x kind width signedp) - (cut-to-width y kind width signedp) - nil ; After fixing above, replace with T. + ;; + ;; FIXME: I think the FIXME (which is from APD) above + ;; implies that CUT-TO-WIDTH should do /everything/ + ;; that's required, including reoptimizing things + ;; itself that it knows are necessary. At the moment, + ;; CUT-TO-WIDTH sets up some new calls with + ;; combination-type :FULL, which later get noticed as + ;; known functions and properly converted. + ;; + ;; We cut to W not WIDTH if SIGNEDP is true, because + ;; signed constant replacement needs to know which bit + ;; in the field is the signed bit. + (let ((xact (cut-to-width x kind (if signedp w width) signedp)) + (yact (cut-to-width y kind (if signedp w width) signedp))) + (declare (ignore xact yact)) + nil) ; After fixing above, replace with T, meaning + ; "don't reoptimize this (LOGAND) node any more". )))))))) (defoptimizer (mask-signed-field optimizer) ((width x) node) @@ -3121,10 +3169,11 @@ (when (and (numberp low) (numberp high)) (let ((width (max (integer-length high) (integer-length low)))) (multiple-value-bind (w kind) - (best-modular-version width t) + (best-modular-version (1+ width) t) (when w - ;; FIXME: This should be (CUT-TO-WIDTH NODE KIND WIDTH T). - (cut-to-width x kind width t) + ;; FIXME: This should be (CUT-TO-WIDTH NODE KIND W T). + ;; [ see comment above in LOGAND optimizer ] + (cut-to-width x kind w t) nil ; After fixing above, replace with T. )))))))) @@ -3186,6 +3235,15 @@ `(- (ash x ,len)) `(ash x ,len)))) +;;; These must come before the ones below, so that they are tried +;;; first. Since %FLOOR and %CEILING are inlined, this allows +;;; the general case to be handled by TRUNCATE transforms. +(deftransform floor ((x y)) + `(%floor x y)) + +(deftransform ceiling ((x y)) + `(%ceiling x y)) + ;;; If arg is a constant power of two, turn FLOOR into a shift and ;;; mask. If CEILING, add in (1- (ABS Y)), do FLOOR and correct a ;;; remainder. @@ -3264,6 +3322,113 @@ `(if (minusp x) (- (logand (- x) ,mask)) (logand x ,mask))))) + +;;; Return an expression to calculate the integer quotient of X and +;;; constant Y, using multiplication, shift and add/sub instead of +;;; division. Both arguments must be unsigned, fit in a machine word and +;;; Y must neither be zero nor a power of two. The quotient is rounded +;;; towards zero. +;;; The algorithm is taken from the paper "Division by Invariant +;;; Integers using Multiplication", 1994 by Torbj\"{o}rn Granlund and +;;; Peter L. Montgomery, Figures 4.2 and 6.2, modified to exclude the +;;; case of division by powers of two. +;;; The algorithm includes an adaptive precision argument. Use it, since +;;; we often have sub-word value ranges. Careful, in this case, we need +;;; p s.t 2^p > n, not the ceiling of the binary log. +;;; Also, for some reason, the paper prefers shifting to masking. Mask +;;; instead. Masking is equivalent to shifting right, then left again; +;;; all the intermediate values are still words, so we just have to shift +;;; right a bit more to compensate, at the end. +;;; +;;; The following two examples show an average case and the worst case +;;; with respect to the complexity of the generated expression, under +;;; a word size of 64 bits: +;;; +;;; (UNSIGNED-DIV-TRANSFORMER 10 MOST-POSITIVE-WORD) -> +;;; (ASH (%MULTIPLY (LOGANDC2 X 0) 14757395258967641293) -3) +;;; +;;; (UNSIGNED-DIV-TRANSFORMER 7 MOST-POSITIVE-WORD) -> +;;; (LET* ((NUM X) +;;; (T1 (%MULTIPLY NUM 2635249153387078803))) +;;; (ASH (LDB (BYTE 64 0) +;;; (+ T1 (ASH (LDB (BYTE 64 0) +;;; (- NUM T1)) +;;; -1))) +;;; -2)) +;;; +(defun gen-unsigned-div-by-constant-expr (y max-x) + (declare (type (integer 3 #.most-positive-word) y) + (type word max-x)) + (aver (not (zerop (logand y (1- y))))) + (labels ((ld (x) + ;; the floor of the binary logarithm of (positive) X + (integer-length (1- x))) + (choose-multiplier (y precision) + (do* ((l (ld y)) + (shift l (1- shift)) + (expt-2-n+l (expt 2 (+ sb!vm:n-word-bits l))) + (m-low (truncate expt-2-n+l y) (ash m-low -1)) + (m-high (truncate (+ expt-2-n+l + (ash expt-2-n+l (- precision))) + y) + (ash m-high -1))) + ((not (and (< (ash m-low -1) (ash m-high -1)) + (> shift 0))) + (values m-high shift))))) + (let ((n (expt 2 sb!vm:n-word-bits)) + (precision (integer-length max-x)) + (shift1 0)) + (multiple-value-bind (m shift2) + (choose-multiplier y precision) + (when (and (>= m n) (evenp y)) + (setq shift1 (ld (logand y (- y)))) + (multiple-value-setq (m shift2) + (choose-multiplier (/ y (ash 1 shift1)) + (- precision shift1)))) + (cond ((>= m n) + (flet ((word (x) + `(truly-the word ,x))) + `(let* ((num x) + (t1 (%multiply-high num ,(- m n)))) + (ash ,(word `(+ t1 (ash ,(word `(- num t1)) + -1))) + ,(- 1 shift2))))) + ((and (zerop shift1) (zerop shift2)) + (let ((max (truncate max-x y))) + ;; Explicit TRULY-THE needed to get the FIXNUM=>FIXNUM + ;; VOP. + `(truly-the (integer 0 ,max) + (%multiply-high x ,m)))) + (t + `(ash (%multiply-high (logandc2 x ,(1- (ash 1 shift1))) ,m) + ,(- (+ shift1 shift2))))))))) + +;;; If the divisor is constant and both args are positive and fit in a +;;; machine word, replace the division by a multiplication and possibly +;;; some shifts and an addition. Calculate the remainder by a second +;;; multiplication and a subtraction. Dead code elimination will +;;; suppress the latter part if only the quotient is needed. If the type +;;; of the dividend allows to derive that the quotient will always have +;;; the same value, emit much simpler code to handle that. (This case +;;; may be rare but it's easy to detect and the compiler doesn't find +;;; this optimization on its own.) +(deftransform truncate ((x y) (word (constant-arg word)) + * + :policy (and (> speed compilation-speed) + (> speed space))) + "convert integer division to multiplication" + (let* ((y (lvar-value y)) + (x-type (lvar-type x)) + (max-x (or (and (numeric-type-p x-type) + (numeric-type-high x-type)) + most-positive-word))) + ;; Division by zero, one or powers of two is handled elsewhere. + (when (zerop (logand y (1- y))) + (give-up-ir1-transform)) + `(let* ((quot ,(gen-unsigned-div-by-constant-expr y max-x)) + (rem (ldb (byte #.sb!vm:n-word-bits 0) + (- x (* quot ,y))))) + (values quot rem)))) ;;;; arithmetic and logical identity operation elimination @@ -3434,6 +3599,24 @@ (def round) (def floor) (def ceiling)) + +(macrolet ((def (name &optional float) + (let ((x (if float '(float x) 'x))) + `(deftransform ,name ((x y) (integer (constant-arg (member 1 -1))) + *) + "fold division by 1" + `(values ,(if (minusp (lvar-value y)) + '(%negate ,x) + ',x) 0))))) + (def truncate) + (def round) + (def floor) + (def ceiling) + (def ftruncate t) + (def fround t) + (def ffloor t) + (def fceiling t)) + ;;;; character operations @@ -3719,7 +3902,7 @@ (define-source-transform > (&rest args) (multi-compare '> args nil 'real)) ;;; We cannot do the inversion for >= and <= here, since both ;;; (< NaN X) and (> NaN X) -;;; are false, and we don't have type-inforation available yet. The +;;; are false, and we don't have type-information available yet. The ;;; deftransforms for two-argument versions of >= and <= takes care of ;;; the inversion to > and < when possible. (define-source-transform <= (&rest args) (multi-compare '<= args nil 'real)) @@ -3896,57 +4079,165 @@ ,@(mapcar (lambda (x) `(values ,x)) (butlast args)) (values-list ,(car (last args)))))) -;;; When &REST argument are at play, we also have extra context and count -;;; arguments -- convert to %VALUES-LIST-OR-CONTEXT when possible, so that the -;;; deftransform can decide what to do after everything has been converted. -(define-source-transform values-list (list) - (if (symbolp list) - (let* ((var (lexenv-find list vars)) - (info (when (lambda-var-p var) - (lambda-var-arg-info var)))) - (if (and info +;;;; transforming references to &REST argument + +;;; We add magical &MORE arguments to all functions with &REST. If ARG names +;;; the &REST argument, this returns the lambda-vars for the context and +;;; count. +(defun possible-rest-arg-context (arg) + (when (symbolp arg) + (let* ((var (lexenv-find arg vars)) + (info (when (lambda-var-p var) + (lambda-var-arg-info var)))) + (when (and info (eq :rest (arg-info-kind info)) (consp (arg-info-default info))) - (destructuring-bind (context count &optional used) (arg-info-default info) - (declare (ignore used)) - `(%values-list-or-context ,list ,context ,count)) - (values nil t))) - (values nil t))) - -(deftransform %values-list-or-context ((list context count) * * :node node) - (let* ((use (lvar-use list)) + (values-list (arg-info-default info)))))) + +(defun mark-more-context-used (rest-var) + (let ((info (lambda-var-arg-info rest-var))) + (aver (eq :rest (arg-info-kind info))) + (destructuring-bind (context count &optional used) (arg-info-default info) + (unless used + (setf (arg-info-default info) (list context count t)))))) + +(defun mark-more-context-invalid (rest-var) + (let ((info (lambda-var-arg-info rest-var))) + (aver (eq :rest (arg-info-kind info))) + (setf (arg-info-default info) t))) + +;;; This determines of we the REF to a &REST variable is headed towards +;;; parts unknown, or if we can really use the context. +(defun rest-var-more-context-ok (lvar) + (let* ((use (lvar-use lvar)) (var (when (ref-p use) (ref-leaf use))) (home (when (lambda-var-p var) (lambda-var-home var))) - (info (when (lambda-var-p var) (lambda-var-arg-info var)))) + (info (when (lambda-var-p var) (lambda-var-arg-info var))) + (restp (when info (eq :rest (arg-info-kind info))))) (flet ((ref-good-for-more-context-p (ref) (let ((dest (principal-lvar-end (node-lvar ref)))) (and (combination-p dest) - ;; Uses outside VALUES-LIST will require a &REST list anyways, - ;; to it's no use saving effort here -- plus they might modify - ;; the list destructively. - (eq '%values-list-or-context (lvar-fun-name (combination-fun dest))) + ;; If the destination is to anything but these, we're going to + ;; actually need the rest list -- and since other operations + ;; might modify the list destructively, the using the context + ;; isn't good anywhere else either. + (lvar-fun-is (combination-fun dest) + '(%rest-values %rest-ref %rest-length + %rest-null %rest-true)) ;; If the home lambda is different and isn't DX, it might ;; escape -- in which case using the more context isn't safe. (let ((clambda (node-home-lambda dest))) (or (eq home clambda) (leaf-dynamic-extent clambda))))))) - (let ((context-ok - (and info - (consp (arg-info-default info)) - (not (lambda-var-specvar var)) - (not (lambda-var-sets var)) - (every #'ref-good-for-more-context-p (lambda-var-refs var)) - (policy node (= 3 rest-conversion))))) - (cond (context-ok - (destructuring-bind (context count &optional used) (arg-info-default info) - (declare (ignore used)) - (setf (arg-info-default info) (list context count t))) - `(%more-arg-values context 0 count)) - (t - (when info - (setf (arg-info-default info) t)) - `(values-list list))))))) - + (let ((ok (and restp + (consp (arg-info-default info)) + (not (lambda-var-specvar var)) + (not (lambda-var-sets var)) + (every #'ref-good-for-more-context-p (lambda-var-refs var))))) + (if ok + (mark-more-context-used var) + (when restp + (mark-more-context-invalid var))) + ok)))) + +;;; VALUES-LIST -> %REST-VALUES +(define-source-transform values-list (list) + (multiple-value-bind (context count) (possible-rest-arg-context list) + (if context + `(%rest-values ,list ,context ,count) + (values nil t)))) + +;;; NTH -> %REST-REF +(define-source-transform nth (n list) + (multiple-value-bind (context count) (possible-rest-arg-context list) + (if context + `(%rest-ref ,n ,list ,context ,count) + `(car (nthcdr ,n ,list))))) + +(define-source-transform elt (seq n) + (if (policy *lexenv* (= safety 3)) + (values nil t) + (multiple-value-bind (context count) (possible-rest-arg-context seq) + (if context + `(%rest-ref ,n ,seq ,context ,count) + (values nil t))))) + +;;; CAxR -> %REST-REF +(defun source-transform-car (list nth) + (multiple-value-bind (context count) (possible-rest-arg-context list) + (if context + `(%rest-ref ,nth ,list ,context ,count) + (values nil t)))) + +(define-source-transform car (list) + (source-transform-car list 0)) + +(define-source-transform cadr (list) + (or (source-transform-car list 1) + `(car (cdr ,list)))) + +(define-source-transform caddr (list) + (or (source-transform-car list 2) + `(car (cdr (cdr ,list))))) + +(define-source-transform cadddr (list) + (or (source-transform-car list 3) + `(car (cdr (cdr (cdr ,list)))))) + +;;; LENGTH -> %REST-LENGTH +(defun source-transform-length (list) + (multiple-value-bind (context count) (possible-rest-arg-context list) + (if context + `(%rest-length ,list ,context ,count) + (values nil t)))) +(define-source-transform length (list) (source-transform-length list)) +(define-source-transform list-length (list) (source-transform-length list)) + +;;; ENDP, NULL and NOT -> %REST-NULL +;;; +;;; Outside &REST convert into an IF so that IF optimizations will eliminate +;;; redundant negations. +(defun source-transform-null (x op) + (multiple-value-bind (context count) (possible-rest-arg-context x) + (cond (context + `(%rest-null ',op ,x ,context ,count)) + ((eq 'endp op) + `(if (the list ,x) nil t)) + (t + `(if ,x nil t))))) +(define-source-transform not (x) (source-transform-null x 'not)) +(define-source-transform null (x) (source-transform-null x 'null)) +(define-source-transform endp (x) (source-transform-null x 'endp)) + +(deftransform %rest-values ((list context count)) + (if (rest-var-more-context-ok list) + `(%more-arg-values context 0 count) + `(values-list list))) + +(deftransform %rest-ref ((n list context count)) + (cond ((rest-var-more-context-ok list) + `(and (< (the index n) count) + (%more-arg context n))) + ((and (constant-lvar-p n) (zerop (lvar-value n))) + `(car list)) + (t + `(nth n list)))) + +(deftransform %rest-length ((list context count)) + (if (rest-var-more-context-ok list) + 'count + `(length list))) + +(deftransform %rest-null ((op list context count)) + (aver (constant-lvar-p op)) + (if (rest-var-more-context-ok list) + `(eql 0 count) + `(,(lvar-value op) list))) + +(deftransform %rest-true ((list context count)) + (if (rest-var-more-context-ok list) + `(not (eql 0 count)) + `list)) ;;;; transforming FORMAT ;;;;