;;;; This file implements local call analysis. A local call is a ;;;; function call between functions being compiled at the same time. ;;;; If we can tell at compile time that such a call is legal, then we ;;;; change the combination to call the correct lambda, mark it as ;;;; local, and add this link to our call graph. Once a call is local, ;;;; it is then eligible for let conversion, which places the body of ;;;; the function inline. ;;;; ;;;; We cannot always do a local call even when we do have the ;;;; function being called. Calls that cannot be shown to have legal ;;;; arg counts are not converted. ;;;; This software is part of the SBCL system. See the README file for ;;;; more information. ;;;; ;;;; This software is derived from the CMU CL system, which was ;;;; written at Carnegie Mellon University and released into the ;;;; public domain. The software is in the public domain and is ;;;; provided with absolutely no warranty. See the COPYING and CREDITS ;;;; files for more information. (in-package "SB!C") ;;; This function propagates information from the variables in the function ;;; Fun to the actual arguments in Call. This is also called by the VALUES IR1 ;;; optimizer when it sleazily converts MV-BINDs to LETs. ;;; ;;; We flush all arguments to Call that correspond to unreferenced variables ;;; in Fun. We leave NILs in the Combination-Args so that the remaining args ;;; still match up with their vars. ;;; ;;; We also apply the declared variable type assertion to the argument ;;; continuations. (defun propagate-to-args (call fun) (declare (type combination call) (type clambda fun)) (do ((args (basic-combination-args call) (cdr args)) (vars (lambda-vars fun) (cdr vars))) ((null args)) (let ((arg (car args)) (var (car vars))) (cond ((leaf-refs var) (assert-continuation-type arg (leaf-type var))) (t (flush-dest arg) (setf (car args) nil))))) (values)) ;;; This function handles merging the tail sets if Call is potentially ;;; tail-recursive, and is a call to a function with a different TAIL-SET than ;;; Call's Fun. This must be called whenever we alter IR1 so as to place a ;;; local call in what might be a TR context. Note that any call which returns ;;; its value to a RETURN is considered potentially TR, since any implicit ;;; MV-PROG1 might be optimized away. ;;; ;;; We destructively modify the set for the calling function to represent both, ;;; and then change all the functions in callee's set to reference the first. ;;; If we do merge, we reoptimize the RETURN-RESULT continuation to cause ;;; IR1-OPTIMIZE-RETURN to recompute the tail set type. (defun merge-tail-sets (call &optional (new-fun (combination-lambda call))) (declare (type basic-combination call) (type clambda new-fun)) (let ((return (continuation-dest (node-cont call)))) (when (return-p return) (let ((call-set (lambda-tail-set (node-home-lambda call))) (fun-set (lambda-tail-set new-fun))) (unless (eq call-set fun-set) (let ((funs (tail-set-functions fun-set))) (dolist (fun funs) (setf (lambda-tail-set fun) call-set)) (setf (tail-set-functions call-set) (nconc (tail-set-functions call-set) funs))) (reoptimize-continuation (return-result return)) t))))) ;;; Convert a combination into a local call. We PROPAGATE-TO-ARGS, set ;;; the combination kind to :LOCAL, add FUN to the CALLS of the ;;; function that the call is in, call MERGE-TAIL-SETS, then replace ;;; the function in the REF node with the new function. ;;; ;;; We change the REF last, since changing the reference can trigger ;;; LET conversion of the new function, but will only do so if the ;;; call is local. Note that the replacement may trigger LET ;;; conversion or other changes in IR1. We must call MERGE-TAIL-SETS ;;; with NEW-FUN before the substitution, since after the substitution ;;; (and LET conversion), the call may no longer be recognizable as ;;; tail-recursive. (defun convert-call (ref call fun) (declare (type ref ref) (type combination call) (type clambda fun)) (propagate-to-args call fun) (setf (basic-combination-kind call) :local) (pushnew fun (lambda-calls (node-home-lambda call))) (merge-tail-sets call fun) (change-ref-leaf ref fun) (values)) ;;;; external entry point creation ;;; Return a Lambda form that can be used as the definition of the XEP ;;; for FUN. ;;; ;;; If FUN is a lambda, then we check the number of arguments ;;; (conditional on policy) and call FUN with all the arguments. ;;; ;;; If FUN is an OPTIONAL-DISPATCH, then we dispatch off of the number ;;; of supplied arguments by doing do an = test for each entry-point, ;;; calling the entry with the appropriate prefix of the passed ;;; arguments. ;;; ;;; If there is a more arg, then there are a couple of optimizations ;;; that we make (more for space than anything else): ;;; -- If MIN-ARGS is 0, then we make the more entry a T clause, since ;;; no argument count error is possible. ;;; -- We can omit the = clause for the last entry-point, allowing the ;;; case of 0 more args to fall through to the more entry. ;;; ;;; We don't bother to policy conditionalize wrong arg errors in ;;; optional dispatches, since the additional overhead is negligible ;;; compared to the cost of everything else going on. ;;; ;;; Note that if policy indicates it, argument type declarations in ;;; Fun will be verified. Since nothing is known about the type of the ;;; XEP arg vars, type checks will be emitted when the XEP's arg vars ;;; are passed to the actual function. (defun make-xep-lambda (fun) (declare (type functional fun)) (etypecase fun (clambda (let ((nargs (length (lambda-vars fun))) (n-supplied (gensym)) (temps (make-gensym-list (length (lambda-vars fun))))) `(lambda (,n-supplied ,@temps) (declare (type index ,n-supplied)) ,(if (policy nil (zerop safety)) `(declare (ignore ,n-supplied)) `(%verify-argument-count ,n-supplied ,nargs)) (%funcall ,fun ,@temps)))) (optional-dispatch (let* ((min (optional-dispatch-min-args fun)) (max (optional-dispatch-max-args fun)) (more (optional-dispatch-more-entry fun)) (n-supplied (gensym)) (temps (make-gensym-list max))) (collect ((entries)) (do ((eps (optional-dispatch-entry-points fun) (rest eps)) (n min (1+ n))) ((null eps)) (entries `((= ,n-supplied ,n) (%funcall ,(first eps) ,@(subseq temps 0 n))))) `(lambda (,n-supplied ,@temps) ;; FIXME: Make sure that INDEX type distinguishes between ;; target and host. (Probably just make the SB!XC:DEFTYPE ;; different from CL:DEFTYPE.) (declare (type index ,n-supplied)) (cond ,@(if more (butlast (entries)) (entries)) ,@(when more `((,(if (zerop min) t `(>= ,n-supplied ,max)) ,(let ((n-context (gensym)) (n-count (gensym))) `(multiple-value-bind (,n-context ,n-count) (%more-arg-context ,n-supplied ,max) (%funcall ,more ,@temps ,n-context ,n-count)))))) (t (%argument-count-error ,n-supplied))))))))) ;;; Make an external entry point (XEP) for FUN and return it. We ;;; convert the result of MAKE-XEP-LAMBDA in the correct environment, ;;; then associate this lambda with FUN as its XEP. After the ;;; conversion, we iterate over the function's associated lambdas, ;;; redoing local call analysis so that the XEP calls will get ;;; converted. ;;; ;;; We set REANALYZE and REOPTIMIZE in the component, just in case we ;;; discover an XEP after the initial local call analyze pass. (defun make-external-entry-point (fun) (declare (type functional fun)) (aver (not (functional-entry-function fun))) (with-ir1-environment (lambda-bind (main-entry fun)) (let ((res (ir1-convert-lambda (make-xep-lambda fun)))) (setf (functional-kind res) :external (leaf-ever-used res) t (functional-entry-function res) fun (functional-entry-function fun) res (component-reanalyze *current-component*) t (component-reoptimize *current-component*) t) (etypecase fun (clambda (local-call-analyze-1 fun)) (optional-dispatch (dolist (ep (optional-dispatch-entry-points fun)) (local-call-analyze-1 ep)) (when (optional-dispatch-more-entry fun) (local-call-analyze-1 (optional-dispatch-more-entry fun))))) res))) ;;; Notice a Ref that is not in a local-call context. If the Ref is ;;; already to an XEP, then do nothing, otherwise change it to the ;;; XEP, making an XEP if necessary. ;;; ;;; If Ref is to a special :Cleanup or :Escape function, then we treat ;;; it as though it was not an XEP reference (i.e. leave it alone.) (defun reference-entry-point (ref) (declare (type ref ref)) (let ((fun (ref-leaf ref))) (unless (or (external-entry-point-p fun) (member (functional-kind fun) '(:escape :cleanup))) (change-ref-leaf ref (or (functional-entry-function fun) (make-external-entry-point fun)))))) ;;; Attempt to convert all references to Fun to local calls. The ;;; reference must be the function for a call, and the function ;;; continuation must be used only once, since otherwise we cannot be ;;; sure what function is to be called. The call continuation would be ;;; multiply used if there is hairy stuff such as conditionals in the ;;; expression that computes the function. ;;; ;;; If we cannot convert a reference, then we mark the referenced ;;; function as an entry-point, creating a new XEP if necessary. We ;;; don't try to convert calls that are in error (:ERROR kind.) ;;; ;;; This is broken off from Local-Call-Analyze so that people can ;;; force analysis of newly introduced calls. Note that we don't do ;;; LET conversion here. (defun local-call-analyze-1 (fun) (declare (type functional fun)) (let ((refs (leaf-refs fun)) (first-time t)) (dolist (ref refs) (let* ((cont (node-cont ref)) (dest (continuation-dest cont))) (cond ((and (basic-combination-p dest) (eq (basic-combination-fun dest) cont) (eq (continuation-use cont) ref)) (convert-call-if-possible ref dest) (unless (eq (basic-combination-kind dest) :local) (reference-entry-point ref))) (t (reference-entry-point ref)))) (setq first-time nil))) (values)) ;;; We examine all New-Functions in component, attempting to convert ;;; calls into local calls when it is legal. We also attempt to ;;; convert each lambda to a LET. LET conversion is also triggered by ;;; deletion of a function reference, but functions that start out ;;; eligible for conversion must be noticed sometime. ;;; ;;; Note that there is a lot of action going on behind the scenes ;;; here, triggered by reference deletion. In particular, the ;;; COMPONENT-LAMBDAS are being hacked to remove newly deleted and let ;;; converted lambdas, so it is important that the lambda is added to ;;; the COMPONENT-LAMBDAS when it is. Also, the ;;; COMPONENT-NEW-FUNCTIONS may contain all sorts of drivel, since it ;;; is not updated when we delete functions, etc. Only ;;; COMPONENT-LAMBDAS is updated. ;;; ;;; COMPONENT-REANALYZE-FUNCTIONS is treated similarly to ;;; NEW-FUNCTIONS, but we don't add lambdas to the LAMBDAS. (defun local-call-analyze (component) (declare (type component component)) (loop (let* ((new (pop (component-new-functions component))) (fun (or new (pop (component-reanalyze-functions component))))) (unless fun (return)) (let ((kind (functional-kind fun))) (cond ((member kind '(:deleted :let :mv-let :assignment))) ((and (null (leaf-refs fun)) (eq kind nil) (not (functional-entry-function fun))) (delete-functional fun)) (t (when (and new (lambda-p fun)) (push fun (component-lambdas component))) (local-call-analyze-1 fun) (when (lambda-p fun) (maybe-let-convert fun))))))) (values)) ;;; If policy is auspicious, CALL is not in an XEP, and we don't seem ;;; to be in an infinite recursive loop, then change the reference to ;;; reference a fresh copy. We return whichever function we decide to ;;; reference. (defun maybe-expand-local-inline (fun ref call) (if (and (policy call (and (>= speed space) (>= speed compilation-speed))) (not (eq (functional-kind (node-home-lambda call)) :external)) (not *converting-for-interpreter*) (inline-expansion-ok call)) (with-ir1-environment call (let* ((*lexenv* (functional-lexenv fun)) (won nil) (res (catch 'local-call-lossage (prog1 (ir1-convert-lambda (functional-inline-expansion fun)) (setq won t))))) (cond (won (change-ref-leaf ref res) res) (t (let ((*compiler-error-context* call)) (compiler-note "couldn't inline expand because expansion ~ calls this let-converted local function:~ ~% ~S" (leaf-name res))) fun)))) fun)) ;;; Dispatch to the appropriate function to attempt to convert a call. Ref ;;; most be a reference to a FUNCTIONAL. This is called in IR1 optimize as ;;; well as in local call analysis. If the call is is already :Local, we do ;;; nothing. If the call is already scheduled for deletion, also do nothing ;;; (in addition to saving time, this also avoids some problems with optimizing ;;; collections of functions that are partially deleted.) ;;; ;;; This is called both before and after FIND-INITIAL-DFO runs. When called ;;; on a :INITIAL component, we don't care whether the caller and callee are in ;;; the same component. Afterward, we must stick with whatever component ;;; division we have chosen. ;;; ;;; Before attempting to convert a call, we see whether the function is ;;; supposed to be inline expanded. Call conversion proceeds as before ;;; after any expansion. ;;; ;;; We bind *Compiler-Error-Context* to the node for the call so that ;;; warnings will get the right context. (defun convert-call-if-possible (ref call) (declare (type ref ref) (type basic-combination call)) (let* ((block (node-block call)) (component (block-component block)) (original-fun (ref-leaf ref))) (aver (functional-p original-fun)) (unless (or (member (basic-combination-kind call) '(:local :error)) (block-delete-p block) (eq (functional-kind (block-home-lambda block)) :deleted) (member (functional-kind original-fun) '(:top-level-xep :deleted)) (not (or (eq (component-kind component) :initial) (eq (block-component (node-block (lambda-bind (main-entry original-fun)))) component)))) (let ((fun (if (external-entry-point-p original-fun) (functional-entry-function original-fun) original-fun)) (*compiler-error-context* call)) (when (and (eq (functional-inlinep fun) :inline) (rest (leaf-refs original-fun))) (setq fun (maybe-expand-local-inline fun ref call))) (aver (member (functional-kind fun) '(nil :escape :cleanup :optional))) (cond ((mv-combination-p call) (convert-mv-call ref call fun)) ((lambda-p fun) (convert-lambda-call ref call fun)) (t (convert-hairy-call ref call fun)))))) (values)) ;;; Attempt to convert a multiple-value call. The only interesting ;;; case is a call to a function that Looks-Like-An-MV-Bind, has ;;; exactly one reference and no XEP, and is called with one values ;;; continuation. ;;; ;;; We change the call to be to the last optional entry point and ;;; change the call to be local. Due to our preconditions, the call ;;; should eventually be converted to a let, but we can't do that now, ;;; since there may be stray references to the e-p lambda due to ;;; optional defaulting code. ;;; ;;; We also use variable types for the called function to construct an ;;; assertion for the values continuation. ;;; ;;; See CONVERT-CALL for additional notes on MERGE-TAIL-SETS, etc. (defun convert-mv-call (ref call fun) (declare (type ref ref) (type mv-combination call) (type functional fun)) (when (and (looks-like-an-mv-bind fun) (not (functional-entry-function fun)) (= (length (leaf-refs fun)) 1) (= (length (basic-combination-args call)) 1)) (let ((ep (car (last (optional-dispatch-entry-points fun))))) (setf (basic-combination-kind call) :local) (pushnew ep (lambda-calls (node-home-lambda call))) (merge-tail-sets call ep) (change-ref-leaf ref ep) (assert-continuation-type (first (basic-combination-args call)) (make-values-type :optional (mapcar #'leaf-type (lambda-vars ep)) :rest *universal-type*)))) (values)) ;;; Attempt to convert a call to a lambda. If the number of args is ;;; wrong, we give a warning and mark the call as :ERROR to remove it ;;; from future consideration. If the argcount is O.K. then we just ;;; convert it. (defun convert-lambda-call (ref call fun) (declare (type ref ref) (type combination call) (type clambda fun)) (let ((nargs (length (lambda-vars fun))) (call-args (length (combination-args call)))) (cond ((= call-args nargs) (convert-call ref call fun)) (t ;; FIXME: ANSI requires in "3.2.5 Exceptional Situations in the ;; Compiler" that calling a function with "the wrong number of ;; arguments" be only a STYLE-ERROR. I think, though, that this ;; should only apply when the number of arguments is inferred ;; from a previous definition. If the number of arguments ;; is DECLAIMed, surely calling with the wrong number is a ;; real WARNING. As long as SBCL continues to use CMU CL's ;; non-ANSI DEFUN-is-a-DECLAIM policy, we're in violation here, ;; but as long as we continue to use that policy, that's the ;; not our biggest problem.:-| When we fix that policy, this ;; should come back into compliance. (So fix that policy!) ;; ..but.. ;; FIXME, continued: Except that section "3.2.2.3 Semantic ;; Constraints" says that if it's within the same file, it's ;; wrong. And we're in locall.lisp here, so it's probably ;; (haven't checked this..) a call to something in the same ;; file. So maybe it deserves a full warning anyway. (compiler-warning "function called with ~R argument~:P, but wants exactly ~R" call-args nargs) (setf (basic-combination-kind call) :error))))) ;;;; optional, more and keyword calls ;;; This is similar to CONVERT-LAMBDA-CALL, but deals with ;;; OPTIONAL-DISPATCHes. If only fixed args are supplied, then convert ;;; a call to the correct entry point. If &KEY args are supplied, then ;;; dispatch to a subfunction. We don't convert calls to functions ;;; that have a &MORE (or &REST) arg. (defun convert-hairy-call (ref call fun) (declare (type ref ref) (type combination call) (type optional-dispatch fun)) (let ((min-args (optional-dispatch-min-args fun)) (max-args (optional-dispatch-max-args fun)) (call-args (length (combination-args call)))) (cond ((< call-args min-args) ;; FIXME: See FIXME note at the previous ;; wrong-number-of-arguments warnings in this file. (compiler-warning "function called with ~R argument~:P, but wants at least ~R" call-args min-args) (setf (basic-combination-kind call) :error)) ((<= call-args max-args) (convert-call ref call (elt (optional-dispatch-entry-points fun) (- call-args min-args)))) ((optional-dispatch-more-entry fun) (convert-more-call ref call fun)) (t ;; FIXME: See FIXME note at the previous ;; wrong-number-of-arguments warnings in this file. (compiler-warning "function called with ~R argument~:P, but wants at most ~R" call-args max-args) (setf (basic-combination-kind call) :error)))) (values)) ;;; This function is used to convert a call to an entry point when complex ;;; transformations need to be done on the original arguments. Entry is the ;;; entry point function that we are calling. Vars is a list of variable names ;;; which are bound to the original call arguments. Ignores is the subset of ;;; Vars which are ignored. Args is the list of arguments to the entry point ;;; function. ;;; ;;; In order to avoid gruesome graph grovelling, we introduce a new function ;;; that rearranges the arguments and calls the entry point. We analyze the ;;; new function and the entry point immediately so that everything gets ;;; converted during the single pass. (defun convert-hairy-fun-entry (ref call entry vars ignores args) (declare (list vars ignores args) (type ref ref) (type combination call) (type clambda entry)) (let ((new-fun (with-ir1-environment call (ir1-convert-lambda `(lambda ,vars (declare (ignorable . ,ignores)) (%funcall ,entry . ,args)))))) (convert-call ref call new-fun) (dolist (ref (leaf-refs entry)) (convert-call-if-possible ref (continuation-dest (node-cont ref)))))) ;;; Use CONVERT-HAIRY-FUN-ENTRY to convert a &MORE-arg call to a known ;;; function into a local call to the MAIN-ENTRY. ;;; ;;; First we verify that all keywords are constant and legal. If there ;;; aren't, then we warn the user and don't attempt to convert the call. ;;; ;;; We massage the supplied &KEY arguments into the order expected ;;; by the main entry. This is done by binding all the arguments to ;;; the keyword call to variables in the introduced lambda, then ;;; passing these values variables in the correct order when calling ;;; the main entry. Unused arguments (such as the keywords themselves) ;;; are discarded simply by not passing them along. ;;; ;;; If there is a &REST arg, then we bundle up the args and pass them ;;; to LIST. (defun convert-more-call (ref call fun) (declare (type ref ref) (type combination call) (type optional-dispatch fun)) (let* ((max (optional-dispatch-max-args fun)) (arglist (optional-dispatch-arglist fun)) (args (combination-args call)) (more (nthcdr max args)) (flame (policy call (or (> speed inhibit-warnings) (> space inhibit-warnings)))) (loser nil) (temps (make-gensym-list max)) (more-temps (make-gensym-list (length more)))) (collect ((ignores) (supplied) (key-vars)) (dolist (var arglist) (let ((info (lambda-var-arg-info var))) (when info (ecase (arg-info-kind info) (:keyword (key-vars var)) ((:rest :optional)) ((:more-context :more-count) (compiler-warning "can't local-call functions with &MORE args") (setf (basic-combination-kind call) :error) (return-from convert-more-call)))))) (when (optional-dispatch-keyp fun) (when (oddp (length more)) (compiler-warning "function called with odd number of ~ arguments in keyword portion") (setf (basic-combination-kind call) :error) (return-from convert-more-call)) (do ((key more (cddr key)) (temp more-temps (cddr temp))) ((null key)) (let ((cont (first key))) (unless (constant-continuation-p cont) (when flame (compiler-note "non-constant keyword in keyword call")) (setf (basic-combination-kind call) :error) (return-from convert-more-call)) (let ((name (continuation-value cont)) (dummy (first temp)) (val (second temp))) (dolist (var (key-vars) (progn (ignores dummy val) (setq loser name))) (let ((info (lambda-var-arg-info var))) (when (eq (arg-info-key info) name) (ignores dummy) (supplied (cons var val)) (return))))))) (when (and loser (not (optional-dispatch-allowp fun))) (compiler-warning "function called with unknown argument keyword ~S" loser) (setf (basic-combination-kind call) :error) (return-from convert-more-call))) (collect ((call-args)) (do ((var arglist (cdr var)) (temp temps (cdr temp))) (()) (let ((info (lambda-var-arg-info (car var)))) (if info (ecase (arg-info-kind info) (:optional (call-args (car temp)) (when (arg-info-supplied-p info) (call-args t))) (:rest (call-args `(list ,@more-temps)) (return)) (:keyword (return))) (call-args (car temp))))) (dolist (var (key-vars)) (let ((info (lambda-var-arg-info var)) (temp (cdr (assoc var (supplied))))) (if temp (call-args temp) (call-args (arg-info-default info))) (when (arg-info-supplied-p info) (call-args (not (null temp)))))) (convert-hairy-fun-entry ref call (optional-dispatch-main-entry fun) (append temps more-temps) (ignores) (call-args))))) (values)) ;;;; LET conversion ;;;; ;;;; Converting to a LET has differing significance to various parts ;;;; of the compiler: ;;;; -- The body of a LET is spliced in immediately after the ;;;; corresponding combination node, making the control transfer ;;;; explicit and allowing LETs to be mashed together into a single ;;;; block. The value of the LET is delivered directly to the ;;;; original continuation for the call,eliminating the need to ;;;; propagate information from the dummy result continuation. ;;;; -- As far as IR1 optimization is concerned, it is interesting in ;;;; that there is only one expression that the variable can be bound ;;;; to, and this is easily substitited for. ;;;; -- LETs are interesting to environment analysis and to the back ;;;; end because in most ways a LET can be considered to be "the ;;;; same function" as its home function. ;;;; -- LET conversion has dynamic scope implications, since control ;;;; transfers within the same environment are local. In a local ;;;; control transfer, cleanup code must be emitted to remove ;;;; dynamic bindings that are no longer in effect. ;;; Set up the control transfer to the called lambda. We split the ;;; call block immediately after the call, and link the head of FUN to ;;; the call block. The successor block after splitting (where we ;;; return to) is returned. ;;; ;;; If the lambda is is a different component than the call, then we ;;; call JOIN-COMPONENTS. This only happens in block compilation ;;; before FIND-INITIAL-DFO. (defun insert-let-body (fun call) (declare (type clambda fun) (type basic-combination call)) (let* ((call-block (node-block call)) (bind-block (node-block (lambda-bind fun))) (component (block-component call-block))) (let ((fun-component (block-component bind-block))) (unless (eq fun-component component) (aver (eq (component-kind component) :initial)) (join-components component fun-component))) (let ((*current-component* component)) (node-ends-block call)) ;; FIXME: Use PROPER-LIST-OF-LENGTH-P here, and look for other ;; uses of '=.*length' which could also be converted to use ;; PROPER-LIST-OF-LENGTH-P. (aver (= (length (block-succ call-block)) 1)) (let ((next-block (first (block-succ call-block)))) (unlink-blocks call-block next-block) (link-blocks call-block bind-block) next-block))) ;;; Handle the environment semantics of LET conversion. We add the ;;; lambda and its LETs to lets for the CALL's home function. We merge ;;; the calls for FUN with the calls for the home function, removing ;;; FUN in the process. We also merge the Entries. ;;; ;;; We also unlink the function head from the component head and set ;;; COMPONENT-REANALYZE to true to indicate that the DFO should be ;;; recomputed. (defun merge-lets (fun call) (declare (type clambda fun) (type basic-combination call)) (let ((component (block-component (node-block call)))) (unlink-blocks (component-head component) (node-block (lambda-bind fun))) (setf (component-lambdas component) (delete fun (component-lambdas component))) (setf (component-reanalyze component) t)) (setf (lambda-call-lexenv fun) (node-lexenv call)) (let ((tails (lambda-tail-set fun))) (setf (tail-set-functions tails) (delete fun (tail-set-functions tails)))) (setf (lambda-tail-set fun) nil) (let* ((home (node-home-lambda call)) (home-env (lambda-environment home))) (push fun (lambda-lets home)) (setf (lambda-home fun) home) (setf (lambda-environment fun) home-env) (let ((lets (lambda-lets fun))) (dolist (let lets) (setf (lambda-home let) home) (setf (lambda-environment let) home-env)) (setf (lambda-lets home) (nconc lets (lambda-lets home))) (setf (lambda-lets fun) ())) (setf (lambda-calls home) (delete fun (nunion (lambda-calls fun) (lambda-calls home)))) (setf (lambda-calls fun) ()) (setf (lambda-entries home) (nconc (lambda-entries fun) (lambda-entries home))) (setf (lambda-entries fun) ())) (values)) ;;; Handle the value semantics of LET conversion. Delete FUN's return ;;; node, and change the control flow to transfer to NEXT-BLOCK ;;; instead. Move all the uses of the result continuation to CALL's ;;; CONT. ;;; ;;; If the actual continuation is only used by the LET call, then we ;;; intersect the type assertion on the dummy continuation with the ;;; assertion for the actual continuation; in all other cases ;;; assertions on the dummy continuation are lost. ;;; ;;; We also intersect the derived type of the CALL with the derived ;;; type of all the dummy continuation's uses. This serves mainly to ;;; propagate TRULY-THE through LETs. (defun move-return-uses (fun call next-block) (declare (type clambda fun) (type basic-combination call) (type cblock next-block)) (let* ((return (lambda-return fun)) (return-block (node-block return))) (unlink-blocks return-block (component-tail (block-component return-block))) (link-blocks return-block next-block) (unlink-node return) (delete-return return) (let ((result (return-result return)) (cont (node-cont call)) (call-type (node-derived-type call))) (when (eq (continuation-use cont) call) (assert-continuation-type cont (continuation-asserted-type result))) (unless (eq call-type *wild-type*) (do-uses (use result) (derive-node-type use call-type))) (substitute-continuation-uses cont result))) (values)) ;;; Change all CONT for all the calls to FUN to be the start ;;; continuation for the bind node. This allows the blocks to be ;;; joined if the caller count ever goes to one. (defun move-let-call-cont (fun) (declare (type clambda fun)) (let ((new-cont (node-prev (lambda-bind fun)))) (dolist (ref (leaf-refs fun)) (let ((dest (continuation-dest (node-cont ref)))) (delete-continuation-use dest) (add-continuation-use dest new-cont)))) (values)) ;;; We are converting FUN to be a LET when the call is in a non-tail ;;; position. Any previously tail calls in FUN are no longer tail ;;; calls, and must be restored to normal calls which transfer to ;;; NEXT-BLOCK (FUN's return point.) We can't do this by DO-USES on ;;; the RETURN-RESULT, because the return might have been deleted (if ;;; all calls were TR.) ;;; ;;; The called function might be an assignment in the case where we ;;; are currently converting that function. In steady-state, ;;; assignments never appear in the lambda-calls. (defun unconvert-tail-calls (fun call next-block) (dolist (called (lambda-calls fun)) (dolist (ref (leaf-refs called)) (let ((this-call (continuation-dest (node-cont ref)))) (when (and (node-tail-p this-call) (eq (node-home-lambda this-call) fun)) (setf (node-tail-p this-call) nil) (ecase (functional-kind called) ((nil :cleanup :optional) (let ((block (node-block this-call)) (cont (node-cont call))) (ensure-block-start cont) (unlink-blocks block (first (block-succ block))) (link-blocks block next-block) (delete-continuation-use this-call) (add-continuation-use this-call cont))) (:deleted) (:assignment (aver (eq called fun)))))))) (values)) ;;; Deal with returning from a LET or assignment that we are ;;; converting. FUN is the function we are calling, CALL is a call to ;;; FUN, and NEXT-BLOCK is the return point for a non-tail call, or ;;; NULL if call is a tail call. ;;; ;;; If the call is not a tail call, then we must do ;;; UNCONVERT-TAIL-CALLS, since a tail call is a call which returns ;;; its value out of the enclosing non-let function. When call is ;;; non-TR, we must convert it back to an ordinary local call, since ;;; the value must be delivered to the receiver of CALL's value. ;;; ;;; We do different things depending on whether the caller and callee ;;; have returns left: ;;; -- If the callee has no return we just do MOVE-LET-CALL-CONT. Either ;;; the function doesn't return, or all returns are via tail-recursive ;;; local calls. ;;; -- If CALL is a non-tail call, or if both have returns, then we ;;; delete the callee's return, move its uses to the call's result ;;; continuation, and transfer control to the appropriate return point. ;;; -- If the callee has a return, but the caller doesn't, then we move the ;;; return to the caller. (defun move-return-stuff (fun call next-block) (declare (type clambda fun) (type basic-combination call) (type (or cblock null) next-block)) (when next-block (unconvert-tail-calls fun call next-block)) (let* ((return (lambda-return fun)) (call-fun (node-home-lambda call)) (call-return (lambda-return call-fun))) (cond ((not return)) ((or next-block call-return) (unless (block-delete-p (node-block return)) (move-return-uses fun call (or next-block (node-block call-return))))) (t (aver (node-tail-p call)) (setf (lambda-return call-fun) return) (setf (return-lambda return) call-fun)))) (move-let-call-cont fun) (values)) ;;; Actually do LET conversion. We call subfunctions to do most of the ;;; work. We change the CALL's cont to be the continuation heading the ;;; bind block, and also do REOPTIMIZE-CONTINUATION on the args and ;;; Cont so that let-specific IR1 optimizations get a chance. We blow ;;; away any entry for the function in *FREE-FUNCTIONS* so that nobody ;;; will create new reference to it. (defun let-convert (fun call) (declare (type clambda fun) (type basic-combination call)) (let ((next-block (if (node-tail-p call) nil (insert-let-body fun call)))) (move-return-stuff fun call next-block) (merge-lets fun call))) ;;; Reoptimize all of Call's args and its result. (defun reoptimize-call (call) (declare (type basic-combination call)) (dolist (arg (basic-combination-args call)) (when arg (reoptimize-continuation arg))) (reoptimize-continuation (node-cont call)) (values)) ;;; We also don't convert calls to named functions which appear in the ;;; initial component, delaying this until optimization. This ;;; minimizes the likelyhood that we well let-convert a function which ;;; may have references added due to later local inline expansion (defun ok-initial-convert-p (fun) (not (and (leaf-name fun) (eq (component-kind (block-component (node-block (lambda-bind fun)))) :initial)))) ;;; This function is called when there is some reason to believe that ;;; the lambda Fun might be converted into a let. This is done after ;;; local call analysis, and also when a reference is deleted. We only ;;; convert to a let when the function is a normal local function, has ;;; no XEP, and is referenced in exactly one local call. Conversion is ;;; also inhibited if the only reference is in a block about to be ;;; deleted. We return true if we converted. ;;; ;;; These rules may seem unnecessarily restrictive, since there are ;;; some cases where we could do the return with a jump that don't ;;; satisfy these requirements. The reason for doing things this way ;;; is that it makes the concept of a LET much more useful at the ;;; level of IR1 semantics. The :ASSIGNMENT function kind provides ;;; another way to optimize calls to single-return/multiple call ;;; functions. ;;; ;;; We don't attempt to convert calls to functions that have an XEP, ;;; since we might be embarrassed later when we want to convert a ;;; newly discovered local call. Also, see OK-INITIAL-CONVERT-P. (defun maybe-let-convert (fun) (declare (type clambda fun)) (let ((refs (leaf-refs fun))) (when (and refs (null (rest refs)) (member (functional-kind fun) '(nil :assignment)) (not (functional-entry-function fun))) (let* ((ref-cont (node-cont (first refs))) (dest (continuation-dest ref-cont))) (when (and (basic-combination-p dest) (eq (basic-combination-fun dest) ref-cont) (eq (basic-combination-kind dest) :local) (not (block-delete-p (node-block dest))) (cond ((ok-initial-convert-p fun) t) (t (reoptimize-continuation ref-cont) nil))) (unless (eq (functional-kind fun) :assignment) (let-convert fun dest)) (reoptimize-call dest) (setf (functional-kind fun) (if (mv-combination-p dest) :mv-let :let)))) t))) ;;;; tail local calls and assignments ;;; Return T if there are no cleanups between BLOCK1 and BLOCK2, or if ;;; they definitely won't generate any cleanup code. Currently we ;;; recognize lexical entry points that are only used locally (if at ;;; all). (defun only-harmless-cleanups (block1 block2) (declare (type cblock block1 block2)) (or (eq block1 block2) (let ((cleanup2 (block-start-cleanup block2))) (do ((cleanup (block-end-cleanup block1) (node-enclosing-cleanup (cleanup-mess-up cleanup)))) ((eq cleanup cleanup2) t) (case (cleanup-kind cleanup) ((:block :tagbody) (unless (null (entry-exits (cleanup-mess-up cleanup))) (return nil))) (t (return nil))))))) ;;; If a potentially TR local call really is TR, then convert it to ;;; jump directly to the called function. We also call ;;; MAYBE-CONVERT-TO-ASSIGNMENT. The first value is true if we ;;; tail-convert. The second is the value of M-C-T-A. We can switch ;;; the succesor (potentially deleting the RETURN node) unless: ;;; -- The call has already been converted. ;;; -- The call isn't TR (some implicit MV PROG1.) ;;; -- The call is in an XEP (thus we might decide to make it non-tail ;;; so that we can use known return inside the component.) ;;; -- There is a change in the cleanup between the call in the return, ;;; so we might need to introduce cleanup code. (defun maybe-convert-tail-local-call (call) (declare (type combination call)) (let ((return (continuation-dest (node-cont call)))) (aver (return-p return)) (when (and (not (node-tail-p call)) (immediately-used-p (return-result return) call) (not (eq (functional-kind (node-home-lambda call)) :external)) (only-harmless-cleanups (node-block call) (node-block return))) (node-ends-block call) (let ((block (node-block call)) (fun (combination-lambda call))) (setf (node-tail-p call) t) (unlink-blocks block (first (block-succ block))) (link-blocks block (node-block (lambda-bind fun))) (values t (maybe-convert-to-assignment fun)))))) ;;; This is called when we believe it might make sense to convert Fun ;;; to an assignment. All this function really does is determine when ;;; a function with more than one call can still be combined with the ;;; calling function's environment. We can convert when: ;;; -- The function is a normal, non-entry function, and ;;; -- Except for one call, all calls must be tail recursive calls ;;; in the called function (i.e. are self-recursive tail calls) ;;; -- OK-INITIAL-CONVERT-P is true. ;;; ;;; There may be one outside call, and it need not be tail-recursive. ;;; Since all tail local calls have already been converted to direct ;;; transfers, the only control semantics needed are to splice in the ;;; body at the non-tail call. If there is no non-tail call, then we ;;; need only merge the environments. Both cases are handled by ;;; LET-CONVERT. ;;; ;;; ### It would actually be possible to allow any number of outside ;;; calls as long as they all return to the same place (i.e. have the ;;; same conceptual continuation.) A special case of this would be ;;; when all of the outside calls are tail recursive. (defun maybe-convert-to-assignment (fun) (declare (type clambda fun)) (when (and (not (functional-kind fun)) (not (functional-entry-function fun))) (let ((non-tail nil) (call-fun nil)) (when (and (dolist (ref (leaf-refs fun) t) (let ((dest (continuation-dest (node-cont ref)))) (when (block-delete-p (node-block dest)) (return nil)) (let ((home (node-home-lambda ref))) (unless (eq home fun) (when call-fun (return nil)) (setq call-fun home)) (unless (node-tail-p dest) (when (or non-tail (eq home fun)) (return nil)) (setq non-tail dest))))) (ok-initial-convert-p fun)) (setf (functional-kind fun) :assignment) (let-convert fun (or non-tail (continuation-dest (node-cont (first (leaf-refs fun)))))) (when non-tail (reoptimize-call non-tail)) t))))