;;;; This file implements the IR1 optimization phase of the compiler. ;;;; IR1 optimization is a grab-bag of optimizations that don't make ;;;; major changes to the block-level control flow and don't use flow ;;;; analysis. These optimizations can mostly be classified as ;;;; "meta-evaluation", but there is a sizable top-down component as ;;;; well. ;;;; 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") ;;;; interface for obtaining results of constant folding ;;; Return true for an LVAR whose sole use is a reference to a ;;; constant leaf. (defun constant-lvar-p (thing) (declare (type (or lvar null) thing)) (and (lvar-p thing) (let ((use (principal-lvar-use thing))) (and (ref-p use) (constant-p (ref-leaf use)))))) ;;; Return the constant value for an LVAR whose only use is a constant ;;; node. (declaim (ftype (function (lvar) t) lvar-value)) (defun lvar-value (lvar) (let ((use (principal-lvar-use lvar))) (constant-value (ref-leaf use)))) ;;;; interface for obtaining results of type inference ;;; Our best guess for the type of this lvar's value. Note that this ;;; may be VALUES or FUNCTION type, which cannot be passed as an ;;; argument to the normal type operations. See LVAR-TYPE. ;;; ;;; The result value is cached in the LVAR-%DERIVED-TYPE slot. If the ;;; slot is true, just return that value, otherwise recompute and ;;; stash the value there. #!-sb-fluid (declaim (inline lvar-derived-type)) (defun lvar-derived-type (lvar) (declare (type lvar lvar)) (or (lvar-%derived-type lvar) (setf (lvar-%derived-type lvar) (%lvar-derived-type lvar)))) (defun %lvar-derived-type (lvar) (declare (type lvar lvar)) (let ((uses (lvar-uses lvar))) (cond ((null uses) *empty-type*) ((listp uses) (do ((res (node-derived-type (first uses)) (values-type-union (node-derived-type (first current)) res)) (current (rest uses) (rest current))) ((or (null current) (eq res *wild-type*)) res))) (t (node-derived-type (lvar-uses lvar)))))) ;;; Return the derived type for LVAR's first value. This is guaranteed ;;; not to be a VALUES or FUNCTION type. (declaim (ftype (sfunction (lvar) ctype) lvar-type)) (defun lvar-type (lvar) (single-value-type (lvar-derived-type lvar))) ;;; If LVAR is an argument of a function, return a type which the ;;; function checks LVAR for. #!-sb-fluid (declaim (inline lvar-externally-checkable-type)) (defun lvar-externally-checkable-type (lvar) (or (lvar-%externally-checkable-type lvar) (%lvar-%externally-checkable-type lvar))) (defun %lvar-%externally-checkable-type (lvar) (declare (type lvar lvar)) (let ((dest (lvar-dest lvar))) (if (not (and dest (combination-p dest))) ;; TODO: MV-COMBINATION (setf (lvar-%externally-checkable-type lvar) *wild-type*) (let* ((fun (combination-fun dest)) (args (combination-args dest)) (fun-type (lvar-type fun))) (setf (lvar-%externally-checkable-type fun) *wild-type*) (if (or (not (call-full-like-p dest)) (not (fun-type-p fun-type)) ;; FUN-TYPE might be (AND FUNCTION (SATISFIES ...)). (fun-type-wild-args fun-type)) (dolist (arg args) (when arg (setf (lvar-%externally-checkable-type arg) *wild-type*))) (map-combination-args-and-types (lambda (arg type) (setf (lvar-%externally-checkable-type arg) (acond ((lvar-%externally-checkable-type arg) (values-type-intersection it (coerce-to-values type))) (t (coerce-to-values type))))) dest))))) (lvar-%externally-checkable-type lvar)) #!-sb-fluid(declaim (inline flush-lvar-externally-checkable-type)) (defun flush-lvar-externally-checkable-type (lvar) (declare (type lvar lvar)) (setf (lvar-%externally-checkable-type lvar) nil)) ;;;; interface routines used by optimizers (declaim (inline reoptimize-component)) (defun reoptimize-component (component kind) (declare (type component component) (type (member nil :maybe t) kind)) (aver kind) (unless (eq (component-reoptimize component) t) (setf (component-reoptimize component) kind))) ;;; This function is called by optimizers to indicate that something ;;; interesting has happened to the value of LVAR. Optimizers must ;;; make sure that they don't call for reoptimization when nothing has ;;; happened, since optimization will fail to terminate. ;;; ;;; We clear any cached type for the lvar and set the reoptimize flags ;;; on everything in sight. (defun reoptimize-lvar (lvar) (declare (type (or lvar null) lvar)) (when lvar (setf (lvar-%derived-type lvar) nil) (let ((dest (lvar-dest lvar))) (when dest (setf (lvar-reoptimize lvar) t) (setf (node-reoptimize dest) t) (binding* (;; Since this may be called during IR1 conversion, ;; PREV may be missing. (prev (node-prev dest) :exit-if-null) (block (ctran-block prev)) (component (block-component block))) (when (typep dest 'cif) (setf (block-test-modified block) t)) (setf (block-reoptimize block) t) (reoptimize-component component :maybe)))) (do-uses (node lvar) (setf (block-type-check (node-block node)) t))) (values)) (defun reoptimize-lvar-uses (lvar) (declare (type lvar lvar)) (do-uses (use lvar) (setf (node-reoptimize use) t) (setf (block-reoptimize (node-block use)) t) (reoptimize-component (node-component use) :maybe))) ;;; Annotate NODE to indicate that its result has been proven to be ;;; TYPEP to RTYPE. After IR1 conversion has happened, this is the ;;; only correct way to supply information discovered about a node's ;;; type. If you screw with the NODE-DERIVED-TYPE directly, then ;;; information may be lost and reoptimization may not happen. ;;; ;;; What we do is intersect RTYPE with NODE's DERIVED-TYPE. If the ;;; intersection is different from the old type, then we do a ;;; REOPTIMIZE-LVAR on the NODE-LVAR. (defun derive-node-type (node rtype) (declare (type valued-node node) (type ctype rtype)) (let ((node-type (node-derived-type node))) (unless (eq node-type rtype) (let ((int (values-type-intersection node-type rtype)) (lvar (node-lvar node))) (when (type/= node-type int) (when (and *check-consistency* (eq int *empty-type*) (not (eq rtype *empty-type*))) (let ((*compiler-error-context* node)) (compiler-warn "New inferred type ~S conflicts with old type:~ ~% ~S~%*** possible internal error? Please report this." (type-specifier rtype) (type-specifier node-type)))) (setf (node-derived-type node) int) ;; If the new type consists of only one object, replace the ;; node with a constant reference. (when (and (ref-p node) (lambda-var-p (ref-leaf node))) (let ((type (single-value-type int))) (when (and (member-type-p type) (null (rest (member-type-members type)))) (change-ref-leaf node (find-constant (first (member-type-members type))))))) (reoptimize-lvar lvar))))) (values)) ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an ;;; error for LVAR's value not to be TYPEP to TYPE. We implement it ;;; splitting off DEST a new CAST node; old LVAR will deliver values ;;; to CAST. If we improve the assertion, we set TYPE-CHECK and ;;; TYPE-ASSERTED to guarantee that the new assertion will be checked. (defun assert-lvar-type (lvar type policy) (declare (type lvar lvar) (type ctype type)) (unless (values-subtypep (lvar-derived-type lvar) type) (let ((internal-lvar (make-lvar)) (dest (lvar-dest lvar))) (substitute-lvar internal-lvar lvar) (let ((cast (insert-cast-before dest lvar type policy))) (use-lvar cast internal-lvar)))) (values)) ;;;; IR1-OPTIMIZE ;;; Do one forward pass over COMPONENT, deleting unreachable blocks ;;; and doing IR1 optimizations. We can ignore all blocks that don't ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when ;;; we are done, then another iteration would be beneficial. (defun ir1-optimize (component fastp) (declare (type component component)) (setf (component-reoptimize component) nil) (loop with block = (block-next (component-head component)) with tail = (component-tail component) for last-block = block until (eq block tail) do (cond ;; We delete blocks when there is either no predecessor or the ;; block is in a lambda that has been deleted. These blocks ;; would eventually be deleted by DFO recomputation, but doing ;; it here immediately makes the effect available to IR1 ;; optimization. ((or (block-delete-p block) (null (block-pred block))) (delete-block-lazily block) (setq block (clean-component component block))) ((eq (functional-kind (block-home-lambda block)) :deleted) ;; Preserve the BLOCK-SUCC invariant that almost every block has ;; one successor (and a block with DELETE-P set is an acceptable ;; exception). (mark-for-deletion block) (setq block (clean-component component block))) (t (loop (let ((succ (block-succ block))) (unless (singleton-p succ) (return))) (let ((last (block-last block))) (typecase last (cif (flush-dest (if-test last)) (when (unlink-node last) (return))) (exit (when (maybe-delete-exit last) (return))))) (unless (join-successor-if-possible block) (return))) (when (and (not fastp) (block-reoptimize block) (block-component block)) (aver (not (block-delete-p block))) (ir1-optimize-block block)) (cond ((and (block-delete-p block) (block-component block)) (setq block (clean-component component block))) ((and (block-flush-p block) (block-component block)) (flush-dead-code block))))) do (when (eq block last-block) (setq block (block-next block)))) (values)) ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE ;;; flags. ;;; ;;; Note that although they are cleared here, REOPTIMIZE flags might ;;; still be set upon return from this function, meaning that further ;;; optimization is wanted (as a consequence of optimizations we did). (defun ir1-optimize-block (block) (declare (type cblock block)) ;; We clear the node and block REOPTIMIZE flags before doing the ;; optimization, not after. This ensures that the node or block will ;; be reoptimized if necessary. (setf (block-reoptimize block) nil) (do-nodes (node nil block :restart-p t) (when (node-reoptimize node) ;; As above, we clear the node REOPTIMIZE flag before optimizing. (setf (node-reoptimize node) nil) (typecase node (ref) (combination ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if ;; any argument changes. (ir1-optimize-combination node)) (cif (ir1-optimize-if node)) (creturn ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to ;; clear the flag itself. -- WHN 2002-02-02, quoting original ;; CMU CL comments (setf (node-reoptimize node) t) (ir1-optimize-return node)) (mv-combination (ir1-optimize-mv-combination node)) (exit ;; With an EXIT, we derive the node's type from the VALUE's ;; type. (let ((value (exit-value node))) (when value (derive-node-type node (lvar-derived-type value))))) (cset (ir1-optimize-set node)) (cast (ir1-optimize-cast node))))) (values)) ;;; Try to join with a successor block. If we succeed, we return true, ;;; otherwise false. (defun join-successor-if-possible (block) (declare (type cblock block)) (let ((next (first (block-succ block)))) (when (block-start next) ; NEXT is not an END-OF-COMPONENT marker (cond ( ;; We cannot combine with a successor block if: (or ;; the successor has more than one predecessor; (rest (block-pred next)) ;; the successor is the current block (infinite loop); (eq next block) ;; the next block has a different cleanup, and thus ;; we may want to insert cleanup code between the ;; two blocks at some point; (not (eq (block-end-cleanup block) (block-start-cleanup next))) ;; the next block has a different home lambda, and ;; thus the control transfer is a non-local exit. (not (eq (block-home-lambda block) (block-home-lambda next))) ;; Stack analysis phase wants ENTRY to start a block... (entry-p (block-start-node next)) (let ((last (block-last block))) (and (valued-node-p last) (awhen (node-lvar last) (or ;; ... and a DX-allocator to end a block. (lvar-dynamic-extent it) ;; FIXME: This is a partial workaround for bug 303. (consp (lvar-uses it))))))) nil) (t (join-blocks block next) t))))) ;;; Join together two blocks. The code in BLOCK2 is moved into BLOCK1 ;;; and BLOCK2 is deleted from the DFO. We combine the optimize flags ;;; for the two blocks so that any indicated optimization gets done. (defun join-blocks (block1 block2) (declare (type cblock block1 block2)) (let* ((last1 (block-last block1)) (last2 (block-last block2)) (succ (block-succ block2)) (start2 (block-start block2))) (do ((ctran start2 (node-next (ctran-next ctran)))) ((not ctran)) (setf (ctran-block ctran) block1)) (unlink-blocks block1 block2) (dolist (block succ) (unlink-blocks block2 block) (link-blocks block1 block)) (setf (ctran-kind start2) :inside-block) (setf (node-next last1) start2) (setf (ctran-use start2) last1) (setf (block-last block1) last2)) (setf (block-flags block1) (attributes-union (block-flags block1) (block-flags block2) (block-attributes type-asserted test-modified))) (let ((next (block-next block2)) (prev (block-prev block2))) (setf (block-next prev) next) (setf (block-prev next) prev)) (values)) ;;; Delete any nodes in BLOCK whose value is unused and which have no ;;; side effects. We can delete sets of lexical variables when the set ;;; variable has no references. (defun flush-dead-code (block) (declare (type cblock block)) (setf (block-flush-p block) nil) (do-nodes-backwards (node lvar block :restart-p t) (unless lvar (typecase node (ref (delete-ref node) (unlink-node node)) (combination (let ((kind (combination-kind node)) (info (combination-fun-info node))) (when (and (eq kind :known) (fun-info-p info)) (let ((attr (fun-info-attributes info))) (when (and (not (ir1-attributep attr call)) ;; ### For now, don't delete potentially ;; flushable calls when they have the CALL ;; attribute. Someday we should look at the ;; functional args to determine if they have ;; any side effects. (if (policy node (= safety 3)) (ir1-attributep attr flushable) (ir1-attributep attr unsafely-flushable))) (flush-combination node)))))) (mv-combination (when (eq (basic-combination-kind node) :local) (let ((fun (combination-lambda node))) (when (dolist (var (lambda-vars fun) t) (when (or (leaf-refs var) (lambda-var-sets var)) (return nil))) (flush-dest (first (basic-combination-args node))) (delete-let fun))))) (exit (let ((value (exit-value node))) (when value (flush-dest value) (setf (exit-value node) nil)))) (cset (let ((var (set-var node))) (when (and (lambda-var-p var) (null (leaf-refs var))) (flush-dest (set-value node)) (setf (basic-var-sets var) (delq node (basic-var-sets var))) (unlink-node node)))) (cast (unless (cast-type-check node) (flush-dest (cast-value node)) (unlink-node node)))))) (values)) ;;;; local call return type propagation ;;; This function is called on RETURN nodes that have their REOPTIMIZE ;;; flag set. It iterates over the uses of the RESULT, looking for ;;; interesting stuff to update the TAIL-SET. If a use isn't a local ;;; call, then we union its type together with the types of other such ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this ;;; type with the RESULT's asserted type. We can make this ;;; intersection now (potentially before type checking) because this ;;; assertion on the result will eventually be checked (if ;;; appropriate.) ;;; ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV ;;; combination, which may change the successor of the call to be the ;;; called function, and if so, checks if the call can become an ;;; assignment. If we convert to an assignment, we abort, since the ;;; RETURN has been deleted. (defun find-result-type (node) (declare (type creturn node)) (let ((result (return-result node))) (collect ((use-union *empty-type* values-type-union)) (do-uses (use result) (let ((use-home (node-home-lambda use))) (cond ((or (eq (functional-kind use-home) :deleted) (block-delete-p (node-block use)))) ((and (basic-combination-p use) (eq (basic-combination-kind use) :local)) (aver (eq (lambda-tail-set use-home) (lambda-tail-set (combination-lambda use)))) (when (combination-p use) (when (nth-value 1 (maybe-convert-tail-local-call use)) (return-from find-result-type t)))) (t (use-union (node-derived-type use)))))) (let ((int ;; (values-type-intersection ;; (continuation-asserted-type result) ; FIXME -- APD, 2002-01-26 (use-union) ;; ) )) (setf (return-result-type node) int)))) nil) ;;; Do stuff to realize that something has changed about the value ;;; delivered to a return node. Since we consider the return values of ;;; all functions in the tail set to be equivalent, this amounts to ;;; bringing the entire tail set up to date. We iterate over the ;;; returns for all the functions in the tail set, reanalyzing them ;;; all (not treating NODE specially.) ;;; ;;; When we are done, we check whether the new type is different from ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize ;;; all the lvars for references to functions in the tail set. This ;;; will cause IR1-OPTIMIZE-COMBINATION to derive the new type as the ;;; results of the calls. (defun ir1-optimize-return (node) (declare (type creturn node)) (tagbody :restart (let* ((tails (lambda-tail-set (return-lambda node))) (funs (tail-set-funs tails))) (collect ((res *empty-type* values-type-union)) (dolist (fun funs) (let ((return (lambda-return fun))) (when return (when (node-reoptimize return) (setf (node-reoptimize return) nil) (when (find-result-type return) (go :restart))) (res (return-result-type return))))) (when (type/= (res) (tail-set-type tails)) (setf (tail-set-type tails) (res)) (dolist (fun (tail-set-funs tails)) (dolist (ref (leaf-refs fun)) (reoptimize-lvar (node-lvar ref)))))))) (values)) ;;;; IF optimization ;;; If the test has multiple uses, replicate the node when possible. ;;; Also check whether the predicate is known to be true or false, ;;; deleting the IF node in favor of the appropriate branch when this ;;; is the case. (defun ir1-optimize-if (node) (declare (type cif node)) (let ((test (if-test node)) (block (node-block node))) (when (and (eq (block-start-node block) node) (listp (lvar-uses test))) (do-uses (use test) (when (immediately-used-p test use) (convert-if-if use node) (when (not (listp (lvar-uses test))) (return))))) (let* ((type (lvar-type test)) (victim (cond ((constant-lvar-p test) (if (lvar-value test) (if-alternative node) (if-consequent node))) ((not (types-equal-or-intersect type (specifier-type 'null))) (if-alternative node)) ((type= type (specifier-type 'null)) (if-consequent node))))) (when victim (flush-dest test) (when (rest (block-succ block)) (unlink-blocks block victim)) (setf (component-reanalyze (node-component node)) t) (unlink-node node)))) (values)) ;;; Create a new copy of an IF node that tests the value of the node ;;; USE. The test must have >1 use, and must be immediately used by ;;; USE. NODE must be the only node in its block (implying that ;;; block-start = if-test). ;;; ;;; This optimization has an effect semantically similar to the ;;; source-to-source transformation: ;;; (IF (IF A B C) D E) ==> ;;; (IF A (IF B D E) (IF C D E)) ;;; ;;; We clobber the NODE-SOURCE-PATH of both the original and the new ;;; node so that dead code deletion notes will definitely not consider ;;; either node to be part of the original source. One node might ;;; become unreachable, resulting in a spurious note. (defun convert-if-if (use node) (declare (type node use) (type cif node)) (with-ir1-environment-from-node node (let* ((block (node-block node)) (test (if-test node)) (cblock (if-consequent node)) (ablock (if-alternative node)) (use-block (node-block use)) (new-ctran (make-ctran)) (new-lvar (make-lvar)) (new-node (make-if :test new-lvar :consequent cblock :alternative ablock)) (new-block (ctran-starts-block new-ctran))) (link-node-to-previous-ctran new-node new-ctran) (setf (lvar-dest new-lvar) new-node) (setf (block-last new-block) new-node) (unlink-blocks use-block block) (%delete-lvar-use use) (add-lvar-use use new-lvar) (link-blocks use-block new-block) (link-blocks new-block cblock) (link-blocks new-block ablock) (push "" (node-source-path node)) (push "" (node-source-path new-node)) (reoptimize-lvar test) (reoptimize-lvar new-lvar) (setf (component-reanalyze *current-component*) t))) (values)) ;;;; exit IR1 optimization ;;; This function attempts to delete an exit node, returning true if ;;; it deletes the block as a consequence: ;;; -- If the exit is degenerate (has no ENTRY), then we don't do ;;; anything, since there is nothing to be done. ;;; -- If the exit node and its ENTRY have the same home lambda then ;;; we know the exit is local, and can delete the exit. We change ;;; uses of the Exit-Value to be uses of the original lvar, ;;; then unlink the node. If the exit is to a TR context, then we ;;; must do MERGE-TAIL-SETS on any local calls which delivered ;;; their value to this exit. ;;; -- If there is no value (as in a GO), then we skip the value ;;; semantics. ;;; ;;; This function is also called by environment analysis, since it ;;; wants all exits to be optimized even if normal optimization was ;;; omitted. (defun maybe-delete-exit (node) (declare (type exit node)) (let ((value (exit-value node)) (entry (exit-entry node))) (when (and entry (eq (node-home-lambda node) (node-home-lambda entry))) (setf (entry-exits entry) (delq node (entry-exits entry))) (if value (delete-filter node (node-lvar node) value) (unlink-node node))))) ;;;; combination IR1 optimization ;;; Report as we try each transform? #!+sb-show (defvar *show-transforms-p* nil) (defun check-important-result (node info) (when (and (null (node-lvar node)) (ir1-attributep (fun-info-attributes info) important-result)) (let ((*compiler-error-context* node)) (compiler-style-warn "The return value of ~A should not be discarded." (lvar-fun-name (basic-combination-fun node)))))) ;;; Do IR1 optimizations on a COMBINATION node. (declaim (ftype (function (combination) (values)) ir1-optimize-combination)) (defun ir1-optimize-combination (node) (when (lvar-reoptimize (basic-combination-fun node)) (propagate-fun-change node) (maybe-terminate-block node nil)) (let ((args (basic-combination-args node)) (kind (basic-combination-kind node)) (info (basic-combination-fun-info node))) (ecase kind (:local (let ((fun (combination-lambda node))) (if (eq (functional-kind fun) :let) (propagate-let-args node fun) (propagate-local-call-args node fun)))) (:error (dolist (arg args) (when arg (setf (lvar-reoptimize arg) nil)))) (:full (dolist (arg args) (when arg (setf (lvar-reoptimize arg) nil))) (when info (check-important-result node info) (let ((fun (fun-info-destroyed-constant-args info))) (when fun (let ((destroyed-constant-args (funcall fun args))) (when destroyed-constant-args (let ((*compiler-error-context* node)) (warn 'constant-modified :fun-name (lvar-fun-name (basic-combination-fun node))) (setf (basic-combination-kind node) :error) (return-from ir1-optimize-combination)))))) (let ((fun (fun-info-derive-type info))) (when fun (let ((res (funcall fun node))) (when res (derive-node-type node (coerce-to-values res)) (maybe-terminate-block node nil))))))) (:known (aver info) (dolist (arg args) (when arg (setf (lvar-reoptimize arg) nil))) (check-important-result node info) (let ((fun (fun-info-destroyed-constant-args info))) (when (and fun ;; If somebody is really sure that they want to modify ;; constants, let them. (policy node (> safety 0))) (let ((destroyed-constant-args (funcall fun args))) (when destroyed-constant-args (let ((*compiler-error-context* node)) (warn 'constant-modified :fun-name (lvar-fun-name (basic-combination-fun node))) (setf (basic-combination-kind node) :error) (return-from ir1-optimize-combination)))))) (let ((attr (fun-info-attributes info))) (when (and (ir1-attributep attr foldable) ;; KLUDGE: The next test could be made more sensitive, ;; only suppressing constant-folding of functions with ;; CALL attributes when they're actually passed ;; function arguments. -- WHN 19990918 (not (ir1-attributep attr call)) (every #'constant-lvar-p args) (node-lvar node)) (constant-fold-call node) (return-from ir1-optimize-combination))) (let ((fun (fun-info-derive-type info))) (when fun (let ((res (funcall fun node))) (when res (derive-node-type node (coerce-to-values res)) (maybe-terminate-block node nil))))) (let ((fun (fun-info-optimizer info))) (unless (and fun (funcall fun node)) ;; First give the VM a peek at the call (multiple-value-bind (style transform) (combination-implementation-style node) (ecase style (:direct ;; The VM knows how to handle this. ) (:transform ;; The VM mostly knows how to handle this. We need ;; to massage the call slightly, though. (transform-call node transform (combination-fun-source-name node))) (:default ;; Let transforms have a crack at it. (dolist (x (fun-info-transforms info)) #!+sb-show (when *show-transforms-p* (let* ((lvar (basic-combination-fun node)) (fname (lvar-fun-name lvar t))) (/show "trying transform" x (transform-function x) "for" fname))) (unless (ir1-transform node x) #!+sb-show (when *show-transforms-p* (/show "quitting because IR1-TRANSFORM result was NIL")) (return))))))))))) (values)) ;;; If NODE doesn't return (i.e. return type is NIL), then terminate ;;; the block there, and link it to the component tail. ;;; ;;; Except when called during IR1 convertion, we delete the ;;; continuation if it has no other uses. (If it does have other uses, ;;; we reoptimize.) ;;; ;;; Termination on the basis of a continuation type is ;;; inhibited when: ;;; -- The continuation is deleted (hence the assertion is spurious), or ;;; -- We are in IR1 conversion (where THE assertions are subject to ;;; weakening.) FIXME: Now THE assertions are not weakened, but new ;;; uses can(?) be added later. -- APD, 2003-07-17 ;;; ;;; Why do we need to consider LVAR type? -- APD, 2003-07-30 (defun maybe-terminate-block (node ir1-converting-not-optimizing-p) (declare (type (or basic-combination cast ref) node)) (let* ((block (node-block node)) (lvar (node-lvar node)) (ctran (node-next node)) (tail (component-tail (block-component block))) (succ (first (block-succ block)))) (declare (ignore lvar)) (unless (or (and (eq node (block-last block)) (eq succ tail)) (block-delete-p block)) (when (eq (node-derived-type node) *empty-type*) (cond (ir1-converting-not-optimizing-p (cond ((block-last block) (aver (eq (block-last block) node))) (t (setf (block-last block) node) (setf (ctran-use ctran) nil) (setf (ctran-kind ctran) :unused) (setf (ctran-block ctran) nil) (setf (node-next node) nil) (link-blocks block (ctran-starts-block ctran))))) (t (node-ends-block node))) (let ((succ (first (block-succ block)))) (unlink-blocks block succ) (setf (component-reanalyze (block-component block)) t) (aver (not (block-succ block))) (link-blocks block tail) (cond (ir1-converting-not-optimizing-p (%delete-lvar-use node)) (t (delete-lvar-use node) (when (null (block-pred succ)) (mark-for-deletion succ))))) t)))) ;;; This is called both by IR1 conversion and IR1 optimization when ;;; they have verified the type signature for the call, and are ;;; wondering if something should be done to special-case the call. If ;;; CALL is a call to a global function, then see whether it defined ;;; or known: ;;; -- If a DEFINED-FUN should be inline expanded, then convert ;;; the expansion and change the call to call it. Expansion is ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is ;;; true, we never expand, since this function has already been ;;; converted. Local call analysis will duplicate the definition ;;; if necessary. We claim that the parent form is LABELS for ;;; context declarations, since we don't want it to be considered ;;; a real global function. ;;; -- If it is a known function, mark it as such by setting the KIND. ;;; ;;; We return the leaf referenced (NIL if not a leaf) and the ;;; FUN-INFO assigned. (defun recognize-known-call (call ir1-converting-not-optimizing-p) (declare (type combination call)) (let* ((ref (lvar-uses (basic-combination-fun call))) (leaf (when (ref-p ref) (ref-leaf ref))) (inlinep (if (defined-fun-p leaf) (defined-fun-inlinep leaf) :no-chance))) (cond ((eq inlinep :notinline) (let ((info (info :function :info (leaf-source-name leaf)))) (when info (setf (basic-combination-fun-info call) info)) (values nil nil))) ((not (and (global-var-p leaf) (eq (global-var-kind leaf) :global-function))) (values leaf nil)) ((and (ecase inlinep (:inline t) (:no-chance nil) ((nil :maybe-inline) (policy call (zerop space)))) (defined-fun-p leaf) (defined-fun-inline-expansion leaf) (let ((fun (defined-fun-functional leaf))) (or (not fun) (and (eq inlinep :inline) (functional-kind fun)))) (inline-expansion-ok call)) (flet (;; FIXME: Is this what the old CMU CL internal documentation ;; called semi-inlining? A more descriptive name would ;; be nice. -- WHN 2002-01-07 (frob () (let* ((name (leaf-source-name leaf)) (res (ir1-convert-inline-expansion name (defined-fun-inline-expansion leaf) leaf inlinep (info :function :info name)))) ;; allow backward references to this function from ;; following top level forms (setf (defined-fun-functional leaf) res) (change-ref-leaf ref res)))) (if ir1-converting-not-optimizing-p (frob) (with-ir1-environment-from-node call (frob) (locall-analyze-component *current-component*)))) (values (ref-leaf (lvar-uses (basic-combination-fun call))) nil)) (t (let ((info (info :function :info (leaf-source-name leaf)))) (if info (values leaf (progn (setf (basic-combination-kind call) :known) (setf (basic-combination-fun-info call) info))) (values leaf nil))))))) ;;; Check whether CALL satisfies TYPE. If so, apply the type to the ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and ;;; return NIL, NIL. If the type is just FUNCTION, then skip the ;;; syntax check, arg/result type processing, but still call ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda, ;;; and that checking is done by local call analysis. (defun validate-call-type (call type ir1-converting-not-optimizing-p) (declare (type combination call) (type ctype type)) (cond ((not (fun-type-p type)) (aver (multiple-value-bind (val win) (csubtypep type (specifier-type 'function)) (or val (not win)))) (recognize-known-call call ir1-converting-not-optimizing-p)) ((valid-fun-use call type :argument-test #'always-subtypep :result-test nil ;; KLUDGE: Common Lisp is such a dynamic ;; language that all we can do here in ;; general is issue a STYLE-WARNING. It ;; would be nice to issue a full WARNING ;; in the special case of of type ;; mismatches within a compilation unit ;; (as in section 3.2.2.3 of the spec) ;; but at least as of sbcl-0.6.11, we ;; don't keep track of whether the ;; mismatched data came from the same ;; compilation unit, so we can't do that. ;; -- WHN 2001-02-11 ;; ;; FIXME: Actually, I think we could ;; issue a full WARNING if the call ;; violates a DECLAIM FTYPE. :lossage-fun #'compiler-style-warn :unwinnage-fun #'compiler-notify) (assert-call-type call type) (maybe-terminate-block call ir1-converting-not-optimizing-p) (recognize-known-call call ir1-converting-not-optimizing-p)) (t (setf (combination-kind call) :error) (values nil nil)))) ;;; This is called by IR1-OPTIMIZE when the function for a call has ;;; changed. If the call is local, we try to LET-convert it, and ;;; derive the result type. If it is a :FULL call, we validate it ;;; against the type, which recognizes known calls, does inline ;;; expansion, etc. If a call to a predicate in a non-conditional ;;; position or to a function with a source transform, then we ;;; reconvert the form to give IR1 another chance. (defun propagate-fun-change (call) (declare (type combination call)) (let ((*compiler-error-context* call) (fun-lvar (basic-combination-fun call))) (setf (lvar-reoptimize fun-lvar) nil) (case (combination-kind call) (:local (let ((fun (combination-lambda call))) (maybe-let-convert fun) (unless (member (functional-kind fun) '(:let :assignment :deleted)) (derive-node-type call (tail-set-type (lambda-tail-set fun)))))) (:full (multiple-value-bind (leaf info) (validate-call-type call (lvar-type fun-lvar) nil) (cond ((functional-p leaf) (convert-call-if-possible (lvar-uses (basic-combination-fun call)) call)) ((not leaf)) ((and (global-var-p leaf) (eq (global-var-kind leaf) :global-function) (leaf-has-source-name-p leaf) (or (info :function :source-transform (leaf-source-name leaf)) (and info (ir1-attributep (fun-info-attributes info) predicate) (let ((lvar (node-lvar call))) (and lvar (not (if-p (lvar-dest lvar)))))))) (let ((name (leaf-source-name leaf)) (dummies (make-gensym-list (length (combination-args call))))) (transform-call call `(lambda ,dummies (,@(if (symbolp name) `(,name) `(funcall #',name)) ,@dummies)) (leaf-source-name leaf))))))))) (values)) ;;;; known function optimization ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE, ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM, ;;; replace it, otherwise add a new one. (defun record-optimization-failure (node transform args) (declare (type combination node) (type transform transform) (type (or fun-type list) args)) (let* ((table (component-failed-optimizations *component-being-compiled*)) (found (assoc transform (gethash node table)))) (if found (setf (cdr found) args) (push (cons transform args) (gethash node table)))) (values)) ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from ;;; doing the transform for some reason and FLAME is true, then we ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1 ;;; finalize to pick up. We return true if the transform failed, and ;;; thus further transformation should be attempted. We return false ;;; if either the transform succeeded or was aborted. (defun ir1-transform (node transform) (declare (type combination node) (type transform transform)) (let* ((type (transform-type transform)) (fun (transform-function transform)) (constrained (fun-type-p type)) (table (component-failed-optimizations *component-being-compiled*)) (flame (if (transform-important transform) (policy node (>= speed inhibit-warnings)) (policy node (> speed inhibit-warnings)))) (*compiler-error-context* node)) (cond ((or (not constrained) (valid-fun-use node type)) (multiple-value-bind (severity args) (catch 'give-up-ir1-transform (transform-call node (funcall fun node) (combination-fun-source-name node)) (values :none nil)) (ecase severity (:none (remhash node table) nil) (:aborted (setf (combination-kind node) :error) (when args (apply #'warn args)) (remhash node table) nil) (:failure (if args (when flame (record-optimization-failure node transform args)) (setf (gethash node table) (remove transform (gethash node table) :key #'car))) t) (:delayed (remhash node table) nil)))) ((and flame (valid-fun-use node type :argument-test #'types-equal-or-intersect :result-test #'values-types-equal-or-intersect)) (record-optimization-failure node transform type) t) (t t)))) ;;; When we don't like an IR1 transform, we throw the severity/reason ;;; and args. ;;; ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform, ;;; aborting this attempt to transform the call, but admitting the ;;; possibility that this or some other transform will later succeed. ;;; If arguments are supplied, they are format arguments for an ;;; efficiency note. ;;; ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and ;;; force a normal call to the function at run time. No further ;;; optimizations will be attempted. ;;; ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and ;;; delay the transform on the node until later. REASONS specifies ;;; when the transform will be later retried. The :OPTIMIZE reason ;;; causes the transform to be delayed until after the current IR1 ;;; optimization pass. The :CONSTRAINT reason causes the transform to ;;; be delayed until after constraint propagation. ;;; ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP, ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to ;;; do CASE operations on the various REASON values, it might be a ;;; good idea to go OO, representing the reasons by objects, using ;;; CLOS methods on the objects instead of CASE, and (possibly) using ;;; SIGNAL instead of THROW. (declaim (ftype (function (&rest t) nil) give-up-ir1-transform)) (defun give-up-ir1-transform (&rest args) (throw 'give-up-ir1-transform (values :failure args))) (defun abort-ir1-transform (&rest args) (throw 'give-up-ir1-transform (values :aborted args))) (defun delay-ir1-transform (node &rest reasons) (let ((assoc (assoc node *delayed-ir1-transforms*))) (cond ((not assoc) (setf *delayed-ir1-transforms* (acons node reasons *delayed-ir1-transforms*)) (throw 'give-up-ir1-transform :delayed)) ((cdr assoc) (dolist (reason reasons) (pushnew reason (cdr assoc))) (throw 'give-up-ir1-transform :delayed))))) ;;; Clear any delayed transform with no reasons - these should have ;;; been tried in the last pass. Then remove the reason from the ;;; delayed transform reasons, and if any become empty then set ;;; reoptimize flags for the node. Return true if any transforms are ;;; to be retried. (defun retry-delayed-ir1-transforms (reason) (setf *delayed-ir1-transforms* (remove-if-not #'cdr *delayed-ir1-transforms*)) (let ((reoptimize nil)) (dolist (assoc *delayed-ir1-transforms*) (let ((reasons (remove reason (cdr assoc)))) (setf (cdr assoc) reasons) (unless reasons (let ((node (car assoc))) (unless (node-deleted node) (setf reoptimize t) (setf (node-reoptimize node) t) (let ((block (node-block node))) (setf (block-reoptimize block) t) (reoptimize-component (block-component block) :maybe))))))) reoptimize)) ;;; Take the lambda-expression RES, IR1 convert it in the proper ;;; environment, and then install it as the function for the call ;;; NODE. We do local call analysis so that the new function is ;;; integrated into the control flow. ;;; ;;; We require the original function source name in order to generate ;;; a meaningful debug name for the lambda we set up. (It'd be ;;; possible to do this starting from debug names as well as source ;;; names, but as of sbcl-0.7.1.5, there was no need for this ;;; generality, since source names are always known to our callers.) (defun transform-call (call res source-name) (declare (type combination call) (list res)) (aver (and (legal-fun-name-p source-name) (not (eql source-name '.anonymous.)))) (node-ends-block call) ;; The internal variables of a transform are not going to be ;; interesting to the debugger, so there's no sense in ;; suppressing the substitution of variables with only one use ;; (the extra variables can slow down constraint propagation). ;; ;; This needs to be done before the WITH-IR1-ENVIRONMENT-FROM-NODE, ;; so that it will bind *LEXENV* to the right environment. (setf (combination-lexenv call) (make-lexenv :default (combination-lexenv call) :policy (process-optimize-decl '(optimize (preserve-single-use-debug-variables 0)) (lexenv-policy (combination-lexenv call))))) (with-ir1-environment-from-node call (with-component-last-block (*current-component* (block-next (node-block call))) (let ((new-fun (ir1-convert-inline-lambda res :debug-name (debug-name 'lambda-inlined source-name) :system-lambda t)) (ref (lvar-use (combination-fun call)))) (change-ref-leaf ref new-fun) (setf (combination-kind call) :full) (locall-analyze-component *current-component*)))) (values)) ;;; Replace a call to a foldable function of constant arguments with ;;; the result of evaluating the form. If there is an error during the ;;; evaluation, we give a warning and leave the call alone, making the ;;; call a :ERROR call. ;;; ;;; If there is more than one value, then we transform the call into a ;;; VALUES form. (defun constant-fold-call (call) (let ((args (mapcar #'lvar-value (combination-args call))) (fun-name (combination-fun-source-name call))) (multiple-value-bind (values win) (careful-call fun-name args call ;; Note: CMU CL had COMPILER-WARN here, and that ;; seems more natural, but it's probably not. ;; ;; It's especially not while bug 173 exists: ;; Expressions like ;; (COND (END ;; (UNLESS (OR UNSAFE? (<= END SIZE))) ;; ...)) ;; can cause constant-folding TYPE-ERRORs (in ;; #'<=) when END can be proved to be NIL, even ;; though the code is perfectly legal and safe ;; because a NIL value of END means that the ;; #'<= will never be executed. ;; ;; Moreover, even without bug 173, ;; quite-possibly-valid code like ;; (COND ((NONINLINED-PREDICATE END) ;; (UNLESS (<= END SIZE)) ;; ...)) ;; (where NONINLINED-PREDICATE is something the ;; compiler can't do at compile time, but which ;; turns out to make the #'<= expression ;; unreachable when END=NIL) could cause errors ;; when the compiler tries to constant-fold (<= ;; END SIZE). ;; ;; So, with or without bug 173, it'd be ;; unnecessarily evil to do a full ;; COMPILER-WARNING (and thus return FAILURE-P=T ;; from COMPILE-FILE) for legal code, so we we ;; use a wimpier COMPILE-STYLE-WARNING instead. #-sb-xc-host #'compiler-style-warn ;; On the other hand, for code we control, we ;; should be able to work around any bug ;; 173-related problems, and in particular we ;; want to be alerted to calls to our own ;; functions which aren't being folded away; a ;; COMPILER-WARNING is butch enough to stop the ;; SBCL build itself in its tracks. #+sb-xc-host #'compiler-warn "constant folding") (cond ((not win) (setf (combination-kind call) :error)) ((and (proper-list-of-length-p values 1)) (with-ir1-environment-from-node call (let* ((lvar (node-lvar call)) (prev (node-prev call)) (intermediate-ctran (make-ctran))) (%delete-lvar-use call) (setf (ctran-next prev) nil) (setf (node-prev call) nil) (reference-constant prev intermediate-ctran lvar (first values)) (link-node-to-previous-ctran call intermediate-ctran) (reoptimize-lvar lvar) (flush-combination call)))) (t (let ((dummies (make-gensym-list (length args)))) (transform-call call `(lambda ,dummies (declare (ignore ,@dummies)) (values ,@(mapcar (lambda (x) `',x) values))) fun-name)))))) (values)) ;;;; local call optimization ;;; Propagate TYPE to LEAF and its REFS, marking things changed. If ;;; the leaf type is a function type, then just leave it alone, since ;;; TYPE is never going to be more specific than that (and ;;; TYPE-INTERSECTION would choke.) (defun propagate-to-refs (leaf type) (declare (type leaf leaf) (type ctype type)) (let ((var-type (leaf-type leaf))) (unless (fun-type-p var-type) (let ((int (type-approx-intersection2 var-type type))) (when (type/= int var-type) (setf (leaf-type leaf) int) (dolist (ref (leaf-refs leaf)) (derive-node-type ref (make-single-value-type int)) ;; KLUDGE: LET var substitution (let* ((lvar (node-lvar ref))) (when (and lvar (combination-p (lvar-dest lvar))) (reoptimize-lvar lvar)))))) (values)))) ;;; Iteration variable: exactly one SETQ of the form: ;;; ;;; (let ((var initial)) ;;; ... ;;; (setq var (+ var step)) ;;; ...) (defun maybe-infer-iteration-var-type (var initial-type) (binding* ((sets (lambda-var-sets var) :exit-if-null) (set (first sets)) (() (null (rest sets)) :exit-if-null) (set-use (principal-lvar-use (set-value set))) (() (and (combination-p set-use) (eq (combination-kind set-use) :known) (fun-info-p (combination-fun-info set-use)) (not (node-to-be-deleted-p set-use)) (or (eq (combination-fun-source-name set-use) '+) (eq (combination-fun-source-name set-use) '-))) :exit-if-null) (minusp (eq (combination-fun-source-name set-use) '-)) (+-args (basic-combination-args set-use)) (() (and (proper-list-of-length-p +-args 2 2) (let ((first (principal-lvar-use (first +-args)))) (and (ref-p first) (eq (ref-leaf first) var)))) :exit-if-null) (step-type (lvar-type (second +-args))) (set-type (lvar-type (set-value set)))) (when (and (numeric-type-p initial-type) (numeric-type-p step-type) (or (numeric-type-equal initial-type step-type) ;; Detect cases like (LOOP FOR 1.0 to 5.0 ...), where ;; the initial and the step are of different types, ;; and the step is less contagious. (numeric-type-equal initial-type (numeric-contagion initial-type step-type)))) (labels ((leftmost (x y cmp cmp=) (cond ((eq x nil) nil) ((eq y nil) nil) ((listp x) (let ((x1 (first x))) (cond ((listp y) (let ((y1 (first y))) (if (funcall cmp x1 y1) x y))) (t (if (funcall cmp x1 y) x y))))) ((listp y) (let ((y1 (first y))) (if (funcall cmp= x y1) x y))) (t (if (funcall cmp x y) x y)))) (max* (x y) (leftmost x y #'> #'>=)) (min* (x y) (leftmost x y #'< #'<=))) (multiple-value-bind (low high) (let ((step-type-non-negative (csubtypep step-type (specifier-type '(real 0 *)))) (step-type-non-positive (csubtypep step-type (specifier-type '(real * 0))))) (cond ((or (and step-type-non-negative (not minusp)) (and step-type-non-positive minusp)) (values (numeric-type-low initial-type) (when (and (numeric-type-p set-type) (numeric-type-equal set-type initial-type)) (max* (numeric-type-high initial-type) (numeric-type-high set-type))))) ((or (and step-type-non-positive (not minusp)) (and step-type-non-negative minusp)) (values (when (and (numeric-type-p set-type) (numeric-type-equal set-type initial-type)) (min* (numeric-type-low initial-type) (numeric-type-low set-type))) (numeric-type-high initial-type))) (t (values nil nil)))) (modified-numeric-type initial-type :low low :high high :enumerable nil)))))) (deftransform + ((x y) * * :result result) "check for iteration variable reoptimization" (let ((dest (principal-lvar-end result)) (use (principal-lvar-use x))) (when (and (ref-p use) (set-p dest) (eq (ref-leaf use) (set-var dest))) (reoptimize-lvar (set-value dest)))) (give-up-ir1-transform)) ;;; Figure out the type of a LET variable that has sets. We compute ;;; the union of the INITIAL-TYPE and the types of all the set ;;; values and to a PROPAGATE-TO-REFS with this type. (defun propagate-from-sets (var initial-type) (collect ((res initial-type type-union)) (dolist (set (basic-var-sets var)) (let ((type (lvar-type (set-value set)))) (res type) (when (node-reoptimize set) (derive-node-type set (make-single-value-type type)) (setf (node-reoptimize set) nil)))) (let ((res (res))) (awhen (maybe-infer-iteration-var-type var initial-type) (setq res it)) (propagate-to-refs var res))) (values)) ;;; If a LET variable, find the initial value's type and do ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's ;;; type. (defun ir1-optimize-set (node) (declare (type cset node)) (let ((var (set-var node))) (when (and (lambda-var-p var) (leaf-refs var)) (let ((home (lambda-var-home var))) (when (eq (functional-kind home) :let) (let* ((initial-value (let-var-initial-value var)) (initial-type (lvar-type initial-value))) (setf (lvar-reoptimize initial-value) nil) (propagate-from-sets var initial-type)))))) (derive-node-type node (make-single-value-type (lvar-type (set-value node)))) (values)) ;;; Return true if the value of REF will always be the same (and is ;;; thus legal to substitute.) (defun constant-reference-p (ref) (declare (type ref ref)) (let ((leaf (ref-leaf ref))) (typecase leaf ((or constant functional) t) (lambda-var (null (lambda-var-sets leaf))) (defined-fun (not (eq (defined-fun-inlinep leaf) :notinline))) (global-var (case (global-var-kind leaf) (:global-function (let ((name (leaf-source-name leaf))) (or #-sb-xc-host (eq (symbol-package (fun-name-block-name name)) *cl-package*) (info :function :info name))))))))) ;;; If we have a non-set LET var with a single use, then (if possible) ;;; replace the variable reference's LVAR with the arg lvar. ;;; ;;; We change the REF to be a reference to NIL with unused value, and ;;; let it be flushed as dead code. A side effect of this substitution ;;; is to delete the variable. (defun substitute-single-use-lvar (arg var) (declare (type lvar arg) (type lambda-var var)) (binding* ((ref (first (leaf-refs var))) (lvar (node-lvar ref) :exit-if-null) (dest (lvar-dest lvar))) (when (and ;; Think about (LET ((A ...)) (IF ... A ...)): two ;; LVAR-USEs should not be met on one path. Another problem ;; is with dynamic-extent. (eq (lvar-uses lvar) ref) (not (block-delete-p (node-block ref))) (typecase dest ;; we should not change lifetime of unknown values lvars (cast (and (type-single-value-p (lvar-derived-type arg)) (multiple-value-bind (pdest pprev) (principal-lvar-end lvar) (declare (ignore pdest)) (lvar-single-value-p pprev)))) (mv-combination (or (eq (basic-combination-fun dest) lvar) (and (eq (basic-combination-kind dest) :local) (type-single-value-p (lvar-derived-type arg))))) ((or creturn exit) ;; While CRETURN and EXIT nodes may be known-values, ;; they have their own complications, such as ;; substitution into CRETURN may create new tail calls. nil) (t (aver (lvar-single-value-p lvar)) t)) (eq (node-home-lambda ref) (lambda-home (lambda-var-home var)))) (let ((ref-type (single-value-type (node-derived-type ref)))) (cond ((csubtypep (single-value-type (lvar-type arg)) ref-type) (substitute-lvar-uses lvar arg ;; Really it is (EQ (LVAR-USES LVAR) REF): t) (delete-lvar-use ref)) (t (let* ((value (make-lvar)) (cast (insert-cast-before ref value ref-type ;; KLUDGE: it should be (TYPE-CHECK 0) *policy*))) (setf (cast-type-to-check cast) *wild-type*) (substitute-lvar-uses value arg ;; FIXME t) (%delete-lvar-use ref) (add-lvar-use cast lvar))))) (setf (node-derived-type ref) *wild-type*) (change-ref-leaf ref (find-constant nil)) (delete-ref ref) (unlink-node ref) (reoptimize-lvar lvar) t))) ;;; Delete a LET, removing the call and bind nodes, and warning about ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come ;;; along right away and delete the REF and then the lambda, since we ;;; flush the FUN lvar. (defun delete-let (clambda) (declare (type clambda clambda)) (aver (functional-letlike-p clambda)) (note-unreferenced-vars clambda) (let ((call (let-combination clambda))) (flush-dest (basic-combination-fun call)) (unlink-node call) (unlink-node (lambda-bind clambda)) (setf (lambda-bind clambda) nil)) (setf (functional-kind clambda) :zombie) (let ((home (lambda-home clambda))) (setf (lambda-lets home) (delete clambda (lambda-lets home)))) (values)) ;;; This function is called when one of the arguments to a LET ;;; changes. We look at each changed argument. If the corresponding ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we ;;; consider substituting for the variable, and also propagate ;;; derived-type information for the arg to all the VAR's refs. ;;; ;;; Substitution is inhibited when the arg leaf's derived type isn't a ;;; subtype of the argument's leaf type. This prevents type checking ;;; from being defeated, and also ensures that the best representation ;;; for the variable can be used. ;;; ;;; Substitution of individual references is inhibited if the ;;; reference is in a different component from the home. This can only ;;; happen with closures over top level lambda vars. In such cases, ;;; the references may have already been compiled, and thus can't be ;;; retroactively modified. ;;; ;;; If all of the variables are deleted (have no references) when we ;;; are done, then we delete the LET. ;;; ;;; Note that we are responsible for clearing the LVAR-REOPTIMIZE ;;; flags. (defun propagate-let-args (call fun) (declare (type combination call) (type clambda fun)) (loop for arg in (combination-args call) and var in (lambda-vars fun) do (when (and arg (lvar-reoptimize arg)) (setf (lvar-reoptimize arg) nil) (cond ((lambda-var-sets var) (propagate-from-sets var (lvar-type arg))) ((let ((use (lvar-uses arg))) (when (ref-p use) (let ((leaf (ref-leaf use))) (when (and (constant-reference-p use) (csubtypep (leaf-type leaf) ;; (NODE-DERIVED-TYPE USE) would ;; be better -- APD, 2003-05-15 (leaf-type var))) (propagate-to-refs var (lvar-type arg)) (let ((use-component (node-component use))) (prog1 (substitute-leaf-if (lambda (ref) (cond ((eq (node-component ref) use-component) t) (t (aver (lambda-toplevelish-p (lambda-home fun))) nil))) leaf var))) t))))) ((and (null (rest (leaf-refs var))) ;; Don't substitute single-ref variables on high-debug / ;; low speed, to improve the debugging experience. (policy call (< preserve-single-use-debug-variables 3)) (substitute-single-use-lvar arg var))) (t (propagate-to-refs var (lvar-type arg)))))) (when (every #'not (combination-args call)) (delete-let fun)) (values)) ;;; This function is called when one of the args to a non-LET local ;;; call changes. For each changed argument corresponding to an unset ;;; variable, we compute the union of the types across all calls and ;;; propagate this type information to the var's refs. ;;; ;;; If the function has an XEP, then we don't do anything, since we ;;; won't discover anything. ;;; ;;; We can clear the LVAR-REOPTIMIZE flags for arguments in all calls ;;; corresponding to changed arguments in CALL, since the only use in ;;; IR1 optimization of the REOPTIMIZE flag for local call args is ;;; right here. (defun propagate-local-call-args (call fun) (declare (type combination call) (type clambda fun)) (unless (or (functional-entry-fun fun) (lambda-optional-dispatch fun)) (let* ((vars (lambda-vars fun)) (union (mapcar (lambda (arg var) (when (and arg (lvar-reoptimize arg) (null (basic-var-sets var))) (lvar-type arg))) (basic-combination-args call) vars)) (this-ref (lvar-use (basic-combination-fun call)))) (dolist (arg (basic-combination-args call)) (when arg (setf (lvar-reoptimize arg) nil))) (dolist (ref (leaf-refs fun)) (let ((dest (node-dest ref))) (unless (or (eq ref this-ref) (not dest)) (setq union (mapcar (lambda (this-arg old) (when old (setf (lvar-reoptimize this-arg) nil) (type-union (lvar-type this-arg) old))) (basic-combination-args dest) union))))) (loop for var in vars and type in union when type do (propagate-to-refs var type)))) (values)) ;;;; multiple values optimization ;;; Do stuff to notice a change to a MV combination node. There are ;;; two main branches here: ;;; -- If the call is local, then it is already a MV let, or should ;;; become one. Note that although all :LOCAL MV calls must eventually ;;; be converted to :MV-LETs, there can be a window when the call ;;; is local, but has not been LET converted yet. This is because ;;; the entry-point lambdas may have stray references (in other ;;; entry points) that have not been deleted yet. ;;; -- The call is full. This case is somewhat similar to the non-MV ;;; combination optimization: we propagate return type information and ;;; notice non-returning calls. We also have an optimization ;;; which tries to convert MV-CALLs into MV-binds. (defun ir1-optimize-mv-combination (node) (ecase (basic-combination-kind node) (:local (let ((fun-lvar (basic-combination-fun node))) (when (lvar-reoptimize fun-lvar) (setf (lvar-reoptimize fun-lvar) nil) (maybe-let-convert (combination-lambda node)))) (setf (lvar-reoptimize (first (basic-combination-args node))) nil) (when (eq (functional-kind (combination-lambda node)) :mv-let) (unless (convert-mv-bind-to-let node) (ir1-optimize-mv-bind node)))) (:full (let* ((fun (basic-combination-fun node)) (fun-changed (lvar-reoptimize fun)) (args (basic-combination-args node))) (when fun-changed (setf (lvar-reoptimize fun) nil) (let ((type (lvar-type fun))) (when (fun-type-p type) (derive-node-type node (fun-type-returns type)))) (maybe-terminate-block node nil) (let ((use (lvar-uses fun))) (when (and (ref-p use) (functional-p (ref-leaf use))) (convert-call-if-possible use node) (when (eq (basic-combination-kind node) :local) (maybe-let-convert (ref-leaf use)))))) (unless (or (eq (basic-combination-kind node) :local) (eq (lvar-fun-name fun) '%throw)) (ir1-optimize-mv-call node)) (dolist (arg args) (setf (lvar-reoptimize arg) nil)))) (:error)) (values)) ;;; Propagate derived type info from the values lvar to the vars. (defun ir1-optimize-mv-bind (node) (declare (type mv-combination node)) (let* ((arg (first (basic-combination-args node))) (vars (lambda-vars (combination-lambda node))) (n-vars (length vars)) (types (values-type-in (lvar-derived-type arg) n-vars))) (loop for var in vars and type in types do (if (basic-var-sets var) (propagate-from-sets var type) (propagate-to-refs var type))) (setf (lvar-reoptimize arg) nil)) (values)) ;;; If possible, convert a general MV call to an MV-BIND. We can do ;;; this if: ;;; -- The call has only one argument, and ;;; -- The function has a known fixed number of arguments, or ;;; -- The argument yields a known fixed number of values. ;;; ;;; What we do is change the function in the MV-CALL to be a lambda ;;; that "looks like an MV bind", which allows ;;; IR1-OPTIMIZE-MV-COMBINATION to notice that this call can be ;;; converted (the next time around.) This new lambda just calls the ;;; actual function with the MV-BIND variables as arguments. Note that ;;; this new MV bind is not let-converted immediately, as there are ;;; going to be stray references from the entry-point functions until ;;; they get deleted. ;;; ;;; In order to avoid loss of argument count checking, we only do the ;;; transformation according to a known number of expected argument if ;;; safety is unimportant. We can always convert if we know the number ;;; of actual values, since the normal call that we build will still ;;; do any appropriate argument count checking. ;;; ;;; We only attempt the transformation if the called function is a ;;; constant reference. This allows us to just splice the leaf into ;;; the new function, instead of trying to somehow bind the function ;;; expression. The leaf must be constant because we are evaluating it ;;; again in a different place. This also has the effect of squelching ;;; multiple warnings when there is an argument count error. (defun ir1-optimize-mv-call (node) (let ((fun (basic-combination-fun node)) (*compiler-error-context* node) (ref (lvar-uses (basic-combination-fun node))) (args (basic-combination-args node))) (unless (and (ref-p ref) (constant-reference-p ref) (singleton-p args)) (return-from ir1-optimize-mv-call)) (multiple-value-bind (min max) (fun-type-nargs (lvar-type fun)) (let ((total-nvals (multiple-value-bind (types nvals) (values-types (lvar-derived-type (first args))) (declare (ignore types)) (if (eq nvals :unknown) nil nvals)))) (when total-nvals (when (and min (< total-nvals min)) (compiler-warn "MULTIPLE-VALUE-CALL with ~R values when the function expects ~ at least ~R." total-nvals min) (setf (basic-combination-kind node) :error) (return-from ir1-optimize-mv-call)) (when (and max (> total-nvals max)) (compiler-warn "MULTIPLE-VALUE-CALL with ~R values when the function expects ~ at most ~R." total-nvals max) (setf (basic-combination-kind node) :error) (return-from ir1-optimize-mv-call))) (let ((count (cond (total-nvals) ((and (policy node (zerop verify-arg-count)) (eql min max)) min) (t nil)))) (when count (with-ir1-environment-from-node node (let* ((dums (make-gensym-list count)) (ignore (gensym)) (fun (ir1-convert-lambda `(lambda (&optional ,@dums &rest ,ignore) (declare (ignore ,ignore)) (funcall ,(ref-leaf ref) ,@dums))))) (change-ref-leaf ref fun) (aver (eq (basic-combination-kind node) :full)) (locall-analyze-component *current-component*) (aver (eq (basic-combination-kind node) :local))))))))) (values)) ;;; If we see: ;;; (multiple-value-bind ;;; (x y) ;;; (values xx yy) ;;; ...) ;;; Convert to: ;;; (let ((x xx) ;;; (y yy)) ;;; ...) ;;; ;;; What we actually do is convert the VALUES combination into a ;;; normal LET combination calling the original :MV-LET lambda. If ;;; there are extra args to VALUES, discard the corresponding ;;; lvars. If there are insufficient args, insert references to NIL. (defun convert-mv-bind-to-let (call) (declare (type mv-combination call)) (let* ((arg (first (basic-combination-args call))) (use (lvar-uses arg))) (when (and (combination-p use) (eq (lvar-fun-name (combination-fun use)) 'values)) (let* ((fun (combination-lambda call)) (vars (lambda-vars fun)) (vals (combination-args use)) (nvars (length vars)) (nvals (length vals))) (cond ((> nvals nvars) (mapc #'flush-dest (subseq vals nvars)) (setq vals (subseq vals 0 nvars))) ((< nvals nvars) (with-ir1-environment-from-node use (let ((node-prev (node-prev use))) (setf (node-prev use) nil) (setf (ctran-next node-prev) nil) (collect ((res vals)) (loop for count below (- nvars nvals) for prev = node-prev then ctran for ctran = (make-ctran) and lvar = (make-lvar use) do (reference-constant prev ctran lvar nil) (res lvar) finally (link-node-to-previous-ctran use ctran)) (setq vals (res))))))) (setf (combination-args use) vals) (flush-dest (combination-fun use)) (let ((fun-lvar (basic-combination-fun call))) (setf (lvar-dest fun-lvar) use) (setf (combination-fun use) fun-lvar) (flush-lvar-externally-checkable-type fun-lvar)) (setf (combination-kind use) :local) (setf (functional-kind fun) :let) (flush-dest (first (basic-combination-args call))) (unlink-node call) (when vals (reoptimize-lvar (first vals))) (propagate-to-args use fun) (reoptimize-call use)) t))) ;;; If we see: ;;; (values-list (list x y z)) ;;; ;;; Convert to: ;;; (values x y z) ;;; ;;; In implementation, this is somewhat similar to ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them ;;; args of the VALUES-LIST call, flushing the old argument lvar ;;; (allowing the LIST to be flushed.) ;;; ;;; FIXME: Thus we lose possible type assertions on (LIST ...). (defoptimizer (values-list optimizer) ((list) node) (let ((use (lvar-uses list))) (when (and (combination-p use) (eq (lvar-fun-name (combination-fun use)) 'list)) ;; FIXME: VALUES might not satisfy an assertion on NODE-LVAR. (change-ref-leaf (lvar-uses (combination-fun node)) (find-free-fun 'values "in a strange place")) (setf (combination-kind node) :full) (let ((args (combination-args use))) (dolist (arg args) (setf (lvar-dest arg) node) (flush-lvar-externally-checkable-type arg)) (setf (combination-args use) nil) (flush-dest list) (setf (combination-args node) args)) t))) ;;; If VALUES appears in a non-MV context, then effectively convert it ;;; to a PROG1. This allows the computation of the additional values ;;; to become dead code. (deftransform values ((&rest vals) * * :node node) (unless (lvar-single-value-p (node-lvar node)) (give-up-ir1-transform)) (setf (node-derived-type node) (make-short-values-type (list (single-value-type (node-derived-type node))))) (principal-lvar-single-valuify (node-lvar node)) (if vals (let ((dummies (make-gensym-list (length (cdr vals))))) `(lambda (val ,@dummies) (declare (ignore ,@dummies)) val)) nil)) ;;; TODO: ;;; - CAST chains; (defun delete-cast (cast) (declare (type cast cast)) (let ((value (cast-value cast)) (lvar (node-lvar cast))) (delete-filter cast lvar value) (when lvar (reoptimize-lvar lvar) (when (lvar-single-value-p lvar) (note-single-valuified-lvar lvar))) (values))) (defun ir1-optimize-cast (cast &optional do-not-optimize) (declare (type cast cast)) (let ((value (cast-value cast)) (atype (cast-asserted-type cast))) (when (not do-not-optimize) (let ((lvar (node-lvar cast))) (when (values-subtypep (lvar-derived-type value) (cast-asserted-type cast)) (delete-cast cast) (return-from ir1-optimize-cast t)) (when (and (listp (lvar-uses value)) lvar) ;; Pathwise removing of CAST (let ((ctran (node-next cast)) (dest (lvar-dest lvar)) next-block) (collect ((merges)) (do-uses (use value) (when (and (values-subtypep (node-derived-type use) atype) (immediately-used-p value use)) (unless next-block (when ctran (ensure-block-start ctran)) (setq next-block (first (block-succ (node-block cast)))) (ensure-block-start (node-prev cast)) (reoptimize-lvar lvar) (setf (lvar-%derived-type value) nil)) (%delete-lvar-use use) (add-lvar-use use lvar) (unlink-blocks (node-block use) (node-block cast)) (link-blocks (node-block use) next-block) (when (and (return-p dest) (basic-combination-p use) (eq (basic-combination-kind use) :local)) (merges use)))) (dolist (use (merges)) (merge-tail-sets use))))))) (let* ((value-type (lvar-derived-type value)) (int (values-type-intersection value-type atype))) (derive-node-type cast int) (when (eq int *empty-type*) (unless (eq value-type *empty-type*) ;; FIXME: Do it in one step. (filter-lvar value (if (cast-single-value-p cast) `(list 'dummy) `(multiple-value-call #'list 'dummy))) (filter-lvar (cast-value cast) ;; FIXME: Derived type. `(%compile-time-type-error 'dummy ',(type-specifier atype) ',(type-specifier value-type))) ;; KLUDGE: FILTER-LVAR does not work for non-returning ;; functions, so we declare the return type of ;; %COMPILE-TIME-TYPE-ERROR to be * and derive the real type ;; here. (setq value (cast-value cast)) (derive-node-type (lvar-uses value) *empty-type*) (maybe-terminate-block (lvar-uses value) nil) ;; FIXME: Is it necessary? (aver (null (block-pred (node-block cast)))) (delete-block-lazily (node-block cast)) (return-from ir1-optimize-cast))) (when (eq (node-derived-type cast) *empty-type*) (maybe-terminate-block cast nil)) (when (and (cast-%type-check cast) (values-subtypep value-type (cast-type-to-check cast))) (setf (cast-%type-check cast) nil)))) (unless do-not-optimize (setf (node-reoptimize cast) nil))) (deftransform make-symbol ((string) (simple-string)) `(%make-symbol string))