| blob | 3a495b496d727f43b57f84e461dfcfb7a6763220 |
1 ;;;; This file implements the IR1 optimization phase of the compiler.
2 ;;;; IR1 optimization is a grab-bag of optimizations that don't make
3 ;;;; major changes to the block-level control flow and don't use flow
4 ;;;; analysis. These optimizations can mostly be classified as
5 ;;;; "meta-evaluation", but there is a sizable top-down component as
6 ;;;; well.
8 ;;;; This software is part of the SBCL system. See the README file for
9 ;;;; more information.
10 ;;;;
11 ;;;; This software is derived from the CMU CL system, which was
12 ;;;; written at Carnegie Mellon University and released into the
13 ;;;; public domain. The software is in the public domain and is
14 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
15 ;;;; files for more information.
18 \f
19 ;;;; interface for obtaining results of constant folding
21 ;;; Return true for an LVAR whose sole use is a reference to a
22 ;;; constant leaf.
29 ;;; Return the constant value for an LVAR whose only use is a constant
30 ;;; node.
35 \f
36 ;;;; interface for obtaining results of type inference
38 ;;; Our best guess for the type of this lvar's value. Note that this
39 ;;; may be VALUES or FUNCTION type, which cannot be passed as an
40 ;;; argument to the normal type operations. See LVAR-TYPE.
41 ;;;
42 ;;; The result value is cached in the LVAR-%DERIVED-TYPE slot. If the
43 ;;; slot is true, just return that value, otherwise recompute and
44 ;;; stash the value there.
58 res))
61 res)))
65 ;;; Return the derived type for LVAR's first value. This is guaranteed
66 ;;; not to be a VALUES or FUNCTION type.
71 ;;; If LVAR is an argument of a function, return a type which the
72 ;;; function checks LVAR for.
81 ;; TODO: MV-COMBINATION
89 ;; FUN-TYPE might be (AND FUNCTION (SATISFIES ...)).
102 dest)))))
108 \f
109 ;;;; interface routines used by optimizers
119 ;;; This function is called by optimizers to indicate that something
120 ;;; interesting has happened to the value of LVAR. Optimizers must
121 ;;; make sure that they don't call for reoptimization when nothing has
122 ;;; happened, since optimization will fail to terminate.
123 ;;;
124 ;;; We clear any cached type for the lvar and set the reoptimize flags
125 ;;; on everything in sight.
135 ;; PREV may be missing.
154 ;;; Annotate NODE to indicate that its result has been proven to be
155 ;;; TYPEP to RTYPE. After IR1 conversion has happened, this is the
156 ;;; only correct way to supply information discovered about a node's
157 ;;; type. If you screw with the NODE-DERIVED-TYPE directly, then
158 ;;; information may be lost and reoptimization may not happen.
159 ;;;
160 ;;; What we do is intersect RTYPE with NODE's DERIVED-TYPE. If the
161 ;;; intersection is different from the old type, then we do a
162 ;;; REOPTIMIZE-LVAR on the NODE-LVAR.
175 "New inferred type ~S conflicts with old type:~
176 ~% ~S~%*** possible internal error? Please report this."
179 ;; If the new type consists of only one object, replace the
180 ;; node with a constant reference.
191 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
192 ;;; error for LVAR's value not to be TYPEP to TYPE. We implement it
193 ;;; splitting off DEST a new CAST node; old LVAR will deliver values
194 ;;; to CAST. If we improve the assertion, we set TYPE-CHECK and
195 ;;; TYPE-ASSERTED to guarantee that the new assertion will be checked.
206 \f
207 ;;;; IR1-OPTIMIZE
209 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
210 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
211 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
212 ;;; we are done, then another iteration would be beneficial.
218 for last-block = block
221 ;; We delete blocks when there is either no predecessor or the
222 ;; block is in a lambda that has been deleted. These blocks
223 ;; would eventually be deleted by DFO recomputation, but doing
224 ;; it here immediately makes the effect available to IR1
225 ;; optimization.
231 ;; Preserve the BLOCK-SUCC invariant that almost every block has
232 ;; one successor (and a block with DELETE-P set is an acceptable
233 ;; exception).
268 ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE
269 ;;; flags.
270 ;;;
271 ;;; Note that although they are cleared here, REOPTIMIZE flags might
272 ;;; still be set upon return from this function, meaning that further
273 ;;; optimization is wanted (as a consequence of optimizations we did).
276 ;; We clear the node and block REOPTIMIZE flags before doing the
277 ;; optimization, not after. This ensures that the node or block will
278 ;; be reoptimized if necessary.
282 ;; As above, we clear the node REOPTIMIZE flag before optimizing.
287 ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever
288 ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if
289 ;; any argument changes.
294 ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into
295 ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
296 ;; clear the flag itself. -- WHN 2002-02-02, quoting original
297 ;; CMU CL comments
303 ;; With an EXIT, we derive the node's type from the VALUE's
304 ;; type.
315 ;;; Try to join with a successor block. If we succeed, we return true,
316 ;;; otherwise false.
323 ;; the successor has more than one predecessor;
325 ;; the successor is the current block (infinite loop);
327 ;; the next block has a different cleanup, and thus
328 ;; we may want to insert cleanup code between the
329 ;; two blocks at some point;
332 ;; the next block has a different home lambda, and
333 ;; thus the control transfer is a non-local exit.
336 ;; Stack analysis phase wants ENTRY to start a block...
342 ;; ... and a DX-allocator to end a block.
344 ;; FIXME: This is a partial workaround for bug 303.
346 nil)
349 t)))))
351 ;;; Join together two blocks. The code in BLOCK2 is moved into BLOCK1
352 ;;; and BLOCK2 is deleted from the DFO. We combine the optimize flags
353 ;;; for the two blocks so that any indicated optimization gets done.
386 ;;; Delete any nodes in BLOCK whose value is unused and which have no
387 ;;; side effects. We can delete sets of lexical variables when the set
388 ;;; variable has no references.
404 ;; ### For now, don't delete potentially
405 ;; flushable calls when they have the CALL
406 ;; attribute. Someday we should look at the
407 ;; functional args to determine if they have
408 ;; any side effects.
441 \f
442 ;;;; local call return type propagation
444 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
445 ;;; flag set. It iterates over the uses of the RESULT, looking for
446 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
447 ;;; call, then we union its type together with the types of other such
448 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
449 ;;; type with the RESULT's asserted type. We can make this
450 ;;; intersection now (potentially before type checking) because this
451 ;;; assertion on the result will eventually be checked (if
452 ;;; appropriate.)
453 ;;;
454 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
455 ;;; combination, which may change the successor of the call to be the
456 ;;; called function, and if so, checks if the call can become an
457 ;;; assignment. If we convert to an assignment, we abort, since the
458 ;;; RETURN has been deleted.
477 ;; (values-type-intersection
478 ;; (continuation-asserted-type result) ; FIXME -- APD, 2002-01-26
480 ;; )
481 ))
483 nil)
485 ;;; Do stuff to realize that something has changed about the value
486 ;;; delivered to a return node. Since we consider the return values of
487 ;;; all functions in the tail set to be equivalent, this amounts to
488 ;;; bringing the entire tail set up to date. We iterate over the
489 ;;; returns for all the functions in the tail set, reanalyzing them
490 ;;; all (not treating NODE specially.)
491 ;;;
492 ;;; When we are done, we check whether the new type is different from
493 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
494 ;;; all the lvars for references to functions in the tail set. This
495 ;;; will cause IR1-OPTIMIZE-COMBINATION to derive the new type as the
496 ;;; results of the calls.
500 :restart
520 \f
521 ;;;; IF optimization
523 ;;; If the test has multiple uses, replicate the node when possible.
524 ;;; Also check whether the predicate is known to be true or false,
525 ;;; deleting the IF node in favor of the appropriate branch when this
526 ;;; is the case.
557 ;;; Create a new copy of an IF node that tests the value of the node
558 ;;; USE. The test must have >1 use, and must be immediately used by
559 ;;; USE. NODE must be the only node in its block (implying that
560 ;;; block-start = if-test).
561 ;;;
562 ;;; This optimization has an effect semantically similar to the
563 ;;; source-to-source transformation:
564 ;;; (IF (IF A B C) D E) ==>
565 ;;; (IF A (IF B D E) (IF C D E))
566 ;;;
567 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
568 ;;; node so that dead code deletion notes will definitely not consider
569 ;;; either node to be part of the original source. One node might
570 ;;; become unreachable, resulting in a spurious note.
582 :consequent cblock
604 \f
605 ;;;; exit IR1 optimization
607 ;;; This function attempts to delete an exit node, returning true if
608 ;;; it deletes the block as a consequence:
609 ;;; -- If the exit is degenerate (has no ENTRY), then we don't do
610 ;;; anything, since there is nothing to be done.
611 ;;; -- If the exit node and its ENTRY have the same home lambda then
612 ;;; we know the exit is local, and can delete the exit. We change
613 ;;; uses of the Exit-Value to be uses of the original lvar,
614 ;;; then unlink the node. If the exit is to a TR context, then we
615 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
616 ;;; their value to this exit.
617 ;;; -- If there is no value (as in a GO), then we skip the value
618 ;;; semantics.
619 ;;;
620 ;;; This function is also called by environment analysis, since it
621 ;;; wants all exits to be optimized even if normal optimization was
622 ;;; omitted.
634 \f
635 ;;;; combination IR1 optimization
637 ;;; Report as we try each transform?
638 #!+sb-show
646 "The return value of ~A should not be discarded."
649 ;;; Do IR1 optimizations on a COMBINATION node.
659 (:local
664 (:error
668 (:full
690 (:known
698 ;; If somebody is really sure that they want to modify
699 ;; constants, let them.
712 ;; KLUDGE: The next test could be made more sensitive,
713 ;; only suppressing constant-folding of functions with
714 ;; CALL attributes when they're actually passed
715 ;; function arguments. -- WHN 19990918
731 ;; First give the VM a peek at the call
735 (:direct
736 ;; The VM knows how to handle this.
737 )
738 (:transform
739 ;; The VM mostly knows how to handle this. We need
740 ;; to massage the call slightly, though.
742 (:default
743 ;; Let transforms have a crack at it.
745 #!+sb-show
751 #!+sb-show
758 ;;; If NODE doesn't return (i.e. return type is NIL), then terminate
759 ;;; the block there, and link it to the component tail.
760 ;;;
761 ;;; Except when called during IR1 convertion, we delete the
762 ;;; continuation if it has no other uses. (If it does have other uses,
763 ;;; we reoptimize.)
764 ;;;
765 ;;; Termination on the basis of a continuation type is
766 ;;; inhibited when:
767 ;;; -- The continuation is deleted (hence the assertion is spurious), or
768 ;;; -- We are in IR1 conversion (where THE assertions are subject to
769 ;;; weakening.) FIXME: Now THE assertions are not weakened, but new
770 ;;; uses can(?) be added later. -- APD, 2003-07-17
771 ;;;
772 ;;; Why do we need to consider LVAR type? -- APD, 2003-07-30
808 t))))
810 ;;; This is called both by IR1 conversion and IR1 optimization when
811 ;;; they have verified the type signature for the call, and are
812 ;;; wondering if something should be done to special-case the call. If
813 ;;; CALL is a call to a global function, then see whether it defined
814 ;;; or known:
815 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
816 ;;; the expansion and change the call to call it. Expansion is
817 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
818 ;;; true, we never expand, since this function has already been
819 ;;; converted. Local call analysis will duplicate the definition
820 ;;; if necessary. We claim that the parent form is LABELS for
821 ;;; context declarations, since we don't want it to be considered
822 ;;; a real global function.
823 ;;; -- If it is a known function, mark it as such by setting the KIND.
824 ;;;
825 ;;; We return the leaf referenced (NIL if not a leaf) and the
826 ;;; FUN-INFO assigned.
854 ;; called semi-inlining? A more descriptive name would
855 ;; be nice. -- WHN 2002-01-07
859 name
861 leaf
862 inlinep
864 ;; allow backward references to this function from
865 ;; following top level forms
875 nil))
885 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
886 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
887 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
888 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
889 ;;; syntax check, arg/result type processing, but still call
890 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
891 ;;; and that checking is done by local call analysis.
901 :result-test nil
902 ;; KLUDGE: Common Lisp is such a dynamic
903 ;; language that all we can do here in
904 ;; general is issue a STYLE-WARNING. It
905 ;; would be nice to issue a full WARNING
906 ;; in the special case of of type
907 ;; mismatches within a compilation unit
908 ;; (as in section 3.2.2.3 of the spec)
909 ;; but at least as of sbcl-0.6.11, we
910 ;; don't keep track of whether the
911 ;; mismatched data came from the same
912 ;; compilation unit, so we can't do that.
913 ;; -- WHN 2001-02-11
914 ;;
915 ;; FIXME: Actually, I think we could
916 ;; issue a full WARNING if the call
917 ;; violates a DECLAIM FTYPE.
927 ;;; This is called by IR1-OPTIMIZE when the function for a call has
928 ;;; changed. If the call is local, we try to LET-convert it, and
929 ;;; derive the result type. If it is a :FULL call, we validate it
930 ;;; against the type, which recognizes known calls, does inline
931 ;;; expansion, etc. If a call to a predicate in a non-conditional
932 ;;; position or to a function with a source transform, then we
933 ;;; reconvert the form to give IR1 another chance.
940 (:local
945 (:full
951 call))
959 predicate)
973 \f
974 ;;;; known function optimization
976 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
977 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
978 ;;; replace it, otherwise add a new one.
989 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
990 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
991 ;;; doing the transform for some reason and FLAME is true, then we
992 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
993 ;;; finalize to pick up. We return true if the transform failed, and
994 ;;; thus further transformation should be attempted. We return false
995 ;;; if either the transform succeeded or was aborted.
1015 (:none
1017 nil)
1018 (:aborted
1023 nil)
1024 (:failure
1030 t)
1031 (:delayed
1033 nil))))
1036 type
1040 t)
1042 t))))
1044 ;;; When we don't like an IR1 transform, we throw the severity/reason
1045 ;;; and args.
1046 ;;;
1047 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
1048 ;;; aborting this attempt to transform the call, but admitting the
1049 ;;; possibility that this or some other transform will later succeed.
1050 ;;; If arguments are supplied, they are format arguments for an
1051 ;;; efficiency note.
1052 ;;;
1053 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
1054 ;;; force a normal call to the function at run time. No further
1055 ;;; optimizations will be attempted.
1056 ;;;
1057 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
1058 ;;; delay the transform on the node until later. REASONS specifies
1059 ;;; when the transform will be later retried. The :OPTIMIZE reason
1060 ;;; causes the transform to be delayed until after the current IR1
1061 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
1062 ;;; be delayed until after constraint propagation.
1063 ;;;
1064 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
1065 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
1066 ;;; do CASE operations on the various REASON values, it might be a
1067 ;;; good idea to go OO, representing the reasons by objects, using
1068 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
1069 ;;; SIGNAL instead of THROW.
1086 ;;; Clear any delayed transform with no reasons - these should have
1087 ;;; been tried in the last pass. Then remove the reason from the
1088 ;;; delayed transform reasons, and if any become empty then set
1089 ;;; reoptimize flags for the node. Return true if any transforms are
1090 ;;; to be retried.
1106 reoptimize))
1108 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1109 ;;; environment, and then install it as the function for the call
1110 ;;; NODE. We do local call analysis so that the new function is
1111 ;;; integrated into the control flow.
1112 ;;;
1113 ;;; We require the original function source name in order to generate
1114 ;;; a meaningful debug name for the lambda we set up. (It'd be
1115 ;;; possible to do this starting from debug names as well as source
1116 ;;; names, but as of sbcl-0.7.1.5, there was no need for this
1117 ;;; generality, since source names are always known to our callers.)
1123 ;; The internal variables of a transform are not going to be
1124 ;; interesting to the debugger, so there's no sense in
1125 ;; suppressing the substitution of variables with only one use
1126 ;; (the extra variables can slow down constraint propagation).
1127 ;;
1128 ;; This needs to be done before the WITH-IR1-ENVIRONMENT-FROM-NODE,
1129 ;; so that it will bind *LEXENV* to the right environment.
1142 res
1151 ;;; Replace a call to a foldable function of constant arguments with
1152 ;;; the result of evaluating the form. If there is an error during the
1153 ;;; evaluation, we give a warning and leave the call alone, making the
1154 ;;; call a :ERROR call.
1155 ;;;
1156 ;;; If there is more than one value, then we transform the call into a
1157 ;;; VALUES form.
1163 args
1164 call
1165 ;; Note: CMU CL had COMPILER-WARN here, and that
1166 ;; seems more natural, but it's probably not.
1167 ;;
1168 ;; It's especially not while bug 173 exists:
1169 ;; Expressions like
1170 ;; (COND (END
1171 ;; (UNLESS (OR UNSAFE? (<= END SIZE)))
1172 ;; ...))
1173 ;; can cause constant-folding TYPE-ERRORs (in
1174 ;; #'<=) when END can be proved to be NIL, even
1175 ;; though the code is perfectly legal and safe
1176 ;; because a NIL value of END means that the
1177 ;; #'<= will never be executed.
1178 ;;
1179 ;; Moreover, even without bug 173,
1180 ;; quite-possibly-valid code like
1181 ;; (COND ((NONINLINED-PREDICATE END)
1182 ;; (UNLESS (<= END SIZE))
1183 ;; ...))
1184 ;; (where NONINLINED-PREDICATE is something the
1185 ;; compiler can't do at compile time, but which
1186 ;; turns out to make the #'<= expression
1187 ;; unreachable when END=NIL) could cause errors
1188 ;; when the compiler tries to constant-fold (<=
1189 ;; END SIZE).
1190 ;;
1191 ;; So, with or without bug 173, it'd be
1192 ;; unnecessarily evil to do a full
1193 ;; COMPILER-WARNING (and thus return FAILURE-P=T
1194 ;; from COMPILE-FILE) for legal code, so we we
1195 ;; use a wimpier COMPILE-STYLE-WARNING instead.
1197 ;; On the other hand, for code we control, we
1198 ;; should be able to work around any bug
1199 ;; 173-related problems, and in particular we
1200 ;; want to be alerted to calls to our own
1201 ;; functions which aren't being folded away; a
1202 ;; COMPILER-WARNING is butch enough to stop the
1203 ;; SBCL build itself in its tracks.
1223 call
1227 fun-name))))))
1229 \f
1230 ;;;; local call optimization
1232 ;;; Propagate TYPE to LEAF and its REFS, marking things changed. If
1233 ;;; the leaf type is a function type, then just leave it alone, since
1234 ;;; TYPE is never going to be more specific than that (and
1235 ;;; TYPE-INTERSECTION would choke.)
1245 ;; KLUDGE: LET var substitution
1251 ;;; Iteration variable: exactly one SETQ of the form:
1252 ;;;
1253 ;;; (let ((var initial))
1254 ;;; ...
1255 ;;; (setq var (+ var step))
1256 ;;; ...)
1282 ;; Detect cases like (LOOP FOR 1.0 to 5.0 ...), where
1283 ;; the initial and the step are of different types,
1284 ;; and the step is less contagious.
1287 step-type))))
1326 :low low
1327 :high high
1330 "check for iteration variable reoptimization"
1340 ;;; Figure out the type of a LET variable that has sets. We compute
1341 ;;; the union of the INITIAL-TYPE and the types of all the set
1342 ;;; values and to a PROPAGATE-TO-REFS with this type.
1357 ;;; If a LET variable, find the initial value's type and do
1358 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1359 ;;; type.
1375 ;;; Return true if the value of REF will always be the same (and is
1376 ;;; thus legal to substitute.)
1388 (:global-function
1395 ;;; If we have a non-set LET var with a single use, then (if possible)
1396 ;;; replace the variable reference's LVAR with the arg lvar.
1397 ;;;
1398 ;;; We change the REF to be a reference to NIL with unused value, and
1399 ;;; let it be flushed as dead code. A side effect of this substitution
1400 ;;; is to delete the variable.
1407 ;; Think about (LET ((A ...)) (IF ... A ...)): two
1408 ;; LVAR-USEs should not be met on one path. Another problem
1409 ;; is with dynamic-extent.
1413 ;; we should not change lifetime of unknown values lvars
1425 ;; While CRETURN and EXIT nodes may be known-values,
1426 ;; they have their own complications, such as
1427 ;; substitution into CRETURN may create new tail calls.
1428 nil)
1431 t))
1437 ;; Really it is (EQ (LVAR-USES LVAR) REF):
1438 t)
1443 ;; KLUDGE: it should be (TYPE-CHECK 0)
1447 ;; FIXME
1448 t)
1456 t)))
1458 ;;; Delete a LET, removing the call and bind nodes, and warning about
1459 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1460 ;;; along right away and delete the REF and then the lambda, since we
1461 ;;; flush the FUN lvar.
1476 ;;; This function is called when one of the arguments to a LET
1477 ;;; changes. We look at each changed argument. If the corresponding
1478 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1479 ;;; consider substituting for the variable, and also propagate
1480 ;;; derived-type information for the arg to all the VAR's refs.
1481 ;;;
1482 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1483 ;;; subtype of the argument's leaf type. This prevents type checking
1484 ;;; from being defeated, and also ensures that the best representation
1485 ;;; for the variable can be used.
1486 ;;;
1487 ;;; Substitution of individual references is inhibited if the
1488 ;;; reference is in a different component from the home. This can only
1489 ;;; happen with closures over top level lambda vars. In such cases,
1490 ;;; the references may have already been compiled, and thus can't be
1491 ;;; retroactively modified.
1492 ;;;
1493 ;;; If all of the variables are deleted (have no references) when we
1494 ;;; are done, then we delete the LET.
1495 ;;;
1496 ;;; Note that we are responsible for clearing the LVAR-REOPTIMIZE
1497 ;;; flags.
1512 ;; (NODE-DERIVED-TYPE USE) would
1513 ;; be better -- APD, 2003-05-15
1520 t)
1523 nil)))
1524 leaf var)))
1525 t)))))
1527 ;; Don't substitute single-ref variables on high-debug /
1528 ;; low speed, to improve the debugging experience.
1539 ;;; This function is called when one of the args to a non-LET local
1540 ;;; call changes. For each changed argument corresponding to an unset
1541 ;;; variable, we compute the union of the types across all calls and
1542 ;;; propagate this type information to the var's refs.
1543 ;;;
1544 ;;; If the function has an XEP, then we don't do anything, since we
1545 ;;; won't discover anything.
1546 ;;;
1547 ;;; We can clear the LVAR-REOPTIMIZE flags for arguments in all calls
1548 ;;; corresponding to changed arguments in CALL, since the only use in
1549 ;;; IR1 optimization of the REOPTIMIZE flag for local call args is
1550 ;;; right here.
1562 vars))
1578 union)))))
1581 and type in union
1585 \f
1586 ;;;; multiple values optimization
1588 ;;; Do stuff to notice a change to a MV combination node. There are
1589 ;;; two main branches here:
1590 ;;; -- If the call is local, then it is already a MV let, or should
1591 ;;; become one. Note that although all :LOCAL MV calls must eventually
1592 ;;; be converted to :MV-LETs, there can be a window when the call
1593 ;;; is local, but has not been LET converted yet. This is because
1594 ;;; the entry-point lambdas may have stray references (in other
1595 ;;; entry points) that have not been deleted yet.
1596 ;;; -- The call is full. This case is somewhat similar to the non-MV
1597 ;;; combination optimization: we propagate return type information and
1598 ;;; notice non-returning calls. We also have an optimization
1599 ;;; which tries to convert MV-CALLs into MV-binds.
1602 (:local
1611 (:full
1634 ;;; Propagate derived type info from the values lvar to the vars.
1641 n-vars)))
1643 and type in types
1650 ;;; If possible, convert a general MV call to an MV-BIND. We can do
1651 ;;; this if:
1652 ;;; -- The call has only one argument, and
1653 ;;; -- The function has a known fixed number of arguments, or
1654 ;;; -- The argument yields a known fixed number of values.
1655 ;;;
1656 ;;; What we do is change the function in the MV-CALL to be a lambda
1657 ;;; that "looks like an MV bind", which allows
1658 ;;; IR1-OPTIMIZE-MV-COMBINATION to notice that this call can be
1659 ;;; converted (the next time around.) This new lambda just calls the
1660 ;;; actual function with the MV-BIND variables as arguments. Note that
1661 ;;; this new MV bind is not let-converted immediately, as there are
1662 ;;; going to be stray references from the entry-point functions until
1663 ;;; they get deleted.
1664 ;;;
1665 ;;; In order to avoid loss of argument count checking, we only do the
1666 ;;; transformation according to a known number of expected argument if
1667 ;;; safety is unimportant. We can always convert if we know the number
1668 ;;; of actual values, since the normal call that we build will still
1669 ;;; do any appropriate argument count checking.
1670 ;;;
1671 ;;; We only attempt the transformation if the called function is a
1672 ;;; constant reference. This allows us to just splice the leaf into
1673 ;;; the new function, instead of trying to somehow bind the function
1674 ;;; expression. The leaf must be constant because we are evaluating it
1675 ;;; again in a different place. This also has the effect of squelching
1676 ;;; multiple warnings when there is an argument count error.
1698 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1699 at least ~R."
1700 total-nvals min)
1705 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1706 at most ~R."
1707 total-nvals max)
1714 min)
1733 ;;; If we see:
1734 ;;; (multiple-value-bind
1735 ;;; (x y)
1736 ;;; (values xx yy)
1737 ;;; ...)
1738 ;;; Convert to:
1739 ;;; (let ((x xx)
1740 ;;; (y yy))
1741 ;;; ...)
1742 ;;;
1743 ;;; What we actually do is convert the VALUES combination into a
1744 ;;; normal LET combination calling the original :MV-LET lambda. If
1745 ;;; there are extra args to VALUES, discard the corresponding
1746 ;;; lvars. If there are insufficient args, insert references to NIL.
1769 for prev = node-prev then ctran
1775 use ctran))
1791 t)))
1793 ;;; If we see:
1794 ;;; (values-list (list x y z))
1795 ;;;
1796 ;;; Convert to:
1797 ;;; (values x y z)
1798 ;;;
1799 ;;; In implementation, this is somewhat similar to
1800 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
1801 ;;; args of the VALUES-LIST call, flushing the old argument lvar
1802 ;;; (allowing the LIST to be flushed.)
1803 ;;;
1804 ;;; FIXME: Thus we lose possible type assertions on (LIST ...).
1811 ;; FIXME: VALUES might not satisfy an assertion on NODE-LVAR.
1822 t)))
1824 ;;; If VALUES appears in a non-MV context, then effectively convert it
1825 ;;; to a PROG1. This allows the computation of the additional values
1826 ;;; to become dead code.
1838 val))
1839 nil))
1841 ;;; TODO:
1842 ;;; - CAST chains;
1866 lvar)
1867 ;; Pathwise removing of CAST
1870 next-block)
1898 ;; FIXME: Do it in one step.
1900 value
1906 ;; FIXME: Derived type.
1910 ;; KLUDGE: FILTER-LVAR does not work for non-returning
1911 ;; functions, so we declare the return type of
1912 ;; %COMPILE-TIME-TYPE-ERROR to be * and derive the real type
1913 ;; here.
1917 ;; FIXME: Is it necessary?