| blob | cd0f573b49f158f13d0442da490e932d29054863 |
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 leaf)
32 ;; LEAF may be a CONSTANT behind a cast that will
33 ;; later turn out to be of the wrong type.
34 ;; And ir1-transforms suffer from this because
35 ;; they expect LVAR-VALUE to be of a restricted type.
38 ;; check for EQL types and singleton numeric types
41 ;;; Return the constant value for an LVAR whose only use is a constant
42 ;;; node.
47 leaf)
54 value))))
55 \f
56 ;;;; interface for obtaining results of type inference
58 ;;; Our best guess for the type of this lvar's value. Note that this
59 ;;; may be VALUES or FUNCTION type, which cannot be passed as an
60 ;;; argument to the normal type operations. See LVAR-TYPE.
61 ;;;
62 ;;; The result value is cached in the LVAR-%DERIVED-TYPE slot. If the
63 ;;; slot is true, just return that value, otherwise recompute and
64 ;;; stash the value there.
74 res))
77 res)))
84 ;;; Return the derived type for LVAR's first value. This is guaranteed
85 ;;; not to be a VALUES or FUNCTION type.
90 ;;; LVAR-CONSERVATIVE-TYPE
91 ;;;
92 ;;; Certain types refer to the contents of an object, which can
93 ;;; change without type derivation noticing: CONS types and ARRAY
94 ;;; types suffer from this:
95 ;;;
96 ;;; (let ((x (the (cons fixnum fixnum) (cons a b))))
97 ;;; (setf (car x) c)
98 ;;; (+ (car x) (cdr x)))
99 ;;;
100 ;;; Python doesn't realize that the SETF CAR can change the type of X -- so we
101 ;;; cannot use LVAR-TYPE which gets the derived results. Worse, still, instead
102 ;;; of (SETF CAR) we might have a call to a user-defined function FOO which
103 ;;; does the same -- so there is no way to use the derived information in
104 ;;; general.
105 ;;;
106 ;;; So, the conservative option is to use the derived type if the leaf has
107 ;;; only a single ref -- in which case there cannot be a prior call that
108 ;;; mutates it. Otherwise we use the declared type or punt to the most general
109 ;;; type we know to be correct for sure.
113 ;; Recompute using NODE-CONSERVATIVE-TYPE instead of derived type if
114 ;; necessary -- picking off some easy cases up front.
116 ;; Can't use CSUBTYPEP!
119 derived-type)
123 derived-type)
129 derived-type)
133 derived-type))))
146 derived-values-type))
147 derived-values-type)))
153 type)
159 ;; ADJUST-ARRAY may change dimensions, but rank stays same.
162 old
164 ;; Complexity cannot change.
166 ;; Element type cannot change.
169 ;; Simple arrays cannot change at all.
170 type))
172 ;; Conservative union type is an union of conservative types.
177 ;; Catch-all.
178 ;;
179 ;; If the type contains some CONS types, the conservative type contains all
180 ;; of them.
183 ;; Similarly for non-simple arrays -- it should be possible to preserve
184 ;; more information here, but really...
188 type)))
192 ;; Excluding T is necessary, because we do want type derivation to
193 ;; be able to narrow it down in case someone (most like a macro-expansion...)
194 ;; actually declares something as having type T.
195 nil)
197 ;; Covered by the next case as well, but this is a quick test.
198 t)
200 t)))
202 ;;; If LVAR is an argument of a function, return a type which the
203 ;;; function checks LVAR for.
212 ;; TODO: MV-COMBINATION
220 ;; FUN-TYPE might be (AND FUNCTION (SATISFIES ...)).
233 dest)))))
235 \f
236 ;;;; interface routines used by optimizers
238 ;;; This function is called by optimizers to indicate that something
239 ;;; interesting has happened to the value of LVAR. Optimizers must
240 ;;; make sure that they don't call for reoptimization when nothing has
241 ;;; happened, since optimization will fail to terminate.
242 ;;;
243 ;;; We clear any cached type for the lvar and set the reoptimize flags
244 ;;; on everything in sight.
254 ;; PREV may be missing.
271 ;;; Annotate NODE to indicate that its result has been proven to be
272 ;;; TYPEP to RTYPE. After IR1 conversion has happened, this is the
273 ;;; only correct way to supply information discovered about a node's
274 ;;; type. If you screw with the NODE-DERIVED-TYPE directly, then
275 ;;; information may be lost and reoptimization may not happen.
276 ;;;
277 ;;; What we do is intersect RTYPE with NODE's DERIVED-TYPE. If the
278 ;;; intersection is different from the old type, then we do a
279 ;;; REOPTIMIZE-LVAR on the NODE-LVAR.
285 initial-type)))
296 "New inferred type ~S conflicts with old type:~
297 ~% ~S~%*** possible internal error? Please report this."
300 ;; If the new type consists of only one object, replace the
301 ;; node with a constant reference.
312 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
313 ;;; error for LVAR's value not to be TYPEP to TYPE. We implement it
314 ;;; splitting off DEST a new CAST node; old LVAR will deliver values
315 ;;; to CAST. If we improve the assertion, we set TYPE-CHECK to
316 ;;; guarantee that the new assertion will be checked.
324 context)))
326 t))))
334 :value lvar
336 :arg-count arg-count
348 cast)))
359 \f
360 ;;;; IR1-OPTIMIZE
362 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
363 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
364 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
365 ;;; we are done, then another iteration would be beneficial.
371 for last-block = block
374 ;; We delete blocks when there is either no predecessor or the
375 ;; block is in a lambda that has been deleted. These blocks
376 ;; would eventually be deleted by DFO recomputation, but doing
377 ;; it here immediately makes the effect available to IR1
378 ;; optimization.
384 ;; Preserve the BLOCK-SUCC invariant that almost every block has
385 ;; one successor (and a block with DELETE-P set is an acceptable
386 ;; exception).
421 ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE
422 ;;; flags.
423 ;;;
424 ;;; Note that although they are cleared here, REOPTIMIZE flags might
425 ;;; still be set upon return from this function, meaning that further
426 ;;; optimization is wanted (as a consequence of optimizations we did).
429 ;; We clear the node and block REOPTIMIZE flags before doing the
430 ;; optimization, not after. This ensures that the node or block will
431 ;; be reoptimized if necessary.
435 ;; As above, we clear the node REOPTIMIZE flag before optimizing.
440 ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever
441 ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if
442 ;; any argument changes.
447 ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into
448 ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
449 ;; clear the flag itself. -- WHN 2002-02-02, quoting original
450 ;; CMU CL comments
456 ;; With an EXIT, we derive the node's type from the VALUE's
457 ;; type.
462 ;; PROPAGATE-FROM-SETS can do a better job if NODE-REOPTIMIZE
463 ;; is accurate till the node actually has been reoptimized.
471 ;;; Try to join with a successor block. If we succeed, we return true,
472 ;;; otherwise false.
479 ;; the successor has more than one predecessor;
481 ;; the successor is the current block (infinite loop);
483 ;; the next block has a different cleanup, and thus
484 ;; we may want to insert cleanup code between the
485 ;; two blocks at some point;
488 ;; the next block has a different home lambda, and
489 ;; thus the control transfer is a non-local exit.
492 ;; Stack analysis phase wants ENTRY to start a block...
498 ;; ... and a DX-allocator to end a block.
500 ;; ... and for there to be no chance of there
501 ;; being two successive USEs of the same
502 ;; multi-valued LVAR in the same block (since
503 ;; we can only insert cleanup code at block
504 ;; boundaries, but need to discard
505 ;; multi-valued LVAR contents before they are
506 ;; overwritten).
509 nil)
512 t)))))
514 ;;; Join together two blocks. The code in BLOCK2 is moved into BLOCK1
515 ;;; and BLOCK2 is deleted from the DFO. We combine the optimize flags
516 ;;; for the two blocks so that any indicated optimization gets done.
548 ;;; Delete any nodes in BLOCK whose value is unused and which have no
549 ;;; side effects. We can delete sets of lexical variables when the set
550 ;;; variable has no references.
559 ;; This must be a preceding node and the current node will
560 ;; overwrite the value, unlink the lvar and the node will
561 ;; get a chance to be deleted on one of the next iterations
603 victim)
604 \f
605 ;;;; local call return type propagation
607 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
608 ;;; flag set. It iterates over the uses of the RESULT, looking for
609 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
610 ;;; call, then we union its type together with the types of other such
611 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
612 ;;; type with the RESULT's asserted type. We can make this
613 ;;; intersection now (potentially before type checking) because this
614 ;;; assertion on the result will eventually be checked (if
615 ;;; appropriate.)
616 ;;;
617 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
618 ;;; combination, which may change the successor of the call to be the
619 ;;; called function, and if so, checks if the call can become an
620 ;;; assignment. If we convert to an assignment, we abort, since the
621 ;;; RETURN has been deleted.
642 ;; (values-type-intersection
643 ;; (continuation-asserted-type result) ; FIXME -- APD, 2002-01-26
645 ;; )
646 ))
648 nil)
650 ;;; Do stuff to realize that something has changed about the value
651 ;;; delivered to a return node. Since we consider the return values of
652 ;;; all functions in the tail set to be equivalent, this amounts to
653 ;;; bringing the entire tail set up to date. We iterate over the
654 ;;; returns for all the functions in the tail set, reanalyzing them
655 ;;; all (not treating NODE specially.)
656 ;;;
657 ;;; When we are done, we check whether the new type is different from
658 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
659 ;;; all the lvars for references to functions in the tail set. This
660 ;;; will cause IR1-OPTIMIZE-COMBINATION to derive the new type as the
661 ;;; results of the calls.
666 :restart
686 \f
687 ;;;; IF optimization
689 ;;; Utility: return T if both argument cblocks are equivalent. For now,
690 ;;; detect only blocks that read the same leaf into the same lvar, and
691 ;;; continue to the same block.
704 ;;; Check whether the predicate is known to be true or false,
705 ;;; deleting the IF node in favor of the appropriate branch when this
706 ;;; is the case.
707 ;;; Similarly, when both branches are equivalent, branch directly to either
708 ;;; of them.
709 ;;; Also, if the test has multiple uses, replicate the node when possible...
710 ;;; in fact, splice in direct jumps to the right branch if possible.
722 alternative)
724 consequent)
727 ;; Even if the references are the same they can have
728 ;; different derived types based on the TEST
729 ;; Don't lose the second type when killing it.
736 alternative))))
744 ;; When we know that we only have a single successor, kill the victim
745 ;; ... unless the victim and the remaining successor are the same.
754 ;; When if/if conversion would leave (if ... (if nil ...)) or
755 ;; (if ... (if not-nil ...)), splice the correct successor right
756 ;; in.
775 ;; only one use left. Just kill the now-useless
776 ;; branch to avoid spurious code deletion notes.
779 node test block
785 ;; Finally, duplicate EQ-nil tests
792 ;; leave the last use as is, instead of replacing
793 ;; the (singly-referenced) CIF node with a duplicate.
796 ;;; Create a new copy of an IF node that tests the value of the node
797 ;;; USE. The test must have >1 use, and must be immediately used by
798 ;;; USE. NODE must be the only node in its block (implying that
799 ;;; block-start = if-test).
800 ;;;
801 ;;; This optimization has an effect semantically similar to the
802 ;;; source-to-source transformation:
803 ;;; (IF (IF A B C) D E) ==>
804 ;;; (IF A (IF B D E) (IF C D E))
805 ;;;
806 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
807 ;;; node so that dead code deletion notes will definitely not consider
808 ;;; either node to be part of the original source. One node might
809 ;;; become unreachable, resulting in a spurious note.
821 :consequent cblock
843 \f
844 ;;;; exit IR1 optimization
846 ;;; This function attempts to delete an exit node, returning true if
847 ;;; it deletes the block as a consequence:
848 ;;; -- If the exit is degenerate (has no ENTRY), then we don't do
849 ;;; anything, since there is nothing to be done.
850 ;;; -- If the exit node and its ENTRY have the same home lambda then
851 ;;; we know the exit is local, and can delete the exit. We change
852 ;;; uses of the Exit-Value to be uses of the original lvar,
853 ;;; then unlink the node. If the exit is to a TR context, then we
854 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
855 ;;; their value to this exit.
856 ;;; -- If there is no value (as in a GO), then we skip the value
857 ;;; semantics.
858 ;;;
859 ;;; This function is also called by environment analysis, since it
860 ;;; wants all exits to be optimized even if normal optimization was
861 ;;; omitted.
873 \f
874 ;;;; combination IR1 optimization
876 ;;; Report as we try each transform?
877 #!+sb-show
885 "The return value of ~A should not be discarded."
888 ;;; Do IR1 optimizations on a COMBINATION node.
904 ;; If somebody is really sure that they want to modify
905 ;; constants, let them.
921 (:local
926 (:error
928 (:full
931 ;; This is a known function marked NOTINLINE
934 ;; Check against the DEFINED-TYPE unless TYPE is already good.
944 (:known
960 ;; First give the VM a peek at the call
964 (:direct
965 ;; The VM knows how to handle this.
966 )
967 (:transform
968 ;; The VM mostly knows how to handle this. We need
969 ;; to massage the call slightly, though.
972 ;; Let transforms have a crack at it.
974 #!+sb-show
980 #!+sb-show
994 ;;; If NODE doesn't return (i.e. return type is NIL), then terminate
995 ;;; the block there, and link it to the component tail.
996 ;;;
997 ;;; Except when called during IR1 convertion, we delete the
998 ;;; continuation if it has no other uses. (If it does have other uses,
999 ;;; we reoptimize.)
1000 ;;;
1001 ;;; Termination on the basis of a continuation type is
1002 ;;; inhibited when:
1003 ;;; -- The continuation is deleted (hence the assertion is spurious), or
1004 ;;; -- We are in IR1 conversion (where THE assertions are subject to
1005 ;;; weakening.) FIXME: Now THE assertions are not weakened, but new
1006 ;;; uses can(?) be added later. -- APD, 2003-07-17
1007 ;;;
1008 ;;; Why do we need to consider LVAR type? -- APD, 2003-07-30
1019 ;; Even if the combination will never return, don't terminate if this
1020 ;; is the tail call of a XEP: doing that would inhibit TCO.
1047 t))))
1049 ;;; This is called both by IR1 conversion and IR1 optimization when
1050 ;;; they have verified the type signature for the call, and are
1051 ;;; wondering if something should be done to special-case the call. If
1052 ;;; CALL is a call to a global function, then see whether it defined
1053 ;;; or known:
1054 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
1055 ;;; the expansion and change the call to call it. Expansion is
1056 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
1057 ;;; true, we never expand, since this function has already been
1058 ;;; converted. Local call analysis will duplicate the definition
1059 ;;; if necessary. We claim that the parent form is LABELS for
1060 ;;; context declarations, since we don't want it to be considered
1061 ;;; a real global function.
1062 ;;; -- If it is a known function, mark it as such by setting the KIND.
1063 ;;;
1064 ;;; We return the leaf referenced (NIL if not a leaf) and the
1065 ;;; FUN-INFO assigned.
1089 ;; Inline: if the function has already been converted at another call
1090 ;; site in this component, we point this REF to the functional. If not,
1091 ;; we convert the expansion.
1092 ;;
1093 ;; For :INLINE case local call analysis will copy the expansion later,
1094 ;; but for :MAYBE-INLINE and NIL cases we only get one copy of the
1095 ;; expansion per component.
1096 ;;
1097 ;; FIXME: We also convert in :INLINE & FUNCTIONAL-KIND case below. What
1098 ;; is it for?
1103 ;; Convert.
1106 name
1108 leaf
1109 inlinep
1111 ;; Allow backward references to this function from following
1112 ;; forms. (Reused only if policy matches.)
1117 ;; If we've already converted, change ref to the converted
1118 ;; functional.
1130 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
1131 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
1132 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
1133 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
1134 ;;; syntax check, arg/result type processing, but still call
1135 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
1136 ;;; and that checking is done by local call analysis.
1145 ;; Using the defined-type too early is a bit of a waste: during
1146 ;; conversion we cannot use the untrusted ASSERT-CALL-TYPE, etc.
1151 ;; Don't validate multiple times against the same leaf --
1152 ;; it doesn't add any information, but may generate the same warning
1153 ;; multiple times.
1157 :result-test nil
1159 #'compiler-warn
1162 same-file-p)
1169 :result-test nil
1179 ;;; This is called by IR1-OPTIMIZE when the function for a call has
1180 ;;; changed. If the call is local, we try to LET-convert it, and
1181 ;;; derive the result type. If it is a :FULL call, we validate it
1182 ;;; against the type, which recognizes known calls, does inline
1183 ;;; expansion, etc. If a call to a predicate in a non-conditional
1184 ;;; position or to a function with a source transform, then we
1185 ;;; reconvert the form to give IR1 another chance.
1192 (:local
1197 (:full
1206 call))
1214 predicate)
1227 nil))))))))
1229 \f
1230 ;;;; known function optimization
1232 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
1233 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
1234 ;;; replace it, otherwise add a new one.
1245 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
1246 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
1247 ;;; doing the transform for some reason and FLAME is true, then we
1248 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
1249 ;;; finalize to pick up. We return true if the transform failed, and
1250 ;;; thus further transformation should be attempted. We return false
1251 ;;; if either the transform succeeded or was aborted.
1275 (:none
1277 nil)
1278 (:aborted
1283 nil)
1284 (:failure
1290 t)
1291 (:delayed
1293 nil))))
1296 type
1300 t)
1302 t))))
1304 ;;; When we don't like an IR1 transform, we throw the severity/reason
1305 ;;; and args.
1306 ;;;
1307 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
1308 ;;; aborting this attempt to transform the call, but admitting the
1309 ;;; possibility that this or some other transform will later succeed.
1310 ;;; If arguments are supplied, they are format arguments for an
1311 ;;; efficiency note.
1312 ;;;
1313 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
1314 ;;; force a normal call to the function at run time. No further
1315 ;;; optimizations will be attempted.
1316 ;;;
1317 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
1318 ;;; delay the transform on the node until later. REASONS specifies
1319 ;;; when the transform will be later retried. The :OPTIMIZE reason
1320 ;;; causes the transform to be delayed until after the current IR1
1321 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
1322 ;;; be delayed until after constraint propagation.
1323 ;;;
1324 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
1325 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
1326 ;;; do CASE operations on the various REASON values, it might be a
1327 ;;; good idea to go OO, representing the reasons by objects, using
1328 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
1329 ;;; SIGNAL instead of THROW.
1347 ;;; Poor man's catching and resignalling
1348 ;;; Implicit %GIVE-UP macrolet will resignal the give-up "condition"
1358 (:delayed
1366 ;;; Clear any delayed transform with no reasons - these should have
1367 ;;; been tried in the last pass. Then remove the reason from the
1368 ;;; delayed transform reasons, and if any become empty then set
1369 ;;; reoptimize flags for the node. Return true if any transforms are
1370 ;;; to be retried.
1386 reoptimize))
1388 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1389 ;;; environment, and then install it as the function for the call
1390 ;;; NODE. We do local call analysis so that the new function is
1391 ;;; integrated into the control flow.
1392 ;;;
1393 ;;; We require the original function source name in order to generate
1394 ;;; a meaningful debug name for the lambda we set up. (It'd be
1395 ;;; possible to do this starting from debug names as well as source
1396 ;;; names, but as of sbcl-0.7.1.5, there was no need for this
1397 ;;; generality, since source names are always known to our callers.)
1405 :policy
1406 ;; The internal variables of a transform are not going to be
1407 ;; interesting to the debugger, so there's no sense in
1408 ;; suppressing the substitution of variables with only one use
1409 ;; (the extra variables can slow down constraint propagation).
1411 preserve-single-use-debug-variables
1412 0
1419 res
1426 ;; Don't lose the original derived type
1435 ;; This is mainly to call PROPAGATE-LET-ARGS so that the
1436 ;; newly converted code gets to better types sooner.
1444 t)
1453 ;;; Return T if the function is foldable and if it's marked as CALL
1454 ;;; all function arguments are FOLDABLE too.
1460 nil)
1465 args)
1470 combination)))
1474 ;;; Replace a call to a foldable function of constant arguments with
1475 ;;; the result of evaluating the form. If there is an error during the
1476 ;;; evaluation, we give a warning and leave the call alone, making the
1477 ;;; call a :ERROR call.
1478 ;;;
1479 ;;; If there is more than one value, then we transform the call into a
1480 ;;; VALUES form.
1491 args
1492 call
1493 ;; Note: CMU CL had COMPILER-WARN here, and that
1494 ;; seems more natural, but it's probably not.
1495 ;;
1496 ;; It's especially not while bug 173 exists:
1497 ;; Expressions like
1498 ;; (COND (END
1499 ;; (UNLESS (OR UNSAFE? (<= END SIZE)))
1500 ;; ...))
1501 ;; can cause constant-folding TYPE-ERRORs (in
1502 ;; #'<=) when END can be proved to be NIL, even
1503 ;; though the code is perfectly legal and safe
1504 ;; because a NIL value of END means that the
1505 ;; #'<= will never be executed.
1506 ;;
1507 ;; Moreover, even without bug 173,
1508 ;; quite-possibly-valid code like
1509 ;; (COND ((NONINLINED-PREDICATE END)
1510 ;; (UNLESS (<= END SIZE))
1511 ;; ...))
1512 ;; (where NONINLINED-PREDICATE is something the
1513 ;; compiler can't do at compile time, but which
1514 ;; turns out to make the #'<= expression
1515 ;; unreachable when END=NIL) could cause errors
1516 ;; when the compiler tries to constant-fold (<=
1517 ;; END SIZE).
1518 ;;
1519 ;; So, with or without bug 173, it'd be
1520 ;; unnecessarily evil to do a full
1521 ;; COMPILER-WARNING (and thus return FAILURE-P=T
1522 ;; from COMPILE-FILE) for legal code, so we we
1523 ;; use a wimpier COMPILE-STYLE-WARNING instead.
1525 ;; On the other hand, for code we control, we
1526 ;; should be able to work around any bug
1527 ;; 173-related problems, and in particular we
1528 ;; want to be alerted to calls to our own
1529 ;; functions which aren't being folded away; a
1530 ;; COMPILER-WARNING is butch enough to stop the
1531 ;; SBCL build itself in its tracks.
1551 call
1555 fun-name))))))
1557 \f
1558 ;;;; local call optimization
1560 ;;; Propagate TYPE to LEAF and its REFS, marking things changed.
1561 ;;;
1562 ;;; If the leaf type is a function type, then just leave it alone, since TYPE
1563 ;;; is never going to be more specific than that (and TYPE-INTERSECTION would
1564 ;;; choke.)
1565 ;;;
1566 ;;; Also, if the type is one requiring special care don't touch it if the leaf
1567 ;;; has multiple references -- otherwise LVAR-CONSERVATIVE-TYPE is screwed.
1582 ;; KLUDGE: LET var substitution
1588 ;;; Iteration variable: exactly one SETQ of the form:
1589 ;;;
1590 ;;; (let ((var initial))
1591 ;;; ...
1592 ;;; (setq var (+ var step))
1593 ;;; ...)
1619 ;; Detect cases like (LOOP FOR 1.0 to 5.0 ...), where
1620 ;; the initial and the step are of different types,
1621 ;; and the step is less contagious.
1624 step-type))))
1663 :low low
1664 :high high
1667 "check for iteration variable reoptimization"
1677 ;;; Figure out the type of a LET variable that has sets. We compute
1678 ;;; the union of the INITIAL-TYPE and the types of all the set
1679 ;;; values and to a PROPAGATE-TO-REFS with this type.
1699 ;;; If a LET variable, find the initial value's type and do
1700 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1701 ;;; type.
1717 ;;; Return true if the value of REF will always be the same (and is
1718 ;;; thus legal to substitute.)
1730 (:global-function
1737 ;;; If we have a non-set LET var with a single use, then (if possible)
1738 ;;; replace the variable reference's LVAR with the arg lvar.
1739 ;;;
1740 ;;; We change the REF to be a reference to NIL with unused value, and
1741 ;;; let it be flushed as dead code. A side effect of this substitution
1742 ;;; is to delete the variable.
1750 ;; Think about (LET ((A ...)) (IF ... A ...)): two
1751 ;; LVAR-USEs should not be met on one path. Another problem
1752 ;; is with dynamic-extent.
1755 ;; If the destinatation is dynamic extent, don't substitute unless
1756 ;; the source is as well.
1761 ;; we should not change lifetime of unknown values lvars
1768 ;; CASTs can disappear, don't substitute if
1769 ;; DEST-LVAR has other uses (this will be
1770 ;; insufficient if we have a CAST-CAST chain, but
1771 ;; works well for a single CAST)
1779 ;; While CRETURN and EXIT nodes may be known-values,
1780 ;; they have their own complications, such as
1781 ;; substitution into CRETURN may create new tail calls.
1782 nil)
1785 t))
1791 ;; Really it is (EQ (LVAR-USES LVAR) REF):
1792 t)
1797 ;; KLUDGE: it should be (TYPE-CHECK 0)
1801 ;; FIXME
1802 t)
1810 t)))
1812 ;;; Delete a LET, removing the call and bind nodes, and warning about
1813 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1814 ;;; along right away and delete the REF and then the lambda, since we
1815 ;;; flush the FUN lvar.
1830 ;;; This function is called when one of the arguments to a LET
1831 ;;; changes. We look at each changed argument. If the corresponding
1832 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1833 ;;; consider substituting for the variable, and also propagate
1834 ;;; derived-type information for the arg to all the VAR's refs.
1835 ;;;
1836 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1837 ;;; subtype of the argument's leaf type. This prevents type checking
1838 ;;; from being defeated, and also ensures that the best representation
1839 ;;; for the variable can be used.
1840 ;;;
1841 ;;; Substitution of individual references is inhibited if the
1842 ;;; reference is in a different component from the home. This can only
1843 ;;; happen with closures over top level lambda vars. In such cases,
1844 ;;; the references may have already been compiled, and thus can't be
1845 ;;; retroactively modified.
1846 ;;;
1847 ;;; If all of the variables are deleted (have no references) when we
1848 ;;; are done, then we delete the LET.
1849 ;;;
1850 ;;; Note that we are responsible for clearing the LVAR-REOPTIMIZE
1851 ;;; flags.
1866 ;; (NODE-DERIVED-TYPE USE) would
1867 ;; be better -- APD, 2003-05-15
1875 t)
1878 nil)))
1879 leaf var)))
1880 t))))))
1887 call
1895 ;;; This function is called when one of the args to a non-LET local
1896 ;;; call changes. For each changed argument corresponding to an unset
1897 ;;; variable, we compute the union of the types across all calls and
1898 ;;; propagate this type information to the var's refs.
1899 ;;;
1900 ;;; If the function has an entry-fun, then we don't do anything: since
1901 ;;; it has a XEP we would not discover anything.
1902 ;;;
1903 ;;; If the function is an optional-entry-point, we will just make sure
1904 ;;; &REST lists are known to be lists. Doing the regular rigamarole
1905 ;;; can erronously propagate too strict types into refs: see
1906 ;;; BUG-655203-REGRESSION in tests/compiler.pure.lisp.
1907 ;;;
1908 ;;; We can clear the LVAR-REOPTIMIZE flags for arguments in all calls
1909 ;;; corresponding to changed arguments in CALL, since the only use in
1910 ;;; IR1 optimization of the REOPTIMIZE flag for local call args is
1911 ;;; right here.
1916 ;; We can still make sure &REST is known to be a list.
1921 ;; The normal case.
1929 vars))
1945 union)))))
1948 and type in union
1952 \f
1953 ;;;; multiple values optimization
1955 ;;; Do stuff to notice a change to a MV combination node. There are
1956 ;;; two main branches here:
1957 ;;; -- If the call is local, then it is already a MV let, or should
1958 ;;; become one. Note that although all :LOCAL MV calls must eventually
1959 ;;; be converted to :MV-LETs, there can be a window when the call
1960 ;;; is local, but has not been LET converted yet. This is because
1961 ;;; the entry-point lambdas may have stray references (in other
1962 ;;; entry points) that have not been deleted yet.
1963 ;;; -- The call is full. This case is somewhat similar to the non-MV
1964 ;;; combination optimization: we propagate return type information and
1965 ;;; notice non-returning calls. We also have an optimization
1966 ;;; which tries to convert MV-CALLs into MV-binds.
1972 (:local
1979 do
1984 (:full
1987 do
2018 sum nvals)))
2022 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
2023 at least ~R."
2024 total-nvals min)
2029 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
2030 at most ~R."
2031 total-nvals max)
2037 min)
2055 ;;; If we see:
2056 ;;; (multiple-value-bind
2057 ;;; (x y)
2058 ;;; (values xx yy)
2059 ;;; ...)
2060 ;;; Convert to:
2061 ;;; (let ((x xx)
2062 ;;; (y yy))
2063 ;;; ...)
2064 ;;;
2065 ;;; What we actually do is convert the VALUES combination into a
2066 ;;; normal LET combination calling the original :MV-LET lambda. If
2067 ;;; there are extra args to VALUES, discard the corresponding
2068 ;;; lvars. If there are insufficient args, insert references to NIL.
2093 for prev = node-prev then ctran
2099 use ctran))
2113 ;; Propagate derived types from the VALUES call to its args:
2114 ;; transforms can leave the VALUES call with a better type
2115 ;; than its args have, so make sure not to throw that away.
2121 ;; Propagate declared types of MV-BIND variables.
2124 t)))
2126 ;;; If we see:
2127 ;;; (values-list (list x y z))
2128 ;;;
2129 ;;; Convert to:
2130 ;;; (values x y z)
2131 ;;;
2132 ;;; In implementation, this is somewhat similar to
2133 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
2134 ;;; args of the VALUES-LIST call, flushing the old argument lvar
2135 ;;; (allowing the LIST to be flushed.)
2136 ;;;
2137 ;;; FIXME: Thus we lose possible type assertions on (LIST ...).
2144 ;; FIXME: VALUES might not satisfy an assertion on NODE-LVAR.
2156 t)))
2158 ;;; If VALUES appears in a non-MV context, then effectively convert it
2159 ;;; to a PROG1. This allows the computation of the additional values
2160 ;;; to become dead code.
2172 val))
2173 nil))
2175 ;;; TODO:
2176 ;;; - CAST chains;
2193 ;; VESTIGIAL-EXIT-CASTs come from MULTIPLE-VALUES-PROG1 to avoid
2194 ;; overwriting their lvars
2198 #+sb-xc-host context
2224 lvar)
2225 ;; Pathwise removing of CAST
2228 next-block)
2262 ;; No need to transform into an analog of
2263 ;; %COMPILE-TIME-TYPE-ERROR, %CHECK-BOUND will signal at
2264 ;; run-time and %CHECK-BOUND ir2-converter will signal at
2265 ;; compile-time if it survives further stages of ir1
2266 ;; optimization.
2269 ;; FIXME: Do it in one step.
2274 value
2280 ;; FIXME: Derived type.
2290 ',detail
2293 ;; KLUDGE: FILTER-LVAR does not work for non-returning
2294 ;; functions, so we declare the return type of
2295 ;; %COMPILE-TIME-TYPE-ERROR to be * and derive the real type
2296 ;; here.
2300 ;; FIXME: Is it necessary?