| blob | 86672e9b52a60a9d9d2f15b640c1fb0f73ef6be6 |
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.
273 ;;; Annotate NODE to indicate that its result has been proven to be
274 ;;; TYPEP to RTYPE. After IR1 conversion has happened, this is the
275 ;;; only correct way to supply information discovered about a node's
276 ;;; type. If you screw with the NODE-DERIVED-TYPE directly, then
277 ;;; information may be lost and reoptimization may not happen.
278 ;;;
279 ;;; What we do is intersect RTYPE with NODE's DERIVED-TYPE. If the
280 ;;; intersection is different from the old type, then we do a
281 ;;; REOPTIMIZE-LVAR on the NODE-LVAR.
287 initial-type)))
298 "New inferred type ~S conflicts with old type:~
299 ~% ~S~%*** possible internal error? Please report this."
302 ;; If the new type consists of only one object, replace the
303 ;; node with a constant reference.
314 ;;; This is similar to DERIVE-NODE-TYPE, but asserts that it is an
315 ;;; error for LVAR's value not to be TYPEP to TYPE. We implement it
316 ;;; splitting off DEST a new CAST node; old LVAR will deliver values
317 ;;; to CAST. If we improve the assertion, we set TYPE-CHECK to
318 ;;; guarantee that the new assertion will be checked.
326 context)))
328 t))))
330 \f
331 ;;;; IR1-OPTIMIZE
333 ;;; Do one forward pass over COMPONENT, deleting unreachable blocks
334 ;;; and doing IR1 optimizations. We can ignore all blocks that don't
335 ;;; have the REOPTIMIZE flag set. If COMPONENT-REOPTIMIZE is true when
336 ;;; we are done, then another iteration would be beneficial.
342 for last-block = block
345 ;; We delete blocks when there is either no predecessor or the
346 ;; block is in a lambda that has been deleted. These blocks
347 ;; would eventually be deleted by DFO recomputation, but doing
348 ;; it here immediately makes the effect available to IR1
349 ;; optimization.
355 ;; Preserve the BLOCK-SUCC invariant that almost every block has
356 ;; one successor (and a block with DELETE-P set is an acceptable
357 ;; exception).
392 ;;; Loop over the nodes in BLOCK, acting on (and clearing) REOPTIMIZE
393 ;;; flags.
394 ;;;
395 ;;; Note that although they are cleared here, REOPTIMIZE flags might
396 ;;; still be set upon return from this function, meaning that further
397 ;;; optimization is wanted (as a consequence of optimizations we did).
400 ;; We clear the node and block REOPTIMIZE flags before doing the
401 ;; optimization, not after. This ensures that the node or block will
402 ;; be reoptimized if necessary.
406 ;; As above, we clear the node REOPTIMIZE flag before optimizing.
411 ;; With a COMBINATION, we call PROPAGATE-FUN-CHANGE whenever
412 ;; the function changes, and call IR1-OPTIMIZE-COMBINATION if
413 ;; any argument changes.
418 ;; KLUDGE: We leave the NODE-OPTIMIZE flag set going into
419 ;; IR1-OPTIMIZE-RETURN, since IR1-OPTIMIZE-RETURN wants to
420 ;; clear the flag itself. -- WHN 2002-02-02, quoting original
421 ;; CMU CL comments
427 ;; With an EXIT, we derive the node's type from the VALUE's
428 ;; type.
433 ;; PROPAGATE-FROM-SETS can do a better job if NODE-REOPTIMIZE
434 ;; is accurate till the node actually has been reoptimized.
442 ;;; Try to join with a successor block. If we succeed, we return true,
443 ;;; otherwise false.
450 ;; the successor has more than one predecessor;
452 ;; the successor is the current block (infinite loop);
454 ;; the next block has a different cleanup, and thus
455 ;; we may want to insert cleanup code between the
456 ;; two blocks at some point;
459 ;; the next block has a different home lambda, and
460 ;; thus the control transfer is a non-local exit.
463 ;; Stack analysis phase wants ENTRY to start a block...
469 ;; ... and a DX-allocator to end a block.
471 ;; ... and for there to be no chance of there
472 ;; being two successive USEs of the same
473 ;; multi-valued LVAR in the same block (since
474 ;; we can only insert cleanup code at block
475 ;; boundaries, but need to discard
476 ;; multi-valued LVAR contents before they are
477 ;; overwritten).
480 nil)
483 t)))))
485 ;;; Join together two blocks. The code in BLOCK2 is moved into BLOCK1
486 ;;; and BLOCK2 is deleted from the DFO. We combine the optimize flags
487 ;;; for the two blocks so that any indicated optimization gets done.
519 ;;; Delete any nodes in BLOCK whose value is unused and which have no
520 ;;; side effects. We can delete sets of lexical variables when the set
521 ;;; variable has no references.
530 ;; This must be a preceding node and the current node will
531 ;; overwrite the value, unlink the lvar and the node will
532 ;; get a chance to be deleted on one of the next iterations
574 victim)
575 \f
576 ;;;; local call return type propagation
578 ;;; This function is called on RETURN nodes that have their REOPTIMIZE
579 ;;; flag set. It iterates over the uses of the RESULT, looking for
580 ;;; interesting stuff to update the TAIL-SET. If a use isn't a local
581 ;;; call, then we union its type together with the types of other such
582 ;;; uses. We assign to the RETURN-RESULT-TYPE the intersection of this
583 ;;; type with the RESULT's asserted type. We can make this
584 ;;; intersection now (potentially before type checking) because this
585 ;;; assertion on the result will eventually be checked (if
586 ;;; appropriate.)
587 ;;;
588 ;;; We call MAYBE-CONVERT-TAIL-LOCAL-CALL on each local non-MV
589 ;;; combination, which may change the successor of the call to be the
590 ;;; called function, and if so, checks if the call can become an
591 ;;; assignment. If we convert to an assignment, we abort, since the
592 ;;; RETURN has been deleted.
613 ;; (values-type-intersection
614 ;; (continuation-asserted-type result) ; FIXME -- APD, 2002-01-26
616 ;; )
617 ))
619 nil)
621 ;;; Do stuff to realize that something has changed about the value
622 ;;; delivered to a return node. Since we consider the return values of
623 ;;; all functions in the tail set to be equivalent, this amounts to
624 ;;; bringing the entire tail set up to date. We iterate over the
625 ;;; returns for all the functions in the tail set, reanalyzing them
626 ;;; all (not treating NODE specially.)
627 ;;;
628 ;;; When we are done, we check whether the new type is different from
629 ;;; the old TAIL-SET-TYPE. If so, we set the type and also reoptimize
630 ;;; all the lvars for references to functions in the tail set. This
631 ;;; will cause IR1-OPTIMIZE-COMBINATION to derive the new type as the
632 ;;; results of the calls.
637 :restart
657 \f
658 ;;;; IF optimization
660 ;;; Utility: return T if both argument cblocks are equivalent. For now,
661 ;;; detect only blocks that read the same leaf into the same lvar, and
662 ;;; continue to the same block.
675 ;;; Check whether the predicate is known to be true or false,
676 ;;; deleting the IF node in favor of the appropriate branch when this
677 ;;; is the case.
678 ;;; Similarly, when both branches are equivalent, branch directly to either
679 ;;; of them.
680 ;;; Also, if the test has multiple uses, replicate the node when possible...
681 ;;; in fact, splice in direct jumps to the right branch if possible.
693 alternative)
695 consequent)
698 ;; Even if the references are the same they can have
699 ;; different derived types based on the TEST
700 ;; Don't lose the second type when killing it.
707 alternative))))
715 ;; When we know that we only have a single successor, kill the victim
716 ;; ... unless the victim and the remaining successor are the same.
725 ;; When if/if conversion would leave (if ... (if nil ...)) or
726 ;; (if ... (if not-nil ...)), splice the correct successor right
727 ;; in.
746 ;; only one use left. Just kill the now-useless
747 ;; branch to avoid spurious code deletion notes.
750 node test block
756 ;; Finally, duplicate EQ-nil tests
763 ;; leave the last use as is, instead of replacing
764 ;; the (singly-referenced) CIF node with a duplicate.
767 ;;; Create a new copy of an IF node that tests the value of the node
768 ;;; USE. The test must have >1 use, and must be immediately used by
769 ;;; USE. NODE must be the only node in its block (implying that
770 ;;; block-start = if-test).
771 ;;;
772 ;;; This optimization has an effect semantically similar to the
773 ;;; source-to-source transformation:
774 ;;; (IF (IF A B C) D E) ==>
775 ;;; (IF A (IF B D E) (IF C D E))
776 ;;;
777 ;;; We clobber the NODE-SOURCE-PATH of both the original and the new
778 ;;; node so that dead code deletion notes will definitely not consider
779 ;;; either node to be part of the original source. One node might
780 ;;; become unreachable, resulting in a spurious note.
792 :consequent cblock
814 \f
815 ;;;; exit IR1 optimization
817 ;;; This function attempts to delete an exit node, returning true if
818 ;;; it deletes the block as a consequence:
819 ;;; -- If the exit is degenerate (has no ENTRY), then we don't do
820 ;;; anything, since there is nothing to be done.
821 ;;; -- If the exit node and its ENTRY have the same home lambda then
822 ;;; we know the exit is local, and can delete the exit. We change
823 ;;; uses of the Exit-Value to be uses of the original lvar,
824 ;;; then unlink the node. If the exit is to a TR context, then we
825 ;;; must do MERGE-TAIL-SETS on any local calls which delivered
826 ;;; their value to this exit.
827 ;;; -- If there is no value (as in a GO), then we skip the value
828 ;;; semantics.
829 ;;;
830 ;;; This function is also called by environment analysis, since it
831 ;;; wants all exits to be optimized even if normal optimization was
832 ;;; omitted.
844 \f
845 ;;;; combination IR1 optimization
847 ;;; Report as we try each transform?
848 #!+sb-show
856 "The return value of ~A should not be discarded."
859 ;;; Do IR1 optimizations on a COMBINATION node.
875 ;; If somebody is really sure that they want to modify
876 ;; constants, let them.
892 (:local
897 (:error
899 (:full
902 ;; This is a known function marked NOTINLINE
905 ;; Check against the DEFINED-TYPE unless TYPE is already good.
915 (:known
931 ;; First give the VM a peek at the call
935 (:direct
936 ;; The VM knows how to handle this.
937 )
938 (:transform
939 ;; The VM mostly knows how to handle this. We need
940 ;; to massage the call slightly, though.
943 ;; Let transforms have a crack at it.
945 #!+sb-show
951 #!+sb-show
965 ;;; If NODE doesn't return (i.e. return type is NIL), then terminate
966 ;;; the block there, and link it to the component tail.
967 ;;;
968 ;;; Except when called during IR1 convertion, we delete the
969 ;;; continuation if it has no other uses. (If it does have other uses,
970 ;;; we reoptimize.)
971 ;;;
972 ;;; Termination on the basis of a continuation type is
973 ;;; inhibited when:
974 ;;; -- The continuation is deleted (hence the assertion is spurious), or
975 ;;; -- We are in IR1 conversion (where THE assertions are subject to
976 ;;; weakening.) FIXME: Now THE assertions are not weakened, but new
977 ;;; uses can(?) be added later. -- APD, 2003-07-17
978 ;;;
979 ;;; Why do we need to consider LVAR type? -- APD, 2003-07-30
990 ;; Even if the combination will never return, don't terminate if this
991 ;; is the tail call of a XEP: doing that would inhibit TCO.
1018 t))))
1020 ;;; This is called both by IR1 conversion and IR1 optimization when
1021 ;;; they have verified the type signature for the call, and are
1022 ;;; wondering if something should be done to special-case the call. If
1023 ;;; CALL is a call to a global function, then see whether it defined
1024 ;;; or known:
1025 ;;; -- If a DEFINED-FUN should be inline expanded, then convert
1026 ;;; the expansion and change the call to call it. Expansion is
1027 ;;; enabled if :INLINE or if SPACE=0. If the FUNCTIONAL slot is
1028 ;;; true, we never expand, since this function has already been
1029 ;;; converted. Local call analysis will duplicate the definition
1030 ;;; if necessary. We claim that the parent form is LABELS for
1031 ;;; context declarations, since we don't want it to be considered
1032 ;;; a real global function.
1033 ;;; -- If it is a known function, mark it as such by setting the KIND.
1034 ;;;
1035 ;;; We return the leaf referenced (NIL if not a leaf) and the
1036 ;;; FUN-INFO assigned.
1060 ;; Inline: if the function has already been converted at another call
1061 ;; site in this component, we point this REF to the functional. If not,
1062 ;; we convert the expansion.
1063 ;;
1064 ;; For :INLINE case local call analysis will copy the expansion later,
1065 ;; but for :MAYBE-INLINE and NIL cases we only get one copy of the
1066 ;; expansion per component.
1067 ;;
1068 ;; FIXME: We also convert in :INLINE & FUNCTIONAL-KIND case below. What
1069 ;; is it for?
1074 ;; Convert.
1077 name
1079 leaf
1080 inlinep
1082 ;; Allow backward references to this function from following
1083 ;; forms. (Reused only if policy matches.)
1088 ;; If we've already converted, change ref to the converted
1089 ;; functional.
1101 ;;; Check whether CALL satisfies TYPE. If so, apply the type to the
1102 ;;; call, and do MAYBE-TERMINATE-BLOCK and return the values of
1103 ;;; RECOGNIZE-KNOWN-CALL. If an error, set the combination kind and
1104 ;;; return NIL, NIL. If the type is just FUNCTION, then skip the
1105 ;;; syntax check, arg/result type processing, but still call
1106 ;;; RECOGNIZE-KNOWN-CALL, since the call might be to a known lambda,
1107 ;;; and that checking is done by local call analysis.
1116 ;; Using the defined-type too early is a bit of a waste: during
1117 ;; conversion we cannot use the untrusted ASSERT-CALL-TYPE, etc.
1122 ;; Don't validate multiple times against the same leaf --
1123 ;; it doesn't add any information, but may generate the same warning
1124 ;; multiple times.
1128 :result-test nil
1130 #'compiler-warn
1133 same-file-p)
1139 :result-test nil
1149 ;;; This is called by IR1-OPTIMIZE when the function for a call has
1150 ;;; changed. If the call is local, we try to LET-convert it, and
1151 ;;; derive the result type. If it is a :FULL call, we validate it
1152 ;;; against the type, which recognizes known calls, does inline
1153 ;;; expansion, etc. If a call to a predicate in a non-conditional
1154 ;;; position or to a function with a source transform, then we
1155 ;;; reconvert the form to give IR1 another chance.
1162 (:local
1167 (:full
1176 call))
1184 predicate)
1197 nil))))))))
1199 \f
1200 ;;;; known function optimization
1202 ;;; Add a failed optimization note to FAILED-OPTIMZATIONS for NODE,
1203 ;;; FUN and ARGS. If there is already a note for NODE and TRANSFORM,
1204 ;;; replace it, otherwise add a new one.
1215 ;;; Attempt to transform NODE using TRANSFORM-FUNCTION, subject to the
1216 ;;; call type constraint TRANSFORM-TYPE. If we are inhibited from
1217 ;;; doing the transform for some reason and FLAME is true, then we
1218 ;;; make a note of the message in FAILED-OPTIMIZATIONS for IR1
1219 ;;; finalize to pick up. We return true if the transform failed, and
1220 ;;; thus further transformation should be attempted. We return false
1221 ;;; if either the transform succeeded or was aborted.
1245 (:none
1247 nil)
1248 (:aborted
1253 nil)
1254 (:failure
1260 t)
1261 (:delayed
1263 nil))))
1266 type
1270 t)
1272 t))))
1274 ;;; When we don't like an IR1 transform, we throw the severity/reason
1275 ;;; and args.
1276 ;;;
1277 ;;; GIVE-UP-IR1-TRANSFORM is used to throw out of an IR1 transform,
1278 ;;; aborting this attempt to transform the call, but admitting the
1279 ;;; possibility that this or some other transform will later succeed.
1280 ;;; If arguments are supplied, they are format arguments for an
1281 ;;; efficiency note.
1282 ;;;
1283 ;;; ABORT-IR1-TRANSFORM is used to throw out of an IR1 transform and
1284 ;;; force a normal call to the function at run time. No further
1285 ;;; optimizations will be attempted.
1286 ;;;
1287 ;;; DELAY-IR1-TRANSFORM is used to throw out of an IR1 transform, and
1288 ;;; delay the transform on the node until later. REASONS specifies
1289 ;;; when the transform will be later retried. The :OPTIMIZE reason
1290 ;;; causes the transform to be delayed until after the current IR1
1291 ;;; optimization pass. The :CONSTRAINT reason causes the transform to
1292 ;;; be delayed until after constraint propagation.
1293 ;;;
1294 ;;; FIXME: Now (0.6.11.44) that there are 4 variants of this (GIVE-UP,
1295 ;;; ABORT, DELAY/:OPTIMIZE, DELAY/:CONSTRAINT) and we're starting to
1296 ;;; do CASE operations on the various REASON values, it might be a
1297 ;;; good idea to go OO, representing the reasons by objects, using
1298 ;;; CLOS methods on the objects instead of CASE, and (possibly) using
1299 ;;; SIGNAL instead of THROW.
1317 ;;; Poor man's catching and resignalling
1318 ;;; Implicit %GIVE-UP macrolet will resignal the give-up "condition"
1328 (:delayed
1336 ;;; Clear any delayed transform with no reasons - these should have
1337 ;;; been tried in the last pass. Then remove the reason from the
1338 ;;; delayed transform reasons, and if any become empty then set
1339 ;;; reoptimize flags for the node. Return true if any transforms are
1340 ;;; to be retried.
1356 reoptimize))
1358 ;;; Take the lambda-expression RES, IR1 convert it in the proper
1359 ;;; environment, and then install it as the function for the call
1360 ;;; NODE. We do local call analysis so that the new function is
1361 ;;; integrated into the control flow.
1362 ;;;
1363 ;;; We require the original function source name in order to generate
1364 ;;; a meaningful debug name for the lambda we set up. (It'd be
1365 ;;; possible to do this starting from debug names as well as source
1366 ;;; names, but as of sbcl-0.7.1.5, there was no need for this
1367 ;;; generality, since source names are always known to our callers.)
1375 :policy
1376 ;; The internal variables of a transform are not going to be
1377 ;; interesting to the debugger, so there's no sense in
1378 ;; suppressing the substitution of variables with only one use
1379 ;; (the extra variables can slow down constraint propagation).
1381 preserve-single-use-debug-variables
1382 0
1389 res
1396 ;; Don't lose the original derived type
1405 ;; This is mainly to call PROPAGATE-LET-ARGS so that the
1406 ;; newly converted code gets to better types sooner.
1414 t)
1423 ;;; Return T if the function is foldable and if it's marked as CALL
1424 ;;; all function arguments are FOLDABLE too.
1430 nil)
1435 args)
1441 combination)))
1445 ;;; Replace a call to a foldable function of constant arguments with
1446 ;;; the result of evaluating the form. If there is an error during the
1447 ;;; evaluation, we give a warning and leave the call alone, making the
1448 ;;; call a :ERROR call.
1449 ;;;
1450 ;;; If there is more than one value, then we transform the call into a
1451 ;;; VALUES form.
1462 args
1463 call
1464 ;; Note: CMU CL had COMPILER-WARN here, and that
1465 ;; seems more natural, but it's probably not.
1466 ;;
1467 ;; It's especially not while bug 173 exists:
1468 ;; Expressions like
1469 ;; (COND (END
1470 ;; (UNLESS (OR UNSAFE? (<= END SIZE)))
1471 ;; ...))
1472 ;; can cause constant-folding TYPE-ERRORs (in
1473 ;; #'<=) when END can be proved to be NIL, even
1474 ;; though the code is perfectly legal and safe
1475 ;; because a NIL value of END means that the
1476 ;; #'<= will never be executed.
1477 ;;
1478 ;; Moreover, even without bug 173,
1479 ;; quite-possibly-valid code like
1480 ;; (COND ((NONINLINED-PREDICATE END)
1481 ;; (UNLESS (<= END SIZE))
1482 ;; ...))
1483 ;; (where NONINLINED-PREDICATE is something the
1484 ;; compiler can't do at compile time, but which
1485 ;; turns out to make the #'<= expression
1486 ;; unreachable when END=NIL) could cause errors
1487 ;; when the compiler tries to constant-fold (<=
1488 ;; END SIZE).
1489 ;;
1490 ;; So, with or without bug 173, it'd be
1491 ;; unnecessarily evil to do a full
1492 ;; COMPILER-WARNING (and thus return FAILURE-P=T
1493 ;; from COMPILE-FILE) for legal code, so we we
1494 ;; use a wimpier COMPILE-STYLE-WARNING instead.
1496 ;; On the other hand, for code we control, we
1497 ;; should be able to work around any bug
1498 ;; 173-related problems, and in particular we
1499 ;; want to be alerted to calls to our own
1500 ;; functions which aren't being folded away; a
1501 ;; COMPILER-WARNING is butch enough to stop the
1502 ;; SBCL build itself in its tracks.
1522 call
1526 fun-name))))))
1528 \f
1529 ;;;; local call optimization
1531 ;;; Propagate TYPE to LEAF and its REFS, marking things changed.
1532 ;;;
1533 ;;; If the leaf type is a function type, then just leave it alone, since TYPE
1534 ;;; is never going to be more specific than that (and TYPE-INTERSECTION would
1535 ;;; choke.)
1536 ;;;
1537 ;;; Also, if the type is one requiring special care don't touch it if the leaf
1538 ;;; has multiple references -- otherwise LVAR-CONSERVATIVE-TYPE is screwed.
1553 ;; KLUDGE: LET var substitution
1559 ;;; Iteration variable: exactly one SETQ of the form:
1560 ;;;
1561 ;;; (let ((var initial))
1562 ;;; ...
1563 ;;; (setq var (+ var step))
1564 ;;; ...)
1590 ;; Detect cases like (LOOP FOR 1.0 to 5.0 ...), where
1591 ;; the initial and the step are of different types,
1592 ;; and the step is less contagious.
1595 step-type))))
1634 :low low
1635 :high high
1638 "check for iteration variable reoptimization"
1648 ;;; Figure out the type of a LET variable that has sets. We compute
1649 ;;; the union of the INITIAL-TYPE and the types of all the set
1650 ;;; values and to a PROPAGATE-TO-REFS with this type.
1670 ;;; If a LET variable, find the initial value's type and do
1671 ;;; PROPAGATE-FROM-SETS. We also derive the VALUE's type as the node's
1672 ;;; type.
1688 ;;; Return true if the value of REF will always be the same (and is
1689 ;;; thus legal to substitute.)
1701 (:global-function
1708 ;;; If we have a non-set LET var with a single use, then (if possible)
1709 ;;; replace the variable reference's LVAR with the arg lvar.
1710 ;;;
1711 ;;; We change the REF to be a reference to NIL with unused value, and
1712 ;;; let it be flushed as dead code. A side effect of this substitution
1713 ;;; is to delete the variable.
1721 ;; Think about (LET ((A ...)) (IF ... A ...)): two
1722 ;; LVAR-USEs should not be met on one path. Another problem
1723 ;; is with dynamic-extent.
1726 ;; If the destinatation is dynamic extent, don't substitute unless
1727 ;; the source is as well.
1732 ;; we should not change lifetime of unknown values lvars
1739 ;; CASTs can disappear, don't substitute if
1740 ;; DEST-LVAR has other uses (this will be
1741 ;; insufficient if we have a CAST-CAST chain, but
1742 ;; works well for a single CAST)
1750 ;; While CRETURN and EXIT nodes may be known-values,
1751 ;; they have their own complications, such as
1752 ;; substitution into CRETURN may create new tail calls.
1753 nil)
1756 t))
1762 ;; Really it is (EQ (LVAR-USES LVAR) REF):
1763 t)
1768 ;; KLUDGE: it should be (TYPE-CHECK 0)
1772 ;; FIXME
1773 t)
1781 t)))
1783 ;;; Delete a LET, removing the call and bind nodes, and warning about
1784 ;;; any unreferenced variables. Note that FLUSH-DEAD-CODE will come
1785 ;;; along right away and delete the REF and then the lambda, since we
1786 ;;; flush the FUN lvar.
1801 ;;; This function is called when one of the arguments to a LET
1802 ;;; changes. We look at each changed argument. If the corresponding
1803 ;;; variable is set, then we call PROPAGATE-FROM-SETS. Otherwise, we
1804 ;;; consider substituting for the variable, and also propagate
1805 ;;; derived-type information for the arg to all the VAR's refs.
1806 ;;;
1807 ;;; Substitution is inhibited when the arg leaf's derived type isn't a
1808 ;;; subtype of the argument's leaf type. This prevents type checking
1809 ;;; from being defeated, and also ensures that the best representation
1810 ;;; for the variable can be used.
1811 ;;;
1812 ;;; Substitution of individual references is inhibited if the
1813 ;;; reference is in a different component from the home. This can only
1814 ;;; happen with closures over top level lambda vars. In such cases,
1815 ;;; the references may have already been compiled, and thus can't be
1816 ;;; retroactively modified.
1817 ;;;
1818 ;;; If all of the variables are deleted (have no references) when we
1819 ;;; are done, then we delete the LET.
1820 ;;;
1821 ;;; Note that we are responsible for clearing the LVAR-REOPTIMIZE
1822 ;;; flags.
1837 ;; (NODE-DERIVED-TYPE USE) would
1838 ;; be better -- APD, 2003-05-15
1847 t)
1850 nil)))
1851 leaf var)))
1852 t))))))
1859 call
1867 ;;; This function is called when one of the args to a non-LET local
1868 ;;; call changes. For each changed argument corresponding to an unset
1869 ;;; variable, we compute the union of the types across all calls and
1870 ;;; propagate this type information to the var's refs.
1871 ;;;
1872 ;;; If the function has an entry-fun, then we don't do anything: since
1873 ;;; it has a XEP we would not discover anything.
1874 ;;;
1875 ;;; If the function is an optional-entry-point, we will just make sure
1876 ;;; &REST lists are known to be lists. Doing the regular rigamarole
1877 ;;; can erronously propagate too strict types into refs: see
1878 ;;; BUG-655203-REGRESSION in tests/compiler.pure.lisp.
1879 ;;;
1880 ;;; We can clear the LVAR-REOPTIMIZE flags for arguments in all calls
1881 ;;; corresponding to changed arguments in CALL, since the only use in
1882 ;;; IR1 optimization of the REOPTIMIZE flag for local call args is
1883 ;;; right here.
1888 ;; We can still make sure &REST is known to be a list.
1893 ;; The normal case.
1901 vars))
1917 union)))))
1920 and type in union
1924 \f
1925 ;;;; multiple values optimization
1927 ;;; Do stuff to notice a change to a MV combination node. There are
1928 ;;; two main branches here:
1929 ;;; -- If the call is local, then it is already a MV let, or should
1930 ;;; become one. Note that although all :LOCAL MV calls must eventually
1931 ;;; be converted to :MV-LETs, there can be a window when the call
1932 ;;; is local, but has not been LET converted yet. This is because
1933 ;;; the entry-point lambdas may have stray references (in other
1934 ;;; entry points) that have not been deleted yet.
1935 ;;; -- The call is full. This case is somewhat similar to the non-MV
1936 ;;; combination optimization: we propagate return type information and
1937 ;;; notice non-returning calls. We also have an optimization
1938 ;;; which tries to convert MV-CALLs into MV-binds.
1944 (:local
1951 do
1956 (:full
1959 do
1990 sum nvals)))
1994 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
1995 at least ~R."
1996 total-nvals min)
2001 "MULTIPLE-VALUE-CALL with ~R values when the function expects ~
2002 at most ~R."
2003 total-nvals max)
2009 min)
2027 ;;; If we see:
2028 ;;; (multiple-value-bind
2029 ;;; (x y)
2030 ;;; (values xx yy)
2031 ;;; ...)
2032 ;;; Convert to:
2033 ;;; (let ((x xx)
2034 ;;; (y yy))
2035 ;;; ...)
2036 ;;;
2037 ;;; What we actually do is convert the VALUES combination into a
2038 ;;; normal LET combination calling the original :MV-LET lambda. If
2039 ;;; there are extra args to VALUES, discard the corresponding
2040 ;;; lvars. If there are insufficient args, insert references to NIL.
2065 for prev = node-prev then ctran
2071 use ctran))
2085 ;; Propagate derived types from the VALUES call to its args:
2086 ;; transforms can leave the VALUES call with a better type
2087 ;; than its args have, so make sure not to throw that away.
2093 ;; Propagate declared types of MV-BIND variables.
2096 t)))
2098 ;;; If we see:
2099 ;;; (values-list (list x y z))
2100 ;;;
2101 ;;; Convert to:
2102 ;;; (values x y z)
2103 ;;;
2104 ;;; In implementation, this is somewhat similar to
2105 ;;; CONVERT-MV-BIND-TO-LET. We grab the args of LIST and make them
2106 ;;; args of the VALUES-LIST call, flushing the old argument lvar
2107 ;;; (allowing the LIST to be flushed.)
2108 ;;;
2109 ;;; FIXME: Thus we lose possible type assertions on (LIST ...).
2116 ;; FIXME: VALUES might not satisfy an assertion on NODE-LVAR.
2128 t)))
2130 ;;; If VALUES appears in a non-MV context, then effectively convert it
2131 ;;; to a PROG1. This allows the computation of the additional values
2132 ;;; to become dead code.
2144 val))
2145 nil))
2147 ;;; TODO:
2148 ;;; - CAST chains;
2165 ;; VESTIGIAL-EXIT-CASTs come from MULTIPLE-VALUES-PROG1 to avoid
2166 ;; overwriting their lvars
2170 #+sb-xc-host context
2196 lvar)
2197 ;; Pathwise removing of CAST
2200 next-block)
2234 ;; No need to transform into an analog of
2235 ;; %COMPILE-TIME-TYPE-ERROR, %CHECK-BOUND will signal at
2236 ;; run-time and %CHECK-BOUND ir2-converter will signal at
2237 ;; compile-time if it survives further stages of ir1
2238 ;; optimization.
2241 ;; FIXME: Do it in one step.
2246 value
2252 ;; FIXME: Derived type.
2262 ',detail
2265 ;; KLUDGE: FILTER-LVAR does not work for non-returning
2266 ;; functions, so we declare the return type of
2267 ;; %COMPILE-TIME-TYPE-ERROR to be * and derive the real type
2268 ;; here.
2272 ;; FIXME: Is it necessary?