1 ;;;; structures for the first intermediate representation in the
4 ;;;; This software is part of the SBCL system. See the README file for
7 ;;;; This software is derived from the CMU CL system, which was
8 ;;;; written at Carnegie Mellon University and released into the
9 ;;;; public domain. The software is in the public domain and is
10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
11 ;;;; files for more information.
15 ;;; The front-end data structure (IR1) is composed of nodes and
16 ;;; continuations. The general idea is that continuations contain
17 ;;; top-down information and nodes contain bottom-up, derived
18 ;;; information. A continuation represents a place in the code, while
19 ;;; a node represents code that does something.
21 ;;; This representation is more of a flow-graph than an augmented
22 ;;; syntax tree. The evaluation order is explicitly represented in the
23 ;;; linkage by continuations, rather than being implicit in the nodes
24 ;;; which receive the the results of evaluation. This allows us to
25 ;;; decouple the flow of results from the flow of control. A
26 ;;; continuation represents both, but the continuation can represent
27 ;;; the case of a discarded result by having no DEST.
29 (def!struct (continuation
30 (:make-load-form-fun ignore-it)
31 (:constructor make-continuation (&optional dest)))
32 ;; an indication of the way that this continuation is currently used
35 ;; A continuation for which all control-related slots have the
36 ;; default values. A continuation is unused during IR1 conversion
37 ;; until it is assigned a block, and may be also be temporarily
38 ;; unused during later manipulations of IR1. In a consistent
39 ;; state there should never be any mention of :UNUSED
40 ;; continuations. Next can have a non-null value if the next node
41 ;; has already been determined.
44 ;; A continuation that has been deleted from IR1. Any pointers into
45 ;; IR1 are cleared. There are two conditions under which a deleted
46 ;; continuation may appear in code:
47 ;; -- The CONT of the LAST node in a block may be a deleted
48 ;; continuation when the original receiver of the continuation's
49 ;; value was deleted. Note that DEST in a deleted continuation is
50 ;; null, so it is easy to know not to attempt delivering any
51 ;; values to the continuation.
52 ;; -- Unreachable code that hasn't been deleted yet may receive
53 ;; deleted continuations. All such code will be in blocks that
54 ;; have DELETE-P set. All unreachable code is deleted by control
55 ;; optimization, so the backend doesn't have to worry about this.
58 ;; The continuation that is the START of BLOCK. This is the only kind
59 ;; of continuation that can have more than one use. The BLOCK's
60 ;; START-USES is a list of all the uses.
62 ;; :DELETED-BLOCK-START
63 ;; Like :BLOCK-START, but BLOCK has been deleted. A block
64 ;; starting continuation is made into a deleted block start when
65 ;; the block is deleted, but the continuation still may have
66 ;; value semantics. Since there isn't any code left, next is
70 ;; A continuation that is the CONT of some node in BLOCK.
71 (kind :unused :type (member :unused :deleted :inside-block :block-start
72 :deleted-block-start))
73 ;; The node which receives this value, if any. In a deleted
74 ;; continuation, this is null even though the node that receives
75 ;; this continuation may not yet be deleted.
76 (dest nil :type (or node null))
77 ;; If this is a NODE, then it is the node which is to be evaluated
78 ;; next. This is always null in :DELETED and :UNUSED continuations,
79 ;; and will be null in a :INSIDE-BLOCK continuation when this is the
81 (next nil :type (or node null))
82 ;; an assertion on the type of this continuation's value
83 (asserted-type *wild-type* :type ctype)
84 ;; cached type of this continuation's value. If NIL, then this must
85 ;; be recomputed: see CONTINUATION-DERIVED-TYPE.
86 (%derived-type nil :type (or ctype null))
87 ;; Node where this continuation is used, if unique. This is always
88 ;; null in :DELETED and :UNUSED continuations, and is never null in
89 ;; :INSIDE-BLOCK continuations. In a :BLOCK-START continuation, the
90 ;; Block's START-USES indicate whether NIL means no uses or more
92 (use nil :type (or node null))
93 ;; the basic block this continuation is in. This is null only in
94 ;; :DELETED and :UNUSED continuations. Note that blocks that are
95 ;; unreachable but still in the DFO may receive deleted
96 ;; continuations, so it isn't o.k. to assume that any continuation
97 ;; that you pick up out of its DEST node has a BLOCK.
98 (block nil :type (or cblock null))
99 ;; set to true when something about this continuation's value has
100 ;; changed. See REOPTIMIZE-CONTINUATION. This provides a way for IR1
101 ;; optimize to determine which operands to a node have changed. If
102 ;; the optimizer for this node type doesn't care, it can elect not
103 ;; to clear this flag.
104 (reoptimize t :type boolean)
105 ;; an indication of what we have proven about how this contination's
106 ;; type assertion is satisfied:
109 ;; No type check is necessary (proven type is a subtype of the assertion.)
112 ;; A type check is needed.
115 ;; Don't do a type check, but believe (intersect) the assertion.
116 ;; A T check can be changed to :DELETED if we somehow prove the
117 ;; check is unnecessary, or if we eliminate it through a policy
121 ;; Type check generation sets the slot to this if a check is
122 ;; called for, but it believes it has proven that the check won't
123 ;; be done for policy reasons or because a safe implementation
124 ;; will be used. In the latter case, LTN must ensure that a safe
125 ;; implementation *is* used.
128 ;; There is a compile-time type error in some use of this
129 ;; continuation. A type check should still be generated, but be
132 ;; This is computed lazily by CONTINUATION-DERIVED-TYPE, so use
133 ;; CONTINUATION-TYPE-CHECK instead of the %'ed slot accessor.
134 (%type-check t :type (member t nil :deleted :no-check :error))
135 ;; something or other that the back end annotates this continuation with
137 ;; uses of this continuation in the lexical environment. They are
138 ;; recorded so that when one continuation is substituted for another
139 ;; the environment may be updated properly.
140 (lexenv-uses nil :type list))
142 (def!method print-object ((x continuation) stream)
143 (print-unreadable-object (x stream :type t :identity t)))
145 (defstruct (node (:constructor nil)
147 ;; the bottom-up derived type for this node. This does not take into
148 ;; consideration output type assertions on this node (actually on its CONT).
149 (derived-type *wild-type* :type ctype)
150 ;; True if this node needs to be optimized. This is set to true
151 ;; whenever something changes about the value of a continuation
152 ;; whose DEST is this node.
153 (reoptimize t :type boolean)
154 ;; the continuation which receives the value of this node. This also
155 ;; indicates what we do controlwise after evaluating this node. This
156 ;; may be null during IR1 conversion.
157 (cont nil :type (or continuation null))
158 ;; the continuation that this node is the next of. This is null
159 ;; during IR1 conversion when we haven't linked the node in yet or
160 ;; in nodes that have been deleted from the IR1 by UNLINK-NODE.
161 (prev nil :type (or continuation null))
162 ;; the lexical environment this node was converted in
163 (lexenv *lexenv* :type lexenv)
164 ;; a representation of the source code responsible for generating
167 ;; For a form introduced by compilation (does not appear in the
168 ;; original source), the path begins with a list of all the
169 ;; enclosing introduced forms. This list is from the inside out,
170 ;; with the form immediately responsible for this node at the head
173 ;; Following the introduced forms is a representation of the
174 ;; location of the enclosing original source form. This transition
175 ;; is indicated by the magic ORIGINAL-SOURCE-START marker. The first
176 ;; element of the original source is the "form number", which is the
177 ;; ordinal number of this form in a depth-first, left-to-right walk
178 ;; of the truly top-level form in which this appears.
180 ;; Following is a list of integers describing the path taken through
181 ;; the source to get to this point:
182 ;; (K L M ...) => (NTH K (NTH L (NTH M ...)))
184 ;; The last element in the list is the top-level form number, which
185 ;; is the ordinal number (in this call to the compiler) of the truly
186 ;; top-level form containing the original source.
187 (source-path *current-path* :type list)
188 ;; If this node is in a tail-recursive position, then this is set to
189 ;; T. At the end of IR1 (in environment analysis) this is computed
190 ;; for all nodes (after cleanup code has been emitted). Before then,
191 ;; a non-null value indicates that IR1 optimization has converted a
192 ;; tail local call to a direct transfer.
194 ;; If the back-end breaks tail-recursion for some reason, then it
195 ;; can null out this slot.
196 (tail-p nil :type boolean))
198 ;;; Flags that are used to indicate various things about a block, such
199 ;;; as what optimizations need to be done on it:
200 ;;; -- REOPTIMIZE is set when something interesting happens the uses of a
201 ;;; continuation whose Dest is in this block. This indicates that the
202 ;;; value-driven (forward) IR1 optimizations should be done on this block.
203 ;;; -- FLUSH-P is set when code in this block becomes potentially flushable,
204 ;;; usually due to a continuation's DEST becoming null.
205 ;;; -- TYPE-CHECK is true when the type check phase should be run on this
206 ;;; block. IR1 optimize can introduce new blocks after type check has
207 ;;; already run. We need to check these blocks, but there is no point in
208 ;;; checking blocks we have already checked.
209 ;;; -- DELETE-P is true when this block is used to indicate that this block
210 ;;; has been determined to be unreachable and should be deleted. IR1
211 ;;; phases should not attempt to examine or modify blocks with DELETE-P
212 ;;; set, since they may:
213 ;;; - be in the process of being deleted, or
214 ;;; - have no successors, or
215 ;;; - receive :DELETED continuations.
216 ;;; -- TYPE-ASSERTED, TEST-MODIFIED
217 ;;; These flags are used to indicate that something in this block
218 ;;; might be of interest to constraint propagation. TYPE-ASSERTED
219 ;;; is set when a continuation type assertion is strengthened.
220 ;;; TEST-MODIFIED is set whenever the test for the ending IF has
221 ;;; changed (may be true when there is no IF.)
222 (def-boolean-attribute block
223 reoptimize flush-p type-check delete-p type-asserted test-modified)
225 (macrolet ((frob (slot)
226 `(defmacro ,(symbolicate "BLOCK-" slot) (block)
227 `(block-attributep (block-flags ,block) ,',slot))))
233 (frob test-modified))
235 ;;; The CBLOCK structure represents a basic block. We include
236 ;;; SSET-ELEMENT so that we can have sets of blocks. Initially the
237 ;;; SSET-ELEMENT-NUMBER is null, DFO analysis numbers in reverse DFO.
238 ;;; During IR2 conversion, IR1 blocks are re-numbered in forward emit
239 ;;; order. This latter numbering also forms the basis of the block
240 ;;; numbering in the debug-info (though that is relative to the start
241 ;;; of the function.)
242 (defstruct (cblock (:include sset-element)
243 (:constructor make-block (start))
244 (:constructor make-block-key)
247 (:copier copy-block))
248 ;; a list of all the blocks that are predecessors/successors of this
249 ;; block. In well-formed IR1, most blocks will have one successor.
250 ;; The only exceptions are:
251 ;; 1. component head blocks (any number)
252 ;; 2. blocks ending in an IF (1 or 2)
253 ;; 3. blocks with DELETE-P set (zero)
254 (pred nil :type list)
255 (succ nil :type list)
256 ;; the continuation which heads this block (either a :BLOCK-START or
257 ;; :DELETED-BLOCK-START), or NIL when we haven't made the start
258 ;; continuation yet (and in the dummy component head and tail
260 (start nil :type (or continuation null))
261 ;; a list of all the nodes that have START as their CONT
262 (start-uses nil :type list)
263 ;; the last node in this block. This is NIL when we are in the
264 ;; process of building a block (and in the dummy component head and
266 (last nil :type (or node null))
267 ;; the forward and backward links in the depth-first ordering of the
268 ;; blocks. These slots are NIL at beginning/end.
269 (next nil :type (or null cblock))
270 (prev nil :type (or null cblock))
271 ;; This block's attributes: see above.
272 (flags (block-attributes reoptimize flush-p type-check type-asserted
275 ;; CMU CL had a KILL slot here, documented as "set used by
276 ;; constraint propagation", which was used in constraint propagation
277 ;; as a list of LAMBDA-VARs killed, and in copy propagation as an
278 ;; SSET, representing I dunno what. I (WHN) found this confusing,
279 ;; and furthermore it caused type errors when I was trying to make
280 ;; the compiler produce fully general LAMBDA functions directly
281 ;; (instead of doing as CMU CL always did, producing extra little
282 ;; functions which return the LAMDBA you need) and therefore taking
283 ;; a new path through the compiler. So I split this into two:
284 ;; KILL-LIST = list of LAMBDA-VARs killed, used in constraint propagation
285 ;; KILL-SSET = an SSET value, used in copy propagation
286 (kill-list nil :type list)
287 (kill-sset nil :type (or sset null))
288 ;; other sets used in constraint propagation and/or copy propagation
292 ;; the component this block is in, or NIL temporarily during IR1
293 ;; conversion and in deleted blocks
294 (component *current-component* :type (or component null))
295 ;; a flag used by various graph-walking code to determine whether
296 ;; this block has been processed already or what. We make this
297 ;; initially NIL so that FIND-INITIAL-DFO doesn't have to scan the
298 ;; entire initial component just to clear the flags.
300 ;; some kind of info used by the back end
302 ;; If true, then constraints that hold in this block and its
303 ;; successors by merit of being tested by its IF predecessor.
304 (test-constraint nil :type (or sset null)))
305 (def!method print-object ((cblock cblock) stream)
306 (print-unreadable-object (cblock stream :type t :identity t)
307 (format stream ":START c~D" (cont-num (block-start cblock)))))
309 ;;; The BLOCK-ANNOTATION class is inherited (via :INCLUDE) by
310 ;;; different BLOCK-INFO annotation structures so that code
311 ;;; (specifically control analysis) can be shared.
312 (defstruct (block-annotation (:constructor nil)
314 ;; The IR1 block that this block is in the INFO for.
315 (block (required-argument) :type cblock)
316 ;; the next and previous block in emission order (not DFO). This
317 ;; determines which block we drop though to, and also used to chain
318 ;; together overflow blocks that result from splitting of IR2 blocks
319 ;; in lifetime analysis.
320 (next nil :type (or block-annotation null))
321 (prev nil :type (or block-annotation null)))
323 ;;; A COMPONENT structure provides a handle on a connected piece of
324 ;;; the flow graph. Most of the passes in the compiler operate on
325 ;;; COMPONENTs rather than on the entire flow graph.
326 (defstruct (component (:copier nil))
327 ;; the kind of component
329 ;; (The terminology here is left over from before
330 ;; sbcl-0.pre7.34.flaky5.2, when there was no such thing as
331 ;; FUNCTIONAL-HAS-EXTERNAL-REFERENCES-P, so that Python was
332 ;; incapable of building standalone :EXTERNAL functions, but instead
333 ;; had to implement things like #'CL:COMPILE as FUNCALL of a little
334 ;; toplevel stub whose sole purpose was to return an :EXTERNAL
337 ;; The possibilities are:
339 ;; an ordinary component, containing non-top-level code
341 ;; a component containing only load-time code
342 ;; :COMPLEX-TOP-LEVEL
343 ;; In the old system, before FUNCTIONAL-HAS-EXTERNAL-REFERENCES-P
344 ;; was defined, this was necessarily a component containing both
345 ;; top-level and run-time code. Now this state is also used for
346 ;; a component with HAS-EXTERNAL-REFERENCES-P functionals in it.
348 ;; the result of initial IR1 conversion, on which component
349 ;; analysis has not been done
351 ;; debris left over from component analysis
353 ;; See also COMPONENT-TOP-LEVELISH-P.
354 (kind nil :type (member nil :top-level :complex-top-level :initial :deleted))
355 ;; the blocks that are the dummy head and tail of the DFO
357 ;; Entry/exit points have these blocks as their
358 ;; predecessors/successors. Null temporarily. The start and return
359 ;; from each non-deleted function is linked to the component head
360 ;; and tail. Until environment analysis links NLX entry stubs to the
361 ;; component head, every successor of the head is a function start
362 ;; (i.e. begins with a BIND node.)
363 (head nil :type (or null cblock))
364 (tail nil :type (or null cblock))
365 ;; This becomes a list of the CLAMBDA structures for all functions
366 ;; in this component. OPTIONAL-DISPATCHes are represented only by
367 ;; their XEP and other associated lambdas. This doesn't contain any
368 ;; deleted or LET lambdas.
370 ;; Note that logical associations between CLAMBDAs and COMPONENTs
371 ;; seem to exist for a while before this is initialized. In
372 ;; particular, I got burned by writing some code to use this value
373 ;; to decide which components need LOCAL-CALL-ANALYZE, when it turns
374 ;; out that LOCAL-CALL-ANALYZE had a role in initializing this value
375 ;; (and DFO stuff does too, maybe). Also, even after it's
376 ;; initialized, it might change as CLAMBDAs are deleted or merged.
378 (lambdas () :type list)
379 ;; a list of FUNCTIONAL structures for functions that are newly
380 ;; converted, and haven't been local-call analyzed yet. Initially
381 ;; functions are not in the LAMBDAS list. LOCAL-CALL-ANALYZE moves
382 ;; them there (possibly as LETs, or implicitly as XEPs if an
383 ;; OPTIONAL-DISPATCH.) Between runs of LOCAL-CALL-ANALYZE there may
384 ;; be some debris of converted or even deleted functions in this
386 (new-functions () :type list)
387 ;; If this is true, then there is stuff in this component that could
388 ;; benefit from further IR1 optimization.
389 (reoptimize t :type boolean)
390 ;; If this is true, then the control flow in this component was
391 ;; messed up by IR1 optimizations, so the DFO should be recomputed.
392 (reanalyze nil :type boolean)
393 ;; some sort of name for the code in this component
394 (name "<unknown>" :type simple-string)
395 ;; some kind of info used by the back end
397 ;; the SOURCE-INFO structure describing where this component was
399 (source-info *source-info* :type source-info)
400 ;; count of the number of inline expansions we have done while
401 ;; compiling this component, to detect infinite or exponential
403 (inline-expansions 0 :type index)
404 ;; a map from combination nodes to things describing how an
405 ;; optimization of the node failed. The description is an alist
406 ;; (TRANSFORM . ARGS), where TRANSFORM is the structure describing
407 ;; the transform that failed, and ARGS is either a list of format
408 ;; arguments for the note, or the FUNCTION-TYPE that would have
409 ;; enabled the transformation but failed to match.
410 (failed-optimizations (make-hash-table :test 'eq) :type hash-table)
411 ;; This is similar to NEW-FUNCTIONS, but is used when a function has
412 ;; already been analyzed, but new references have been added by
413 ;; inline expansion. Unlike NEW-FUNCTIONS, this is not disjoint from
414 ;; COMPONENT-LAMBDAS.
415 (reanalyze-functions nil :type list))
416 (defprinter (component :identity t)
418 (reanalyze :test reanalyze))
420 ;;; Before sbcl-0.7.0, there were :TOP-LEVEL things which were magical
421 ;;; in multiple ways. That's since been refactored into the orthogonal
422 ;;; properties "optimized for locall with no arguments" and "externally
423 ;;; visible/referenced (so don't delete it)". The code <0.7.0 did a lot
424 ;;; of tests a la (EQ KIND :TOP_LEVEL) in the "don't delete it?" sense;
425 ;;; this function is a sort of literal translation of those tests into
428 ;;; FIXME: After things settle down, bare :TOP-LEVEL might go away, at
429 ;;; which time it might be possible to replace the COMPONENT-KIND
430 ;;; :TOP-LEVEL mess with a flag COMPONENT-HAS-EXTERNAL-REFERENCES-P
431 ;;; along the lines of FUNCTIONAL-HAS-EXTERNAL-REFERENCES-P.
432 (defun lambda-top-levelish-p (clambda)
433 (or (eql (lambda-kind clambda) :top-level)
434 (lambda-has-external-references-p clambda)))
435 (defun component-top-levelish-p (component)
436 (member (component-kind component)
437 '(:top-level :complex-top-level)))
439 ;;; A CLEANUP structure represents some dynamic binding action. Blocks
440 ;;; are annotated with the current CLEANUP so that dynamic bindings
441 ;;; can be removed when control is transferred out of the binding
442 ;;; environment. We arrange for changes in dynamic bindings to happen
443 ;;; at block boundaries, so that cleanup code may easily be inserted.
444 ;;; The "mess-up" action is explicitly represented by a funny function
445 ;;; call or ENTRY node.
447 ;;; We guarantee that CLEANUPs only need to be done at block boundaries
448 ;;; by requiring that the exit continuations initially head their
449 ;;; blocks, and then by not merging blocks when there is a cleanup
451 (defstruct (cleanup (:copier nil))
452 ;; the kind of thing that has to be cleaned up
453 (kind (required-argument)
454 :type (member :special-bind :catch :unwind-protect :block :tagbody))
455 ;; the node that messes things up. This is the last node in the
456 ;; non-messed-up environment. Null only temporarily. This could be
457 ;; deleted due to unreachability.
458 (mess-up nil :type (or node null))
459 ;; a list of all the NLX-INFO structures whose NLX-INFO-CLEANUP is
460 ;; this cleanup. This is filled in by environment analysis.
461 (nlx-info nil :type list))
462 (defprinter (cleanup :identity t)
465 (nlx-info :test nlx-info))
467 ;;; original CMU CL comment:
468 ;;; An ENVIRONMENT structure represents the result of environment
471 ;;; As far as I can tell from reverse engineering, this IR1 structure
472 ;;; represents the physical environment (which is probably not the
473 ;;; standard Lispy term for this concept, but I dunno what is the
474 ;;; standard term): those things in the lexical environment which a
475 ;;; LAMBDA actually interacts with. Thus in
476 ;;; (DEFUN FROB-THINGS (THINGS)
477 ;;; (DOLIST (THING THINGS)
478 ;;; (BLOCK FROBBING-ONE-THING
479 ;;; (MAPCAR (LAMBDA (PATTERN)
480 ;;; (WHEN (FITS-P THING PATTERN)
481 ;;; (RETURN-FROM FROB-THINGS (LIST :FIT THING PATTERN))))
483 ;;; the variables THINGS, THING, and PATTERN and the block names
484 ;;; FROB-THINGS and FROBBING-ONE-THING are all in the inner LAMBDA's
485 ;;; lexical environment, but of those only THING, PATTERN, and
486 ;;; FROB-THINGS are in its physical environment. In IR1, we largely
487 ;;; just collect the names of these things; in IR2 an IR2-ENVIRONMENT
488 ;;; structure is attached to INFO and used to keep track of
489 ;;; associations between these names and less-abstract things (like
490 ;;; TNs, or eventually stack slots and registers). -- WHN 2001-09-29
491 (defstruct (environment (:copier nil))
492 ;; the function that allocates this environment
493 (function (required-argument) :type clambda)
494 ;; a list of all the lambdas that allocate variables in this environment
495 (lambdas nil :type list)
496 ;; This ultimately converges to a list of all the LAMBDA-VARs and
497 ;; NLX-INFOs needed from enclosing environments by code in this
498 ;; environment. In the meantime, it may be
499 ;; * NIL at object creation time
500 ;; * a superset of the correct result, generated somewhat later
501 ;; * smaller and smaller sets converging to the correct result as
502 ;; we notice and delete unused elements in the superset
503 (closure nil :type list)
504 ;; a list of NLX-INFO structures describing all the non-local exits
505 ;; into this environment
506 (nlx-info nil :type list)
507 ;; some kind of info used by the back end
509 (defprinter (environment :identity t)
511 (closure :test closure)
512 (nlx-info :test nlx-info))
514 ;;; An TAIL-SET structure is used to accumulate information about
515 ;;; tail-recursive local calls. The "tail set" is effectively the
516 ;;; transitive closure of the "is called tail-recursively by"
519 ;;; All functions in the same tail set share the same TAIL-SET
520 ;;; structure. Initially each function has its own TAIL-SET, but when
521 ;;; IR1-OPTIMIZE-RETURN notices a tail local call, it joins the tail
522 ;;; sets of the called function and the calling function.
524 ;;; The tail set is somewhat approximate, because it is too early to
525 ;;; be sure which calls will be tail-recursive. Any call that *might*
526 ;;; end up tail-recursive causes TAIL-SET merging.
527 (defstruct (tail-set)
528 ;; a list of all the LAMBDAs in this tail set
529 (functions nil :type list)
530 ;; our current best guess of the type returned by these functions.
531 ;; This is the union across all the functions of the return node's
532 ;; RESULT-TYPE, excluding local calls.
533 (type *wild-type* :type ctype)
534 ;; some info used by the back end
536 (defprinter (tail-set :identity t)
541 ;;; The NLX-Info structure is used to collect various information
542 ;;; about non-local exits. This is effectively an annotation on the
543 ;;; CONTINUATION, although it is accessed by searching in the
544 ;;; ENVIRONMENT-NLX-INFO.
545 (def!struct (nlx-info (:make-load-form-fun ignore-it))
546 ;; the cleanup associated with this exit. In a catch or
547 ;; unwind-protect, this is the :CATCH or :UNWIND-PROTECT cleanup,
548 ;; and not the cleanup for the escape block. The CLEANUP-KIND of
549 ;; this thus provides a good indication of what kind of exit is
551 (cleanup (required-argument) :type cleanup)
552 ;; the continuation exited to (the CONT of the EXIT nodes). If this
553 ;; exit is from an escape function (CATCH or UNWIND-PROTECT), then
554 ;; environment analysis deletes the escape function and instead has
555 ;; the %NLX-ENTRY use this continuation.
557 ;; This slot is primarily an indication of where this exit delivers
558 ;; its values to (if any), but it is also used as a sort of name to
559 ;; allow us to find the NLX-Info that corresponds to a given exit.
560 ;; For this purpose, the Entry must also be used to disambiguate,
561 ;; since exits to different places may deliver their result to the
562 ;; same continuation.
563 (continuation (required-argument) :type continuation)
564 ;; the entry stub inserted by environment analysis. This is a block
565 ;; containing a call to the %NLX-Entry funny function that has the
566 ;; original exit destination as its successor. Null only
568 (target nil :type (or cblock null))
569 ;; some kind of info used by the back end
571 (defprinter (nlx-info :identity t)
578 ;;; Variables, constants and functions are all represented by LEAF
579 ;;; structures. A reference to a LEAF is indicated by a REF node. This
580 ;;; allows us to easily substitute one for the other without actually
581 ;;; hacking the flow graph.
582 (def!struct (leaf (:make-load-form-fun ignore-it)
584 ;; some name for this leaf. The exact significance of the name
585 ;; depends on what kind of leaf it is. In a LAMBDA-VAR or
586 ;; GLOBAL-VAR, this is the symbol name of the variable. In a
587 ;; functional that is from a DEFUN, this is the defined name. In
588 ;; other functionals, this is a descriptive string.
590 ;; the type which values of this leaf must have
591 (type *universal-type* :type ctype)
592 ;; where the TYPE information came from:
593 ;; :DECLARED, from a declaration.
594 ;; :ASSUMED, from uses of the object.
595 ;; :DEFINED, from examination of the definition.
596 ;; FIXME: This should be a named type. (LEAF-WHERE-FROM? Or
597 ;; perhaps just WHERE-FROM, since it's not just used in LEAF,
598 ;; but also in various DEFINE-INFO-TYPEs in globaldb.lisp,
599 ;; and very likely elsewhere too.)
600 (where-from :assumed :type (member :declared :assumed :defined))
601 ;; list of the REF nodes for this leaf
603 ;; true if there was ever a REF or SET node for this leaf. This may
604 ;; be true when REFS and SETS are null, since code can be deleted.
605 (ever-used nil :type boolean)
606 ;; some kind of info used by the back end
609 ;;; The CONSTANT structure is used to represent known constant values.
610 ;;; If NAME is not null, then it is the name of the named constant
611 ;;; which this leaf corresponds to, otherwise this is an anonymous
613 (def!struct (constant (:include leaf))
614 ;; the value of the constant
616 (defprinter (constant :identity t)
620 ;;; The BASIC-VAR structure represents information common to all
621 ;;; variables which don't correspond to known local functions.
622 (def!struct (basic-var (:include leaf) (:constructor nil))
623 ;; Lists of the set nodes for this variable.
624 (sets () :type list))
626 ;;; The GLOBAL-VAR structure represents a value hung off of the symbol
627 ;;; NAME. We use a :CONSTANT VAR when we know that the thing is a
628 ;;; constant, but don't know what the value is at compile time.
629 (def!struct (global-var (:include basic-var))
630 ;; kind of variable described
631 (kind (required-argument)
632 :type (member :special :global-function :constant :global)))
633 (defprinter (global-var :identity t)
635 (type :test (not (eq type *universal-type*)))
636 (where-from :test (not (eq where-from :assumed)))
639 ;;; The SLOT-ACCESSOR structure represents slot accessor functions. It
640 ;;; is a subtype of GLOBAL-VAR to make it look more like a normal
642 (def!struct (slot-accessor (:include global-var
643 (where-from :defined)
644 (kind :global-function)))
645 ;; The description of the structure that this is an accessor for.
646 (for (required-argument) :type sb!xc:class)
647 ;; The slot description of the slot.
648 (slot (required-argument)))
649 (defprinter (slot-accessor :identity t)
654 ;;; The DEFINED-FUNCTION structure represents functions that are
655 ;;; defined in the same compilation block, or that have inline
656 ;;; expansions, or have a non-NIL INLINEP value. Whenever we change
657 ;;; the INLINEP state (i.e. an inline proclamation) we copy the
658 ;;; structure so that former INLINEP values are preserved.
659 (def!struct (defined-function (:include global-var
660 (where-from :defined)
661 (kind :global-function)))
662 ;; The values of INLINEP and INLINE-EXPANSION initialized from the
663 ;; global environment.
664 (inlinep nil :type inlinep)
665 (inline-expansion nil :type (or cons null))
666 ;; The block-local definition of this function (either because it
667 ;; was semi-inline, or because it was defined in this block.) If
668 ;; this function is not an entry point, then this may be deleted or
669 ;; let-converted. Null if we haven't converted the expansion yet.
670 (functional nil :type (or functional null)))
671 (defprinter (defined-function :identity t)
674 (functional :test functional))
678 ;;; We default the WHERE-FROM and TYPE slots to :DEFINED and FUNCTION.
679 ;;; We don't normally manipulate function types for defined functions,
680 ;;; but if someone wants to know, an approximation is there.
681 (def!struct (functional (:include leaf
682 (where-from :defined)
683 (type (specifier-type 'function))))
684 ;; Some information about how this function is used. These values are
688 ;; an ordinary function, callable using local call
691 ;; a lambda that is used in only one local call, and has in
692 ;; effect been substituted directly inline. The return node is
693 ;; deleted, and the result is computed with the actual result
694 ;; continuation for the call.
697 ;; Similar to :LET, but the call is an MV-CALL.
700 ;; similar to a LET, but can have other than one call as long as
701 ;; there is at most one non-tail call.
704 ;; a lambda that is an entry-point for an optional-dispatch.
705 ;; Similar to NIL, but requires greater caution, since local call
706 ;; analysis may create new references to this function. Also, the
707 ;; function cannot be deleted even if it has *no* references. The
708 ;; OPTIONAL-DISPATCH is in the LAMDBA-OPTIONAL-DISPATCH.
711 ;; an external entry point lambda. The function it is an entry
712 ;; for is in the ENTRY-FUNCTION slot.
715 ;; a top-level lambda, holding a compiled top-level form.
716 ;; Compiled very much like NIL, but provides an indication of
717 ;; top-level context. A top-level lambda should have *no*
718 ;; references. Its Entry-Function is a self-pointer.
721 ;; After a component is compiled, we clobber any top-level code
722 ;; references to its non-closure XEPs with dummy FUNCTIONAL
723 ;; structures having this kind. This prevents the retained
724 ;; top-level code from holding onto the IR for the code it
729 ;; special functions used internally by CATCH and UNWIND-PROTECT.
730 ;; These are pretty much like a normal function (NIL), but are
731 ;; treated specially by local call analysis and stuff. Neither
732 ;; kind should ever be given an XEP even though they appear as
733 ;; args to funny functions. An :ESCAPE function is never actually
734 ;; called, and thus doesn't need to have code generated for it.
737 ;; This function has been found to be uncallable, and has been
738 ;; marked for deletion.
739 (kind nil :type (member nil :optional :deleted :external :top-level
740 :escape :cleanup :let :mv-let :assignment
742 ;; Is this a function that some external entity (e.g. the fasl dumper)
743 ;; refers to, so that even when it appears to have no references, it
744 ;; shouldn't be deleted? In the old days (before
745 ;; sbcl-0.pre7.37.flaky5.2) this was sort of implicitly true when
746 ;; KIND was :TOP-LEVEL. Now it must be set explicitly, both for
747 ;; :TOP-LEVEL functions and for any other kind of functions that we
748 ;; want to dump or return from #'CL:COMPILE or whatever.
749 (has-external-references-p nil)
750 ;; In a normal function, this is the external entry point (XEP)
751 ;; lambda for this function, if any. Each function that is used
752 ;; other than in a local call has an XEP, and all of the
753 ;; non-local-call references are replaced with references to the
756 ;; In an XEP lambda (indicated by the :EXTERNAL kind), this is the
757 ;; function that the XEP is an entry-point for. The body contains
758 ;; local calls to all the actual entry points in the function. In a
759 ;; :TOP-LEVEL lambda (which is its own XEP) this is a self-pointer.
761 ;; With all other kinds, this is null.
762 (entry-function nil :type (or functional null))
763 ;; the value of any inline/notinline declaration for a local function
764 (inlinep nil :type inlinep)
765 ;; If we have a lambda that can be used as in inline expansion for
766 ;; this function, then this is it. If there is no source-level
767 ;; lambda corresponding to this function then this is Null (but then
768 ;; INLINEP will always be NIL as well.)
769 (inline-expansion nil :type list)
770 ;; the lexical environment that the inline-expansion should be converted in
771 (lexenv *lexenv* :type lexenv)
772 ;; the original function or macro lambda list, or :UNSPECIFIED if
773 ;; this is a compiler created function
774 (arg-documentation nil :type (or list (member :unspecified)))
775 ;; various rare miscellaneous info that drives code generation & stuff
776 (plist () :type list))
777 (defprinter (functional :identity t)
780 ;;; The CLAMBDA only deals with required lexical arguments. Special,
781 ;;; optional, keyword and rest arguments are handled by transforming
782 ;;; into simpler stuff.
783 (def!struct (clambda (:include functional)
785 (:predicate lambda-p)
786 (:constructor make-lambda)
787 (:copier copy-lambda))
788 ;; list of LAMBDA-VAR descriptors for args
789 (vars nil :type list)
790 ;; If this function was ever a :OPTIONAL function (an entry-point
791 ;; for an OPTIONAL-DISPATCH), then this is that OPTIONAL-DISPATCH.
792 ;; The optional dispatch will be :DELETED if this function is no
794 (optional-dispatch nil :type (or optional-dispatch null))
795 ;; the BIND node for this LAMBDA. This node marks the beginning of
796 ;; the lambda, and serves to explicitly represent the lambda binding
797 ;; semantics within the flow graph representation. This is null in
798 ;; deleted functions, and also in LETs where we deleted the call and
799 ;; bind (because there are no variables left), but have not yet
800 ;; actually deleted the LAMBDA yet.
801 (bind nil :type (or bind null))
802 ;; the RETURN node for this LAMBDA, or NIL if it has been deleted.
803 ;; This marks the end of the lambda, receiving the result of the
804 ;; body. In a LET, the return node is deleted, and the body delivers
805 ;; the value to the actual continuation. The return may also be
806 ;; deleted if it is unreachable.
807 (return nil :type (or creturn null))
808 ;; If this CLAMBDA is a LET, then this slot holds the LAMBDA whose
809 ;; LETS list we are in, otherwise it is a self-pointer.
810 (home nil :type (or clambda null))
811 ;; a list of all the all the lambdas that have been LET-substituted
812 ;; in this lambda. This is only non-null in lambdas that aren't
815 ;; a list of all the ENTRY nodes in this function and its LETs, or
817 (entries () :type list)
818 ;; a list of all the functions directly called from this function
819 ;; (or one of its LETs) using a non-LET local call. This may include
820 ;; deleted functions because nobody bothers to clear them out.
821 (calls () :type list)
822 ;; the TAIL-SET that this LAMBDA is in. This is null during creation.
824 ;; In CMU CL, and old SBCL, this was also NILed out when LET
825 ;; conversion happened. That caused some problems, so as of
826 ;; sbcl-0.pre7.37.flaky5.2 when I was trying to get the compiler to
827 ;; emit :EXTERNAL functions directly, and so now the value
828 ;; is no longer NILed out in LET conversion, but instead copied
829 ;; (so that any further optimizations on the rest of the tail
830 ;; set won't modify the value) if necessary.
831 (tail-set nil :type (or tail-set null))
832 ;; the structure which represents the environment that this
833 ;; function's variables are allocated in. This is filled in by
834 ;; environment analysis. In a LET, this is EQ to our home's
836 (environment nil :type (or environment null))
837 ;; In a LET, this is the NODE-LEXENV of the combination node. We
838 ;; retain it so that if the LET is deleted (due to a lack of vars),
839 ;; we will still have caller's lexenv to figure out which cleanup is
841 (call-lexenv nil :type (or lexenv null)))
842 (defprinter (clambda :conc-name lambda- :identity t)
844 (type :test (not (eq type *universal-type*)))
845 (where-from :test (not (eq where-from :assumed)))
846 (vars :prin1 (mapcar #'leaf-name vars)))
848 ;;; The OPTIONAL-DISPATCH leaf is used to represent hairy lambdas. It
849 ;;; is a FUNCTIONAL, like LAMBDA. Each legal number of arguments has a
850 ;;; function which is called when that number of arguments is passed.
851 ;;; The function is called with all the arguments actually passed. If
852 ;;; additional arguments are legal, then the LEXPR style MORE-ENTRY
853 ;;; handles them. The value returned by the function is the value
854 ;;; which results from calling the OPTIONAL-DISPATCH.
856 ;;; The theory is that each entry-point function calls the next entry
857 ;;; point tail-recursively, passing all the arguments passed in and
858 ;;; the default for the argument the entry point is for. The last
859 ;;; entry point calls the real body of the function. In the presence
860 ;;; of SUPPLIED-P args and other hair, things are more complicated. In
861 ;;; general, there is a distinct internal function that takes the
862 ;;; SUPPLIED-P args as parameters. The preceding entry point calls
863 ;;; this function with NIL filled in for the SUPPLIED-P args, while
864 ;;; the current entry point calls it with T in the SUPPLIED-P
867 ;;; Note that it is easy to turn a call with a known number of
868 ;;; arguments into a direct call to the appropriate entry-point
869 ;;; function, so functions that are compiled together can avoid doing
871 (def!struct (optional-dispatch (:include functional))
872 ;; the original parsed argument list, for anyone who cares
873 (arglist nil :type list)
874 ;; true if &ALLOW-OTHER-KEYS was supplied
875 (allowp nil :type boolean)
876 ;; true if &KEY was specified (which doesn't necessarily mean that
877 ;; there are any &KEY arguments..)
878 (keyp nil :type boolean)
879 ;; the number of required arguments. This is the smallest legal
880 ;; number of arguments.
881 (min-args 0 :type unsigned-byte)
882 ;; the total number of required and optional arguments. Args at
883 ;; positions >= to this are &REST, &KEY or illegal args.
884 (max-args 0 :type unsigned-byte)
885 ;; list of the LAMBDAs which are the entry points for non-rest,
886 ;; non-key calls. The entry for MIN-ARGS is first, MIN-ARGS+1
887 ;; second, ... MAX-ARGS last. The last entry-point always calls the
888 ;; main entry; in simple cases it may be the main entry.
889 (entry-points nil :type list)
890 ;; an entry point which takes MAX-ARGS fixed arguments followed by
891 ;; an argument context pointer and an argument count. This entry
892 ;; point deals with listifying rest args and parsing keywords. This
893 ;; is null when extra arguments aren't legal.
894 (more-entry nil :type (or clambda null))
895 ;; the main entry-point into the function, which takes all arguments
896 ;; including keywords as fixed arguments. The format of the
897 ;; arguments must be determined by examining the arglist. This may
898 ;; be used by callers that supply at least MAX-ARGS arguments and
899 ;; know what they are doing.
900 (main-entry nil :type (or clambda null)))
901 (defprinter (optional-dispatch :identity t)
903 (type :test (not (eq type *universal-type*)))
904 (where-from :test (not (eq where-from :assumed)))
910 (entry-points :test entry-points)
911 (more-entry :test more-entry)
914 ;;; The ARG-INFO structure allows us to tack various information onto
915 ;;; LAMBDA-VARs during IR1 conversion. If we use one of these things,
916 ;;; then the var will have to be massaged a bit before it is simple
919 ;; true if this arg is to be specially bound
920 (specialp nil :type boolean)
921 ;; the kind of argument being described. Required args only have arg
922 ;; info structures if they are special.
923 (kind (required-argument) :type (member :required :optional :keyword :rest
924 :more-context :more-count))
925 ;; If true, this is the VAR for SUPPLIED-P variable of a keyword or
926 ;; optional arg. This is true for keywords with non-constant
927 ;; defaults even when there is no user-specified supplied-p var.
928 (supplied-p nil :type (or lambda-var null))
929 ;; the default for a keyword or optional, represented as the
930 ;; original Lisp code. This is set to NIL in &KEY arguments that are
931 ;; defaulted using the SUPPLIED-P arg.
932 (default nil :type t)
933 ;; the actual key for a &KEY argument. Note that in ANSI CL this is not
934 ;; necessarily a keyword: (DEFUN FOO (&KEY ((BAR BAR))) ..).
935 (key nil :type symbol))
936 (defprinter (arg-info :identity t)
937 (specialp :test specialp)
939 (supplied-p :test supplied-p)
940 (default :test default)
943 ;;; The LAMBDA-VAR structure represents a lexical lambda variable.
944 ;;; This structure is also used during IR1 conversion to describe
945 ;;; lambda arguments which may ultimately turn out not to be simple
948 ;;; LAMBDA-VARs with no REFs are considered to be deleted; environment
949 ;;; analysis isn't done on these variables, so the back end must check
950 ;;; for and ignore unreferenced variables. Note that a deleted
951 ;;; lambda-var may have sets; in this case the back end is still
952 ;;; responsible for propagating the Set-Value to the set's Cont.
953 (def!struct (lambda-var (:include basic-var))
954 ;; true if this variable has been declared IGNORE
955 (ignorep nil :type boolean)
956 ;; the CLAMBDA that this var belongs to. This may be null when we are
957 ;; building a lambda during IR1 conversion.
958 (home nil :type (or null clambda))
959 ;; This is set by environment analysis if it chooses an indirect
960 ;; (value cell) representation for this variable because it is both
961 ;; set and closed over.
962 (indirect nil :type boolean)
963 ;; The following two slots are only meaningful during IR1 conversion
964 ;; of hairy lambda vars:
966 ;; The ARG-INFO structure which holds information obtained from
968 (arg-info nil :type (or arg-info null))
969 ;; if true, the GLOBAL-VAR structure for the special variable which
970 ;; is to be bound to the value of this argument
971 (specvar nil :type (or global-var null))
972 ;; Set of the CONSTRAINTs on this variable. Used by constraint
973 ;; propagation. This is left null by the lambda pre-pass if it
974 ;; determine that this is a set closure variable, and is thus not a
975 ;; good subject for flow analysis.
976 (constraints nil :type (or sset null)))
977 (defprinter (lambda-var :identity t)
979 (type :test (not (eq type *universal-type*)))
980 (where-from :test (not (eq where-from :assumed)))
981 (ignorep :test ignorep)
982 (arg-info :test arg-info)
983 (specvar :test specvar))
985 ;;;; basic node types
987 ;;; A REF represents a reference to a LEAF. REF-REOPTIMIZE is
988 ;;; initially (and forever) NIL, since REFs don't receive any values
989 ;;; and don't have any IR1 optimizer.
990 (defstruct (ref (:include node (:reoptimize nil))
991 (:constructor make-ref (derived-type leaf))
993 ;; The leaf referenced.
994 (leaf nil :type leaf))
995 (defprinter (ref :identity t)
998 ;;; Naturally, the IF node always appears at the end of a block.
999 ;;; NODE-CONT is a dummy continuation, and is there only to keep
1001 (defstruct (cif (:include node)
1004 (:constructor make-if)
1006 ;; CONTINUATION for the predicate
1007 (test (required-argument) :type continuation)
1008 ;; the blocks that we execute next in true and false case,
1009 ;; respectively (may be the same)
1010 (consequent (required-argument) :type cblock)
1011 (alternative (required-argument) :type cblock))
1012 (defprinter (cif :conc-name if- :identity t)
1013 (test :prin1 (continuation-use test))
1017 (defstruct (cset (:include node
1018 (derived-type *universal-type*))
1021 (:constructor make-set)
1023 ;; descriptor for the variable set
1024 (var (required-argument) :type basic-var)
1025 ;; continuation for the value form
1026 (value (required-argument) :type continuation))
1027 (defprinter (cset :conc-name set- :identity t)
1029 (value :prin1 (continuation-use value)))
1031 ;;; The BASIC-COMBINATION structure is used to represent both normal
1032 ;;; and multiple value combinations. In a local function call, this
1033 ;;; node appears at the end of its block and the body of the called
1034 ;;; function appears as the successor. The NODE-CONT remains the
1035 ;;; continuation which receives the value of the call.
1036 (defstruct (basic-combination (:include node)
1039 ;; continuation for the function
1040 (fun (required-argument) :type continuation)
1041 ;; list of CONTINUATIONs for the args. In a local call, an argument
1042 ;; continuation may be replaced with NIL to indicate that the
1043 ;; corresponding variable is unreferenced, and thus no argument
1044 ;; value need be passed.
1045 (args nil :type list)
1046 ;; the kind of function call being made. :LOCAL means that this is a
1047 ;; local call to a function in the same component, and that argument
1048 ;; syntax checking has been done, etc. Calls to known global
1049 ;; functions are represented by storing the FUNCTION-INFO for the
1050 ;; function in this slot. :FULL is a call to an (as yet) unknown
1051 ;; function. :ERROR is like :FULL, but means that we have discovered
1052 ;; that the call contains an error, and should not be reconsidered
1053 ;; for optimization.
1054 (kind :full :type (or (member :local :full :error) function-info))
1055 ;; some kind of information attached to this node by the back end
1058 ;;; The COMBINATION node represents all normal function calls,
1059 ;;; including FUNCALL. This is distinct from BASIC-COMBINATION so that
1060 ;;; an MV-COMBINATION isn't COMBINATION-P.
1061 (defstruct (combination (:include basic-combination)
1062 (:constructor make-combination (fun))
1064 (defprinter (combination :identity t)
1065 (fun :prin1 (continuation-use fun))
1066 (args :prin1 (mapcar (lambda (x)
1068 (continuation-use x)
1072 ;;; An MV-COMBINATION is to MULTIPLE-VALUE-CALL as a COMBINATION is to
1073 ;;; FUNCALL. This is used to implement all the multiple-value
1074 ;;; receiving forms.
1075 (defstruct (mv-combination (:include basic-combination)
1076 (:constructor make-mv-combination (fun))
1078 (defprinter (mv-combination)
1079 (fun :prin1 (continuation-use fun))
1080 (args :prin1 (mapcar #'continuation-use args)))
1082 ;;; The BIND node marks the beginning of a lambda body and represents
1083 ;;; the creation and initialization of the variables.
1084 (defstruct (bind (:include node)
1086 ;; the lambda we are binding variables for. Null when we are
1087 ;; creating the LAMBDA during IR1 translation.
1088 (lambda nil :type (or clambda null)))
1092 ;;; The RETURN node marks the end of a lambda body. It collects the
1093 ;;; return values and represents the control transfer on return. This
1094 ;;; is also where we stick information used for TAIL-SET type
1096 (defstruct (creturn (:include node)
1097 (:conc-name return-)
1098 (:predicate return-p)
1099 (:constructor make-return)
1100 (:copier copy-return))
1101 ;; the lambda we are returning from. Null temporarily during
1103 (lambda nil :type (or clambda null))
1104 ;; the continuation which yields the value of the lambda
1105 (result (required-argument) :type continuation)
1106 ;; the union of the node-derived-type of all uses of the result
1107 ;; other than by a local call, intersected with the result's
1108 ;; asserted-type. If there are no non-call uses, this is
1110 (result-type *wild-type* :type ctype))
1111 (defprinter (creturn :conc-name return- :identity t)
1115 ;;;; non-local exit support
1117 ;;;; In IR1, we insert special nodes to mark potentially non-local
1120 ;;; The ENTRY node serves to mark the start of the dynamic extent of a
1121 ;;; lexical exit. It is the mess-up node for the corresponding :Entry
1123 (defstruct (entry (:include node)
1125 ;; All of the Exit nodes for potential non-local exits to this point.
1126 (exits nil :type list)
1127 ;; The cleanup for this entry. NULL only temporarily.
1128 (cleanup nil :type (or cleanup null)))
1129 (defprinter (entry :identity t))
1131 ;;; The EXIT node marks the place at which exit code would be emitted,
1132 ;;; if necessary. This is interposed between the uses of the exit
1133 ;;; continuation and the exit continuation's DEST. Instead of using
1134 ;;; the returned value being delivered directly to the exit
1135 ;;; continuation, it is delivered to our VALUE continuation. The
1136 ;;; original exit continuation is the exit node's CONT.
1137 (defstruct (exit (:include node)
1139 ;; The Entry node that this is an exit for. If null, this is a
1140 ;; degenerate exit. A degenerate exit is used to "fill" an empty
1141 ;; block (which isn't allowed in IR1.) In a degenerate exit, Value
1142 ;; is always also null.
1143 (entry nil :type (or entry null))
1144 ;; The continuation yeilding the value we are to exit with. If NIL,
1145 ;; then no value is desired (as in GO).
1146 (value nil :type (or continuation null)))
1147 (defprinter (exit :identity t)
1149 (value :test value))
1151 ;;;; miscellaneous IR1 structures
1153 (defstruct (undefined-warning
1154 #-no-ansi-print-object
1155 (:print-object (lambda (x s)
1156 (print-unreadable-object (x s :type t)
1157 (prin1 (undefined-warning-name x) s))))
1159 ;; the name of the unknown thing
1160 (name nil :type (or symbol list))
1161 ;; the kind of reference to NAME
1162 (kind (required-argument) :type (member :function :type :variable))
1163 ;; the number of times this thing was used
1164 (count 0 :type unsigned-byte)
1165 ;; a list of COMPILER-ERROR-CONTEXT structures describing places
1166 ;; where this thing was used. Note that we only record the first
1167 ;; *UNDEFINED-WARNING-LIMIT* calls.
1168 (warnings () :type list))
1170 ;;; a helper for the POLICY macro, defined late here so that the
1171 ;;; various type tests can be inlined
1172 (declaim (ftype (function ((or list lexenv node functional)) list)
1174 (defun %coerce-to-policy (thing)
1175 (let ((result (etypecase thing
1177 (lexenv (lexenv-policy thing))
1178 (node (lexenv-policy (node-lexenv thing)))
1179 (functional (lexenv-policy (functional-lexenv thing))))))
1180 ;; Test the first element of the list as a rudimentary sanity
1181 ;; that it really does look like a valid policy.
1182 (aver (or (null result) (policy-quality-name-p (caar result))))
1186 ;;;; Freeze some structure types to speed type testing.
1189 (declaim (freeze-type node leaf lexenv continuation cblock component cleanup
1190 environment tail-set nlx-info))