1 ;;;; This file contains the implementation-independent code for Pack
2 ;;;; phase in the compiler. Pack is responsible for assigning TNs to
3 ;;;; storage allocations or "register allocation".
5 ;;;; This software is part of the SBCL system. See the README file for
8 ;;;; This software is derived from the CMU CL system, which was
9 ;;;; written at Carnegie Mellon University and released into the
10 ;;;; public domain. The software is in the public domain and is
11 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
12 ;;;; files for more information.
16 ;;; for debugging: some parameters controlling which optimizations we
18 (defvar *pack-assign-costs* t)
19 (defvar *pack-optimize-saves* t)
20 ;;; FIXME: Perhaps SB-FLUID should be renamed to SB-TWEAK and these
21 ;;; should be made conditional on SB-TWEAK.
23 (declaim (ftype (function (component) index) ir2-block-count))
25 ;;;; conflict determination
27 ;;; Return true if the element at the specified offset in SB has a
29 ;;; -- If a component-live TN (:COMPONENT kind), then iterate over
30 ;;; all the blocks. If the element at OFFSET is used anywhere in
31 ;;; any of the component's blocks (always-live /= 0), then there
33 ;;; -- If TN is global (Confs true), then iterate over the blocks TN
34 ;;; is live in (using TN-GLOBAL-CONFLICTS). If the TN is live
35 ;;; everywhere in the block (:LIVE), then there is a conflict
36 ;;; if the element at offset is used anywhere in the block
37 ;;; (Always-Live /= 0). Otherwise, we use the local TN number for
38 ;;; TN in block to find whether TN has a conflict at Offset in
40 ;;; -- If TN is local, then we just check for a conflict in the block
42 (defun offset-conflicts-in-sb (tn sb offset)
43 (declare (type tn tn) (type finite-sb sb) (type index offset))
44 (let ((confs (tn-global-conflicts tn))
48 (let ((loc-live (svref (finite-sb-always-live sb) offset)))
49 (dotimes (i (ir2-block-count *component-being-compiled*) nil)
50 (when (/= (sbit loc-live i) 0)
53 (let ((loc-confs (svref (finite-sb-conflicts sb) offset))
54 (loc-live (svref (finite-sb-always-live sb) offset)))
55 (do ((conf confs (global-conflicts-next-tnwise conf)))
58 (let* ((block (global-conflicts-block conf))
59 (num (ir2-block-number block)))
60 (if (eq (global-conflicts-kind conf) :live)
61 (when (/= (sbit loc-live num) 0)
63 (when (/= (sbit (svref loc-confs num)
64 (global-conflicts-number conf))
68 (/= (sbit (svref (svref (finite-sb-conflicts sb) offset)
69 (ir2-block-number (tn-local tn)))
73 ;;; Return true if TN has a conflict in SC at the specified offset.
74 (defun conflicts-in-sc (tn sc offset)
75 (declare (type tn tn) (type sc sc) (type index offset))
76 (let ((sb (sc-sb sc)))
77 (dotimes (i (sc-element-size sc) nil)
78 (when (offset-conflicts-in-sb tn sb (+ offset i))
81 ;;; Add TN's conflicts into the conflicts for the location at OFFSET
82 ;;; in SC. We iterate over each location in TN, adding to the
83 ;;; conflicts for that location:
84 ;;; -- If TN is a :COMPONENT TN, then iterate over all the blocks,
85 ;;; setting all of the local conflict bits and the always-live bit.
86 ;;; This records a conflict with any TN that has a LTN number in
87 ;;; the block, as well as with :ALWAYS-LIVE and :ENVIRONMENT TNs.
88 ;;; -- If TN is global, then iterate over the blocks TN is live in. In
89 ;;; addition to setting the always-live bit to represent the conflict
90 ;;; with TNs live throughout the block, we also set bits in the
91 ;;; local conflicts. If TN is :ALWAYS-LIVE in the block, we set all
92 ;;; the bits, otherwise we OR in the local conflict bits.
93 ;;; -- If the TN is local, then we just do the block it is local to,
94 ;;; setting always-live and OR'ing in the local conflicts.
95 (defun add-location-conflicts (tn sc offset optimize)
96 (declare (type tn tn) (type sc sc) (type index offset))
97 (let ((confs (tn-global-conflicts tn))
100 (dotimes (i (sc-element-size sc))
101 (declare (type index i))
102 (let* ((this-offset (+ offset i))
103 (loc-confs (svref (finite-sb-conflicts sb) this-offset))
104 (loc-live (svref (finite-sb-always-live sb) this-offset)))
106 ((eq kind :component)
107 (dotimes (num (ir2-block-count *component-being-compiled*))
108 (declare (type index num))
109 (setf (sbit loc-live num) 1)
110 (set-bit-vector (svref loc-confs num))))
112 (do ((conf confs (global-conflicts-next-tnwise conf)))
114 (let* ((block (global-conflicts-block conf))
115 (num (ir2-block-number block))
116 (local-confs (svref loc-confs num)))
117 (declare (type local-tn-bit-vector local-confs))
118 (setf (sbit loc-live num) 1)
119 (if (eq (global-conflicts-kind conf) :live)
120 (set-bit-vector local-confs)
121 (bit-ior local-confs (global-conflicts-conflicts conf) t)))))
123 (let ((num (ir2-block-number (tn-local tn))))
124 (setf (sbit loc-live num) 1)
125 (bit-ior (the local-tn-bit-vector (svref loc-confs num))
126 (tn-local-conflicts tn) t))))
127 ;; Calculating ALWAYS-LIVE-COUNT is moderately expensive, and
128 ;; currently the information isn't used unless (> SPEED
131 (setf (svref (finite-sb-always-live-count sb) this-offset)
132 (find-location-usage sb this-offset))))))
135 ;; A rought measure of how much a given OFFSET in SB is currently
136 ;; used. Current implementation counts the amount of blocks where the
137 ;; offset has been marked as ALWAYS-LIVE.
138 (defun find-location-usage (sb offset)
139 (declare (optimize speed))
140 (declare (type sb sb) (type index offset))
141 (let* ((always-live (svref (finite-sb-always-live sb) offset)))
142 (declare (simple-bit-vector always-live))
143 (count 1 always-live)))
145 ;;; Return the total number of IR2-BLOCKs in COMPONENT.
146 (defun ir2-block-count (component)
147 (declare (type component component))
148 (do ((2block (block-info (block-next (component-head component)))
149 (ir2-block-next 2block)))
151 (error "What? No ir2 blocks have a non-nil number?"))
152 (when (ir2-block-number 2block)
153 (return (1+ (ir2-block-number 2block))))))
155 ;;; Ensure that the conflicts vectors for each :FINITE SB are large
156 ;;; enough for the number of blocks allocated. Also clear any old
157 ;;; conflicts and reset the current size to the initial size.
158 (defun init-sb-vectors (component)
159 (let ((nblocks (ir2-block-count component)))
160 (dolist (sb *backend-sb-list*)
161 (unless (eq (sb-kind sb) :non-packed)
162 (let* ((conflicts (finite-sb-conflicts sb))
163 (always-live (finite-sb-always-live sb))
164 (always-live-count (finite-sb-always-live-count sb))
165 (max-locs (length conflicts))
166 (last-count (finite-sb-last-block-count sb)))
167 (unless (zerop max-locs)
168 (let ((current-size (length (the simple-vector
169 (svref conflicts 0)))))
171 ((> nblocks current-size)
172 (let ((new-size (max nblocks (* current-size 2))))
173 (declare (type index new-size))
174 (dotimes (i max-locs)
175 (declare (type index i))
176 (let ((new-vec (make-array new-size)))
177 (let ((old (svref conflicts i)))
178 (declare (simple-vector old))
179 (dotimes (j current-size)
180 (declare (type index j))
181 (setf (svref new-vec j)
182 (clear-bit-vector (svref old j)))))
184 (do ((j current-size (1+ j)))
186 (declare (type index j))
187 (setf (svref new-vec j)
188 (make-array local-tn-limit :element-type 'bit
189 :initial-element 0)))
190 (setf (svref conflicts i) new-vec))
191 (setf (svref always-live i)
192 (make-array new-size :element-type 'bit
194 (setf (svref always-live-count i) 0))))
196 (dotimes (i (finite-sb-current-size sb))
197 (declare (type index i))
198 (let ((conf (svref conflicts i)))
199 (declare (simple-vector conf))
200 (dotimes (j last-count)
201 (declare (type index j))
202 (clear-bit-vector (svref conf j))))
203 (clear-bit-vector (svref always-live i))
204 (setf (svref always-live-count i) 0))))))
206 (setf (finite-sb-last-block-count sb) nblocks)
207 (setf (finite-sb-current-size sb) (sb-size sb))
208 (setf (finite-sb-last-offset sb) 0))))))
210 ;;; Expand the :UNBOUNDED SB backing SC by either the initial size or
211 ;;; the SC element size, whichever is larger. If NEEDED-SIZE is
212 ;;; larger, then use that size.
213 (defun grow-sc (sc &optional (needed-size 0))
214 (declare (type sc sc) (type index needed-size))
215 (let* ((sb (sc-sb sc))
216 (size (finite-sb-current-size sb))
217 (align-mask (1- (sc-alignment sc)))
218 (inc (max (finite-sb-size-increment sb)
219 (+ (sc-element-size sc)
220 (- (logandc2 (+ size align-mask) align-mask)
222 (- needed-size size)))
223 (new-size (let ((align-mask (1- (finite-sb-size-alignment sb))))
224 (logandc2 (+ size inc align-mask) align-mask)))
225 (conflicts (finite-sb-conflicts sb))
226 (block-size (if (zerop (length conflicts))
227 (ir2-block-count *component-being-compiled*)
228 (length (the simple-vector (svref conflicts 0)))))
229 (padded-size (ash 1 (integer-length (1- new-size)))))
230 (declare (type index inc new-size padded-size))
231 (aver (eq (sb-kind sb) :unbounded))
233 (when (> padded-size (length conflicts))
234 (let ((new-conf (make-array padded-size)))
235 (replace new-conf conflicts)
236 (do ((i size (1+ i)))
238 (declare (type index i))
239 (let ((loc-confs (make-array block-size)))
240 (dotimes (j block-size)
241 (setf (svref loc-confs j)
242 (make-array local-tn-limit
244 :element-type 'bit)))
245 (setf (svref new-conf i) loc-confs)))
246 (setf (finite-sb-conflicts sb) new-conf))
248 (let ((new-live (make-array padded-size)))
249 (replace new-live (finite-sb-always-live sb))
250 (do ((i size (1+ i)))
252 (setf (svref new-live i)
253 (make-array block-size
255 :element-type 'bit)))
256 (setf (finite-sb-always-live sb) new-live))
258 (let ((new-live-count (make-array padded-size)))
259 (declare (optimize speed)) ;; FILL deftransform
260 (replace new-live-count (finite-sb-always-live-count sb))
261 (fill new-live-count 0 :start size)
262 (setf (finite-sb-always-live-count sb) new-live-count))
264 (let ((new-tns (make-array padded-size :initial-element nil)))
265 (replace new-tns (finite-sb-live-tns sb))
266 (fill (finite-sb-live-tns sb) nil)
267 (setf (finite-sb-live-tns sb) new-tns)))
269 (setf (finite-sb-current-size sb) new-size))
275 ;;; Give someone a hard time because there isn't any load function
276 ;;; defined to move from SRC to DEST.
277 (defun no-load-fun-error (src dest)
278 (let* ((src-sc (tn-sc src))
279 (src-name (sc-name src-sc))
280 (dest-sc (tn-sc dest))
281 (dest-name (sc-name dest-sc)))
282 (cond ((eq (sb-kind (sc-sb src-sc)) :non-packed)
283 (unless (member src-sc (sc-constant-scs dest-sc))
284 (error "loading from an invalid constant SC?~@
285 VM definition inconsistent, try recompiling."))
286 (error "no load function defined to load SC ~S ~
287 from its constant SC ~S"
289 ((member src-sc (sc-alternate-scs dest-sc))
290 (error "no load function defined to load SC ~S from its ~
293 ((member dest-sc (sc-alternate-scs src-sc))
294 (error "no load function defined to save SC ~S in its ~
298 ;; FIXME: "VM definition is inconsistent" shouldn't be a
299 ;; possibility in SBCL.
300 (error "loading to/from SCs that aren't alternates?~@
301 VM definition is inconsistent, try recompiling.")))))
303 ;;; Called when we failed to pack TN. If RESTRICTED is true, then we
304 ;;; are restricted to pack TN in its SC.
305 (defun failed-to-pack-error (tn restricted)
306 (declare (type tn tn))
307 (let* ((sc (tn-sc tn))
308 (scs (cons sc (sc-alternate-scs sc))))
311 (error "failed to pack restricted TN ~S in its SC ~S"
314 (aver (not (find :unbounded scs
315 :key (lambda (x) (sb-kind (sc-sb x))))))
316 (let ((ptype (tn-primitive-type tn)))
319 (aver (member (sc-number sc) (primitive-type-scs ptype)))
320 (error "SC ~S doesn't have any :UNBOUNDED alternate SCs, but is~@
321 a SC for primitive-type ~S."
322 (sc-name sc) (primitive-type-name ptype)))
324 (error "SC ~S doesn't have any :UNBOUNDED alternate SCs."
327 ;;; Return a list of format arguments describing how TN is used in
329 (defun describe-tn-use (loc tn op)
330 (let* ((vop (tn-ref-vop op))
331 (args (vop-args vop))
332 (results (vop-results vop))
333 (name (with-output-to-string (stream)
334 (print-tn-guts tn stream)))
335 (2comp (component-info *component-being-compiled*))
338 ((setq temp (position-in #'tn-ref-across tn args :key #'tn-ref-tn))
339 `("~2D: ~A (~:R argument)" ,loc ,name ,(1+ temp)))
340 ((setq temp (position-in #'tn-ref-across tn results :key #'tn-ref-tn))
341 `("~2D: ~A (~:R result)" ,loc ,name ,(1+ temp)))
342 ((setq temp (position-in #'tn-ref-across tn args :key #'tn-ref-load-tn))
343 `("~2D: ~A (~:R argument load TN)" ,loc ,name ,(1+ temp)))
344 ((setq temp (position-in #'tn-ref-across tn results :key
346 `("~2D: ~A (~:R result load TN)" ,loc ,name ,(1+ temp)))
347 ((setq temp (position-in #'tn-ref-across tn (vop-temps vop)
349 `("~2D: ~A (temporary ~A)" ,loc ,name
350 ,(operand-parse-name (elt (vop-parse-temps
352 (vop-info-name (vop-info vop))))
354 ((eq (tn-kind tn) :component)
355 `("~2D: ~A (component live)" ,loc ,name))
356 ((position-in #'tn-next tn (ir2-component-wired-tns 2comp))
357 `("~2D: ~A (wired)" ,loc ,name))
358 ((position-in #'tn-next tn (ir2-component-restricted-tns 2comp))
359 `("~2D: ~A (restricted)" ,loc ,name))
361 `("~2D: not referenced?" ,loc)))))
363 ;;; If load TN packing fails, try to give a helpful error message. We
364 ;;; find a TN in each location that conflicts, and print it.
365 (defun failed-to-pack-load-tn-error (scs op)
366 (declare (list scs) (type tn-ref op))
370 (let* ((sb (sc-sb sc))
371 (confs (finite-sb-live-tns sb)))
372 (aver (eq (sb-kind sb) :finite))
373 (dolist (el (sc-locations sc))
374 (declare (type index el))
375 (let ((conf (load-tn-conflicts-in-sc op sc el t)))
377 (used (describe-tn-use el conf op))
379 (end (+ el (sc-element-size sc))))
382 (declare (type index i end))
383 (let ((victim (svref confs i)))
385 (used (describe-tn-use el victim op))
388 (multiple-value-bind (arg-p n more-p costs load-scs incon)
389 (get-operand-info op)
390 (declare (ignore costs load-scs))
392 (error "unable to pack a Load-TN in SC ~{~A~#[~^~;, or ~:;,~]~} ~
393 for the ~:R ~:[result~;argument~] to~@
395 ~:[since all SC elements are in use:~:{~%~@?~}~%~;~
396 ~:*but these SC elements are not in use:~% ~S~%Bug?~*~]~
398 Current cost info inconsistent with that in effect at compile ~
399 time. Recompile.~%Compilation order may be incorrect.~]"
400 (mapcar #'sc-name scs)
402 (vop-info-name (vop-info (tn-ref-vop op)))
406 ;;; This is called when none of the SCs that we can load OP into are
407 ;;; allowed by OP's primitive-type.
408 (defun no-load-scs-allowed-by-primitive-type-error (ref)
409 (declare (type tn-ref ref))
410 (let* ((tn (tn-ref-tn ref))
411 (ptype (tn-primitive-type tn)))
412 (multiple-value-bind (arg-p pos more-p costs load-scs incon)
413 (get-operand-info ref)
414 (declare (ignore costs))
416 (error "~S is not valid as the ~:R ~:[result~;argument~] to VOP:~
418 since the TN's primitive type ~S doesn't allow any of the SCs~@
419 allowed by the operand restriction:~% ~S~
421 Current cost info inconsistent with that in effect at compile ~
422 time. Recompile.~%Compilation order may be incorrect.~]"
424 (template-name (vop-info (tn-ref-vop ref)))
425 (primitive-type-name ptype)
426 (mapcar #'sc-name (listify-restrictions load-scs))
431 ;;; Do stuff to note that TN is spilled at VOP for the debugger's benefit.
432 (defun note-spilled-tn (tn vop)
433 (when (and (tn-leaf tn) (vop-save-set vop))
434 (let ((2comp (component-info *component-being-compiled*)))
435 (setf (gethash tn (ir2-component-spilled-tns 2comp)) t)
436 (pushnew tn (gethash vop (ir2-component-spilled-vops 2comp)))))
439 ;;; Make a save TN for TN, pack it, and return it. We copy various
440 ;;; conflict information from the TN so that pack does the right
442 (defun pack-save-tn (tn)
443 (declare (type tn tn))
444 (let ((res (make-tn 0 :save nil nil)))
445 (dolist (alt (sc-alternate-scs (tn-sc tn))
446 (error "no unbounded alternate for SC ~S"
447 (sc-name (tn-sc tn))))
448 (when (eq (sb-kind (sc-sb alt)) :unbounded)
449 (setf (tn-save-tn tn) res)
450 (setf (tn-save-tn res) tn)
451 (setf (tn-sc res) alt)
455 ;;; Find the load function for moving from SRC to DEST and emit a
456 ;;; MOVE-OPERAND VOP with that function as its info arg.
457 (defun emit-operand-load (node block src dest before)
458 (declare (type node node) (type ir2-block block)
459 (type tn src dest) (type (or vop null) before))
460 (emit-load-template node block
461 (template-or-lose 'move-operand)
463 (list (or (svref (sc-move-funs (tn-sc dest))
464 (sc-number (tn-sc src)))
465 (no-load-fun-error src dest)))
469 ;;; Find the preceding use of the VOP NAME in the emit order, starting
470 ;;; with VOP. We must find the VOP in the same IR1 block.
471 (defun reverse-find-vop (name vop)
472 (do* ((block (vop-block vop) (ir2-block-prev block))
473 (last vop (ir2-block-last-vop block)))
475 (aver (eq (ir2-block-block block) (ir2-block-block (vop-block vop))))
476 (do ((current last (vop-prev current)))
478 (when (eq (vop-info-name (vop-info current)) name)
479 (return-from reverse-find-vop current)))))
481 ;;; For TNs that have other than one writer, we save the TN before
482 ;;; each call. If a local call (MOVE-ARGS is :LOCAL-CALL), then we
483 ;;; scan back for the ALLOCATE-FRAME VOP, and emit the save there.
484 ;;; This is necessary because in a self-recursive local call, the
485 ;;; registers holding the current arguments may get trashed by setting
486 ;;; up the call arguments. The ALLOCATE-FRAME VOP marks a place at
487 ;;; which the values are known to be good.
488 (defun save-complex-writer-tn (tn vop)
489 (let ((save (or (tn-save-tn tn)
491 (node (vop-node vop))
492 (block (vop-block vop))
493 (next (vop-next vop)))
494 (when (eq (tn-kind save) :specified-save)
495 (setf (tn-kind save) :save))
496 (aver (eq (tn-kind save) :save))
497 (emit-operand-load node block tn save
498 (if (eq (vop-info-move-args (vop-info vop))
500 (reverse-find-vop 'allocate-frame vop)
502 (emit-operand-load node block save tn next)))
504 ;;; Return a VOP after which is an OK place to save the value of TN.
505 ;;; For correctness, it is only required that this location be after
506 ;;; any possible write and before any possible restore location.
508 ;;; In practice, we return the unique writer VOP, but give up if the
509 ;;; TN is ever read by a VOP with MOVE-ARGS :LOCAL-CALL. This prevents
510 ;;; us from being confused by non-tail local calls.
512 ;;; When looking for writes, we have to ignore uses of MOVE-OPERAND,
513 ;;; since they will correspond to restores that we have already done.
514 (defun find-single-writer (tn)
515 (declare (type tn tn))
516 (do ((write (tn-writes tn) (tn-ref-next write))
520 (do ((read (tn-reads tn) (tn-ref-next read)))
522 (when (eq (vop-info-move-args
529 (unless (eq (vop-info-name (vop-info (tn-ref-vop write)))
531 (when res (return nil))
534 ;;; Try to save TN at a single location. If we succeed, return T,
536 (defun save-single-writer-tn (tn)
537 (declare (type tn tn))
538 (let* ((old-save (tn-save-tn tn))
539 (save (or old-save (pack-save-tn tn)))
540 (writer (find-single-writer tn)))
543 (eq (tn-kind old-save) :specified-save)))
544 (emit-operand-load (vop-node writer) (vop-block writer)
545 tn save (vop-next writer))
546 (setf (tn-kind save) :save-once)
549 ;;; Restore a TN with a :SAVE-ONCE save TN.
550 (defun restore-single-writer-tn (tn vop)
551 (declare (type tn) (type vop vop))
552 (let ((save (tn-save-tn tn)))
553 (aver (eq (tn-kind save) :save-once))
554 (emit-operand-load (vop-node vop) (vop-block vop) save tn (vop-next vop)))
557 ;;; Save a single TN that needs to be saved, choosing save-once if
558 ;;; appropriate. This is also called by SPILL-AND-PACK-LOAD-TN.
559 (defun basic-save-tn (tn vop)
560 (declare (type tn tn) (type vop vop))
561 (let ((save (tn-save-tn tn)))
562 (cond ((and save (eq (tn-kind save) :save-once))
563 (restore-single-writer-tn tn vop))
564 ((save-single-writer-tn tn)
565 (restore-single-writer-tn tn vop))
567 (save-complex-writer-tn tn vop))))
570 ;;; Scan over the VOPs in BLOCK, emiting saving code for TNs noted in
571 ;;; the codegen info that are packed into saved SCs.
572 (defun emit-saves (block)
573 (declare (type ir2-block block))
574 (do ((vop (ir2-block-start-vop block) (vop-next vop)))
576 (when (eq (vop-info-save-p (vop-info vop)) t)
577 (do-live-tns (tn (vop-save-set vop) block)
578 (when (and (sc-save-p (tn-sc tn))
579 (not (eq (tn-kind tn) :component)))
580 (basic-save-tn tn vop)))))
584 ;;;; optimized saving
586 ;;; Save TN if it isn't a single-writer TN that has already been
587 ;;; saved. If multi-write, we insert the save BEFORE the specified
588 ;;; VOP. CONTEXT is a VOP used to tell which node/block to use for the
590 (defun save-if-necessary (tn before context)
591 (declare (type tn tn) (type (or vop null) before) (type vop context))
592 (let ((save (tn-save-tn tn)))
593 (when (eq (tn-kind save) :specified-save)
594 (setf (tn-kind save) :save))
595 (aver (member (tn-kind save) '(:save :save-once)))
596 (unless (eq (tn-kind save) :save-once)
597 (or (save-single-writer-tn tn)
598 (emit-operand-load (vop-node context) (vop-block context)
602 ;;; Load the TN from its save location, allocating one if necessary.
603 ;;; The load is inserted BEFORE the specified VOP. CONTEXT is a VOP
604 ;;; used to tell which node/block to use for the new VOP.
605 (defun restore-tn (tn before context)
606 (declare (type tn tn) (type (or vop null) before) (type vop context))
607 (let ((save (or (tn-save-tn tn) (pack-save-tn tn))))
608 (emit-operand-load (vop-node context) (vop-block context)
612 ;;; Start scanning backward at the end of BLOCK, looking which TNs are
613 ;;; live and looking for places where we have to save. We manipulate
614 ;;; two sets: SAVES and RESTORES.
616 ;;; SAVES is a set of all the TNs that have to be saved because they
617 ;;; are restored after some call. We normally delay saving until the
618 ;;; beginning of the block, but we must save immediately if we see a
619 ;;; write of the saved TN. We also immediately save all TNs and exit
620 ;;; when we see a NOTE-ENVIRONMENT-START VOP, since saves can't be
621 ;;; done before the environment is properly initialized.
623 ;;; RESTORES is a set of all the TNs read (and not written) between
624 ;;; here and the next call, i.e. the set of TNs that must be restored
625 ;;; when we reach the next (earlier) call VOP. Unlike SAVES, this set
626 ;;; is cleared when we do the restoring after a call. Any TNs that
627 ;;; were in RESTORES are moved into SAVES to ensure that they are
628 ;;; saved at some point.
630 ;;; SAVES and RESTORES are represented using both a list and a
631 ;;; bit-vector so that we can quickly iterate and test for membership.
632 ;;; The incoming SAVES and RESTORES args are used for computing these
633 ;;; sets (the initial contents are ignored.)
635 ;;; When we hit a VOP with :COMPUTE-ONLY SAVE-P (an internal error
636 ;;; location), we pretend that all live TNs were read, unless (= speed
637 ;;; 3), in which case we mark all the TNs that are live but not
638 ;;; restored as spilled.
639 (defun optimized-emit-saves-block (block saves restores)
640 (declare (type ir2-block block) (type simple-bit-vector saves restores))
641 (let ((1block (ir2-block-block block))
645 (declare (list saves-list restores-list))
646 (clear-bit-vector saves)
647 (clear-bit-vector restores)
648 (do-live-tns (tn (ir2-block-live-in block) block)
649 (when (and (sc-save-p (tn-sc tn))
650 (not (eq (tn-kind tn) :component)))
651 (let ((num (tn-number tn)))
652 (setf (sbit restores num) 1)
653 (push tn restores-list))))
655 (do ((block block (ir2-block-prev block))
657 ((not (eq (ir2-block-block block) 1block))
658 (aver (not skipping))
659 (dolist (save saves-list)
660 (let ((start (ir2-block-start-vop prev)))
661 (save-if-necessary save start start)))
663 (do ((vop (ir2-block-last-vop block) (vop-prev vop)))
665 (let ((info (vop-info vop)))
666 (case (vop-info-name info)
670 (note-environment-start
671 (aver (not skipping))
672 (dolist (save saves-list)
673 (save-if-necessary save (vop-next vop) vop))
674 (return-from optimized-emit-saves-block block)))
677 (do ((write (vop-results vop) (tn-ref-across write)))
679 (let* ((tn (tn-ref-tn write))
680 (num (tn-number tn)))
681 (unless (zerop (sbit restores num))
682 (setf (sbit restores num) 0)
684 (delete tn restores-list :test #'eq)))
685 (unless (zerop (sbit saves num))
686 (setf (sbit saves num) 0)
687 (save-if-necessary tn (vop-next vop) vop)
689 (delete tn saves-list :test #'eq))))))
691 (macrolet ((save-note-read (tn)
693 (num (tn-number tn)))
694 (when (and (sc-save-p (tn-sc tn))
695 (zerop (sbit restores num))
696 (not (eq (tn-kind tn) :component)))
697 (setf (sbit restores num) 1)
698 (push tn restores-list)))))
700 (case (vop-info-save-p info)
702 (dolist (tn restores-list)
703 (restore-tn tn (vop-next vop) vop)
704 (let ((num (tn-number tn)))
705 (when (zerop (sbit saves num))
707 (setf (sbit saves num) 1))))
708 (setq restores-list nil)
709 (clear-bit-vector restores))
711 (cond ((policy (vop-node vop) (= speed 3))
712 (do-live-tns (tn (vop-save-set vop) block)
713 (when (zerop (sbit restores (tn-number tn)))
714 (note-spilled-tn tn vop))))
716 (do-live-tns (tn (vop-save-set vop) block)
717 (save-note-read tn))))))
719 (if (eq (vop-info-move-args info) :local-call)
721 (do ((read (vop-args vop) (tn-ref-across read)))
723 (save-note-read (tn-ref-tn read))))))))))
725 ;;; This is like EMIT-SAVES, only different. We avoid redundant saving
726 ;;; within the block, and don't restore values that aren't used before
727 ;;; the next call. This function is just the top level loop over the
728 ;;; blocks in the component, which locates blocks that need saving
730 (defun optimized-emit-saves (component)
731 (declare (type component component))
732 (let* ((gtn-count (1+ (ir2-component-global-tn-counter
733 (component-info component))))
734 (saves (make-array gtn-count :element-type 'bit))
735 (restores (make-array gtn-count :element-type 'bit))
736 (block (ir2-block-prev (block-info (component-tail component))))
737 (head (block-info (component-head component))))
739 (when (eq block head) (return))
740 (when (do ((vop (ir2-block-start-vop block) (vop-next vop)))
742 (when (eq (vop-info-save-p (vop-info vop)) t)
744 (setq block (optimized-emit-saves-block block saves restores)))
745 (setq block (ir2-block-prev block)))))
747 ;;; Iterate over the normal TNs, finding the cost of packing on the
748 ;;; stack in units of the number of references. We count all
749 ;;; references as +1, and subtract out REGISTER-SAVE-PENALTY for each
750 ;;; place where we would have to save a register.
751 (defun assign-tn-costs (component)
752 (do-ir2-blocks (block component)
753 (do ((vop (ir2-block-start-vop block) (vop-next vop)))
755 (when (eq (vop-info-save-p (vop-info vop)) t)
756 (do-live-tns (tn (vop-save-set vop) block)
757 (decf (tn-cost tn) *backend-register-save-penalty*)))))
759 (do ((tn (ir2-component-normal-tns (component-info component))
762 (let ((cost (tn-cost tn)))
763 (declare (fixnum cost))
764 (do ((ref (tn-reads tn) (tn-ref-next ref)))
767 (do ((ref (tn-writes tn) (tn-ref-next ref)))
770 (setf (tn-cost tn) cost))))
772 ;;; Iterate over the normal TNs, storing the depth of the deepest loop
773 ;;; that the TN is used in TN-LOOP-DEPTH.
774 (defun assign-tn-depths (component)
776 (do-ir2-blocks (block component)
777 (do ((vop (ir2-block-start-vop block)
780 (flet ((find-all-tns (head-fun)
782 (do ((ref (funcall head-fun vop) (tn-ref-across ref)))
784 (tns (tn-ref-tn ref)))
786 (dolist (tn (nconc (find-all-tns #'vop-args)
787 (find-all-tns #'vop-results)
788 (find-all-tns #'vop-temps)
789 ;; What does "references in this VOP
790 ;; mean"? Probably something that isn't
791 ;; useful in this context, since these
792 ;; TN-REFs are linked with TN-REF-NEXT
793 ;; instead of TN-REF-ACROSS. --JES
795 ;; (find-all-tns #'vop-refs)
797 (setf (tn-loop-depth tn)
798 (max (tn-loop-depth tn)
799 (let* ((ir1-block (ir2-block-block (vop-block vop)))
800 (loop (block-loop ir1-block)))
808 ;;; These variables indicate the last location at which we computed
809 ;;; the Live-TNs. They hold the BLOCK and VOP values that were passed
810 ;;; to COMPUTE-LIVE-TNS.
811 (defvar *live-block*)
814 ;;; If we unpack some TNs, then we mark all affected blocks by
815 ;;; sticking them in this hash-table. This is initially null. We
816 ;;; create the hashtable if we do any unpacking.
817 (defvar *repack-blocks*)
818 (declaim (type list *repack-blocks*))
820 ;;; Set the LIVE-TNS vectors in all :FINITE SBs to represent the TNs
821 ;;; live at the end of BLOCK.
822 (defun init-live-tns (block)
823 (dolist (sb *backend-sb-list*)
824 (when (eq (sb-kind sb) :finite)
825 (fill (finite-sb-live-tns sb) nil)))
827 (do-live-tns (tn (ir2-block-live-in block) block)
828 (let* ((sc (tn-sc tn))
830 (when (eq (sb-kind sb) :finite)
831 ;; KLUDGE: we can have "live" TNs that are neither read
832 ;; to nor written from, due to more aggressive (type-
833 ;; directed) constant propagation. Such TNs will never
834 ;; be assigned an offset nor be in conflict with anything.
836 ;; Ideally, it seems to me we could make sure these TNs
837 ;; are never allocated in the first place in
838 ;; ASSIGN-LAMBDA-VAR-TNS.
840 (do ((offset (tn-offset tn) (1+ offset))
841 (end (+ (tn-offset tn) (sc-element-size sc))))
843 (declare (type index offset end))
844 (setf (svref (finite-sb-live-tns sb) offset) tn))
845 (assert (and (null (tn-reads tn))
846 (null (tn-writes tn))))))))
848 (setq *live-block* block)
849 (setq *live-vop* (ir2-block-last-vop block))
853 ;;; Set the LIVE-TNs in :FINITE SBs to represent the TNs live
854 ;;; immediately after the evaluation of VOP in BLOCK, excluding
855 ;;; results of the VOP. If VOP is null, then compute the live TNs at
856 ;;; the beginning of the block. Sequential calls on the same block
857 ;;; must be in reverse VOP order.
858 (defun compute-live-tns (block vop)
859 (declare (type ir2-block block) (type vop vop))
860 (unless (eq block *live-block*)
861 (init-live-tns block))
863 (do ((current *live-vop* (vop-prev current)))
865 (do ((res (vop-results vop) (tn-ref-across res)))
867 (let* ((tn (tn-ref-tn res))
870 (when (eq (sb-kind sb) :finite)
871 (do ((offset (tn-offset tn) (1+ offset))
872 (end (+ (tn-offset tn) (sc-element-size sc))))
874 (declare (type index offset end))
875 (setf (svref (finite-sb-live-tns sb) offset) nil))))))
876 (do ((ref (vop-refs current) (tn-ref-next-ref ref)))
878 (let ((ltn (tn-ref-load-tn ref)))
880 (let* ((sc (tn-sc ltn))
882 (when (eq (sb-kind sb) :finite)
883 (let ((tns (finite-sb-live-tns sb)))
884 (do ((offset (tn-offset ltn) (1+ offset))
885 (end (+ (tn-offset ltn) (sc-element-size sc))))
887 (declare (type index offset end))
888 (aver (null (svref tns offset)))))))))
890 (let* ((tn (tn-ref-tn ref))
893 (when (eq (sb-kind sb) :finite)
894 (let ((tns (finite-sb-live-tns sb)))
895 (do ((offset (tn-offset tn) (1+ offset))
896 (end (+ (tn-offset tn) (sc-element-size sc))))
898 (declare (type index offset end))
899 (if (tn-ref-write-p ref)
900 (setf (svref tns offset) nil)
901 (let ((old (svref tns offset)))
902 (aver (or (null old) (eq old tn)))
903 (setf (svref tns offset) tn)))))))))
905 (setq *live-vop* vop)
908 ;;; This is kind of like OFFSET-CONFLICTS-IN-SB, except that it uses
909 ;;; the VOP refs to determine whether a Load-TN for OP could be packed
910 ;;; in the specified location, disregarding conflicts with TNs not
911 ;;; referenced by this VOP. There is a conflict if either:
912 ;;; 1. The reference is a result, and the same location is either:
913 ;;; -- Used by some other result.
914 ;;; -- Used in any way after the reference (exclusive).
915 ;;; 2. The reference is an argument, and the same location is either:
916 ;;; -- Used by some other argument.
917 ;;; -- Used in any way before the reference (exclusive).
919 ;;; In 1 (and 2) above, the first bullet corresponds to result-result
920 ;;; (and argument-argument) conflicts. We need this case because there
921 ;;; aren't any TN-REFs to represent the implicit reading of results or
922 ;;; writing of arguments.
924 ;;; The second bullet corresponds to conflicts with temporaries or
925 ;;; between arguments and results.
927 ;;; We consider both the TN-REF-TN and the TN-REF-LOAD-TN (if any) to
928 ;;; be referenced simultaneously and in the same way. This causes
929 ;;; load-TNs to appear live to the beginning (or end) of the VOP, as
932 ;;; We return a conflicting TN if there is a conflict.
933 (defun load-tn-offset-conflicts-in-sb (op sb offset)
934 (declare (type tn-ref op) (type finite-sb sb) (type index offset))
935 (aver (eq (sb-kind sb) :finite))
936 (let ((vop (tn-ref-vop op)))
937 (labels ((tn-overlaps (tn)
938 (let ((sc (tn-sc tn))
939 (tn-offset (tn-offset tn)))
940 (when (and (eq (sc-sb sc) sb)
941 (<= tn-offset offset)
944 (+ tn-offset (sc-element-size sc)))))
947 (let ((tn (tn-ref-tn ref))
948 (ltn (tn-ref-load-tn ref)))
950 (and ltn (tn-overlaps ltn)))))
952 (do ((ops ops (tn-ref-across ops)))
954 (let ((found (same ops)))
955 (when (and found (not (eq ops op)))
958 (do ((refs refs (tn-ref-next-ref refs)))
960 (let ((found (same refs)))
961 (when found (return found))))))
962 (declare (inline is-op is-ref tn-overlaps))
963 (if (tn-ref-write-p op)
964 (or (is-op (vop-results vop))
965 (is-ref (vop-refs vop) op))
966 (or (is-op (vop-args vop))
967 (is-ref (tn-ref-next-ref op) nil))))))
969 ;;; Iterate over all the elements in the SB that would be allocated by
970 ;;; allocating a TN in SC at Offset, checking for conflict with
971 ;;; load-TNs or other TNs (live in the LIVE-TNS, which must be set
972 ;;; up.) We also return true if there aren't enough locations after
973 ;;; Offset to hold a TN in SC. If Ignore-Live is true, then we ignore
974 ;;; the live-TNs, considering only references within Op's VOP.
976 ;;; We return a conflicting TN, or :OVERFLOW if the TN won't fit.
977 (defun load-tn-conflicts-in-sc (op sc offset ignore-live)
978 (let* ((sb (sc-sb sc))
979 (size (finite-sb-current-size sb)))
980 (do ((i offset (1+ i))
981 (end (+ offset (sc-element-size sc))))
983 (declare (type index i end))
984 (let ((res (or (when (>= i size) :overflow)
985 (and (not ignore-live)
986 (svref (finite-sb-live-tns sb) i))
987 (load-tn-offset-conflicts-in-sb op sb i))))
988 (when res (return res))))))
990 ;;; If a load-TN for OP is targeted to a legal location in SC, then
991 ;;; return the offset, otherwise return NIL. We see whether the target
992 ;;; of the operand is packed, and try that location. There isn't any
993 ;;; need to chain down the target path, since everything is packed
996 ;;; We require the target to be in SC (and not merely to overlap with
997 ;;; SC). This prevents SC information from being lost in load TNs (we
998 ;;; won't pack a load TN in ANY-REG when it is targeted to a
999 ;;; DESCRIPTOR-REG.) This shouldn't hurt the code as long as all
1000 ;;; relevant overlapping SCs are allowed in the operand SC
1002 (defun find-load-tn-target (op sc)
1003 (declare (inline member))
1004 (let ((target (tn-ref-target op)))
1006 (let* ((tn (tn-ref-tn target))
1007 (loc (tn-offset tn)))
1008 (if (and (eq (tn-sc tn) sc)
1009 (member (the index loc) (sc-locations sc))
1010 (not (load-tn-conflicts-in-sc op sc loc nil)))
1014 ;;; Select a legal location for a load TN for Op in SC. We just
1015 ;;; iterate over the SC's locations. If we can't find a legal
1016 ;;; location, return NIL.
1017 (defun select-load-tn-location (op sc)
1018 (declare (type tn-ref op) (type sc sc))
1020 ;; Check any target location first.
1021 (let ((target (tn-ref-target op)))
1023 (let* ((tn (tn-ref-tn target))
1024 (loc (tn-offset tn)))
1025 (when (and (eq (sc-sb sc) (sc-sb (tn-sc tn)))
1026 (member (the index loc) (sc-locations sc))
1027 (not (load-tn-conflicts-in-sc op sc loc nil)))
1028 (return-from select-load-tn-location loc)))))
1030 (dolist (loc (sc-locations sc) nil)
1031 (unless (load-tn-conflicts-in-sc op sc loc nil)
1034 (defevent unpack-tn "Unpacked a TN to satisfy operand SC restriction.")
1036 ;;; Make TN's location the same as for its save TN (allocating a save
1037 ;;; TN if necessary.) Delete any save/restore code that has been
1038 ;;; emitted thus far. Mark all blocks containing references as needing
1040 (defun unpack-tn (tn)
1042 (let ((stn (or (tn-save-tn tn)
1043 (pack-save-tn tn))))
1044 (setf (tn-sc tn) (tn-sc stn))
1045 (setf (tn-offset tn) (tn-offset stn))
1047 (do ((ref refs (tn-ref-next ref)))
1049 (let ((vop (tn-ref-vop ref)))
1050 (if (eq (vop-info-name (vop-info vop)) 'move-operand)
1052 (pushnew (vop-block vop) *repack-blocks*))))))
1054 (zot (tn-writes tn))))
1058 (defevent unpack-fallback "Unpacked some operand TN.")
1060 ;;; This is called by PACK-LOAD-TN where there isn't any location free
1061 ;;; that we can pack into. What we do is move some live TN in one of
1062 ;;; the specified SCs to memory, then mark all blocks that reference
1063 ;;; the TN as needing repacking. If we succeed, we throw to UNPACKED-TN.
1064 ;;; If we fail, we return NIL.
1066 ;;; We can unpack any live TN that appears in the NORMAL-TNs list
1067 ;;; (isn't wired or restricted.) We prefer to unpack TNs that are not
1068 ;;; used by the VOP. If we can't find any such TN, then we unpack some
1069 ;;; argument or result TN. The only way we can fail is if all
1070 ;;; locations in SC are used by load-TNs or temporaries in VOP.
1071 (defun unpack-for-load-tn (sc op)
1072 (declare (type sc sc) (type tn-ref op))
1073 (let ((sb (sc-sb sc))
1074 (normal-tns (ir2-component-normal-tns
1075 (component-info *component-being-compiled*)))
1076 (node (vop-node (tn-ref-vop op)))
1078 (flet ((unpack-em (victims)
1079 (pushnew (vop-block (tn-ref-vop op)) *repack-blocks*)
1080 (dolist (victim victims)
1081 (event unpack-tn node)
1083 (throw 'unpacked-tn nil)))
1084 (dolist (loc (sc-locations sc))
1085 (declare (type index loc))
1087 (collect ((victims nil adjoin))
1089 (end (+ loc (sc-element-size sc))))
1091 (declare (type index i end))
1092 (let ((victim (svref (finite-sb-live-tns sb) i)))
1094 (unless (find-in #'tn-next victim normal-tns)
1098 (let ((conf (load-tn-conflicts-in-sc op sc loc t)))
1100 (unpack-em (victims)))
1101 ((eq conf :overflow))
1103 (cond ((find conf (victims))
1104 (setq fallback (victims)))
1105 ((find-in #'tn-next conf normal-tns)
1106 (setq fallback (list conf))))))))))
1109 (event unpack-fallback node)
1110 (unpack-em fallback))))
1114 ;;; Try to pack a load TN in the SCs indicated by Load-SCs. If we run
1115 ;;; out of SCs, then we unpack some TN and try again. We return the
1118 ;;; Note: we allow a Load-TN to be packed in the target location even
1119 ;;; if that location is in a SC not allowed by the primitive type.
1120 ;;; (The SC must still be allowed by the operand restriction.) This
1121 ;;; makes move VOPs more efficient, since we won't do a move from the
1122 ;;; stack into a non-descriptor any-reg through a descriptor argument
1123 ;;; load-TN. This does give targeting some real semantics, making it
1124 ;;; not a pure advisory to pack. It allows pack to do some packing it
1125 ;;; wouldn't have done before.
1126 (defun pack-load-tn (load-scs op)
1127 (declare (type sc-vector load-scs) (type tn-ref op))
1128 (let ((vop (tn-ref-vop op)))
1129 (compute-live-tns (vop-block vop) vop))
1131 (let* ((tn (tn-ref-tn op))
1132 (ptype (tn-primitive-type tn))
1133 (scs (svref load-scs (sc-number (tn-sc tn)))))
1134 (let ((current-scs scs)
1140 (no-load-scs-allowed-by-primitive-type-error op))
1141 (dolist (sc allowed)
1142 (unpack-for-load-tn sc op))
1143 (failed-to-pack-load-tn-error allowed op))
1145 (let* ((sc (svref *backend-sc-numbers* (pop current-scs)))
1146 (target (find-load-tn-target op sc)))
1147 (when (or target (sc-allowed-by-primitive-type sc ptype))
1148 (let ((loc (or target
1149 (select-load-tn-location op sc))))
1151 (let ((res (make-tn 0 :load nil sc)))
1152 (setf (tn-offset res) loc)
1154 (push sc allowed)))))))))
1156 ;;; Scan a list of load-SCs vectors and a list of TN-REFS threaded by
1157 ;;; TN-REF-ACROSS. When we find a reference whose TN doesn't satisfy
1158 ;;; the restriction, we pack a Load-TN and load the operand into it.
1159 ;;; If a load-tn has already been allocated, we can assume that the
1160 ;;; restriction is satisfied.
1161 #!-sb-fluid (declaim (inline check-operand-restrictions))
1162 (defun check-operand-restrictions (scs ops)
1163 (declare (list scs) (type (or tn-ref null) ops))
1165 ;; Check the targeted operands first.
1166 (do ((scs scs (cdr scs))
1167 (op ops (tn-ref-across op)))
1169 (let ((target (tn-ref-target op)))
1171 (let* ((load-tn (tn-ref-load-tn op))
1172 (load-scs (svref (car scs)
1174 (tn-sc (or load-tn (tn-ref-tn op)))))))
1176 (aver (eq load-scs t))
1177 (unless (eq load-scs t)
1178 (setf (tn-ref-load-tn op)
1179 (pack-load-tn (car scs) op))))))))
1181 (do ((scs scs (cdr scs))
1182 (op ops (tn-ref-across op)))
1184 (let ((target (tn-ref-target op)))
1186 (let* ((load-tn (tn-ref-load-tn op))
1187 (load-scs (svref (car scs)
1189 (tn-sc (or load-tn (tn-ref-tn op)))))))
1191 (aver (eq load-scs t))
1192 (unless (eq load-scs t)
1193 (setf (tn-ref-load-tn op)
1194 (pack-load-tn (car scs) op))))))))
1198 ;;; Scan the VOPs in BLOCK, looking for operands whose SC restrictions
1199 ;;; aren't satisfied. We do the results first, since they are
1200 ;;; evaluated later, and our conflict analysis is a backward scan.
1201 (defun pack-load-tns (block)
1203 (let ((*live-block* nil)
1205 (do ((vop (ir2-block-last-vop block) (vop-prev vop)))
1207 (let ((info (vop-info vop)))
1208 (check-operand-restrictions (vop-info-result-load-scs info)
1210 (check-operand-restrictions (vop-info-arg-load-scs info)
1216 ;;; Link the TN-REFS READ and WRITE together using the TN-REF-TARGET
1217 ;;; when this seems like a good idea. Currently we always do, as this
1218 ;;; increases the success of load-TN targeting.
1219 (defun target-if-desirable (read write)
1220 (declare (type tn-ref read write))
1221 ;; As per the comments at the definition of TN-REF-TARGET, read and
1222 ;; write refs are always paired, with TARGET in the read pointing to
1223 ;; the write and vice versa.
1224 (aver (eq (tn-ref-write-p read)
1225 (not (tn-ref-write-p write))))
1226 (setf (tn-ref-target read) write)
1227 (setf (tn-ref-target write) read))
1229 ;;; If TN can be packed into SC so as to honor a preference to TARGET,
1230 ;;; then return the offset to pack at, otherwise return NIL. TARGET
1231 ;;; must be already packed.
1232 (defun check-ok-target (target tn sc)
1233 (declare (type tn target tn) (type sc sc) (inline member))
1234 (let* ((loc (tn-offset target))
1235 (target-sc (tn-sc target))
1236 (target-sb (sc-sb target-sc)))
1237 (declare (type index loc))
1238 ;; We can honor a preference if:
1239 ;; -- TARGET's location is in SC's locations.
1240 ;; -- The element sizes of the two SCs are the same.
1241 ;; -- TN doesn't conflict with target's location.
1242 (if (and (eq target-sb (sc-sb sc))
1243 (or (eq (sb-kind target-sb) :unbounded)
1244 (member loc (sc-locations sc)))
1245 (= (sc-element-size target-sc) (sc-element-size sc))
1246 (not (conflicts-in-sc tn sc loc))
1247 (zerop (mod loc (sc-alignment sc))))
1251 ;;; Scan along the target path from TN, looking at readers or writers.
1252 ;;; When we find a packed TN, return CHECK-OK-TARGET of that TN. If
1253 ;;; there is no target, or if the TN has multiple readers (writers),
1254 ;;; then we return NIL. We also always return NIL after 10 iterations
1255 ;;; to get around potential circularity problems.
1257 ;;; FIXME: (30 minutes of reverse engineering?) It'd be nice to
1258 ;;; rewrite the header comment here to explain the interface and its
1259 ;;; motivation, and move remarks about implementation details (like
1261 (defun find-ok-target-offset (tn sc)
1262 (declare (type tn tn) (type sc sc))
1263 (flet ((frob-slot (slot-fun)
1264 (declare (type function slot-fun))
1267 (declare (type index count))
1269 (let ((refs (funcall slot-fun current)))
1270 (unless (and (plusp count)
1272 (not (tn-ref-next refs)))
1274 (let ((target (tn-ref-target refs)))
1275 (unless target (return nil))
1276 (setq current (tn-ref-tn target))
1277 (when (tn-offset current)
1278 (return (check-ok-target current tn sc)))
1280 (declare (inline frob-slot)) ; until DYNAMIC-EXTENT works
1281 (or (frob-slot #'tn-reads)
1282 (frob-slot #'tn-writes))))
1284 ;;;; location selection
1286 ;;; Select some location for TN in SC, returning the offset if we
1287 ;;; succeed, and NIL if we fail.
1289 ;;; For :UNBOUNDED SCs just find the smallest correctly aligned offset
1290 ;;; where the TN doesn't conflict with the TNs that have already been
1291 ;;; packed. For :FINITE SCs try to pack the TN into the most heavily
1292 ;;; used locations first (as estimated in FIND-LOCATION-USAGE).
1294 ;;; Historically SELECT-LOCATION tried did the opposite and tried to
1295 ;;; distribute the TNs evenly across the available locations. At least
1296 ;;; on register-starved architectures (x86) this seems to be a bad
1297 ;;; strategy. -- JES 2004-09-11
1298 (defun select-location (tn sc &key use-reserved-locs optimize)
1299 (declare (type tn tn) (type sc sc) (inline member))
1300 (let* ((sb (sc-sb sc))
1301 (element-size (sc-element-size sc))
1302 (alignment (sc-alignment sc))
1303 (align-mask (1- alignment))
1304 (size (finite-sb-current-size sb)))
1305 (flet ((attempt-location (start-offset)
1306 (dotimes (i element-size
1307 (return-from select-location start-offset))
1308 (declare (type index i))
1309 (let ((offset (+ start-offset i)))
1310 (when (offset-conflicts-in-sb tn sb offset)
1311 (return (logandc2 (the index (+ (the index (1+ offset))
1314 (if (eq (sb-kind sb) :unbounded)
1315 (loop with offset = 0
1316 until (> (+ offset element-size) size) do
1317 (setf offset (attempt-location offset)))
1318 (let ((locations (sc-locations sc)))
1321 (stable-sort (copy-list locations) #'>
1322 :key (lambda (location-offset)
1323 (loop for offset from location-offset
1326 (finite-sb-always-live-count sb)
1328 (dolist (offset locations)
1329 (when (or use-reserved-locs
1331 (sc-reserve-locations sc))))
1332 (attempt-location offset))))))))
1334 ;;; If a save TN, return the saved TN, otherwise return TN. This is
1335 ;;; useful for getting the conflicts of a TN that might be a save TN.
1336 (defun original-tn (tn)
1337 (declare (type tn tn))
1338 (if (member (tn-kind tn) '(:save :save-once :specified-save))
1344 ;;; Attempt to pack TN in all possible SCs, first in the SC chosen by
1345 ;;; representation selection, then in the alternate SCs in the order
1346 ;;; they were specified in the SC definition. If the TN-COST is
1347 ;;; negative, then we don't attempt to pack in SCs that must be saved.
1348 ;;; If Restricted, then we can only pack in TN-SC, not in any
1351 ;;; If we are attempting to pack in the SC of the save TN for a TN
1352 ;;; with a :SPECIFIED-SAVE TN, then we pack in that location, instead
1353 ;;; of allocating a new stack location.
1354 (defun pack-tn (tn restricted optimize &key (allow-unbounded-sc t))
1355 (declare (type tn tn))
1356 (let* ((original (original-tn tn))
1358 (alternates (unless restricted (sc-alternate-scs fsc)))
1359 (save (tn-save-tn tn))
1362 (eq (tn-kind save) :specified-save))
1364 (do ((sc fsc (pop alternates)))
1366 (failed-to-pack-error tn restricted))
1367 (unless (or allow-unbounded-sc
1368 (neq (sb-kind (sc-sb sc)) :unbounded))
1370 (when (eq sc specified-save-sc)
1371 (unless (tn-offset save)
1372 (pack-tn save nil optimize))
1373 (setf (tn-offset tn) (tn-offset save))
1374 (setf (tn-sc tn) (tn-sc save))
1376 (when (or restricted
1377 (not (and (minusp (tn-cost tn)) (sc-save-p sc))))
1378 (let ((loc (or (find-ok-target-offset original sc)
1379 (select-location original sc)
1381 (select-location original sc :use-reserved-locs t))
1382 (when (eq (sb-kind (sc-sb sc)) :unbounded)
1384 (or (select-location original sc)
1385 (error "failed to pack after growing SC?"))))))
1387 (add-location-conflicts original sc loc optimize)
1388 (setf (tn-sc tn) sc)
1389 (setf (tn-offset tn) loc)
1393 ;;; Pack a wired TN, checking that the offset is in bounds for the SB,
1394 ;;; and that the TN doesn't conflict with some other TN already packed
1395 ;;; in that location. If the TN is wired to a location beyond the end
1396 ;;; of a :UNBOUNDED SB, then grow the SB enough to hold the TN.
1398 ;;; ### Checking for conflicts is disabled for :SPECIFIED-SAVE TNs.
1399 ;;; This is kind of a hack to make specifying wired stack save
1400 ;;; locations for local call arguments (such as OLD-FP) work, since
1401 ;;; the caller and callee OLD-FP save locations may conflict when the
1402 ;;; save locations don't really (due to being in different frames.)
1403 (defun pack-wired-tn (tn optimize)
1404 (declare (type tn tn))
1405 (let* ((sc (tn-sc tn))
1407 (offset (tn-offset tn))
1408 (end (+ offset (sc-element-size sc)))
1409 (original (original-tn tn)))
1410 (when (> end (finite-sb-current-size sb))
1411 (unless (eq (sb-kind sb) :unbounded)
1412 (error "~S is wired to a location that is out of bounds." tn))
1415 ;; For non-x86 ports the presence of a save-tn associated with a
1416 ;; tn is used to identify the old-fp and return-pc tns. It depends
1417 ;; on the old-fp and return-pc being passed in registers.
1419 (when (and (not (eq (tn-kind tn) :specified-save))
1420 (conflicts-in-sc original sc offset))
1421 (error "~S is wired to a location that it conflicts with." tn))
1423 ;; Use the above check, but only print a verbose warning. This can
1424 ;; be helpful for debugging the x86 port.
1426 (when (and (not (eq (tn-kind tn) :specified-save))
1427 (conflicts-in-sc original sc offset))
1428 (format t "~&* Pack-wired-tn possible conflict:~% ~
1429 tn: ~S; tn-kind: ~S~% ~
1431 sb: ~S; sb-name: ~S; sb-kind: ~S~% ~
1432 offset: ~S; end: ~S~% ~
1434 tn-save-tn: ~S; tn-kind of tn-save-tn: ~S~%"
1436 sb (sb-name sb) (sb-kind sb)
1439 (tn-save-tn tn) (tn-kind (tn-save-tn tn))))
1441 ;; On the x86 ports the old-fp and return-pc are often passed on
1442 ;; the stack so the above hack for the other ports does not always
1443 ;; work. Here the old-fp and return-pc tns are identified by being
1444 ;; on the stack in their standard save locations.
1446 (when (and (not (eq (tn-kind tn) :specified-save))
1447 (not (and (string= (sb-name sb) "STACK")
1450 (conflicts-in-sc original sc offset))
1451 (error "~S is wired to a location that it conflicts with." tn))
1453 (add-location-conflicts original sc offset optimize)))
1455 (defevent repack-block "Repacked a block due to TN unpacking.")
1457 ;;; KLUDGE: Prior to SBCL version 0.8.9.xx, this function was known as
1458 ;;; PACK-BEFORE-GC-HOOK, but was non-functional since approximately
1459 ;;; version 0.8.3.xx since the removal of GC hooks from the system.
1460 ;;; This currently (as of 2004-04-12) runs now after every call to
1461 ;;; PACK, rather than -- as was originally intended -- once per GC
1462 ;;; cycle; this is probably non-optimal, and might require tuning,
1463 ;;; maybe to be called when the data structures exceed a certain size,
1464 ;;; or maybe once every N times. The KLUDGE is that this rewrite has
1465 ;;; done nothing to improve the reentrance or threadsafety of the
1466 ;;; compiler; it still fails to be callable from several threads at
1469 ;;; Brief experiments indicate that during a compilation cycle this
1470 ;;; causes about 10% more consing, and takes about 1%-2% more time.
1472 ;;; -- CSR, 2004-04-12
1473 (defun clean-up-pack-structures ()
1474 (dolist (sb *backend-sb-list*)
1475 (unless (eq (sb-kind sb) :non-packed)
1476 (let ((size (sb-size sb)))
1477 (fill (finite-sb-always-live sb) nil)
1478 (setf (finite-sb-always-live sb)
1482 ;; The cross-compiler isn't very good at
1483 ;; dumping specialized arrays, so we delay
1484 ;; construction of this SIMPLE-BIT-VECTOR
1486 #+sb-xc (make-array 0 :element-type 'bit)))
1487 (setf (finite-sb-always-live-count sb)
1492 #+sb-xc (make-array 0 :element-type 'fixnum)))
1494 (fill (finite-sb-conflicts sb) nil)
1495 (setf (finite-sb-conflicts sb)
1496 (make-array size :initial-element '#()))
1498 (fill (finite-sb-live-tns sb) nil)
1499 (setf (finite-sb-live-tns sb)
1500 (make-array size :initial-element nil))))))
1502 (defun tn-lexical-depth (tn)
1503 (let ((path t)) ; dummy initial value
1504 (labels ((path (lambda)
1505 (nreverse (loop while lambda
1507 do (setf lambda (lambda-parent lambda)))))
1508 (register-scope (lambda)
1509 (let ((new-path (path lambda)))
1510 (setf path (if (eql path t)
1513 0 (mismatch path new-path))))))
1515 (do ((ref ref (tn-ref-next ref)))
1517 (binding* ((node (vop-node (tn-ref-vop ref))
1519 (register-scope (lexenv-lambda
1520 (node-lexenv node)))))))
1521 (walk-tn-refs (tn-reads tn))
1522 (walk-tn-refs (tn-writes tn))
1524 most-positive-fixnum
1527 (defun pack (component)
1529 (let ((optimize nil)
1530 (2comp (component-info component)))
1531 (init-sb-vectors component)
1533 ;; Determine whether we want to do more expensive packing by
1534 ;; checking whether any blocks in the component have (> SPEED
1537 ;; FIXME: This means that a declaration can have a minor
1538 ;; effect even outside its scope, and as the packing is done
1539 ;; component-globally it'd be tricky to use strict scoping. I
1540 ;; think this is still acceptable since it's just a tradeoff
1541 ;; between compilation speed and allocation quality and
1542 ;; doesn't affect the semantics of the generated code in any
1543 ;; way. -- JES 2004-10-06
1544 (do-ir2-blocks (block component)
1545 (when (policy (block-last (ir2-block-block block))
1546 (> speed compilation-speed))
1550 ;; Call the target functions.
1551 (do-ir2-blocks (block component)
1552 (do ((vop (ir2-block-start-vop block) (vop-next vop)))
1554 (let ((target-fun (vop-info-target-fun (vop-info vop))))
1556 (funcall target-fun vop)))))
1558 ;; Pack wired TNs first.
1559 (do ((tn (ir2-component-wired-tns 2comp) (tn-next tn)))
1561 (pack-wired-tn tn optimize))
1563 ;; Pack restricted component TNs.
1564 (do ((tn (ir2-component-restricted-tns 2comp) (tn-next tn)))
1566 (when (eq (tn-kind tn) :component)
1567 (pack-tn tn t optimize)))
1569 ;; Pack other restricted TNs.
1570 (do ((tn (ir2-component-restricted-tns 2comp) (tn-next tn)))
1572 (unless (tn-offset tn)
1573 (pack-tn tn t optimize)))
1575 ;; Assign costs to normal TNs so we know which ones should
1576 ;; always be packed on the stack.
1577 (when *pack-assign-costs*
1578 (assign-tn-costs component)
1579 (assign-tn-depths component))
1581 ;; Allocate normal TNs, starting with the TNs that are used
1582 ;; in deep loops. Only allocate in finite SCs (i.e. not on
1585 (do-ir2-blocks (block component)
1586 (let ((ltns (ir2-block-local-tns block)))
1587 (do ((i (1- (ir2-block-local-tn-count block)) (1- i)))
1589 (declare (fixnum i))
1590 (let ((tn (svref ltns i)))
1591 (unless (or (null tn)
1594 ;; If loop analysis has been disabled we might as
1595 ;; well revert to the old behaviour of just
1596 ;; packing TNs linearly as they appear.
1597 (unless *loop-analyze*
1598 (pack-tn tn nil optimize :allow-unbounded-sc nil))
1600 (dolist (tn (stable-sort (tns)
1603 ((> (tn-loop-depth a)
1606 ((= (tn-loop-depth a)
1608 (> (tn-cost a) (tn-cost b)))
1610 (unless (tn-offset tn)
1611 (pack-tn tn nil optimize :allow-unbounded-sc nil))))
1613 ;; Pack any leftover normal TNs that could not be allocated
1614 ;; to finite SCs, or TNs that do not appear in any local TN
1615 ;; map (e.g. :MORE TNs). Since we'll likely be allocating
1616 ;; on the stack, first allocate TNs that are associated with
1617 ;; code at shallow lexical depths: this will allocate long
1618 ;; live ranges (i.e. TNs with more conflicts) first, and
1619 ;; hopefully minimise stack fragmentation.
1621 ;; Collect in reverse order to give priority to older TNs.
1622 (let ((contiguous-tns '())
1624 (do ((tn (ir2-component-normal-tns 2comp) (tn-next tn)))
1626 (unless (tn-offset tn)
1627 (let ((key (cons tn (tn-lexical-depth tn))))
1628 (if (memq (tn-kind tn) '(:environment :debug-environment
1630 (push key contiguous-tns)
1632 (flet ((pack-tns (tns)
1633 (dolist (tn (stable-sort tns #'< :key #'cdr))
1634 (let ((tn (car tn)))
1635 (unless (tn-offset tn)
1636 (pack-tn tn nil optimize))))))
1637 ;; first pack TNs that are known to have simple
1638 ;; live ranges (contiguous lexical scopes)
1639 (pack-tns contiguous-tns)
1642 ;; Do load TN packing and emit saves.
1643 (let ((*repack-blocks* nil))
1644 (cond ((and optimize *pack-optimize-saves*)
1645 (optimized-emit-saves component)
1646 (do-ir2-blocks (block component)
1647 (pack-load-tns block)))
1649 (do-ir2-blocks (block component)
1651 (pack-load-tns block))))
1653 (unless *repack-blocks* (return))
1654 (let ((orpb *repack-blocks*))
1655 (setq *repack-blocks* nil)
1656 (dolist (block orpb)
1657 (event repack-block)
1658 (pack-load-tns block)))))
1661 (clean-up-pack-structures)))