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 (declare (type index inc new-size))
230 (aver (eq (sb-kind sb) :unbounded))
232 (when (> new-size (length conflicts))
233 (let ((new-conf (make-array new-size)))
234 (replace new-conf conflicts)
235 (do ((i size (1+ i)))
237 (declare (type index i))
238 (let ((loc-confs (make-array block-size)))
239 (dotimes (j block-size)
240 (setf (svref loc-confs j)
241 (make-array local-tn-limit
243 :element-type 'bit)))
244 (setf (svref new-conf i) loc-confs)))
245 (setf (finite-sb-conflicts sb) new-conf))
247 (let ((new-live (make-array new-size)))
248 (replace new-live (finite-sb-always-live sb))
249 (do ((i size (1+ i)))
251 (setf (svref new-live i)
252 (make-array block-size
254 :element-type 'bit)))
255 (setf (finite-sb-always-live sb) new-live))
257 (let ((new-live-count (make-array new-size)))
258 (declare (optimize speed)) ;; FILL deftransform
259 (replace new-live-count (finite-sb-always-live-count sb))
260 (fill new-live-count 0 :start size)
261 (setf (finite-sb-always-live-count sb) new-live-count))
263 (let ((new-tns (make-array new-size :initial-element nil)))
264 (replace new-tns (finite-sb-live-tns sb))
265 (fill (finite-sb-live-tns sb) nil)
266 (setf (finite-sb-live-tns sb) new-tns)))
268 (setf (finite-sb-current-size sb) new-size))
274 ;;; Give someone a hard time because there isn't any load function
275 ;;; defined to move from SRC to DEST.
276 (defun no-load-fun-error (src dest)
277 (let* ((src-sc (tn-sc src))
278 (src-name (sc-name src-sc))
279 (dest-sc (tn-sc dest))
280 (dest-name (sc-name dest-sc)))
281 (cond ((eq (sb-kind (sc-sb src-sc)) :non-packed)
282 (unless (member src-sc (sc-constant-scs dest-sc))
283 (error "loading from an invalid constant SC?~@
284 VM definition inconsistent, try recompiling."))
285 (error "no load function defined to load SC ~S ~
286 from its constant SC ~S"
288 ((member src-sc (sc-alternate-scs dest-sc))
289 (error "no load function defined to load SC ~S from its ~
292 ((member dest-sc (sc-alternate-scs src-sc))
293 (error "no load function defined to save SC ~S in its ~
297 ;; FIXME: "VM definition is inconsistent" shouldn't be a
298 ;; possibility in SBCL.
299 (error "loading to/from SCs that aren't alternates?~@
300 VM definition is inconsistent, try recompiling.")))))
302 ;;; Called when we failed to pack TN. If RESTRICTED is true, then we
303 ;;; are restricted to pack TN in its SC.
304 (defun failed-to-pack-error (tn restricted)
305 (declare (type tn tn))
306 (let* ((sc (tn-sc tn))
307 (scs (cons sc (sc-alternate-scs sc))))
310 (error "failed to pack restricted TN ~S in its SC ~S"
313 (aver (not (find :unbounded scs
314 :key (lambda (x) (sb-kind (sc-sb x))))))
315 (let ((ptype (tn-primitive-type tn)))
318 (aver (member (sc-number sc) (primitive-type-scs ptype)))
319 (error "SC ~S doesn't have any :UNBOUNDED alternate SCs, but is~@
320 a SC for primitive-type ~S."
321 (sc-name sc) (primitive-type-name ptype)))
323 (error "SC ~S doesn't have any :UNBOUNDED alternate SCs."
326 ;;; Return a list of format arguments describing how TN is used in
328 (defun describe-tn-use (loc tn op)
329 (let* ((vop (tn-ref-vop op))
330 (args (vop-args vop))
331 (results (vop-results vop))
332 (name (with-output-to-string (stream)
333 (print-tn-guts tn stream)))
334 (2comp (component-info *component-being-compiled*))
337 ((setq temp (position-in #'tn-ref-across tn args :key #'tn-ref-tn))
338 `("~2D: ~A (~:R argument)" ,loc ,name ,(1+ temp)))
339 ((setq temp (position-in #'tn-ref-across tn results :key #'tn-ref-tn))
340 `("~2D: ~A (~:R result)" ,loc ,name ,(1+ temp)))
341 ((setq temp (position-in #'tn-ref-across tn args :key #'tn-ref-load-tn))
342 `("~2D: ~A (~:R argument load TN)" ,loc ,name ,(1+ temp)))
343 ((setq temp (position-in #'tn-ref-across tn results :key
345 `("~2D: ~A (~:R result load TN)" ,loc ,name ,(1+ temp)))
346 ((setq temp (position-in #'tn-ref-across tn (vop-temps vop)
348 `("~2D: ~A (temporary ~A)" ,loc ,name
349 ,(operand-parse-name (elt (vop-parse-temps
351 (vop-info-name (vop-info vop))))
353 ((eq (tn-kind tn) :component)
354 `("~2D: ~A (component live)" ,loc ,name))
355 ((position-in #'tn-next tn (ir2-component-wired-tns 2comp))
356 `("~2D: ~A (wired)" ,loc ,name))
357 ((position-in #'tn-next tn (ir2-component-restricted-tns 2comp))
358 `("~2D: ~A (restricted)" ,loc ,name))
360 `("~2D: not referenced?" ,loc)))))
362 ;;; If load TN packing fails, try to give a helpful error message. We
363 ;;; find a TN in each location that conflicts, and print it.
364 (defun failed-to-pack-load-tn-error (scs op)
365 (declare (list scs) (type tn-ref op))
369 (let* ((sb (sc-sb sc))
370 (confs (finite-sb-live-tns sb)))
371 (aver (eq (sb-kind sb) :finite))
372 (dolist (el (sc-locations sc))
373 (declare (type index el))
374 (let ((conf (load-tn-conflicts-in-sc op sc el t)))
376 (used (describe-tn-use el conf op))
378 (end (+ el (sc-element-size sc))))
381 (declare (type index i end))
382 (let ((victim (svref confs i)))
384 (used (describe-tn-use el victim op))
387 (multiple-value-bind (arg-p n more-p costs load-scs incon)
388 (get-operand-info op)
389 (declare (ignore costs load-scs))
391 (error "unable to pack a Load-TN in SC ~{~A~#[~^~;, or ~:;,~]~} ~
392 for the ~:R ~:[result~;argument~] to~@
394 ~:[since all SC elements are in use:~:{~%~@?~}~%~;~
395 ~:*but these SC elements are not in use:~% ~S~%Bug?~*~]~
397 Current cost info inconsistent with that in effect at compile ~
398 time. Recompile.~%Compilation order may be incorrect.~]"
399 (mapcar #'sc-name scs)
401 (vop-info-name (vop-info (tn-ref-vop op)))
405 ;;; This is called when none of the SCs that we can load OP into are
406 ;;; allowed by OP's primitive-type.
407 (defun no-load-scs-allowed-by-primitive-type-error (ref)
408 (declare (type tn-ref ref))
409 (let* ((tn (tn-ref-tn ref))
410 (ptype (tn-primitive-type tn)))
411 (multiple-value-bind (arg-p pos more-p costs load-scs incon)
412 (get-operand-info ref)
413 (declare (ignore costs))
415 (error "~S is not valid as the ~:R ~:[result~;argument~] to VOP:~
417 since the TN's primitive type ~S doesn't allow any of the SCs~@
418 allowed by the operand restriction:~% ~S~
420 Current cost info inconsistent with that in effect at compile ~
421 time. Recompile.~%Compilation order may be incorrect.~]"
423 (template-name (vop-info (tn-ref-vop ref)))
424 (primitive-type-name ptype)
425 (mapcar #'sc-name (listify-restrictions load-scs))
430 ;;; Do stuff to note that TN is spilled at VOP for the debugger's benefit.
431 (defun note-spilled-tn (tn vop)
432 (when (and (tn-leaf tn) (vop-save-set vop))
433 (let ((2comp (component-info *component-being-compiled*)))
434 (setf (gethash tn (ir2-component-spilled-tns 2comp)) t)
435 (pushnew tn (gethash vop (ir2-component-spilled-vops 2comp)))))
438 ;;; Make a save TN for TN, pack it, and return it. We copy various
439 ;;; conflict information from the TN so that pack does the right
441 (defun pack-save-tn (tn)
442 (declare (type tn tn))
443 (let ((res (make-tn 0 :save nil nil)))
444 (dolist (alt (sc-alternate-scs (tn-sc tn))
445 (error "no unbounded alternate for SC ~S"
446 (sc-name (tn-sc tn))))
447 (when (eq (sb-kind (sc-sb alt)) :unbounded)
448 (setf (tn-save-tn tn) res)
449 (setf (tn-save-tn res) tn)
450 (setf (tn-sc res) alt)
454 ;;; Find the load function for moving from SRC to DEST and emit a
455 ;;; MOVE-OPERAND VOP with that function as its info arg.
456 (defun emit-operand-load (node block src dest before)
457 (declare (type node node) (type ir2-block block)
458 (type tn src dest) (type (or vop null) before))
459 (emit-load-template node block
460 (template-or-lose 'move-operand)
462 (list (or (svref (sc-move-funs (tn-sc dest))
463 (sc-number (tn-sc src)))
464 (no-load-fun-error src dest)))
468 ;;; Find the preceding use of the VOP NAME in the emit order, starting
469 ;;; with VOP. We must find the VOP in the same IR1 block.
470 (defun reverse-find-vop (name vop)
471 (do* ((block (vop-block vop) (ir2-block-prev block))
472 (last vop (ir2-block-last-vop block)))
474 (aver (eq (ir2-block-block block) (ir2-block-block (vop-block vop))))
475 (do ((current last (vop-prev current)))
477 (when (eq (vop-info-name (vop-info current)) name)
478 (return-from reverse-find-vop current)))))
480 ;;; For TNs that have other than one writer, we save the TN before
481 ;;; each call. If a local call (MOVE-ARGS is :LOCAL-CALL), then we
482 ;;; scan back for the ALLOCATE-FRAME VOP, and emit the save there.
483 ;;; This is necessary because in a self-recursive local call, the
484 ;;; registers holding the current arguments may get trashed by setting
485 ;;; up the call arguments. The ALLOCATE-FRAME VOP marks a place at
486 ;;; which the values are known to be good.
487 (defun save-complex-writer-tn (tn vop)
488 (let ((save (or (tn-save-tn tn)
490 (node (vop-node vop))
491 (block (vop-block vop))
492 (next (vop-next vop)))
493 (when (eq (tn-kind save) :specified-save)
494 (setf (tn-kind save) :save))
495 (aver (eq (tn-kind save) :save))
496 (emit-operand-load node block tn save
497 (if (eq (vop-info-move-args (vop-info vop))
499 (reverse-find-vop 'allocate-frame vop)
501 (emit-operand-load node block save tn next)))
503 ;;; Return a VOP after which is an OK place to save the value of TN.
504 ;;; For correctness, it is only required that this location be after
505 ;;; any possible write and before any possible restore location.
507 ;;; In practice, we return the unique writer VOP, but give up if the
508 ;;; TN is ever read by a VOP with MOVE-ARGS :LOCAL-CALL. This prevents
509 ;;; us from being confused by non-tail local calls.
511 ;;; When looking for writes, we have to ignore uses of MOVE-OPERAND,
512 ;;; since they will correspond to restores that we have already done.
513 (defun find-single-writer (tn)
514 (declare (type tn tn))
515 (do ((write (tn-writes tn) (tn-ref-next write))
519 (do ((read (tn-reads tn) (tn-ref-next read)))
521 (when (eq (vop-info-move-args
528 (unless (eq (vop-info-name (vop-info (tn-ref-vop write)))
530 (when res (return nil))
533 ;;; Try to save TN at a single location. If we succeed, return T,
535 (defun save-single-writer-tn (tn)
536 (declare (type tn tn))
537 (let* ((old-save (tn-save-tn tn))
538 (save (or old-save (pack-save-tn tn)))
539 (writer (find-single-writer tn)))
542 (eq (tn-kind old-save) :specified-save)))
543 (emit-operand-load (vop-node writer) (vop-block writer)
544 tn save (vop-next writer))
545 (setf (tn-kind save) :save-once)
548 ;;; Restore a TN with a :SAVE-ONCE save TN.
549 (defun restore-single-writer-tn (tn vop)
550 (declare (type tn) (type vop vop))
551 (let ((save (tn-save-tn tn)))
552 (aver (eq (tn-kind save) :save-once))
553 (emit-operand-load (vop-node vop) (vop-block vop) save tn (vop-next vop)))
556 ;;; Save a single TN that needs to be saved, choosing save-once if
557 ;;; appropriate. This is also called by SPILL-AND-PACK-LOAD-TN.
558 (defun basic-save-tn (tn vop)
559 (declare (type tn tn) (type vop vop))
560 (let ((save (tn-save-tn tn)))
561 (cond ((and save (eq (tn-kind save) :save-once))
562 (restore-single-writer-tn tn vop))
563 ((save-single-writer-tn tn)
564 (restore-single-writer-tn tn vop))
566 (save-complex-writer-tn tn vop))))
569 ;;; Scan over the VOPs in BLOCK, emiting saving code for TNs noted in
570 ;;; the codegen info that are packed into saved SCs.
571 (defun emit-saves (block)
572 (declare (type ir2-block block))
573 (do ((vop (ir2-block-start-vop block) (vop-next vop)))
575 (when (eq (vop-info-save-p (vop-info vop)) t)
576 (do-live-tns (tn (vop-save-set vop) block)
577 (when (and (sc-save-p (tn-sc tn))
578 (not (eq (tn-kind tn) :component)))
579 (basic-save-tn tn vop)))))
583 ;;;; optimized saving
585 ;;; Save TN if it isn't a single-writer TN that has already been
586 ;;; saved. If multi-write, we insert the save BEFORE the specified
587 ;;; VOP. CONTEXT is a VOP used to tell which node/block to use for the
589 (defun save-if-necessary (tn before context)
590 (declare (type tn tn) (type (or vop null) before) (type vop context))
591 (let ((save (tn-save-tn tn)))
592 (when (eq (tn-kind save) :specified-save)
593 (setf (tn-kind save) :save))
594 (aver (member (tn-kind save) '(:save :save-once)))
595 (unless (eq (tn-kind save) :save-once)
596 (or (save-single-writer-tn tn)
597 (emit-operand-load (vop-node context) (vop-block context)
601 ;;; Load the TN from its save location, allocating one if necessary.
602 ;;; The load is inserted BEFORE the specified VOP. CONTEXT is a VOP
603 ;;; used to tell which node/block to use for the new VOP.
604 (defun restore-tn (tn before context)
605 (declare (type tn tn) (type (or vop null) before) (type vop context))
606 (let ((save (or (tn-save-tn tn) (pack-save-tn tn))))
607 (emit-operand-load (vop-node context) (vop-block context)
611 ;;; Start scanning backward at the end of BLOCK, looking which TNs are
612 ;;; live and looking for places where we have to save. We manipulate
613 ;;; two sets: SAVES and RESTORES.
615 ;;; SAVES is a set of all the TNs that have to be saved because they
616 ;;; are restored after some call. We normally delay saving until the
617 ;;; beginning of the block, but we must save immediately if we see a
618 ;;; write of the saved TN. We also immediately save all TNs and exit
619 ;;; when we see a NOTE-ENVIRONMENT-START VOP, since saves can't be
620 ;;; done before the environment is properly initialized.
622 ;;; RESTORES is a set of all the TNs read (and not written) between
623 ;;; here and the next call, i.e. the set of TNs that must be restored
624 ;;; when we reach the next (earlier) call VOP. Unlike SAVES, this set
625 ;;; is cleared when we do the restoring after a call. Any TNs that
626 ;;; were in RESTORES are moved into SAVES to ensure that they are
627 ;;; saved at some point.
629 ;;; SAVES and RESTORES are represented using both a list and a
630 ;;; bit-vector so that we can quickly iterate and test for membership.
631 ;;; The incoming SAVES and RESTORES args are used for computing these
632 ;;; sets (the initial contents are ignored.)
634 ;;; When we hit a VOP with :COMPUTE-ONLY SAVE-P (an internal error
635 ;;; location), we pretend that all live TNs were read, unless (= speed
636 ;;; 3), in which case we mark all the TNs that are live but not
637 ;;; restored as spilled.
638 (defun optimized-emit-saves-block (block saves restores)
639 (declare (type ir2-block block) (type simple-bit-vector saves restores))
640 (let ((1block (ir2-block-block block))
644 (declare (list saves-list restores-list))
645 (clear-bit-vector saves)
646 (clear-bit-vector restores)
647 (do-live-tns (tn (ir2-block-live-in block) block)
648 (when (and (sc-save-p (tn-sc tn))
649 (not (eq (tn-kind tn) :component)))
650 (let ((num (tn-number tn)))
651 (setf (sbit restores num) 1)
652 (push tn restores-list))))
654 (do ((block block (ir2-block-prev block))
656 ((not (eq (ir2-block-block block) 1block))
657 (aver (not skipping))
658 (dolist (save saves-list)
659 (let ((start (ir2-block-start-vop prev)))
660 (save-if-necessary save start start)))
662 (do ((vop (ir2-block-last-vop block) (vop-prev vop)))
664 (let ((info (vop-info vop)))
665 (case (vop-info-name info)
669 (note-environment-start
670 (aver (not skipping))
671 (dolist (save saves-list)
672 (save-if-necessary save (vop-next vop) vop))
673 (return-from optimized-emit-saves-block block)))
676 (do ((write (vop-results vop) (tn-ref-across write)))
678 (let* ((tn (tn-ref-tn write))
679 (num (tn-number tn)))
680 (unless (zerop (sbit restores num))
681 (setf (sbit restores num) 0)
683 (delete tn restores-list :test #'eq)))
684 (unless (zerop (sbit saves num))
685 (setf (sbit saves num) 0)
686 (save-if-necessary tn (vop-next vop) vop)
688 (delete tn saves-list :test #'eq))))))
690 (macrolet ((save-note-read (tn)
692 (num (tn-number tn)))
693 (when (and (sc-save-p (tn-sc tn))
694 (zerop (sbit restores num))
695 (not (eq (tn-kind tn) :component)))
696 (setf (sbit restores num) 1)
697 (push tn restores-list)))))
699 (case (vop-info-save-p info)
701 (dolist (tn restores-list)
702 (restore-tn tn (vop-next vop) vop)
703 (let ((num (tn-number tn)))
704 (when (zerop (sbit saves num))
706 (setf (sbit saves num) 1))))
707 (setq restores-list nil)
708 (clear-bit-vector restores))
710 (cond ((policy (vop-node vop) (= speed 3))
711 (do-live-tns (tn (vop-save-set vop) block)
712 (when (zerop (sbit restores (tn-number tn)))
713 (note-spilled-tn tn vop))))
715 (do-live-tns (tn (vop-save-set vop) block)
716 (save-note-read tn))))))
718 (if (eq (vop-info-move-args info) :local-call)
720 (do ((read (vop-args vop) (tn-ref-across read)))
722 (save-note-read (tn-ref-tn read))))))))))
724 ;;; This is like EMIT-SAVES, only different. We avoid redundant saving
725 ;;; within the block, and don't restore values that aren't used before
726 ;;; the next call. This function is just the top level loop over the
727 ;;; blocks in the component, which locates blocks that need saving
729 (defun optimized-emit-saves (component)
730 (declare (type component component))
731 (let* ((gtn-count (1+ (ir2-component-global-tn-counter
732 (component-info component))))
733 (saves (make-array gtn-count :element-type 'bit))
734 (restores (make-array gtn-count :element-type 'bit))
735 (block (ir2-block-prev (block-info (component-tail component))))
736 (head (block-info (component-head component))))
738 (when (eq block head) (return))
739 (when (do ((vop (ir2-block-start-vop block) (vop-next vop)))
741 (when (eq (vop-info-save-p (vop-info vop)) t)
743 (setq block (optimized-emit-saves-block block saves restores)))
744 (setq block (ir2-block-prev block)))))
746 ;;; Iterate over the normal TNs, finding the cost of packing on the
747 ;;; stack in units of the number of references. We count all
748 ;;; references as +1, and subtract out REGISTER-SAVE-PENALTY for each
749 ;;; place where we would have to save a register.
750 (defun assign-tn-costs (component)
751 (do-ir2-blocks (block component)
752 (do ((vop (ir2-block-start-vop block) (vop-next vop)))
754 (when (eq (vop-info-save-p (vop-info vop)) t)
755 (do-live-tns (tn (vop-save-set vop) block)
756 (decf (tn-cost tn) *backend-register-save-penalty*)))))
758 (do ((tn (ir2-component-normal-tns (component-info component))
761 (let ((cost (tn-cost tn)))
762 (declare (fixnum cost))
763 (do ((ref (tn-reads tn) (tn-ref-next ref)))
766 (do ((ref (tn-writes tn) (tn-ref-next ref)))
769 (setf (tn-cost tn) cost))))
771 ;;; Iterate over the normal TNs, storing the depth of the deepest loop
772 ;;; that the TN is used in TN-LOOP-DEPTH.
773 (defun assign-tn-depths (component)
775 (do-ir2-blocks (block component)
776 (do ((vop (ir2-block-start-vop block)
779 (flet ((find-all-tns (head-fun)
781 (do ((ref (funcall head-fun vop) (tn-ref-across ref)))
783 (tns (tn-ref-tn ref)))
785 (dolist (tn (nconc (find-all-tns #'vop-args)
786 (find-all-tns #'vop-results)
787 (find-all-tns #'vop-temps)
788 ;; What does "references in this VOP
789 ;; mean"? Probably something that isn't
790 ;; useful in this context, since these
791 ;; TN-REFs are linked with TN-REF-NEXT
792 ;; instead of TN-REF-ACROSS. --JES
794 ;; (find-all-tns #'vop-refs)
796 (setf (tn-loop-depth tn)
797 (max (tn-loop-depth tn)
798 (let* ((ir1-block (ir2-block-block (vop-block vop)))
799 (loop (block-loop ir1-block)))
807 ;;; These variables indicate the last location at which we computed
808 ;;; the Live-TNs. They hold the BLOCK and VOP values that were passed
809 ;;; to COMPUTE-LIVE-TNS.
810 (defvar *live-block*)
813 ;;; If we unpack some TNs, then we mark all affected blocks by
814 ;;; sticking them in this hash-table. This is initially null. We
815 ;;; create the hashtable if we do any unpacking.
816 (defvar *repack-blocks*)
817 (declaim (type list *repack-blocks*))
819 ;;; Set the LIVE-TNS vectors in all :FINITE SBs to represent the TNs
820 ;;; live at the end of BLOCK.
821 (defun init-live-tns (block)
822 (dolist (sb *backend-sb-list*)
823 (when (eq (sb-kind sb) :finite)
824 (fill (finite-sb-live-tns sb) nil)))
826 (do-live-tns (tn (ir2-block-live-in block) block)
827 (let* ((sc (tn-sc tn))
829 (when (eq (sb-kind sb) :finite)
830 ;; KLUDGE: we can have "live" TNs that are neither read
831 ;; to nor written from, due to more aggressive (type-
832 ;; directed) constant propagation. Such TNs will never
833 ;; be assigned an offset nor be in conflict with anything.
835 ;; Ideally, it seems to me we could make sure these TNs
836 ;; are never allocated in the first place in
837 ;; ASSIGN-LAMBDA-VAR-TNS.
839 (do ((offset (tn-offset tn) (1+ offset))
840 (end (+ (tn-offset tn) (sc-element-size sc))))
842 (declare (type index offset end))
843 (setf (svref (finite-sb-live-tns sb) offset) tn))
844 (assert (and (null (tn-reads tn))
845 (null (tn-writes tn))))))))
847 (setq *live-block* block)
848 (setq *live-vop* (ir2-block-last-vop block))
852 ;;; Set the LIVE-TNs in :FINITE SBs to represent the TNs live
853 ;;; immediately after the evaluation of VOP in BLOCK, excluding
854 ;;; results of the VOP. If VOP is null, then compute the live TNs at
855 ;;; the beginning of the block. Sequential calls on the same block
856 ;;; must be in reverse VOP order.
857 (defun compute-live-tns (block vop)
858 (declare (type ir2-block block) (type vop vop))
859 (unless (eq block *live-block*)
860 (init-live-tns block))
862 (do ((current *live-vop* (vop-prev current)))
864 (do ((res (vop-results vop) (tn-ref-across res)))
866 (let* ((tn (tn-ref-tn res))
869 (when (eq (sb-kind sb) :finite)
870 (do ((offset (tn-offset tn) (1+ offset))
871 (end (+ (tn-offset tn) (sc-element-size sc))))
873 (declare (type index offset end))
874 (setf (svref (finite-sb-live-tns sb) offset) nil))))))
875 (do ((ref (vop-refs current) (tn-ref-next-ref ref)))
877 (let ((ltn (tn-ref-load-tn ref)))
879 (let* ((sc (tn-sc ltn))
881 (when (eq (sb-kind sb) :finite)
882 (let ((tns (finite-sb-live-tns sb)))
883 (do ((offset (tn-offset ltn) (1+ offset))
884 (end (+ (tn-offset ltn) (sc-element-size sc))))
886 (declare (type index offset end))
887 (aver (null (svref tns offset)))))))))
889 (let* ((tn (tn-ref-tn ref))
892 (when (eq (sb-kind sb) :finite)
893 (let ((tns (finite-sb-live-tns sb)))
894 (do ((offset (tn-offset tn) (1+ offset))
895 (end (+ (tn-offset tn) (sc-element-size sc))))
897 (declare (type index offset end))
898 (if (tn-ref-write-p ref)
899 (setf (svref tns offset) nil)
900 (let ((old (svref tns offset)))
901 (aver (or (null old) (eq old tn)))
902 (setf (svref tns offset) tn)))))))))
904 (setq *live-vop* vop)
907 ;;; This is kind of like OFFSET-CONFLICTS-IN-SB, except that it uses
908 ;;; the VOP refs to determine whether a Load-TN for OP could be packed
909 ;;; in the specified location, disregarding conflicts with TNs not
910 ;;; referenced by this VOP. There is a conflict if either:
911 ;;; 1. The reference is a result, and the same location is either:
912 ;;; -- Used by some other result.
913 ;;; -- Used in any way after the reference (exclusive).
914 ;;; 2. The reference is an argument, and the same location is either:
915 ;;; -- Used by some other argument.
916 ;;; -- Used in any way before the reference (exclusive).
918 ;;; In 1 (and 2) above, the first bullet corresponds to result-result
919 ;;; (and argument-argument) conflicts. We need this case because there
920 ;;; aren't any TN-REFs to represent the implicit reading of results or
921 ;;; writing of arguments.
923 ;;; The second bullet corresponds to conflicts with temporaries or
924 ;;; between arguments and results.
926 ;;; We consider both the TN-REF-TN and the TN-REF-LOAD-TN (if any) to
927 ;;; be referenced simultaneously and in the same way. This causes
928 ;;; load-TNs to appear live to the beginning (or end) of the VOP, as
931 ;;; We return a conflicting TN if there is a conflict.
932 (defun load-tn-offset-conflicts-in-sb (op sb offset)
933 (declare (type tn-ref op) (type finite-sb sb) (type index offset))
934 (aver (eq (sb-kind sb) :finite))
935 (let ((vop (tn-ref-vop op)))
936 (labels ((tn-overlaps (tn)
937 (let ((sc (tn-sc tn))
938 (tn-offset (tn-offset tn)))
939 (when (and (eq (sc-sb sc) sb)
940 (<= tn-offset offset)
943 (+ tn-offset (sc-element-size sc)))))
946 (let ((tn (tn-ref-tn ref))
947 (ltn (tn-ref-load-tn ref)))
949 (and ltn (tn-overlaps ltn)))))
951 (do ((ops ops (tn-ref-across ops)))
953 (let ((found (same ops)))
954 (when (and found (not (eq ops op)))
957 (do ((refs refs (tn-ref-next-ref refs)))
959 (let ((found (same refs)))
960 (when found (return found))))))
961 (declare (inline is-op is-ref tn-overlaps))
962 (if (tn-ref-write-p op)
963 (or (is-op (vop-results vop))
964 (is-ref (vop-refs vop) op))
965 (or (is-op (vop-args vop))
966 (is-ref (tn-ref-next-ref op) nil))))))
968 ;;; Iterate over all the elements in the SB that would be allocated by
969 ;;; allocating a TN in SC at Offset, checking for conflict with
970 ;;; load-TNs or other TNs (live in the LIVE-TNS, which must be set
971 ;;; up.) We also return true if there aren't enough locations after
972 ;;; Offset to hold a TN in SC. If Ignore-Live is true, then we ignore
973 ;;; the live-TNs, considering only references within Op's VOP.
975 ;;; We return a conflicting TN, or :OVERFLOW if the TN won't fit.
976 (defun load-tn-conflicts-in-sc (op sc offset ignore-live)
977 (let* ((sb (sc-sb sc))
978 (size (finite-sb-current-size sb)))
979 (do ((i offset (1+ i))
980 (end (+ offset (sc-element-size sc))))
982 (declare (type index i end))
983 (let ((res (or (when (>= i size) :overflow)
984 (and (not ignore-live)
985 (svref (finite-sb-live-tns sb) i))
986 (load-tn-offset-conflicts-in-sb op sb i))))
987 (when res (return res))))))
989 ;;; If a load-TN for OP is targeted to a legal location in SC, then
990 ;;; return the offset, otherwise return NIL. We see whether the target
991 ;;; of the operand is packed, and try that location. There isn't any
992 ;;; need to chain down the target path, since everything is packed
995 ;;; We require the target to be in SC (and not merely to overlap with
996 ;;; SC). This prevents SC information from being lost in load TNs (we
997 ;;; won't pack a load TN in ANY-REG when it is targeted to a
998 ;;; DESCRIPTOR-REG.) This shouldn't hurt the code as long as all
999 ;;; relevant overlapping SCs are allowed in the operand SC
1001 (defun find-load-tn-target (op sc)
1002 (declare (inline member))
1003 (let ((target (tn-ref-target op)))
1005 (let* ((tn (tn-ref-tn target))
1006 (loc (tn-offset tn)))
1007 (if (and (eq (tn-sc tn) sc)
1008 (member (the index loc) (sc-locations sc))
1009 (not (load-tn-conflicts-in-sc op sc loc nil)))
1013 ;;; Select a legal location for a load TN for Op in SC. We just
1014 ;;; iterate over the SC's locations. If we can't find a legal
1015 ;;; location, return NIL.
1016 (defun select-load-tn-location (op sc)
1017 (declare (type tn-ref op) (type sc sc))
1019 ;; Check any target location first.
1020 (let ((target (tn-ref-target op)))
1022 (let* ((tn (tn-ref-tn target))
1023 (loc (tn-offset tn)))
1024 (when (and (eq (sc-sb sc) (sc-sb (tn-sc tn)))
1025 (member (the index loc) (sc-locations sc))
1026 (not (load-tn-conflicts-in-sc op sc loc nil)))
1027 (return-from select-load-tn-location loc)))))
1029 (dolist (loc (sc-locations sc) nil)
1030 (unless (load-tn-conflicts-in-sc op sc loc nil)
1033 (defevent unpack-tn "Unpacked a TN to satisfy operand SC restriction.")
1035 ;;; Make TN's location the same as for its save TN (allocating a save
1036 ;;; TN if necessary.) Delete any save/restore code that has been
1037 ;;; emitted thus far. Mark all blocks containing references as needing
1039 (defun unpack-tn (tn)
1041 (let ((stn (or (tn-save-tn tn)
1042 (pack-save-tn tn))))
1043 (setf (tn-sc tn) (tn-sc stn))
1044 (setf (tn-offset tn) (tn-offset stn))
1046 (do ((ref refs (tn-ref-next ref)))
1048 (let ((vop (tn-ref-vop ref)))
1049 (if (eq (vop-info-name (vop-info vop)) 'move-operand)
1051 (pushnew (vop-block vop) *repack-blocks*))))))
1053 (zot (tn-writes tn))))
1057 (defevent unpack-fallback "Unpacked some operand TN.")
1059 ;;; This is called by PACK-LOAD-TN where there isn't any location free
1060 ;;; that we can pack into. What we do is move some live TN in one of
1061 ;;; the specified SCs to memory, then mark all blocks that reference
1062 ;;; the TN as needing repacking. If we succeed, we throw to UNPACKED-TN.
1063 ;;; If we fail, we return NIL.
1065 ;;; We can unpack any live TN that appears in the NORMAL-TNs list
1066 ;;; (isn't wired or restricted.) We prefer to unpack TNs that are not
1067 ;;; used by the VOP. If we can't find any such TN, then we unpack some
1068 ;;; argument or result TN. The only way we can fail is if all
1069 ;;; locations in SC are used by load-TNs or temporaries in VOP.
1070 (defun unpack-for-load-tn (sc op)
1071 (declare (type sc sc) (type tn-ref op))
1072 (let ((sb (sc-sb sc))
1073 (normal-tns (ir2-component-normal-tns
1074 (component-info *component-being-compiled*)))
1075 (node (vop-node (tn-ref-vop op)))
1077 (flet ((unpack-em (victims)
1078 (pushnew (vop-block (tn-ref-vop op)) *repack-blocks*)
1079 (dolist (victim victims)
1080 (event unpack-tn node)
1082 (throw 'unpacked-tn nil)))
1083 (dolist (loc (sc-locations sc))
1084 (declare (type index loc))
1086 (collect ((victims nil adjoin))
1088 (end (+ loc (sc-element-size sc))))
1090 (declare (type index i end))
1091 (let ((victim (svref (finite-sb-live-tns sb) i)))
1093 (unless (find-in #'tn-next victim normal-tns)
1097 (let ((conf (load-tn-conflicts-in-sc op sc loc t)))
1099 (unpack-em (victims)))
1100 ((eq conf :overflow))
1102 (cond ((find conf (victims))
1103 (setq fallback (victims)))
1104 ((find-in #'tn-next conf normal-tns)
1105 (setq fallback (list conf))))))))))
1108 (event unpack-fallback node)
1109 (unpack-em fallback))))
1113 ;;; Try to pack a load TN in the SCs indicated by Load-SCs. If we run
1114 ;;; out of SCs, then we unpack some TN and try again. We return the
1117 ;;; Note: we allow a Load-TN to be packed in the target location even
1118 ;;; if that location is in a SC not allowed by the primitive type.
1119 ;;; (The SC must still be allowed by the operand restriction.) This
1120 ;;; makes move VOPs more efficient, since we won't do a move from the
1121 ;;; stack into a non-descriptor any-reg through a descriptor argument
1122 ;;; load-TN. This does give targeting some real semantics, making it
1123 ;;; not a pure advisory to pack. It allows pack to do some packing it
1124 ;;; wouldn't have done before.
1125 (defun pack-load-tn (load-scs op)
1126 (declare (type sc-vector load-scs) (type tn-ref op))
1127 (let ((vop (tn-ref-vop op)))
1128 (compute-live-tns (vop-block vop) vop))
1130 (let* ((tn (tn-ref-tn op))
1131 (ptype (tn-primitive-type tn))
1132 (scs (svref load-scs (sc-number (tn-sc tn)))))
1133 (let ((current-scs scs)
1139 (no-load-scs-allowed-by-primitive-type-error op))
1140 (dolist (sc allowed)
1141 (unpack-for-load-tn sc op))
1142 (failed-to-pack-load-tn-error allowed op))
1144 (let* ((sc (svref *backend-sc-numbers* (pop current-scs)))
1145 (target (find-load-tn-target op sc)))
1146 (when (or target (sc-allowed-by-primitive-type sc ptype))
1147 (let ((loc (or target
1148 (select-load-tn-location op sc))))
1150 (let ((res (make-tn 0 :load nil sc)))
1151 (setf (tn-offset res) loc)
1153 (push sc allowed)))))))))
1155 ;;; Scan a list of load-SCs vectors and a list of TN-REFS threaded by
1156 ;;; TN-REF-ACROSS. When we find a reference whose TN doesn't satisfy
1157 ;;; the restriction, we pack a Load-TN and load the operand into it.
1158 ;;; If a load-tn has already been allocated, we can assume that the
1159 ;;; restriction is satisfied.
1160 #!-sb-fluid (declaim (inline check-operand-restrictions))
1161 (defun check-operand-restrictions (scs ops)
1162 (declare (list scs) (type (or tn-ref null) ops))
1164 ;; Check the targeted operands first.
1165 (do ((scs scs (cdr scs))
1166 (op ops (tn-ref-across op)))
1168 (let ((target (tn-ref-target op)))
1170 (let* ((load-tn (tn-ref-load-tn op))
1171 (load-scs (svref (car scs)
1173 (tn-sc (or load-tn (tn-ref-tn op)))))))
1175 (aver (eq load-scs t))
1176 (unless (eq load-scs t)
1177 (setf (tn-ref-load-tn op)
1178 (pack-load-tn (car scs) op))))))))
1180 (do ((scs scs (cdr scs))
1181 (op ops (tn-ref-across op)))
1183 (let ((target (tn-ref-target op)))
1185 (let* ((load-tn (tn-ref-load-tn op))
1186 (load-scs (svref (car scs)
1188 (tn-sc (or load-tn (tn-ref-tn op)))))))
1190 (aver (eq load-scs t))
1191 (unless (eq load-scs t)
1192 (setf (tn-ref-load-tn op)
1193 (pack-load-tn (car scs) op))))))))
1197 ;;; Scan the VOPs in BLOCK, looking for operands whose SC restrictions
1198 ;;; aren't satisfied. We do the results first, since they are
1199 ;;; evaluated later, and our conflict analysis is a backward scan.
1200 (defun pack-load-tns (block)
1202 (let ((*live-block* nil)
1204 (do ((vop (ir2-block-last-vop block) (vop-prev vop)))
1206 (let ((info (vop-info vop)))
1207 (check-operand-restrictions (vop-info-result-load-scs info)
1209 (check-operand-restrictions (vop-info-arg-load-scs info)
1215 ;;; Link the TN-REFS READ and WRITE together using the TN-REF-TARGET
1216 ;;; when this seems like a good idea. Currently we always do, as this
1217 ;;; increases the success of load-TN targeting.
1218 (defun target-if-desirable (read write)
1219 (declare (type tn-ref read write))
1220 ;; As per the comments at the definition of TN-REF-TARGET, read and
1221 ;; write refs are always paired, with TARGET in the read pointing to
1222 ;; the write and vice versa.
1223 (aver (eq (tn-ref-write-p read)
1224 (not (tn-ref-write-p write))))
1225 (setf (tn-ref-target read) write)
1226 (setf (tn-ref-target write) read))
1228 ;;; If TN can be packed into SC so as to honor a preference to TARGET,
1229 ;;; then return the offset to pack at, otherwise return NIL. TARGET
1230 ;;; must be already packed.
1231 (defun check-ok-target (target tn sc)
1232 (declare (type tn target tn) (type sc sc) (inline member))
1233 (let* ((loc (tn-offset target))
1234 (target-sc (tn-sc target))
1235 (target-sb (sc-sb target-sc)))
1236 (declare (type index loc))
1237 ;; We can honor a preference if:
1238 ;; -- TARGET's location is in SC's locations.
1239 ;; -- The element sizes of the two SCs are the same.
1240 ;; -- TN doesn't conflict with target's location.
1241 (if (and (eq target-sb (sc-sb sc))
1242 (or (eq (sb-kind target-sb) :unbounded)
1243 (member loc (sc-locations sc)))
1244 (= (sc-element-size target-sc) (sc-element-size sc))
1245 (not (conflicts-in-sc tn sc loc))
1246 (zerop (mod loc (sc-alignment sc))))
1250 ;;; Scan along the target path from TN, looking at readers or writers.
1251 ;;; When we find a packed TN, return CHECK-OK-TARGET of that TN. If
1252 ;;; there is no target, or if the TN has multiple readers (writers),
1253 ;;; then we return NIL. We also always return NIL after 10 iterations
1254 ;;; to get around potential circularity problems.
1256 ;;; FIXME: (30 minutes of reverse engineering?) It'd be nice to
1257 ;;; rewrite the header comment here to explain the interface and its
1258 ;;; motivation, and move remarks about implementation details (like
1260 (defun find-ok-target-offset (tn sc)
1261 (declare (type tn tn) (type sc sc))
1262 (flet ((frob-slot (slot-fun)
1263 (declare (type function slot-fun))
1266 (declare (type index count))
1268 (let ((refs (funcall slot-fun current)))
1269 (unless (and (plusp count)
1271 (not (tn-ref-next refs)))
1273 (let ((target (tn-ref-target refs)))
1274 (unless target (return nil))
1275 (setq current (tn-ref-tn target))
1276 (when (tn-offset current)
1277 (return (check-ok-target current tn sc)))
1279 (declare (inline frob-slot)) ; until DYNAMIC-EXTENT works
1280 (or (frob-slot #'tn-reads)
1281 (frob-slot #'tn-writes))))
1283 ;;;; location selection
1285 ;;; Select some location for TN in SC, returning the offset if we
1286 ;;; succeed, and NIL if we fail.
1288 ;;; For :UNBOUNDED SCs just find the smallest correctly aligned offset
1289 ;;; where the TN doesn't conflict with the TNs that have already been
1290 ;;; packed. For :FINITE SCs try to pack the TN into the most heavily
1291 ;;; used locations first (as estimated in FIND-LOCATION-USAGE).
1293 ;;; Historically SELECT-LOCATION tried did the opposite and tried to
1294 ;;; distribute the TNs evenly across the available locations. At least
1295 ;;; on register-starved architectures (x86) this seems to be a bad
1296 ;;; strategy. -- JES 2004-09-11
1297 (defun select-location (tn sc &key use-reserved-locs optimize)
1298 (declare (type tn tn) (type sc sc) (inline member))
1299 (let* ((sb (sc-sb sc))
1300 (element-size (sc-element-size sc))
1301 (alignment (sc-alignment sc))
1302 (align-mask (1- alignment))
1303 (size (finite-sb-current-size sb)))
1304 (flet ((attempt-location (start-offset)
1305 (dotimes (i element-size
1306 (return-from select-location start-offset))
1307 (declare (type index i))
1308 (let ((offset (+ start-offset i)))
1309 (when (offset-conflicts-in-sb tn sb offset)
1310 (return (logandc2 (the index (+ (the index (1+ offset))
1313 (if (eq (sb-kind sb) :unbounded)
1314 (loop with offset = 0
1315 until (> (+ offset element-size) size) do
1316 (setf offset (attempt-location offset)))
1317 (let ((locations (sc-locations sc)))
1320 (stable-sort (copy-list locations) #'>
1321 :key (lambda (location-offset)
1322 (loop for offset from location-offset
1325 (finite-sb-always-live-count sb)
1327 (dolist (offset locations)
1328 (when (or use-reserved-locs
1330 (sc-reserve-locations sc))))
1331 (attempt-location offset))))))))
1333 ;;; If a save TN, return the saved TN, otherwise return TN. This is
1334 ;;; useful for getting the conflicts of a TN that might be a save TN.
1335 (defun original-tn (tn)
1336 (declare (type tn tn))
1337 (if (member (tn-kind tn) '(:save :save-once :specified-save))
1343 ;;; Attempt to pack TN in all possible SCs, first in the SC chosen by
1344 ;;; representation selection, then in the alternate SCs in the order
1345 ;;; they were specified in the SC definition. If the TN-COST is
1346 ;;; negative, then we don't attempt to pack in SCs that must be saved.
1347 ;;; If Restricted, then we can only pack in TN-SC, not in any
1350 ;;; If we are attempting to pack in the SC of the save TN for a TN
1351 ;;; with a :SPECIFIED-SAVE TN, then we pack in that location, instead
1352 ;;; of allocating a new stack location.
1353 (defun pack-tn (tn restricted optimize)
1354 (declare (type tn tn))
1355 (let* ((original (original-tn tn))
1357 (alternates (unless restricted (sc-alternate-scs fsc)))
1358 (save (tn-save-tn tn))
1361 (eq (tn-kind save) :specified-save))
1363 (do ((sc fsc (pop alternates)))
1365 (failed-to-pack-error tn restricted))
1366 (when (eq sc specified-save-sc)
1367 (unless (tn-offset save)
1368 (pack-tn save nil optimize))
1369 (setf (tn-offset tn) (tn-offset save))
1370 (setf (tn-sc tn) (tn-sc save))
1372 (when (or restricted
1373 (not (and (minusp (tn-cost tn)) (sc-save-p sc))))
1374 (let ((loc (or (find-ok-target-offset original sc)
1375 (select-location original sc)
1377 (select-location original sc :use-reserved-locs t))
1378 (when (eq (sb-kind (sc-sb sc)) :unbounded)
1380 (or (select-location original sc)
1381 (error "failed to pack after growing SC?"))))))
1383 (add-location-conflicts original sc loc optimize)
1384 (setf (tn-sc tn) sc)
1385 (setf (tn-offset tn) loc)
1389 ;;; Pack a wired TN, checking that the offset is in bounds for the SB,
1390 ;;; and that the TN doesn't conflict with some other TN already packed
1391 ;;; in that location. If the TN is wired to a location beyond the end
1392 ;;; of a :UNBOUNDED SB, then grow the SB enough to hold the TN.
1394 ;;; ### Checking for conflicts is disabled for :SPECIFIED-SAVE TNs.
1395 ;;; This is kind of a hack to make specifying wired stack save
1396 ;;; locations for local call arguments (such as OLD-FP) work, since
1397 ;;; the caller and callee OLD-FP save locations may conflict when the
1398 ;;; save locations don't really (due to being in different frames.)
1399 (defun pack-wired-tn (tn optimize)
1400 (declare (type tn tn))
1401 (let* ((sc (tn-sc tn))
1403 (offset (tn-offset tn))
1404 (end (+ offset (sc-element-size sc)))
1405 (original (original-tn tn)))
1406 (when (> end (finite-sb-current-size sb))
1407 (unless (eq (sb-kind sb) :unbounded)
1408 (error "~S is wired to a location that is out of bounds." tn))
1411 ;; For non-x86 ports the presence of a save-tn associated with a
1412 ;; tn is used to identify the old-fp and return-pc tns. It depends
1413 ;; on the old-fp and return-pc being passed in registers.
1415 (when (and (not (eq (tn-kind tn) :specified-save))
1416 (conflicts-in-sc original sc offset))
1417 (error "~S is wired to a location that it conflicts with." tn))
1419 ;; Use the above check, but only print a verbose warning. This can
1420 ;; be helpful for debugging the x86 port.
1422 (when (and (not (eq (tn-kind tn) :specified-save))
1423 (conflicts-in-sc original sc offset))
1424 (format t "~&* Pack-wired-tn possible conflict:~% ~
1425 tn: ~S; tn-kind: ~S~% ~
1427 sb: ~S; sb-name: ~S; sb-kind: ~S~% ~
1428 offset: ~S; end: ~S~% ~
1430 tn-save-tn: ~S; tn-kind of tn-save-tn: ~S~%"
1432 sb (sb-name sb) (sb-kind sb)
1435 (tn-save-tn tn) (tn-kind (tn-save-tn tn))))
1437 ;; On the x86 ports the old-fp and return-pc are often passed on
1438 ;; the stack so the above hack for the other ports does not always
1439 ;; work. Here the old-fp and return-pc tns are identified by being
1440 ;; on the stack in their standard save locations.
1442 (when (and (not (eq (tn-kind tn) :specified-save))
1443 (not (and (string= (sb-name sb) "STACK")
1446 (conflicts-in-sc original sc offset))
1447 (error "~S is wired to a location that it conflicts with." tn))
1449 (add-location-conflicts original sc offset optimize)))
1451 (defevent repack-block "Repacked a block due to TN unpacking.")
1453 ;;; KLUDGE: Prior to SBCL version 0.8.9.xx, this function was known as
1454 ;;; PACK-BEFORE-GC-HOOK, but was non-functional since approximately
1455 ;;; version 0.8.3.xx since the removal of GC hooks from the system.
1456 ;;; This currently (as of 2004-04-12) runs now after every call to
1457 ;;; PACK, rather than -- as was originally intended -- once per GC
1458 ;;; cycle; this is probably non-optimal, and might require tuning,
1459 ;;; maybe to be called when the data structures exceed a certain size,
1460 ;;; or maybe once every N times. The KLUDGE is that this rewrite has
1461 ;;; done nothing to improve the reentrance or threadsafety of the
1462 ;;; compiler; it still fails to be callable from several threads at
1465 ;;; Brief experiments indicate that during a compilation cycle this
1466 ;;; causes about 10% more consing, and takes about 1%-2% more time.
1468 ;;; -- CSR, 2004-04-12
1469 (defun clean-up-pack-structures ()
1470 (dolist (sb *backend-sb-list*)
1471 (unless (eq (sb-kind sb) :non-packed)
1472 (let ((size (sb-size sb)))
1473 (fill (finite-sb-always-live sb) nil)
1474 (setf (finite-sb-always-live sb)
1478 ;; The cross-compiler isn't very good at
1479 ;; dumping specialized arrays, so we delay
1480 ;; construction of this SIMPLE-BIT-VECTOR
1482 #+sb-xc (make-array 0 :element-type 'bit)))
1483 (setf (finite-sb-always-live-count sb)
1488 #+sb-xc (make-array 0 :element-type 'fixnum)))
1490 (fill (finite-sb-conflicts sb) nil)
1491 (setf (finite-sb-conflicts sb)
1492 (make-array size :initial-element '#()))
1494 (fill (finite-sb-live-tns sb) nil)
1495 (setf (finite-sb-live-tns sb)
1496 (make-array size :initial-element nil))))))
1498 (defun pack (component)
1500 (let ((optimize nil)
1501 (2comp (component-info component)))
1502 (init-sb-vectors component)
1504 ;; Determine whether we want to do more expensive packing by
1505 ;; checking whether any blocks in the component have (> SPEED
1508 ;; FIXME: This means that a declaration can have a minor
1509 ;; effect even outside its scope, and as the packing is done
1510 ;; component-globally it'd be tricky to use strict scoping. I
1511 ;; think this is still acceptable since it's just a tradeoff
1512 ;; between compilation speed and allocation quality and
1513 ;; doesn't affect the semantics of the generated code in any
1514 ;; way. -- JES 2004-10-06
1515 (do-ir2-blocks (block component)
1516 (when (policy (block-last (ir2-block-block block))
1517 (> speed compilation-speed))
1521 ;; Call the target functions.
1522 (do-ir2-blocks (block component)
1523 (do ((vop (ir2-block-start-vop block) (vop-next vop)))
1525 (let ((target-fun (vop-info-target-fun (vop-info vop))))
1527 (funcall target-fun vop)))))
1529 ;; Pack wired TNs first.
1530 (do ((tn (ir2-component-wired-tns 2comp) (tn-next tn)))
1532 (pack-wired-tn tn optimize))
1534 ;; Pack restricted component TNs.
1535 (do ((tn (ir2-component-restricted-tns 2comp) (tn-next tn)))
1537 (when (eq (tn-kind tn) :component)
1538 (pack-tn tn t optimize)))
1540 ;; Pack other restricted TNs.
1541 (do ((tn (ir2-component-restricted-tns 2comp) (tn-next tn)))
1543 (unless (tn-offset tn)
1544 (pack-tn tn t optimize)))
1546 ;; Assign costs to normal TNs so we know which ones should
1547 ;; always be packed on the stack.
1548 (when *pack-assign-costs*
1549 (assign-tn-costs component)
1550 (assign-tn-depths component))
1552 ;; Allocate normal TNs, starting with the TNs that are used
1555 (do-ir2-blocks (block component)
1556 (let ((ltns (ir2-block-local-tns block)))
1557 (do ((i (1- (ir2-block-local-tn-count block)) (1- i)))
1559 (declare (fixnum i))
1560 (let ((tn (svref ltns i)))
1561 (unless (or (null tn)
1564 ;; If loop analysis has been disabled we might as
1565 ;; well revert to the old behaviour of just
1566 ;; packing TNs linearly as they appear.
1567 (unless *loop-analyze*
1568 (pack-tn tn nil optimize))
1570 (dolist (tn (stable-sort (tns)
1573 ((> (tn-loop-depth a)
1576 ((= (tn-loop-depth a)
1578 (> (tn-cost a) (tn-cost b)))
1580 (unless (tn-offset tn)
1581 (pack-tn tn nil optimize))))
1583 ;; Pack any leftover normal TNs. This is to deal with :MORE TNs,
1584 ;; which could possibly not appear in any local TN map.
1585 (do ((tn (ir2-component-normal-tns 2comp) (tn-next tn)))
1587 (unless (tn-offset tn)
1588 (pack-tn tn nil optimize)))
1590 ;; Do load TN packing and emit saves.
1591 (let ((*repack-blocks* nil))
1592 (cond ((and optimize *pack-optimize-saves*)
1593 (optimized-emit-saves component)
1594 (do-ir2-blocks (block component)
1595 (pack-load-tns block)))
1597 (do-ir2-blocks (block component)
1599 (pack-load-tns block))))
1601 (unless *repack-blocks* (return))
1602 (let ((orpb *repack-blocks*))
1603 (setq *repack-blocks* nil)
1604 (dolist (block orpb)
1605 (event repack-block)
1606 (pack-load-tns block)))))
1609 (clean-up-pack-structures)))