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;;;; This file contains the implementation-independent code for Pack
;;;; phase in the compiler. Pack is responsible for assigning TNs to
;;;; storage allocations or "register allocation".
;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.
(in-package "SB!C")
;;; for debugging: some parameters controlling which optimizations we
;;; attempt
(defvar *pack-assign-costs* t)
(defvar *pack-optimize-saves* t)
;;; FIXME: Perhaps SB-FLUID should be renamed to SB-TWEAK and these
;;; should be made conditional on SB-TWEAK.
(declaim (ftype (function (component) index) ir2-block-count))
;;;; conflict determination
;;; Return true if the element at the specified offset in SB has a
;;; conflict with TN:
;;; -- If a component-live TN (:COMPONENT kind), then iterate over
;;; all the blocks. If the element at OFFSET is used anywhere in
;;; any of the component's blocks (always-live /= 0), then there
;;; is a conflict.
;;; -- If TN is global (Confs true), then iterate over the blocks TN
;;; is live in (using TN-GLOBAL-CONFLICTS). If the TN is live
;;; everywhere in the block (:LIVE), then there is a conflict
;;; if the element at offset is used anywhere in the block
;;; (Always-Live /= 0). Otherwise, we use the local TN number for
;;; TN in block to find whether TN has a conflict at Offset in
;;; that block.
;;; -- If TN is local, then we just check for a conflict in the block
;;; it is local to.
(defun offset-conflicts-in-sb (tn sb offset)
(declare (type tn tn) (type finite-sb sb) (type index offset))
(let ((confs (tn-global-conflicts tn))
(kind (tn-kind tn)))
(cond
((eq kind :component)
(let ((loc-live (svref (finite-sb-always-live sb) offset)))
(dotimes (i (ir2-block-count *component-being-compiled*) nil)
(when (/= (sbit loc-live i) 0)
(return t)))))
(confs
(let ((loc-confs (svref (finite-sb-conflicts sb) offset))
(loc-live (svref (finite-sb-always-live sb) offset)))
(do ((conf confs (global-conflicts-next-tnwise conf)))
((null conf)
nil)
(let* ((block (global-conflicts-block conf))
(num (ir2-block-number block)))
(if (eq (global-conflicts-kind conf) :live)
(when (/= (sbit loc-live num) 0)
(return t))
(when (/= (sbit (svref loc-confs num)
(global-conflicts-number conf))
0)
(return t)))))))
(t
(/= (sbit (svref (svref (finite-sb-conflicts sb) offset)
(ir2-block-number (tn-local tn)))
(tn-local-number tn))
0)))))
;;; Return true if TN has a conflict in SC at the specified offset.
(defun conflicts-in-sc (tn sc offset)
(declare (type tn tn) (type sc sc) (type index offset))
(let ((sb (sc-sb sc)))
(dotimes (i (sc-element-size sc) nil)
(when (offset-conflicts-in-sb tn sb (+ offset i))
(return t)))))
;;; Add TN's conflicts into the conflicts for the location at OFFSET
;;; in SC. We iterate over each location in TN, adding to the
;;; conflicts for that location:
;;; -- If TN is a :COMPONENT TN, then iterate over all the blocks,
;;; setting all of the local conflict bits and the always-live bit.
;;; This records a conflict with any TN that has a LTN number in
;;; the block, as well as with :ALWAYS-LIVE and :ENVIRONMENT TNs.
;;; -- If TN is global, then iterate over the blocks TN is live in. In
;;; addition to setting the always-live bit to represent the conflict
;;; with TNs live throughout the block, we also set bits in the
;;; local conflicts. If TN is :ALWAYS-LIVE in the block, we set all
;;; the bits, otherwise we OR in the local conflict bits.
;;; -- If the TN is local, then we just do the block it is local to,
;;; setting always-live and OR'ing in the local conflicts.
(defun add-location-conflicts (tn sc offset optimize)
(declare (type tn tn) (type sc sc) (type index offset))
(let ((confs (tn-global-conflicts tn))
(sb (sc-sb sc))
(kind (tn-kind tn)))
(dotimes (i (sc-element-size sc))
(declare (type index i))
(let* ((this-offset (+ offset i))
(loc-confs (svref (finite-sb-conflicts sb) this-offset))
(loc-live (svref (finite-sb-always-live sb) this-offset)))
(cond
((eq kind :component)
(dotimes (num (ir2-block-count *component-being-compiled*))
(declare (type index num))
(setf (sbit loc-live num) 1)
(set-bit-vector (svref loc-confs num))))
(confs
(do ((conf confs (global-conflicts-next-tnwise conf)))
((null conf))
(let* ((block (global-conflicts-block conf))
(num (ir2-block-number block))
(local-confs (svref loc-confs num)))
(declare (type local-tn-bit-vector local-confs))
(setf (sbit loc-live num) 1)
(if (eq (global-conflicts-kind conf) :live)
(set-bit-vector local-confs)
(bit-ior local-confs (global-conflicts-conflicts conf) t)))))
(t
(let ((num (ir2-block-number (tn-local tn))))
(setf (sbit loc-live num) 1)
(bit-ior (the local-tn-bit-vector (svref loc-confs num))
(tn-local-conflicts tn) t))))
;; Calculating ALWAYS-LIVE-COUNT is moderately expensive, and
;; currently the information isn't used unless (> SPEED
;; COMPILE-SPEED).
(when optimize
(setf (svref (finite-sb-always-live-count sb) this-offset)
(find-location-usage sb this-offset))))))
(values))
;; A rought measure of how much a given OFFSET in SB is currently
;; used. Current implementation counts the amount of blocks where the
;; offset has been marked as ALWAYS-LIVE.
(defun find-location-usage (sb offset)
(declare (optimize speed))
(declare (type sb sb) (type index offset))
(let* ((always-live (svref (finite-sb-always-live sb) offset)))
(declare (simple-bit-vector always-live))
(count 1 always-live)))
;;; Return the total number of IR2-BLOCKs in COMPONENT.
(defun ir2-block-count (component)
(declare (type component component))
(do ((2block (block-info (block-next (component-head component)))
(ir2-block-next 2block)))
((null 2block)
(error "What? No ir2 blocks have a non-nil number?"))
(when (ir2-block-number 2block)
(return (1+ (ir2-block-number 2block))))))
;;; Ensure that the conflicts vectors for each :FINITE SB are large
;;; enough for the number of blocks allocated. Also clear any old
;;; conflicts and reset the current size to the initial size.
(defun init-sb-vectors (component)
(let ((nblocks (ir2-block-count component)))
(dolist (sb *backend-sb-list*)
(unless (eq (sb-kind sb) :non-packed)
(let* ((conflicts (finite-sb-conflicts sb))
(always-live (finite-sb-always-live sb))
(always-live-count (finite-sb-always-live-count sb))
(max-locs (length conflicts))
(last-count (finite-sb-last-block-count sb)))
(unless (zerop max-locs)
(let ((current-size (length (the simple-vector
(svref conflicts 0)))))
(cond
((> nblocks current-size)
(let ((new-size (max nblocks (* current-size 2))))
(declare (type index new-size))
(dotimes (i max-locs)
(declare (type index i))
(let ((new-vec (make-array new-size)))
(let ((old (svref conflicts i)))
(declare (simple-vector old))
(dotimes (j current-size)
(declare (type index j))
(setf (svref new-vec j)
(clear-bit-vector (svref old j)))))
(do ((j current-size (1+ j)))
((= j new-size))
(declare (type index j))
(setf (svref new-vec j)
(make-array local-tn-limit :element-type 'bit
:initial-element 0)))
(setf (svref conflicts i) new-vec))
(setf (svref always-live i)
(make-array new-size :element-type 'bit
:initial-element 0))
(setf (svref always-live-count i) 0))))
(t
(dotimes (i (finite-sb-current-size sb))
(declare (type index i))
(let ((conf (svref conflicts i)))
(declare (simple-vector conf))
(dotimes (j last-count)
(declare (type index j))
(clear-bit-vector (svref conf j))))
(clear-bit-vector (svref always-live i))
(setf (svref always-live-count i) 0))))))
(setf (finite-sb-last-block-count sb) nblocks)
(setf (finite-sb-current-size sb) (sb-size sb))
(setf (finite-sb-last-offset sb) 0))))))
;;; Expand the :UNBOUNDED SB backing SC by either the initial size or
;;; the SC element size, whichever is larger. If NEEDED-SIZE is
;;; larger, then use that size.
(defun grow-sc (sc &optional (needed-size 0))
(declare (type sc sc) (type index needed-size))
(let* ((sb (sc-sb sc))
(size (finite-sb-current-size sb))
(align-mask (1- (sc-alignment sc)))
(inc (max (finite-sb-size-increment sb)
(+ (sc-element-size sc)
(- (logandc2 (+ size align-mask) align-mask)
size))
(- needed-size size)))
(new-size (let ((align-mask (1- (finite-sb-size-alignment sb))))
(logandc2 (+ size inc align-mask) align-mask)))
(conflicts (finite-sb-conflicts sb))
(block-size (if (zerop (length conflicts))
(ir2-block-count *component-being-compiled*)
(length (the simple-vector (svref conflicts 0)))))
(padded-size (ash 1 (integer-length (1- new-size)))))
(declare (type index inc new-size padded-size))
(aver (eq (sb-kind sb) :unbounded))
(when (> padded-size (length conflicts))
(let ((new-conf (make-array padded-size)))
(replace new-conf conflicts)
(do ((i size (1+ i)))
((= i padded-size))
(declare (type index i))
(let ((loc-confs (make-array block-size)))
(dotimes (j block-size)
(setf (svref loc-confs j)
(make-array local-tn-limit
:initial-element 0
:element-type 'bit)))
(setf (svref new-conf i) loc-confs)))
(setf (finite-sb-conflicts sb) new-conf))
(let ((new-live (make-array padded-size)))
(replace new-live (finite-sb-always-live sb))
(do ((i size (1+ i)))
((= i padded-size))
(setf (svref new-live i)
(make-array block-size
:initial-element 0
:element-type 'bit)))
(setf (finite-sb-always-live sb) new-live))
(let ((new-live-count (make-array padded-size)))
(declare (optimize speed)) ;; FILL deftransform
(replace new-live-count (finite-sb-always-live-count sb))
(fill new-live-count 0 :start size)
(setf (finite-sb-always-live-count sb) new-live-count))
(let ((new-tns (make-array padded-size :initial-element nil)))
(replace new-tns (finite-sb-live-tns sb))
(fill (finite-sb-live-tns sb) nil)
(setf (finite-sb-live-tns sb) new-tns)))
(setf (finite-sb-current-size sb) new-size))
(values))
;;;; internal errors
;;; Give someone a hard time because there isn't any load function
;;; defined to move from SRC to DEST.
(defun no-load-fun-error (src dest)
(let* ((src-sc (tn-sc src))
(src-name (sc-name src-sc))
(dest-sc (tn-sc dest))
(dest-name (sc-name dest-sc)))
(cond ((eq (sb-kind (sc-sb src-sc)) :non-packed)
(unless (member src-sc (sc-constant-scs dest-sc))
(error "loading from an invalid constant SC?~@
VM definition inconsistent, try recompiling."))
(error "no load function defined to load SC ~S ~
from its constant SC ~S"
dest-name src-name))
((member src-sc (sc-alternate-scs dest-sc))
(error "no load function defined to load SC ~S from its ~
alternate SC ~S"
dest-name src-name))
((member dest-sc (sc-alternate-scs src-sc))
(error "no load function defined to save SC ~S in its ~
alternate SC ~S"
src-name dest-name))
(t
;; FIXME: "VM definition is inconsistent" shouldn't be a
;; possibility in SBCL.
(error "loading to/from SCs that aren't alternates?~@
VM definition is inconsistent, try recompiling.")))))
;;; Called when we failed to pack TN. If RESTRICTED is true, then we
;;; are restricted to pack TN in its SC.
(defun failed-to-pack-error (tn restricted)
(declare (type tn tn))
(let* ((sc (tn-sc tn))
(scs (cons sc (sc-alternate-scs sc))))
(cond
(restricted
(error "failed to pack restricted TN ~S in its SC ~S"
tn (sc-name sc)))
(t
(aver (not (find :unbounded scs
:key (lambda (x) (sb-kind (sc-sb x))))))
(let ((ptype (tn-primitive-type tn)))
(cond
(ptype
(aver (member (sc-number sc) (primitive-type-scs ptype)))
(error "SC ~S doesn't have any :UNBOUNDED alternate SCs, but is~@
a SC for primitive-type ~S."
(sc-name sc) (primitive-type-name ptype)))
(t
(error "SC ~S doesn't have any :UNBOUNDED alternate SCs."
(sc-name sc)))))))))
;;; Return a list of format arguments describing how TN is used in
;;; OP's VOP.
(defun describe-tn-use (loc tn op)
(let* ((vop (tn-ref-vop op))
(args (vop-args vop))
(results (vop-results vop))
(name (with-output-to-string (stream)
(print-tn-guts tn stream)))
(2comp (component-info *component-being-compiled*))
temp)
(cond
((setq temp (position-in #'tn-ref-across tn args :key #'tn-ref-tn))
`("~2D: ~A (~:R argument)" ,loc ,name ,(1+ temp)))
((setq temp (position-in #'tn-ref-across tn results :key #'tn-ref-tn))
`("~2D: ~A (~:R result)" ,loc ,name ,(1+ temp)))
((setq temp (position-in #'tn-ref-across tn args :key #'tn-ref-load-tn))
`("~2D: ~A (~:R argument load TN)" ,loc ,name ,(1+ temp)))
((setq temp (position-in #'tn-ref-across tn results :key
#'tn-ref-load-tn))
`("~2D: ~A (~:R result load TN)" ,loc ,name ,(1+ temp)))
((setq temp (position-in #'tn-ref-across tn (vop-temps vop)
:key #'tn-ref-tn))
`("~2D: ~A (temporary ~A)" ,loc ,name
,(operand-parse-name (elt (vop-parse-temps
(vop-parse-or-lose
(vop-info-name (vop-info vop))))
temp))))
((eq (tn-kind tn) :component)
`("~2D: ~A (component live)" ,loc ,name))
((position-in #'tn-next tn (ir2-component-wired-tns 2comp))
`("~2D: ~A (wired)" ,loc ,name))
((position-in #'tn-next tn (ir2-component-restricted-tns 2comp))
`("~2D: ~A (restricted)" ,loc ,name))
(t
`("~2D: not referenced?" ,loc)))))
;;; If load TN packing fails, try to give a helpful error message. We
;;; find a TN in each location that conflicts, and print it.
(defun failed-to-pack-load-tn-error (scs op)
(declare (list scs) (type tn-ref op))
(collect ((used)
(unused))
(dolist (sc scs)
(let* ((sb (sc-sb sc))
(confs (finite-sb-live-tns sb)))
(aver (eq (sb-kind sb) :finite))
(dolist (el (sc-locations sc))
(declare (type index el))
(let ((conf (load-tn-conflicts-in-sc op sc el t)))
(if conf
(used (describe-tn-use el conf op))
(do ((i el (1+ i))
(end (+ el (sc-element-size sc))))
((= i end)
(unused el))
(declare (type index i end))
(let ((victim (svref confs i)))
(when victim
(used (describe-tn-use el victim op))
(return t)))))))))
(multiple-value-bind (arg-p n more-p costs load-scs incon)
(get-operand-info op)
(declare (ignore costs load-scs))
(aver (not more-p))
(error "unable to pack a Load-TN in SC ~{~A~#[~^~;, or ~:;,~]~} ~
for the ~:R ~:[result~;argument~] to~@
the ~S VOP,~@
~:[since all SC elements are in use:~:{~%~@?~}~%~;~
~:*but these SC elements are not in use:~% ~S~%Bug?~*~]~
~:[~;~@
Current cost info inconsistent with that in effect at compile ~
time. Recompile.~%Compilation order may be incorrect.~]"
(mapcar #'sc-name scs)
n arg-p
(vop-info-name (vop-info (tn-ref-vop op)))
(unused) (used)
incon))))
;;; This is called when none of the SCs that we can load OP into are
;;; allowed by OP's primitive-type.
(defun no-load-scs-allowed-by-primitive-type-error (ref)
(declare (type tn-ref ref))
(let* ((tn (tn-ref-tn ref))
(ptype (tn-primitive-type tn)))
(multiple-value-bind (arg-p pos more-p costs load-scs incon)
(get-operand-info ref)
(declare (ignore costs))
(aver (not more-p))
(error "~S is not valid as the ~:R ~:[result~;argument~] to VOP:~
~% ~S,~@
since the TN's primitive type ~S doesn't allow any of the SCs~@
allowed by the operand restriction:~% ~S~
~:[~;~@
Current cost info inconsistent with that in effect at compile ~
time. Recompile.~%Compilation order may be incorrect.~]"
tn pos arg-p
(template-name (vop-info (tn-ref-vop ref)))
(primitive-type-name ptype)
(mapcar #'sc-name (listify-restrictions load-scs))
incon))))
;;;; register saving
;;; Do stuff to note that TN is spilled at VOP for the debugger's benefit.
(defun note-spilled-tn (tn vop)
(when (and (tn-leaf tn) (vop-save-set vop))
(let ((2comp (component-info *component-being-compiled*)))
(setf (gethash tn (ir2-component-spilled-tns 2comp)) t)
(pushnew tn (gethash vop (ir2-component-spilled-vops 2comp)))))
(values))
;;; Make a save TN for TN, pack it, and return it. We copy various
;;; conflict information from the TN so that pack does the right
;;; thing.
(defun pack-save-tn (tn)
(declare (type tn tn))
(let ((res (make-tn 0 :save nil nil)))
(dolist (alt (sc-alternate-scs (tn-sc tn))
(error "no unbounded alternate for SC ~S"
(sc-name (tn-sc tn))))
(when (eq (sb-kind (sc-sb alt)) :unbounded)
(setf (tn-save-tn tn) res)
(setf (tn-save-tn res) tn)
(setf (tn-sc res) alt)
(pack-tn res t nil)
(return res)))))
;;; Find the load function for moving from SRC to DEST and emit a
;;; MOVE-OPERAND VOP with that function as its info arg.
(defun emit-operand-load (node block src dest before)
(declare (type node node) (type ir2-block block)
(type tn src dest) (type (or vop null) before))
(emit-load-template node block
(template-or-lose 'move-operand)
src dest
(list (or (svref (sc-move-funs (tn-sc dest))
(sc-number (tn-sc src)))
(no-load-fun-error src dest)))
before)
(values))
;;; Find the preceding use of the VOP NAME in the emit order, starting
;;; with VOP. We must find the VOP in the same IR1 block.
(defun reverse-find-vop (name vop)
(do* ((block (vop-block vop) (ir2-block-prev block))
(last vop (ir2-block-last-vop block)))
(nil)
(aver (eq (ir2-block-block block) (ir2-block-block (vop-block vop))))
(do ((current last (vop-prev current)))
((null current))
(when (eq (vop-info-name (vop-info current)) name)
(return-from reverse-find-vop current)))))
;;; For TNs that have other than one writer, we save the TN before
;;; each call. If a local call (MOVE-ARGS is :LOCAL-CALL), then we
;;; scan back for the ALLOCATE-FRAME VOP, and emit the save there.
;;; This is necessary because in a self-recursive local call, the
;;; registers holding the current arguments may get trashed by setting
;;; up the call arguments. The ALLOCATE-FRAME VOP marks a place at
;;; which the values are known to be good.
(defun save-complex-writer-tn (tn vop)
(let ((save (or (tn-save-tn tn)
(pack-save-tn tn)))
(node (vop-node vop))
(block (vop-block vop))
(next (vop-next vop)))
(when (eq (tn-kind save) :specified-save)
(setf (tn-kind save) :save))
(aver (eq (tn-kind save) :save))
(emit-operand-load node block tn save
(if (eq (vop-info-move-args (vop-info vop))
:local-call)
(reverse-find-vop 'allocate-frame vop)
vop))
(emit-operand-load node block save tn next)))
;;; Return a VOP after which is an OK place to save the value of TN.
;;; For correctness, it is only required that this location be after
;;; any possible write and before any possible restore location.
;;;
;;; In practice, we return the unique writer VOP, but give up if the
;;; TN is ever read by a VOP with MOVE-ARGS :LOCAL-CALL. This prevents
;;; us from being confused by non-tail local calls.
;;;
;;; When looking for writes, we have to ignore uses of MOVE-OPERAND,
;;; since they will correspond to restores that we have already done.
(defun find-single-writer (tn)
(declare (type tn tn))
(do ((write (tn-writes tn) (tn-ref-next write))
(res nil))
((null write)
(when (and res
(do ((read (tn-reads tn) (tn-ref-next read)))
((not read) t)
(when (eq (vop-info-move-args
(vop-info
(tn-ref-vop read)))
:local-call)
(return nil))))
(tn-ref-vop res)))
(unless (eq (vop-info-name (vop-info (tn-ref-vop write)))
'move-operand)
(when res (return nil))
(setq res write))))
;;; Try to save TN at a single location. If we succeed, return T,
;;; otherwise NIL.
(defun save-single-writer-tn (tn)
(declare (type tn tn))
(let* ((old-save (tn-save-tn tn))
(save (or old-save (pack-save-tn tn)))
(writer (find-single-writer tn)))
(when (and writer
(or (not old-save)
(eq (tn-kind old-save) :specified-save)))
(emit-operand-load (vop-node writer) (vop-block writer)
tn save (vop-next writer))
(setf (tn-kind save) :save-once)
t)))
;;; Restore a TN with a :SAVE-ONCE save TN.
(defun restore-single-writer-tn (tn vop)
(declare (type tn) (type vop vop))
(let ((save (tn-save-tn tn)))
(aver (eq (tn-kind save) :save-once))
(emit-operand-load (vop-node vop) (vop-block vop) save tn (vop-next vop)))
(values))
;;; Save a single TN that needs to be saved, choosing save-once if
;;; appropriate. This is also called by SPILL-AND-PACK-LOAD-TN.
(defun basic-save-tn (tn vop)
(declare (type tn tn) (type vop vop))
(let ((save (tn-save-tn tn)))
(cond ((and save (eq (tn-kind save) :save-once))
(restore-single-writer-tn tn vop))
((save-single-writer-tn tn)
(restore-single-writer-tn tn vop))
(t
(save-complex-writer-tn tn vop))))
(values))
;;; Scan over the VOPs in BLOCK, emiting saving code for TNs noted in
;;; the codegen info that are packed into saved SCs.
(defun emit-saves (block)
(declare (type ir2-block block))
(do ((vop (ir2-block-start-vop block) (vop-next vop)))
((null vop))
(when (eq (vop-info-save-p (vop-info vop)) t)
(do-live-tns (tn (vop-save-set vop) block)
(when (and (sc-save-p (tn-sc tn))
(not (eq (tn-kind tn) :component)))
(basic-save-tn tn vop)))))
(values))
;;;; optimized saving
;;; Save TN if it isn't a single-writer TN that has already been
;;; saved. If multi-write, we insert the save BEFORE the specified
;;; VOP. CONTEXT is a VOP used to tell which node/block to use for the
;;; new VOP.
(defun save-if-necessary (tn before context)
(declare (type tn tn) (type (or vop null) before) (type vop context))
(let ((save (tn-save-tn tn)))
(when (eq (tn-kind save) :specified-save)
(setf (tn-kind save) :save))
(aver (member (tn-kind save) '(:save :save-once)))
(unless (eq (tn-kind save) :save-once)
(or (save-single-writer-tn tn)
(emit-operand-load (vop-node context) (vop-block context)
tn save before))))
(values))
;;; Load the TN from its save location, allocating one if necessary.
;;; The load is inserted BEFORE the specified VOP. CONTEXT is a VOP
;;; used to tell which node/block to use for the new VOP.
(defun restore-tn (tn before context)
(declare (type tn tn) (type (or vop null) before) (type vop context))
(let ((save (or (tn-save-tn tn) (pack-save-tn tn))))
(emit-operand-load (vop-node context) (vop-block context)
save tn before))
(values))
;;; Start scanning backward at the end of BLOCK, looking which TNs are
;;; live and looking for places where we have to save. We manipulate
;;; two sets: SAVES and RESTORES.
;;;
;;; SAVES is a set of all the TNs that have to be saved because they
;;; are restored after some call. We normally delay saving until the
;;; beginning of the block, but we must save immediately if we see a
;;; write of the saved TN. We also immediately save all TNs and exit
;;; when we see a NOTE-ENVIRONMENT-START VOP, since saves can't be
;;; done before the environment is properly initialized.
;;;
;;; RESTORES is a set of all the TNs read (and not written) between
;;; here and the next call, i.e. the set of TNs that must be restored
;;; when we reach the next (earlier) call VOP. Unlike SAVES, this set
;;; is cleared when we do the restoring after a call. Any TNs that
;;; were in RESTORES are moved into SAVES to ensure that they are
;;; saved at some point.
;;;
;;; SAVES and RESTORES are represented using both a list and a
;;; bit-vector so that we can quickly iterate and test for membership.
;;; The incoming SAVES and RESTORES args are used for computing these
;;; sets (the initial contents are ignored.)
;;;
;;; When we hit a VOP with :COMPUTE-ONLY SAVE-P (an internal error
;;; location), we pretend that all live TNs were read, unless (= speed
;;; 3), in which case we mark all the TNs that are live but not
;;; restored as spilled.
(defun optimized-emit-saves-block (block saves restores)
(declare (type ir2-block block) (type simple-bit-vector saves restores))
(let ((1block (ir2-block-block block))
(saves-list ())
(restores-list ())
(skipping nil))
(declare (list saves-list restores-list))
(clear-bit-vector saves)
(clear-bit-vector restores)
(do-live-tns (tn (ir2-block-live-in block) block)
(when (and (sc-save-p (tn-sc tn))
(not (eq (tn-kind tn) :component)))
(let ((num (tn-number tn)))
(setf (sbit restores num) 1)
(push tn restores-list))))
(do ((block block (ir2-block-prev block))
(prev nil block))
((not (eq (ir2-block-block block) 1block))
(aver (not skipping))
(dolist (save saves-list)
(let ((start (ir2-block-start-vop prev)))
(save-if-necessary save start start)))
prev)
(do ((vop (ir2-block-last-vop block) (vop-prev vop)))
((null vop))
(let ((info (vop-info vop)))
(case (vop-info-name info)
(allocate-frame
(aver skipping)
(setq skipping nil))
(note-environment-start
(aver (not skipping))
(dolist (save saves-list)
(save-if-necessary save (vop-next vop) vop))
(return-from optimized-emit-saves-block block)))
(unless skipping
(do ((write (vop-results vop) (tn-ref-across write)))
((null write))
(let* ((tn (tn-ref-tn write))
(num (tn-number tn)))
(unless (zerop (sbit restores num))
(setf (sbit restores num) 0)
(setq restores-list
(delete tn restores-list :test #'eq)))
(unless (zerop (sbit saves num))
(setf (sbit saves num) 0)
(save-if-necessary tn (vop-next vop) vop)
(setq saves-list
(delete tn saves-list :test #'eq))))))
(macrolet ((save-note-read (tn)
`(let* ((tn ,tn)
(num (tn-number tn)))
(when (and (sc-save-p (tn-sc tn))
(zerop (sbit restores num))
(not (eq (tn-kind tn) :component)))
(setf (sbit restores num) 1)
(push tn restores-list)))))
(case (vop-info-save-p info)
((t)
(dolist (tn restores-list)
(restore-tn tn (vop-next vop) vop)
(let ((num (tn-number tn)))
(when (zerop (sbit saves num))
(push tn saves-list)
(setf (sbit saves num) 1))))
(setq restores-list nil)
(clear-bit-vector restores))
(:compute-only
(cond ((policy (vop-node vop) (= speed 3))
(do-live-tns (tn (vop-save-set vop) block)
(when (zerop (sbit restores (tn-number tn)))
(note-spilled-tn tn vop))))
(t
(do-live-tns (tn (vop-save-set vop) block)
(save-note-read tn))))))
(if (eq (vop-info-move-args info) :local-call)
(setq skipping t)
(do ((read (vop-args vop) (tn-ref-across read)))
((null read))
(save-note-read (tn-ref-tn read))))))))))
;;; This is like EMIT-SAVES, only different. We avoid redundant saving
;;; within the block, and don't restore values that aren't used before
;;; the next call. This function is just the top level loop over the
;;; blocks in the component, which locates blocks that need saving
;;; done.
(defun optimized-emit-saves (component)
(declare (type component component))
(let* ((gtn-count (1+ (ir2-component-global-tn-counter
(component-info component))))
(saves (make-array gtn-count :element-type 'bit))
(restores (make-array gtn-count :element-type 'bit))
(block (ir2-block-prev (block-info (component-tail component))))
(head (block-info (component-head component))))
(loop
(when (eq block head) (return))
(when (do ((vop (ir2-block-start-vop block) (vop-next vop)))
((null vop) nil)
(when (eq (vop-info-save-p (vop-info vop)) t)
(return t)))
(setq block (optimized-emit-saves-block block saves restores)))
(setq block (ir2-block-prev block)))))
;;; Iterate over the normal TNs, finding the cost of packing on the
;;; stack in units of the number of references. We count all
;;; references as +1, and subtract out REGISTER-SAVE-PENALTY for each
;;; place where we would have to save a register.
(defun assign-tn-costs (component)
(do-ir2-blocks (block component)
(do ((vop (ir2-block-start-vop block) (vop-next vop)))
((null vop))
(when (eq (vop-info-save-p (vop-info vop)) t)
(do-live-tns (tn (vop-save-set vop) block)
(decf (tn-cost tn) *backend-register-save-penalty*)))))
(do ((tn (ir2-component-normal-tns (component-info component))
(tn-next tn)))
((null tn))
(let ((cost (tn-cost tn)))
(declare (fixnum cost))
(do ((ref (tn-reads tn) (tn-ref-next ref)))
((null ref))
(incf cost))
(do ((ref (tn-writes tn) (tn-ref-next ref)))
((null ref))
(incf cost))
(setf (tn-cost tn) cost))))
;;; Iterate over the normal TNs, storing the depth of the deepest loop
;;; that the TN is used in TN-LOOP-DEPTH.
(defun assign-tn-depths (component)
(when *loop-analyze*
(do-ir2-blocks (block component)
(do ((vop (ir2-block-start-vop block)
(vop-next vop)))
((null vop))
(flet ((find-all-tns (head-fun)
(collect ((tns))
(do ((ref (funcall head-fun vop) (tn-ref-across ref)))
((null ref))
(tns (tn-ref-tn ref)))
(tns))))
(dolist (tn (nconc (find-all-tns #'vop-args)
(find-all-tns #'vop-results)
(find-all-tns #'vop-temps)
;; What does "references in this VOP
;; mean"? Probably something that isn't
;; useful in this context, since these
;; TN-REFs are linked with TN-REF-NEXT
;; instead of TN-REF-ACROSS. --JES
;; 2004-09-11
;; (find-all-tns #'vop-refs)
))
(setf (tn-loop-depth tn)
(max (tn-loop-depth tn)
(let* ((ir1-block (ir2-block-block (vop-block vop)))
(loop (block-loop ir1-block)))
(if loop
(loop-depth loop)
0))))))))))
;;;; load TN packing
;;; These variables indicate the last location at which we computed
;;; the Live-TNs. They hold the BLOCK and VOP values that were passed
;;; to COMPUTE-LIVE-TNS.
(defvar *live-block*)
(defvar *live-vop*)
;;; If we unpack some TNs, then we mark all affected blocks by
;;; sticking them in this hash-table. This is initially null. We
;;; create the hashtable if we do any unpacking.
(defvar *repack-blocks*)
(declaim (type list *repack-blocks*))
;;; Set the LIVE-TNS vectors in all :FINITE SBs to represent the TNs
;;; live at the end of BLOCK.
(defun init-live-tns (block)
(dolist (sb *backend-sb-list*)
(when (eq (sb-kind sb) :finite)
(fill (finite-sb-live-tns sb) nil)))
(do-live-tns (tn (ir2-block-live-in block) block)
(let* ((sc (tn-sc tn))
(sb (sc-sb sc)))
(when (eq (sb-kind sb) :finite)
;; KLUDGE: we can have "live" TNs that are neither read
;; to nor written from, due to more aggressive (type-
;; directed) constant propagation. Such TNs will never
;; be assigned an offset nor be in conflict with anything.
;;
;; Ideally, it seems to me we could make sure these TNs
;; are never allocated in the first place in
;; ASSIGN-LAMBDA-VAR-TNS.
(if (tn-offset tn)
(do ((offset (tn-offset tn) (1+ offset))
(end (+ (tn-offset tn) (sc-element-size sc))))
((= offset end))
(declare (type index offset end))
(setf (svref (finite-sb-live-tns sb) offset) tn))
(assert (and (null (tn-reads tn))
(null (tn-writes tn))))))))
(setq *live-block* block)
(setq *live-vop* (ir2-block-last-vop block))
(values))
;;; Set the LIVE-TNs in :FINITE SBs to represent the TNs live
;;; immediately after the evaluation of VOP in BLOCK, excluding
;;; results of the VOP. If VOP is null, then compute the live TNs at
;;; the beginning of the block. Sequential calls on the same block
;;; must be in reverse VOP order.
(defun compute-live-tns (block vop)
(declare (type ir2-block block) (type vop vop))
(unless (eq block *live-block*)
(init-live-tns block))
(do ((current *live-vop* (vop-prev current)))
((eq current vop)
(do ((res (vop-results vop) (tn-ref-across res)))
((null res))
(let* ((tn (tn-ref-tn res))
(sc (tn-sc tn))
(sb (sc-sb sc)))
(when (eq (sb-kind sb) :finite)
(do ((offset (tn-offset tn) (1+ offset))
(end (+ (tn-offset tn) (sc-element-size sc))))
((= offset end))
(declare (type index offset end))
(setf (svref (finite-sb-live-tns sb) offset) nil))))))
(do ((ref (vop-refs current) (tn-ref-next-ref ref)))
((null ref))
(let ((ltn (tn-ref-load-tn ref)))
(when ltn
(let* ((sc (tn-sc ltn))
(sb (sc-sb sc)))
(when (eq (sb-kind sb) :finite)
(let ((tns (finite-sb-live-tns sb)))
(do ((offset (tn-offset ltn) (1+ offset))
(end (+ (tn-offset ltn) (sc-element-size sc))))
((= offset end))
(declare (type index offset end))
(aver (null (svref tns offset)))))))))
(let* ((tn (tn-ref-tn ref))
(sc (tn-sc tn))
(sb (sc-sb sc)))
(when (eq (sb-kind sb) :finite)
(let ((tns (finite-sb-live-tns sb)))
(do ((offset (tn-offset tn) (1+ offset))
(end (+ (tn-offset tn) (sc-element-size sc))))
((= offset end))
(declare (type index offset end))
(if (tn-ref-write-p ref)
(setf (svref tns offset) nil)
(let ((old (svref tns offset)))
(aver (or (null old) (eq old tn)))
(setf (svref tns offset) tn)))))))))
(setq *live-vop* vop)
(values))
;;; This is kind of like OFFSET-CONFLICTS-IN-SB, except that it uses
;;; the VOP refs to determine whether a Load-TN for OP could be packed
;;; in the specified location, disregarding conflicts with TNs not
;;; referenced by this VOP. There is a conflict if either:
;;; 1. The reference is a result, and the same location is either:
;;; -- Used by some other result.
;;; -- Used in any way after the reference (exclusive).
;;; 2. The reference is an argument, and the same location is either:
;;; -- Used by some other argument.
;;; -- Used in any way before the reference (exclusive).
;;;
;;; In 1 (and 2) above, the first bullet corresponds to result-result
;;; (and argument-argument) conflicts. We need this case because there
;;; aren't any TN-REFs to represent the implicit reading of results or
;;; writing of arguments.
;;;
;;; The second bullet corresponds to conflicts with temporaries or
;;; between arguments and results.
;;;
;;; We consider both the TN-REF-TN and the TN-REF-LOAD-TN (if any) to
;;; be referenced simultaneously and in the same way. This causes
;;; load-TNs to appear live to the beginning (or end) of the VOP, as
;;; appropriate.
;;;
;;; We return a conflicting TN if there is a conflict.
(defun load-tn-offset-conflicts-in-sb (op sb offset)
(declare (type tn-ref op) (type finite-sb sb) (type index offset))
(aver (eq (sb-kind sb) :finite))
(let ((vop (tn-ref-vop op)))
(labels ((tn-overlaps (tn)
(let ((sc (tn-sc tn))
(tn-offset (tn-offset tn)))
(when (and (eq (sc-sb sc) sb)
(<= tn-offset offset)
(< offset
(the index
(+ tn-offset (sc-element-size sc)))))
tn)))
(same (ref)
(let ((tn (tn-ref-tn ref))
(ltn (tn-ref-load-tn ref)))
(or (tn-overlaps tn)
(and ltn (tn-overlaps ltn)))))
(is-op (ops)
(do ((ops ops (tn-ref-across ops)))
((null ops) nil)
(let ((found (same ops)))
(when (and found (not (eq ops op)))
(return found)))))
(is-ref (refs end)
(do ((refs refs (tn-ref-next-ref refs)))
((eq refs end) nil)
(let ((found (same refs)))
(when found (return found))))))
(declare (inline is-op is-ref tn-overlaps))
(if (tn-ref-write-p op)
(or (is-op (vop-results vop))
(is-ref (vop-refs vop) op))
(or (is-op (vop-args vop))
(is-ref (tn-ref-next-ref op) nil))))))
;;; Iterate over all the elements in the SB that would be allocated by
;;; allocating a TN in SC at Offset, checking for conflict with
;;; load-TNs or other TNs (live in the LIVE-TNS, which must be set
;;; up.) We also return true if there aren't enough locations after
;;; Offset to hold a TN in SC. If Ignore-Live is true, then we ignore
;;; the live-TNs, considering only references within Op's VOP.
;;;
;;; We return a conflicting TN, or :OVERFLOW if the TN won't fit.
(defun load-tn-conflicts-in-sc (op sc offset ignore-live)
(let* ((sb (sc-sb sc))
(size (finite-sb-current-size sb)))
(do ((i offset (1+ i))
(end (+ offset (sc-element-size sc))))
((= i end) nil)
(declare (type index i end))
(let ((res (or (when (>= i size) :overflow)
(and (not ignore-live)
(svref (finite-sb-live-tns sb) i))
(load-tn-offset-conflicts-in-sb op sb i))))
(when res (return res))))))
;;; If a load-TN for OP is targeted to a legal location in SC, then
;;; return the offset, otherwise return NIL. We see whether the target
;;; of the operand is packed, and try that location. There isn't any
;;; need to chain down the target path, since everything is packed
;;; now.
;;;
;;; We require the target to be in SC (and not merely to overlap with
;;; SC). This prevents SC information from being lost in load TNs (we
;;; won't pack a load TN in ANY-REG when it is targeted to a
;;; DESCRIPTOR-REG.) This shouldn't hurt the code as long as all
;;; relevant overlapping SCs are allowed in the operand SC
;;; restriction.
(defun find-load-tn-target (op sc)
(declare (inline member))
(let ((target (tn-ref-target op)))
(when target
(let* ((tn (tn-ref-tn target))
(loc (tn-offset tn)))
(if (and (eq (tn-sc tn) sc)
(member (the index loc) (sc-locations sc))
(not (load-tn-conflicts-in-sc op sc loc nil)))
loc
nil)))))
;;; Select a legal location for a load TN for Op in SC. We just
;;; iterate over the SC's locations. If we can't find a legal
;;; location, return NIL.
(defun select-load-tn-location (op sc)
(declare (type tn-ref op) (type sc sc))
;; Check any target location first.
(let ((target (tn-ref-target op)))
(when target
(let* ((tn (tn-ref-tn target))
(loc (tn-offset tn)))
(when (and (eq (sc-sb sc) (sc-sb (tn-sc tn)))
(member (the index loc) (sc-locations sc))
(not (load-tn-conflicts-in-sc op sc loc nil)))
(return-from select-load-tn-location loc)))))
(dolist (loc (sc-locations sc) nil)
(unless (load-tn-conflicts-in-sc op sc loc nil)
(return loc))))
(defevent unpack-tn "Unpacked a TN to satisfy operand SC restriction.")
;;; Make TN's location the same as for its save TN (allocating a save
;;; TN if necessary.) Delete any save/restore code that has been
;;; emitted thus far. Mark all blocks containing references as needing
;;; to be repacked.
(defun unpack-tn (tn)
(event unpack-tn)
(let ((stn (or (tn-save-tn tn)
(pack-save-tn tn))))
(setf (tn-sc tn) (tn-sc stn))
(setf (tn-offset tn) (tn-offset stn))
(flet ((zot (refs)
(do ((ref refs (tn-ref-next ref)))
((null ref))
(let ((vop (tn-ref-vop ref)))
(if (eq (vop-info-name (vop-info vop)) 'move-operand)
(delete-vop vop)
(pushnew (vop-block vop) *repack-blocks*))))))
(zot (tn-reads tn))
(zot (tn-writes tn))))
(values))
(defevent unpack-fallback "Unpacked some operand TN.")
;;; This is called by PACK-LOAD-TN where there isn't any location free
;;; that we can pack into. What we do is move some live TN in one of
;;; the specified SCs to memory, then mark all blocks that reference
;;; the TN as needing repacking. If we succeed, we throw to UNPACKED-TN.
;;; If we fail, we return NIL.
;;;
;;; We can unpack any live TN that appears in the NORMAL-TNs list
;;; (isn't wired or restricted.) We prefer to unpack TNs that are not
;;; used by the VOP. If we can't find any such TN, then we unpack some
;;; argument or result TN. The only way we can fail is if all
;;; locations in SC are used by load-TNs or temporaries in VOP.
(defun unpack-for-load-tn (sc op)
(declare (type sc sc) (type tn-ref op))
(let ((sb (sc-sb sc))
(normal-tns (ir2-component-normal-tns
(component-info *component-being-compiled*)))
(node (vop-node (tn-ref-vop op)))
(fallback nil))
(flet ((unpack-em (victims)
(pushnew (vop-block (tn-ref-vop op)) *repack-blocks*)
(dolist (victim victims)
(event unpack-tn node)
(unpack-tn victim))
(throw 'unpacked-tn nil)))
(dolist (loc (sc-locations sc))
(declare (type index loc))
(block SKIP
(collect ((victims nil adjoin))
(do ((i loc (1+ i))
(end (+ loc (sc-element-size sc))))
((= i end))
(declare (type index i end))
(let ((victim (svref (finite-sb-live-tns sb) i)))
(when victim
(unless (find-in #'tn-next victim normal-tns)
(return-from SKIP))
(victims victim))))
(let ((conf (load-tn-conflicts-in-sc op sc loc t)))
(cond ((not conf)
(unpack-em (victims)))
((eq conf :overflow))
((not fallback)
(cond ((find conf (victims))
(setq fallback (victims)))
((find-in #'tn-next conf normal-tns)
(setq fallback (list conf))))))))))
(when fallback
(event unpack-fallback node)
(unpack-em fallback))))
nil)
;;; Try to pack a load TN in the SCs indicated by Load-SCs. If we run
;;; out of SCs, then we unpack some TN and try again. We return the
;;; packed load TN.
;;;
;;; Note: we allow a Load-TN to be packed in the target location even
;;; if that location is in a SC not allowed by the primitive type.
;;; (The SC must still be allowed by the operand restriction.) This
;;; makes move VOPs more efficient, since we won't do a move from the
;;; stack into a non-descriptor any-reg through a descriptor argument
;;; load-TN. This does give targeting some real semantics, making it
;;; not a pure advisory to pack. It allows pack to do some packing it
;;; wouldn't have done before.
(defun pack-load-tn (load-scs op)
(declare (type sc-vector load-scs) (type tn-ref op))
(let ((vop (tn-ref-vop op)))
(compute-live-tns (vop-block vop) vop))
(let* ((tn (tn-ref-tn op))
(ptype (tn-primitive-type tn))
(scs (svref load-scs (sc-number (tn-sc tn)))))
(let ((current-scs scs)
(allowed ()))
(loop
(cond
((null current-scs)
(unless allowed
(no-load-scs-allowed-by-primitive-type-error op))
(dolist (sc allowed)
(unpack-for-load-tn sc op))
(failed-to-pack-load-tn-error allowed op))
(t
(let* ((sc (svref *backend-sc-numbers* (pop current-scs)))
(target (find-load-tn-target op sc)))
(when (or target (sc-allowed-by-primitive-type sc ptype))
(let ((loc (or target
(select-load-tn-location op sc))))
(when loc
(let ((res (make-tn 0 :load nil sc)))
(setf (tn-offset res) loc)
(return res))))
(push sc allowed)))))))))
;;; Scan a list of load-SCs vectors and a list of TN-REFS threaded by
;;; TN-REF-ACROSS. When we find a reference whose TN doesn't satisfy
;;; the restriction, we pack a Load-TN and load the operand into it.
;;; If a load-tn has already been allocated, we can assume that the
;;; restriction is satisfied.
#!-sb-fluid (declaim (inline check-operand-restrictions))
(defun check-operand-restrictions (scs ops)
(declare (list scs) (type (or tn-ref null) ops))
;; Check the targeted operands first.
(do ((scs scs (cdr scs))
(op ops (tn-ref-across op)))
((null scs))
(let ((target (tn-ref-target op)))
(when target
(let* ((load-tn (tn-ref-load-tn op))
(load-scs (svref (car scs)
(sc-number
(tn-sc (or load-tn (tn-ref-tn op)))))))
(if load-tn
(aver (eq load-scs t))
(unless (eq load-scs t)
(setf (tn-ref-load-tn op)
(pack-load-tn (car scs) op))))))))
(do ((scs scs (cdr scs))
(op ops (tn-ref-across op)))
((null scs))
(let ((target (tn-ref-target op)))
(unless target
(let* ((load-tn (tn-ref-load-tn op))
(load-scs (svref (car scs)
(sc-number
(tn-sc (or load-tn (tn-ref-tn op)))))))
(if load-tn
(aver (eq load-scs t))
(unless (eq load-scs t)
(setf (tn-ref-load-tn op)
(pack-load-tn (car scs) op))))))))
(values))
;;; Scan the VOPs in BLOCK, looking for operands whose SC restrictions
;;; aren't satisfied. We do the results first, since they are
;;; evaluated later, and our conflict analysis is a backward scan.
(defun pack-load-tns (block)
(catch 'unpacked-tn
(let ((*live-block* nil)
(*live-vop* nil))
(do ((vop (ir2-block-last-vop block) (vop-prev vop)))
((null vop))
(let ((info (vop-info vop)))
(check-operand-restrictions (vop-info-result-load-scs info)
(vop-results vop))
(check-operand-restrictions (vop-info-arg-load-scs info)
(vop-args vop))))))
(values))
;;;; targeting
;;; Link the TN-REFS READ and WRITE together using the TN-REF-TARGET
;;; when this seems like a good idea. Currently we always do, as this
;;; increases the success of load-TN targeting.
(defun target-if-desirable (read write)
(declare (type tn-ref read write))
;; As per the comments at the definition of TN-REF-TARGET, read and
;; write refs are always paired, with TARGET in the read pointing to
;; the write and vice versa.
(aver (eq (tn-ref-write-p read)
(not (tn-ref-write-p write))))
(setf (tn-ref-target read) write)
(setf (tn-ref-target write) read))
;;; If TN can be packed into SC so as to honor a preference to TARGET,
;;; then return the offset to pack at, otherwise return NIL. TARGET
;;; must be already packed.
(defun check-ok-target (target tn sc)
(declare (type tn target tn) (type sc sc) (inline member))
(let* ((loc (tn-offset target))
(target-sc (tn-sc target))
(target-sb (sc-sb target-sc)))
(declare (type index loc))
;; We can honor a preference if:
;; -- TARGET's location is in SC's locations.
;; -- The element sizes of the two SCs are the same.
;; -- TN doesn't conflict with target's location.
(if (and (eq target-sb (sc-sb sc))
(or (eq (sb-kind target-sb) :unbounded)
(member loc (sc-locations sc)))
(= (sc-element-size target-sc) (sc-element-size sc))
(not (conflicts-in-sc tn sc loc))
(zerop (mod loc (sc-alignment sc))))
loc
nil)))
;;; Scan along the target path from TN, looking at readers or writers.
;;; When we find a packed TN, return CHECK-OK-TARGET of that TN. If
;;; there is no target, or if the TN has multiple readers (writers),
;;; then we return NIL. We also always return NIL after 10 iterations
;;; to get around potential circularity problems.
;;;
;;; FIXME: (30 minutes of reverse engineering?) It'd be nice to
;;; rewrite the header comment here to explain the interface and its
;;; motivation, and move remarks about implementation details (like
;;; 10!) inside.
(defun find-ok-target-offset (tn sc)
(declare (type tn tn) (type sc sc))
(flet ((frob-slot (slot-fun)
(declare (type function slot-fun))
(let ((count 10)
(current tn))
(declare (type index count))
(loop
(let ((refs (funcall slot-fun current)))
(unless (and (plusp count)
refs
(not (tn-ref-next refs)))
(return nil))
(let ((target (tn-ref-target refs)))
(unless target (return nil))
(setq current (tn-ref-tn target))
(when (tn-offset current)
(return (check-ok-target current tn sc)))
(decf count)))))))
(declare (inline frob-slot)) ; until DYNAMIC-EXTENT works
(or (frob-slot #'tn-reads)
(frob-slot #'tn-writes))))
;;;; location selection
;;; Select some location for TN in SC, returning the offset if we
;;; succeed, and NIL if we fail.
;;;
;;; For :UNBOUNDED SCs just find the smallest correctly aligned offset
;;; where the TN doesn't conflict with the TNs that have already been
;;; packed. For :FINITE SCs try to pack the TN into the most heavily
;;; used locations first (as estimated in FIND-LOCATION-USAGE).
;;;
;;; Historically SELECT-LOCATION tried did the opposite and tried to
;;; distribute the TNs evenly across the available locations. At least
;;; on register-starved architectures (x86) this seems to be a bad
;;; strategy. -- JES 2004-09-11
(defun select-location (tn sc &key use-reserved-locs optimize)
(declare (type tn tn) (type sc sc) (inline member))
(let* ((sb (sc-sb sc))
(element-size (sc-element-size sc))
(alignment (sc-alignment sc))
(align-mask (1- alignment))
(size (finite-sb-current-size sb)))
(flet ((attempt-location (start-offset)
(dotimes (i element-size
(return-from select-location start-offset))
(declare (type index i))
(let ((offset (+ start-offset i)))
(when (offset-conflicts-in-sb tn sb offset)
(return (logandc2 (the index (+ (the index (1+ offset))
align-mask))
align-mask)))))))
(if (eq (sb-kind sb) :unbounded)
(loop with offset = 0
until (> (+ offset element-size) size) do
(setf offset (attempt-location offset)))
(let ((locations (sc-locations sc)))
(when optimize
(setf locations
(stable-sort (copy-list locations) #'>
:key (lambda (location-offset)
(loop for offset from location-offset
repeat element-size
maximize (svref
(finite-sb-always-live-count sb)
offset))))))
(dolist (offset locations)
(when (or use-reserved-locs
(not (member offset
(sc-reserve-locations sc))))
(attempt-location offset))))))))
;;; If a save TN, return the saved TN, otherwise return TN. This is
;;; useful for getting the conflicts of a TN that might be a save TN.
(defun original-tn (tn)
(declare (type tn tn))
(if (member (tn-kind tn) '(:save :save-once :specified-save))
(tn-save-tn tn)
tn))
;;;; pack interface
;;; Attempt to pack TN in all possible SCs, first in the SC chosen by
;;; representation selection, then in the alternate SCs in the order
;;; they were specified in the SC definition. If the TN-COST is
;;; negative, then we don't attempt to pack in SCs that must be saved.
;;; If Restricted, then we can only pack in TN-SC, not in any
;;; Alternate-SCs.
;;;
;;; If we are attempting to pack in the SC of the save TN for a TN
;;; with a :SPECIFIED-SAVE TN, then we pack in that location, instead
;;; of allocating a new stack location.
(defun pack-tn (tn restricted optimize &key (allow-unbounded-sc t))
(declare (type tn tn))
(let* ((original (original-tn tn))
(fsc (tn-sc tn))
(alternates (unless restricted (sc-alternate-scs fsc)))
(save (tn-save-tn tn))
(specified-save-sc
(when (and save
(eq (tn-kind save) :specified-save))
(tn-sc save))))
(do ((sc fsc (pop alternates)))
((null sc)
(failed-to-pack-error tn restricted))
(unless (or allow-unbounded-sc
(neq (sb-kind (sc-sb sc)) :unbounded))
(return nil))
(when (eq sc specified-save-sc)
(unless (tn-offset save)
(pack-tn save nil optimize))
(setf (tn-offset tn) (tn-offset save))
(setf (tn-sc tn) (tn-sc save))
(return t))
(when (or restricted
(not (and (minusp (tn-cost tn)) (sc-save-p sc))))
(let ((loc (or (find-ok-target-offset original sc)
(select-location original sc)
(and restricted
(select-location original sc :use-reserved-locs t))
(when (eq (sb-kind (sc-sb sc)) :unbounded)
(grow-sc sc)
(or (select-location original sc)
(error "failed to pack after growing SC?"))))))
(when loc
(add-location-conflicts original sc loc optimize)
(setf (tn-sc tn) sc)
(setf (tn-offset tn) loc)
(return t))))))
(values))
;;; Pack a wired TN, checking that the offset is in bounds for the SB,
;;; and that the TN doesn't conflict with some other TN already packed
;;; in that location. If the TN is wired to a location beyond the end
;;; of a :UNBOUNDED SB, then grow the SB enough to hold the TN.
;;;
;;; ### Checking for conflicts is disabled for :SPECIFIED-SAVE TNs.
;;; This is kind of a hack to make specifying wired stack save
;;; locations for local call arguments (such as OLD-FP) work, since
;;; the caller and callee OLD-FP save locations may conflict when the
;;; save locations don't really (due to being in different frames.)
(defun pack-wired-tn (tn optimize)
(declare (type tn tn))
(let* ((sc (tn-sc tn))
(sb (sc-sb sc))
(offset (tn-offset tn))
(end (+ offset (sc-element-size sc)))
(original (original-tn tn)))
(when (> end (finite-sb-current-size sb))
(unless (eq (sb-kind sb) :unbounded)
(error "~S is wired to a location that is out of bounds." tn))
(grow-sc sc end))
;; For non-x86 ports the presence of a save-tn associated with a
;; tn is used to identify the old-fp and return-pc tns. It depends
;; on the old-fp and return-pc being passed in registers.
#!-(or x86 x86-64)
(when (and (not (eq (tn-kind tn) :specified-save))
(conflicts-in-sc original sc offset))
(error "~S is wired to a location that it conflicts with." tn))
;; Use the above check, but only print a verbose warning. This can
;; be helpful for debugging the x86 port.
#+nil
(when (and (not (eq (tn-kind tn) :specified-save))
(conflicts-in-sc original sc offset))
(format t "~&* Pack-wired-tn possible conflict:~% ~
tn: ~S; tn-kind: ~S~% ~
sc: ~S~% ~
sb: ~S; sb-name: ~S; sb-kind: ~S~% ~
offset: ~S; end: ~S~% ~
original ~S~% ~
tn-save-tn: ~S; tn-kind of tn-save-tn: ~S~%"
tn (tn-kind tn) sc
sb (sb-name sb) (sb-kind sb)
offset end
original
(tn-save-tn tn) (tn-kind (tn-save-tn tn))))
;; On the x86 ports the old-fp and return-pc are often passed on
;; the stack so the above hack for the other ports does not always
;; work. Here the old-fp and return-pc tns are identified by being
;; on the stack in their standard save locations.
#!+(or x86 x86-64)
(when (and (not (eq (tn-kind tn) :specified-save))
(not (and (string= (sb-name sb) "STACK")
(or (= offset 0)
(= offset 1))))
(conflicts-in-sc original sc offset))
(error "~S is wired to a location that it conflicts with." tn))
(add-location-conflicts original sc offset optimize)))
(defevent repack-block "Repacked a block due to TN unpacking.")
;;; KLUDGE: Prior to SBCL version 0.8.9.xx, this function was known as
;;; PACK-BEFORE-GC-HOOK, but was non-functional since approximately
;;; version 0.8.3.xx since the removal of GC hooks from the system.
;;; This currently (as of 2004-04-12) runs now after every call to
;;; PACK, rather than -- as was originally intended -- once per GC
;;; cycle; this is probably non-optimal, and might require tuning,
;;; maybe to be called when the data structures exceed a certain size,
;;; or maybe once every N times. The KLUDGE is that this rewrite has
;;; done nothing to improve the reentrance or threadsafety of the
;;; compiler; it still fails to be callable from several threads at
;;; the same time.
;;;
;;; Brief experiments indicate that during a compilation cycle this
;;; causes about 10% more consing, and takes about 1%-2% more time.
;;;
;;; -- CSR, 2004-04-12
(defun clean-up-pack-structures ()
(dolist (sb *backend-sb-list*)
(unless (eq (sb-kind sb) :non-packed)
(let ((size (sb-size sb)))
(fill (finite-sb-always-live sb) nil)
(setf (finite-sb-always-live sb)
(make-array size
:initial-element
#-sb-xc #*
;; The cross-compiler isn't very good at
;; dumping specialized arrays, so we delay
;; construction of this SIMPLE-BIT-VECTOR
;; until runtime.
#+sb-xc (make-array 0 :element-type 'bit)))
(setf (finite-sb-always-live-count sb)
(make-array size
:initial-element
#-sb-xc #*
;; Ibid
#+sb-xc (make-array 0 :element-type 'fixnum)))
(fill (finite-sb-conflicts sb) nil)
(setf (finite-sb-conflicts sb)
(make-array size :initial-element '#()))
(fill (finite-sb-live-tns sb) nil)
(setf (finite-sb-live-tns sb)
(make-array size :initial-element nil))))))
(defun tn-lexical-depth (tn)
(let ((path t)) ; dummy initial value
(labels ((path (lambda)
(nreverse (loop while lambda
collect lambda
do (setf lambda (lambda-parent lambda)))))
(register-scope (lambda)
(let ((new-path (path lambda)))
(setf path (if (eql path t)
new-path
(subseq path
0 (mismatch path new-path))))))
(walk-tn-refs (ref)
(do ((ref ref (tn-ref-next ref)))
((null ref))
(binding* ((node (vop-node (tn-ref-vop ref))
:exit-if-null))
(register-scope (lexenv-lambda
(node-lexenv node)))))))
(walk-tn-refs (tn-reads tn))
(walk-tn-refs (tn-writes tn))
(if (eql path t)
most-positive-fixnum
(length path)))))
(defun pack (component)
(unwind-protect
(let ((optimize nil)
(2comp (component-info component)))
(init-sb-vectors component)
;; Determine whether we want to do more expensive packing by
;; checking whether any blocks in the component have (> SPEED
;; COMPILE-SPEED).
;;
;; FIXME: This means that a declaration can have a minor
;; effect even outside its scope, and as the packing is done
;; component-globally it'd be tricky to use strict scoping. I
;; think this is still acceptable since it's just a tradeoff
;; between compilation speed and allocation quality and
;; doesn't affect the semantics of the generated code in any
;; way. -- JES 2004-10-06
(do-ir2-blocks (block component)
(when (policy (block-last (ir2-block-block block))
(> speed compilation-speed))
(setf optimize t)
(return)))
;; Call the target functions.
(do-ir2-blocks (block component)
(do ((vop (ir2-block-start-vop block) (vop-next vop)))
((null vop))
(let ((target-fun (vop-info-target-fun (vop-info vop))))
(when target-fun
(funcall target-fun vop)))))
;; Pack wired TNs first.
(do ((tn (ir2-component-wired-tns 2comp) (tn-next tn)))
((null tn))
(pack-wired-tn tn optimize))
;; Pack restricted component TNs.
(do ((tn (ir2-component-restricted-tns 2comp) (tn-next tn)))
((null tn))
(when (eq (tn-kind tn) :component)
(pack-tn tn t optimize)))
;; Pack other restricted TNs.
(do ((tn (ir2-component-restricted-tns 2comp) (tn-next tn)))
((null tn))
(unless (tn-offset tn)
(pack-tn tn t optimize)))
;; Assign costs to normal TNs so we know which ones should
;; always be packed on the stack.
(when *pack-assign-costs*
(assign-tn-costs component)
(assign-tn-depths component))
;; Allocate normal TNs, starting with the TNs that are used
;; in deep loops. Only allocate in finite SCs (i.e. not on
;; the stack).
(collect ((tns))
(do-ir2-blocks (block component)
(let ((ltns (ir2-block-local-tns block)))
(do ((i (1- (ir2-block-local-tn-count block)) (1- i)))
((minusp i))
(declare (fixnum i))
(let ((tn (svref ltns i)))
(unless (or (null tn)
(eq tn :more)
(tn-offset tn))
;; If loop analysis has been disabled we might as
;; well revert to the old behaviour of just
;; packing TNs linearly as they appear.
(unless *loop-analyze*
(pack-tn tn nil optimize :allow-unbounded-sc nil))
(tns tn))))))
(dolist (tn (stable-sort (tns)
(lambda (a b)
(cond
((> (tn-loop-depth a)
(tn-loop-depth b))
t)
((= (tn-loop-depth a)
(tn-loop-depth b))
(> (tn-cost a) (tn-cost b)))
(t nil)))))
(unless (tn-offset tn)
(pack-tn tn nil optimize :allow-unbounded-sc nil))))
;; Pack any leftover normal TNs that could not be allocated
;; to finite SCs, or TNs that do not appear in any local TN
;; map (e.g. :MORE TNs). Since we'll likely be allocating
;; on the stack, first allocate TNs that are associated with
;; code at shallow lexical depths: this will allocate long
;; live ranges (i.e. TNs with more conflicts) first, and
;; hopefully minimise stack fragmentation.
;;
;; Collect in reverse order to give priority to older TNs.
(let ((contiguous-tns '())
(tns '()))
(do ((tn (ir2-component-normal-tns 2comp) (tn-next tn)))
((null tn))
(unless (tn-offset tn)
(let ((key (cons tn (tn-lexical-depth tn))))
(if (memq (tn-kind tn) '(:environment :debug-environment
:component))
(push key contiguous-tns)
(push key tns)))))
(flet ((pack-tns (tns)
(dolist (tn (stable-sort tns #'< :key #'cdr))
(let ((tn (car tn)))
(unless (tn-offset tn)
(pack-tn tn nil optimize))))))
;; first pack TNs that are known to have simple
;; live ranges (contiguous lexical scopes)
(pack-tns contiguous-tns)
(pack-tns tns)))
;; Do load TN packing and emit saves.
(let ((*repack-blocks* nil))
(cond ((and optimize *pack-optimize-saves*)
(optimized-emit-saves component)
(do-ir2-blocks (block component)
(pack-load-tns block)))
(t
(do-ir2-blocks (block component)
(emit-saves block)
(pack-load-tns block))))
(loop
(unless *repack-blocks* (return))
(let ((orpb *repack-blocks*))
(setq *repack-blocks* nil)
(dolist (block orpb)
(event repack-block)
(pack-load-tns block)))))
(values))
(clean-up-pack-structures)))