X-Git-Url: https://git.hcoop.net/bpt/guile.git/blobdiff_plain/54f17b7b597a3695a25babac92255ed52fbeec4a..a9ec16f9c5574d80f66c173b495285579f5894b4:/module/language/cps/slot-allocation.scm diff --git a/module/language/cps/slot-allocation.scm b/module/language/cps/slot-allocation.scm index 24a6d5fd7..f9a86951d 100644 --- a/module/language/cps/slot-allocation.scm +++ b/module/language/cps/slot-allocation.scm @@ -1,6 +1,6 @@ ;;; Continuation-passing style (CPS) intermediate language (IL) -;; Copyright (C) 2013, 2014 Free Software Foundation, Inc. +;; Copyright (C) 2013, 2014, 2015 Free Software Foundation, Inc. ;;;; This library is free software; you can redistribute it and/or ;;;; modify it under the terms of the GNU Lesser General Public @@ -29,6 +29,7 @@ #:use-module (srfi srfi-26) #:use-module (language cps) #:use-module (language cps dfg) + #:use-module (language cps intset) #:export (allocate-slots lookup-slot lookup-maybe-slot @@ -223,20 +224,18 @@ are comparable with eqv?. A tmp slot may be used." tmp) (loop to-move b (cons s+d moved) last-source)))))))))) -(define (dead-after-def? def-k v-idx dfa) - (let ((l (dfa-k-idx dfa def-k))) - (not (bitvector-ref (dfa-k-in dfa l) v-idx)))) +(define (dead-after-def? k-idx v-idx dfa) + (not (intset-ref (dfa-k-in dfa k-idx) v-idx))) -(define (dead-after-use? use-k v-idx dfa) - (let ((l (dfa-k-idx dfa use-k))) - (not (bitvector-ref (dfa-k-out dfa l) v-idx)))) +(define (dead-after-use? k-idx v-idx dfa) + (not (intset-ref (dfa-k-out dfa k-idx) v-idx))) (define (allocate-slots fun dfg) (let* ((dfa (compute-live-variables fun dfg)) - (cfa (analyze-control-flow fun dfg)) - (usev (make-vector (cfa-k-count cfa) '())) - (defv (make-vector (cfa-k-count cfa) '())) - (contv (make-vector (cfa-k-count cfa) #f)) + (min-label (dfg-min-label dfg)) + (label-count (dfg-label-count dfg)) + (usev (make-vector label-count '())) + (defv (make-vector label-count '())) (slots (make-vector (dfa-var-count dfa) #f)) (constant-values (make-vector (dfa-var-count dfa) #f)) (has-constv (make-bitvector (dfa-var-count dfa) #f)) @@ -247,6 +246,9 @@ are comparable with eqv?. A tmp slot may be used." (nlocals 0) ; Mutable. It pains me. (nlocals-table (make-hash-table))) + (define (label->idx label) (- label min-label)) + (define (idx->label idx) (+ idx min-label)) + (define (bump-nlocals! nlocals*) (when (< nlocals nlocals*) (set! nlocals nlocals*))) @@ -261,20 +263,28 @@ are comparable with eqv?. A tmp slot may be used." (logand live-slots (lognot (ash 1 slot)))) (define (compute-slot live-slots hint) - (if (and hint (not (logbit? hint live-slots))) + ;; Slots 253-255 are reserved for shuffling; see comments in + ;; assembler.scm. + (if (and hint (not (logbit? hint live-slots)) + (or (< hint 253) (> hint 255))) hint - (find-first-zero live-slots))) + (let ((slot (find-first-zero live-slots))) + (if (or (< slot 253) (> slot 255)) + slot + (+ 256 (find-first-zero (ash live-slots -256))))))) (define (compute-call-proc-slot live-slots) (+ 2 (find-first-trailing-zero live-slots))) (define (compute-prompt-handler-proc-slot live-slots) - (1- (find-first-trailing-zero live-slots))) + (if (zero? live-slots) + 0 + (1- (find-first-trailing-zero live-slots)))) (define (recompute-live-slots k nargs) - (let ((in (dfa-k-in dfa (dfa-k-idx dfa k)))) - (let lp ((v 0) (live-slots (1- (ash 1 (1+ nargs))))) - (let ((v (bit-position #t in v))) + (let ((in (dfa-k-in dfa (label->idx k)))) + (let lp ((v 0) (live-slots 0)) + (let ((v (intset-next in v))) (if v (let ((slot (vector-ref slots v))) (lp (1+ v) @@ -304,6 +314,12 @@ are comparable with eqv?. A tmp slot may be used." ;; or to function return values -- it could be that they are out of ;; the computed live set. In that case they need to be adjoined to ;; the live set, used when choosing a temporary slot. + ;; + ;; Note that although we reserve slots 253-255 for shuffling + ;; operands that address less than the full 24-bit range of locals, + ;; that reservation doesn't apply here, because this temporary + ;; itself is used while doing parallel assignment via "mov", and + ;; "mov" does not need shuffling. (define (compute-tmp-slot live stack-slots) (find-first-zero (fold add-live-slot live stack-slots))) @@ -328,22 +344,13 @@ are comparable with eqv?. A tmp slot may be used." (bitvector-set! needs-slotv n #f))) (lp (1+ n)))))))) - ;; Transform the DFG's continuation table to a vector, for easy - ;; access. - (define (compute-conts!) - (let ((cont-table (dfg-cont-table dfg))) - (let lp ((n 0)) - (when (< n (vector-length contv)) - (vector-set! contv n (lookup-cont (cfa-k-sym cfa n) cont-table)) - (lp (1+ n)))))) - ;; Record uses and defs, as lists of variable indexes, indexed by - ;; CFA continuation index. + ;; label index. (define (compute-uses-and-defs!) (let lp ((n 0)) (when (< n (vector-length usev)) - (match (vector-ref contv n) - (($ $kentry self) + (match (lookup-cont (idx->label n) dfg) + (($ $kfun src meta self) (vector-set! defv n (list (dfa-var-idx dfa self)))) (($ $kargs names syms body) (vector-set! defv n (map (cut dfa-var-idx dfa <>) syms)) @@ -356,6 +363,10 @@ are comparable with eqv?. A tmp slot may be used." (cons proc args)) (($ $primcall name args) args) + (($ $branch kt ($ $primcall name args)) + args) + (($ $branch kt ($ $values args)) + args) (($ $values args) args) (($ $prompt escape? tag handler) @@ -367,30 +378,30 @@ are comparable with eqv?. A tmp slot may be used." ;; Results of function calls that are not used don't need to be ;; allocated to slots. (define (compute-unused-results!) - (define (kreceive-get-kargs n) - (match (vector-ref contv n) - (($ $kreceive arity kargs) (cfa-k-idx cfa kargs)) + (define (kreceive-get-kargs kreceive) + (match (lookup-cont kreceive dfg) + (($ $kreceive arity kargs) kargs) (_ #f))) - (let ((candidates (make-bitvector (vector-length contv) #f))) + (let ((candidates (make-bitvector label-count #f))) ;; Find all $kargs that are the successors of $kreceive nodes. (let lp ((n 0)) - (when (< n (vector-length contv)) - (and=> (kreceive-get-kargs n) + (when (< n label-count) + (and=> (kreceive-get-kargs (idx->label n)) (lambda (kargs) - (bitvector-set! candidates kargs #t))) + (bitvector-set! candidates (label->idx kargs) #t))) (lp (1+ n)))) ;; For $kargs that only have $kreceive predecessors, remove unused ;; variables from the needs-slotv set. (let lp ((n 0)) (let ((n (bit-position #t candidates n))) (when n - (match (cfa-predecessors cfa n) + (match (lookup-predecessors (idx->label n) dfg) ;; At least one kreceive is in the predecessor set, so we ;; only need to do the check for nodes with >1 ;; predecessor. ((or (_) ((? kreceive-get-kargs) ...)) (for-each (lambda (var) - (when (dead-after-def? (cfa-k-sym cfa n) var dfa) + (when (dead-after-def? n var dfa) (bitvector-set! needs-slotv var #f))) (vector-ref defv n))) (_ #f)) @@ -405,33 +416,26 @@ are comparable with eqv?. A tmp slot may be used." ;; frames as soon as it's known that a call will happen. It would ;; be nice to recast this as a proper data-flow problem. (define (compute-needs-hint!) - ;; We traverse the graph using reverse-post-order on a forward - ;; control-flow graph, but we did the live variable analysis in - ;; the opposite direction -- so the continuation numbers don't - ;; correspond. This helper adapts them. - (define (cfa-k-idx->dfa-k-idx n) - (dfa-k-idx dfa (cfa-k-sym cfa n))) - (define (live-before n) - (dfa-k-in dfa (cfa-k-idx->dfa-k-idx n))) + (dfa-k-in dfa n)) (define (live-after n) - (dfa-k-out dfa (cfa-k-idx->dfa-k-idx n))) + (dfa-k-out dfa n)) + (define needs-slot + (bitvector->intset needs-slotv)) ;; Walk backwards. At a call, compute the set of variables that ;; have allocated slots and are live before but not after. This ;; set contains candidates for needs-hintv. (define (scan-for-call n) (when (<= 0 n) - (match (vector-ref contv n) + (match (lookup-cont (idx->label n) dfg) (($ $kargs names syms body) (match (find-expression body) ((or ($ $call) ($ $callk)) - (let ((args (make-bitvector (bitvector-length needs-slotv) #f))) - (bit-set*! args (live-before n) #t) - (bit-set*! args (live-after n) #f) - (bit-set*! args no-slot-needed #f) - (if (bit-position #t args 0) - (scan-for-hints (1- n) args) + (let* ((args (intset-subtract (live-before n) (live-after n))) + (args-needing-slots (intset-intersect args needs-slot))) + (if (intset-next args-needing-slots #f) + (scan-for-hints (1- n) args-needing-slots) (scan-for-call (1- n))))) (_ (scan-for-call (1- n))))) (_ (scan-for-call (1- n)))))) @@ -440,29 +444,26 @@ are comparable with eqv?. A tmp slot may be used." ;; ends, we reach a call, or when an expression kills a value. (define (scan-for-hints n args) (when (< 0 n) - (match (vector-ref contv n) + (match (lookup-cont (idx->label n) dfg) (($ $kargs names syms body) - (match (cfa-predecessors cfa (1+ n)) - (((? (cut eqv? <> n))) + (match (lookup-predecessors (idx->label (1+ n)) dfg) + (((? (cut eqv? <> (idx->label n)))) ;; If we are indeed in the same basic block, then if we ;; are finished with the scan, we kill uses of the ;; terminator, but leave its definitions. (match (find-expression body) - ((or ($ $void) ($ $const) ($ $prim) ($ $fun) + ((or ($ $const) ($ $prim) ($ $closure) ($ $primcall) ($ $prompt) ;; If $values has more than one argument, it may ;; use a temporary, which would invalidate our ;; assumptions that slots not allocated are not ;; used. ($ $values (or () (_)))) - (let ((dead (make-bitvector (bitvector-length args) #f))) - (bit-set*! dead (live-before n) #t) - (bit-set*! dead (live-after n) #f) - (bit-set*! dead no-slot-needed #f) - (if (bit-position #t dead 0) + (let ((killed (intset-subtract (live-before n) (live-after n)))) + (if (intset-next (intset-intersect killed needs-slot) #f) (finish-hints n (live-before n) args) (scan-for-hints (1- n) args)))) - ((or ($ $call) ($ $callk) ($ $values)) + ((or ($ $call) ($ $callk) ($ $values) ($ $branch)) (finish-hints n (live-before n) args)))) ;; Otherwise we kill uses of the block entry. (_ (finish-hints n (live-before (1+ n)) args)))) @@ -471,21 +472,18 @@ are comparable with eqv?. A tmp slot may be used." ;; Add definitions ARGS minus KILL to NEED-HINTS, and go back to ;; looking for calls. (define (finish-hints n kill args) - (bit-invert! args) - (bit-set*! args kill #t) - (bit-invert! args) - (bit-set*! needs-hintv args #t) + (let ((new-hints (intset-subtract args kill))) + (let lp ((n 0)) + (let ((n (intset-next new-hints n))) + (when n + (bitvector-set! needs-hintv n #t) + (lp (1+ n)))))) (scan-for-call n)) - (define no-slot-needed - (make-bitvector (bitvector-length needs-slotv) #f)) - - (bit-set*! no-slot-needed needs-slotv #t) - (bit-invert! no-slot-needed) - (scan-for-call (1- (vector-length contv)))) + (scan-for-call (1- label-count))) (define (allocate-call label k uses pre-live post-live) - (match (vector-ref contv (cfa-k-idx cfa k)) + (match (lookup-cont k dfg) (($ $ktail) (let* ((tail-nlocals (length uses)) (tail-slots (iota tail-nlocals)) @@ -504,7 +502,7 @@ are comparable with eqv?. A tmp slot may be used." call-slots (compute-tmp-slot pre-live call-slots))) - (result-vars (vector-ref defv (cfa-k-idx cfa kargs))) + (result-vars (vector-ref defv (label->idx kargs))) (value-slots (map (cut + proc-slot 1 <>) (iota (length result-vars)))) ;; Shuffle the first result down to the lowest slot, and @@ -548,7 +546,7 @@ are comparable with eqv?. A tmp slot may be used." (make-call-allocation proc-slot arg-moves #f)))))) (define (allocate-values label k uses pre-live post-live) - (match (vector-ref contv (cfa-k-idx cfa k)) + (match (lookup-cont k dfg) (($ $ktail) (let* ((src-slots (map (cut vector-ref slots <>) uses)) (tail-nlocals (1+ (length uses))) @@ -566,27 +564,26 @@ are comparable with eqv?. A tmp slot may be used." ;; slot, we can't really compute the parallel moves in that ;; case, so just bail and rely on the bytecode emitter to ;; handle the one-value case specially. - (match (cons uses (vector-ref defv (cfa-k-idx cfa k))) + (match (cons uses (vector-ref defv (label->idx k))) (((src) . (dst)) (allocate! dst (vector-ref slots src) post-live)))) (($ $kargs) (let* ((src-slots (map (cut vector-ref slots <>) uses)) - (dst-vars (vector-ref defv (cfa-k-idx cfa k))) + (dst-vars (vector-ref defv (label->idx k))) (result-live (fold allocate! post-live dst-vars src-slots)) (dst-slots (map (cut vector-ref slots <>) dst-vars)) (moves (parallel-move src-slots dst-slots (compute-tmp-slot (logior pre-live result-live) '())))) (hashq-set! call-allocations label - (make-call-allocation #f moves #f)))) - (($ $kif) #f))) + (make-call-allocation #f moves #f)))))) (define (allocate-prompt label k handler nargs) - (match (vector-ref contv (cfa-k-idx cfa handler)) + (match (lookup-cont handler dfg) (($ $kreceive arity kargs) (let* ((handler-live (recompute-live-slots handler nargs)) (proc-slot (compute-prompt-handler-proc-slot handler-live)) - (result-vars (vector-ref defv (cfa-k-idx cfa kargs))) + (result-vars (vector-ref defv (label->idx kargs))) (value-slots (map (cut + proc-slot 1 <>) (iota (length result-vars)))) (result-live (fold allocate! @@ -611,24 +608,22 @@ are comparable with eqv?. A tmp slot may be used." ;; definitions dominate uses and a block's dominator will appear ;; before it, in reverse post-order. (define (visit-clause n nargs live) - (let lp ((n n) (live live)) - (define (kill-dead live vars-by-cfa-idx pred) + (let lp ((n n) (live (recompute-live-slots (idx->label n) nargs))) + (define (kill-dead live vars-by-label-idx pred) (fold (lambda (v live) (let ((slot (vector-ref slots v))) - (if (and slot - (> slot nargs) - (pred (cfa-k-sym cfa n) v dfa)) + (if (and slot (pred n v dfa)) (kill-dead-slot slot live) live))) live - (vector-ref vars-by-cfa-idx n))) + (vector-ref vars-by-label-idx n))) (define (kill-dead-defs live) (kill-dead live defv dead-after-def?)) (define (kill-dead-uses live) (kill-dead live usev dead-after-use?)) - (if (= n (cfa-k-count cfa)) + (if (= n label-count) n - (let* ((label (cfa-k-sym cfa n)) + (let* ((label (idx->label n)) (live (if (control-point? label dfg) (recompute-live-slots label nargs) live)) @@ -637,21 +632,25 @@ are comparable with eqv?. A tmp slot may be used." ;; LIVE are the live slots coming into the term. ;; POST-LIVE is the subset that is still live after the ;; term uses its inputs. - (match (vector-ref contv n) + (match (lookup-cont (idx->label n) dfg) (($ $kclause) n) (($ $kargs names syms body) + (define (compute-k-live k) + (match (lookup-predecessors k dfg) + ((_) post-live) + (_ (recompute-live-slots k nargs)))) (let ((uses (vector-ref usev n))) (match (find-call body) (($ $continue k src (or ($ $call) ($ $callk))) - (allocate-call label k uses live post-live)) + (allocate-call label k uses live (compute-k-live k))) (($ $continue k src ($ $primcall)) #t) (($ $continue k src ($ $values)) - (allocate-values label k uses live post-live)) + (allocate-values label k uses live (compute-k-live k))) (($ $continue k src ($ $prompt escape? tag handler)) (allocate-prompt label k handler nargs)) (_ #f))) (lp (1+ n) post-live)) - ((or ($ $kreceive) ($ $kif) ($ $ktail)) + ((or ($ $kreceive) ($ $ktail)) (lp (1+ n) post-live))))))) (define (visit-entry) @@ -659,24 +658,27 @@ are comparable with eqv?. A tmp slot may be used." (unless (eqv? live (add-live-slot 0 (empty-live-slots))) (error "Unexpected clause live set")) (set! nlocals 1) - (match (vector-ref contv n) - (($ $kclause arity ($ $cont kbody ($ $kargs names))) - (unless (eq? (cfa-k-sym cfa (1+ n)) kbody) - (error "Unexpected CFA order")) + (match (lookup-cont (idx->label n) dfg) + (($ $kclause arity ($ $cont kbody ($ $kargs names)) alternate) + (unless (eq? (idx->label (1+ n)) kbody) + (error "Unexpected label order")) (let* ((nargs (length names)) (next (visit-clause (1+ n) nargs (fold allocate! live (vector-ref defv (1+ n)) (cdr (iota (1+ nargs))))))) - (hashq-set! nlocals-table (cfa-k-sym cfa n) nlocals) - (when (< next (cfa-k-count cfa)) + (hashq-set! nlocals-table (idx->label n) nlocals) + (when (< next label-count) + (match alternate + (($ $cont kalt) + (unless (eq? kalt (idx->label next)) + (error "Unexpected clause order")))) (visit-clauses next live)))))) - (match (vector-ref contv 0) - (($ $kentry self) + (match (lookup-cont (idx->label 0) dfg) + (($ $kfun src meta self) (visit-clauses 1 (allocate-defs! 0 (empty-live-slots)))))) - (compute-conts!) (compute-constants!) (compute-uses-and-defs!) (compute-unused-results!)