137 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			Factor
		
	
	
			
		
		
	
	
			137 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			Factor
		
	
	
| ! Copyright (C) 2008, 2009 Slava Pestov.
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| ! See http://factorcode.org/license.txt for BSD license.
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| USING: accessors combinators.short-circuit compiler.tree fry
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| kernel namespaces sequences sets ;
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| IN: compiler.tree.recursive
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| 
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| TUPLE: call-site tail? node label ;
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| 
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| : recursive-phi-in ( #enter-recursive -- seq )
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|     [ label>> calls>> [ node>> in-d>> ] map ] [ in-d>> ] bi suffix ;
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| 
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| <PRIVATE
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| 
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| TUPLE: call-graph-node tail? label children calls ;
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| 
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| : (tail-calls) ( tail? seq -- seq' )
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|     reverse [ swap [ and ] keep ] map nip reverse ;
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| 
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| : tail-calls ( tail? node -- seq )
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|     [
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|         {
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|             [ #phi? ]
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|             [ #return? ]
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|             [ #return-recursive? ]
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|         } 1||
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|     ] map (tail-calls) ;
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| 
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| SYMBOLS: children calls ;
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| 
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| GENERIC: node-call-graph ( tail? node -- )
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| 
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| : (build-call-graph) ( tail? nodes -- )
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|     [ tail-calls ] keep
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|     [ node-call-graph ] 2each ;
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| 
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| : build-call-graph ( nodes -- labels calls )
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|     [
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|         V{ } clone children namespaces:set
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|         V{ } clone calls namespaces:set
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|         [ t ] dip (build-call-graph)
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|         children get
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|         calls get
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|     ] with-scope ;
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| 
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| M: #return-recursive node-call-graph
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|     nip dup label>> return<< ;
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| 
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| M: #call-recursive node-call-graph
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|     [ dup label>> call-site boa ] keep
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|     [ drop calls get push ]
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|     [ label>> calls>> push ] 2bi ;
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| 
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| M: #recursive node-call-graph
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|     [ label>> V{ } clone >>calls drop ]
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|     [
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|         [ label>> ] [ child>> build-call-graph ] bi
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|         call-graph-node boa children get push
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|     ] bi ;
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| 
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| M: #branch node-call-graph
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|     children>> [ (build-call-graph) ] with each ;
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| 
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| M: #alien-callback node-call-graph
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|     child>> (build-call-graph) ;
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| 
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| M: node node-call-graph 2drop ;
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| 
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| SYMBOLS: not-loops recursive-nesting ;
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| 
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| : not-a-loop ( label -- ) not-loops get adjoin ;
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| 
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| : not-a-loop? ( label -- ? ) not-loops get in? ;
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| 
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| : non-tail-calls ( call-graph-node -- seq )
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|     calls>> [ tail?>> ] reject ;
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| 
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| : visit-back-edges ( call-graph -- )
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|     [
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|         [ non-tail-calls [ label>> not-a-loop ] each ]
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|         [ children>> visit-back-edges ]
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|         bi
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|     ] each ;
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| 
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| SYMBOL: changed?
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| 
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| : check-cross-frame-call ( call-site -- )
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|     label>> dup not-a-loop? [ drop ] [
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|         recursive-nesting get <reversed> [
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|             2dup label>> eq? [ 2drop f ] [
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|                 [ label>> not-a-loop? ] [ tail?>> not ] bi or
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|                 [ not-a-loop changed? on ] [ drop ] if t
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|             ] if
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|         ] with all? drop
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|     ] if ;
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| 
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| : detect-cross-frame-calls ( call-graph -- )
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|     ! Suppose we have a nesting of recursives A --> B --> C
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|     ! B tail-calls A, and C non-tail-calls B. Then A cannot be
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|     ! a loop, it needs its own procedure, since the call from
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|     ! C to A crosses a call-frame boundary.
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|     [
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|         [ recursive-nesting get push ]
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|         [ calls>> [ check-cross-frame-call ] each ]
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|         [ children>> detect-cross-frame-calls ] tri
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|         recursive-nesting get pop*
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|     ] each ;
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| 
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| : while-changing ( ... quot: ( ... -- ... ) -- ... )
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|     changed? off
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|     [ call ]
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|     [ changed? get [ while-changing ] [ drop ] if ] bi ; inline recursive
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| 
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| : detect-loops ( call-graph -- )
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|     HS{ } clone not-loops namespaces:set
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|     V{ } clone recursive-nesting namespaces:set
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|     [ visit-back-edges ]
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|     [ '[ _ detect-cross-frame-calls ] while-changing ]
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|     bi ;
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| 
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| : mark-loops ( call-graph -- )
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|     [
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|         [ label>> dup not-a-loop? [ t >>loop? ] unless drop ]
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|         [ children>> mark-loops ]
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|         bi
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|     ] each ;
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| 
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| PRIVATE>
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| 
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| SYMBOL: call-graph
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| 
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| : analyze-recursive ( nodes -- nodes )
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|     dup build-call-graph drop
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|     [ call-graph namespaces:set ]
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|     [ detect-loops ]
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|     [ mark-loops ]
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|     tri ;
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