factor/library/compiler/linearizer.factor

! :folding=indent:collapseFolds=1:

! $Id$
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! Copyright (C) 2004 Slava Pestov.
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IN: compiler
USE: lists
USE: words
USE: stack
USE: namespaces
USE: inference
USE: combinators

! Linear IR nodes. This is in addition to the symbols already
! defined in dataflow vocab.

SYMBOL: #jump-label-t ( branch if top of stack is true )
SYMBOL: #jump-label ( unconditional branch )
SYMBOL: #jump ( tail-call )

: linear, ( node -- )
    #! Add a node to the linear IR.
    [ node-op get node-param get ] bind cons , ;

: >linear ( node -- )
    #! Dataflow OPs have a linearizer word property. This
    #! quotation is executed to convert the node into linear
    #! form.
    "linearizer" [ linear, ] apply-dataflow ;

: (linearize) ( dataflow -- )
    [ >linear ] each ;

: linearize ( dataflow -- linear )
    #! Transform dataflow IR into linear IR. This strips out
    #! stack flow information, flattens conditionals into
    #! jumps and labels, and turns dataflow IR nodes into
    #! lists where the first element is an operation, and the
    #! rest is arguments.
    [ (linearize) ] make-list ;

: <label> ( -- label )
    gensym ;

: label, ( label -- )
    #label swons , ;

: linearize-ifte ( param -- )
    #! The parameter is a list of two lists, each one a dataflow
    #! IR.
    uncons car
    <label> [
        #jump-label-t swons ,
        (linearize) ( false branch )
        <label> dup #jump-label swons ,
    ] keep label, ( branch target of BRANCH-T )
    swap (linearize) ( true branch )
    label, ( branch target of false branch end ) ;

#label [
    dup [ node-label get ] bind label,
    [ node-param get ] bind (linearize)
] "linearizer" set-word-property

#ifte [
    [ node-param get ] bind linearize-ifte
] "linearizer" set-word-property