create-loop-preheader ( loop entering -- preheader )

Vocabulary

compiler.cfg.loop-optimization

Inputs

loop	an object
entering	an object

Outputs

preheader

an object

Definition

USING: accessors compiler.cfg compiler.cfg.instructions
compiler.cfg.utilities kernel sequences ;

IN: compiler.cfg.loop-optimization

:: create-loop-preheader ( loop entering -- preheader )
    <basic-block> :> preheader loop header>> :> header header
    [ entering preheader merge-entry-phi ] each-phi
    ##branch new-insn preheader instructions>> push
    V{ header } preheader successors<< entering V{ } like
    preheader predecessors<< entering
    [| pred | pred header preheader update-successors ] each
    header predecessors>> [ entering member-eq? not ] filter
    preheader suffix! header predecessors<<
    "preheaders" count-loop-event preheader ;