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(*
* This module inserts preheaders and other stuff.
* This is probably no longer used.
*
* -- Allen
*)
functor ControlFlowGraphRestructure
(structure Loop : LOOP_STRUCTURE) : CONTROL_FLOW_GRAPH_RESTRUCTURE =
struct
structure Loop = Loop
structure G = Graph
fun restructure (G.GRAPH cfg,G.GRAPH loop)
{ add_preheader,
add_landing_pad
} =
let val add_node = #add_node cfg
fun preheader f =
fn {header,backedges} =>
let val in_edges = #in_edges cfg header
fun g([],entries) = entries
| g((e as (i,j,_))::es,entries) =
if List.exists (fn (i',j',_) => i=i' andalso j=j')
backedges then g(es,entries)
else g(es,e::entries)
in f{header =(header,#node_info cfg header),
entries=g(in_edges,[])
}
end
fun landing_pads f = fn {exits} => app (fn e => f {exit=e}) exits
fun nop _ = ()
val insert_preheader = case add_preheader of
SOME f => preheader f
| NONE => nop
val insert_landing_pads = case add_landing_pad of
SOME f => landing_pads f
| NONE => nop
fun process_loop(i,Loop.LOOP{header,backedges=[],exits,...}) = ()
| process_loop(i,Loop.LOOP{header,backedges,exits,...}) =
(insert_preheader{header=header,backedges=backedges};
insert_landing_pads{exits=exits}
)
in
#forall_nodes loop process_loop
end
end
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