[MLton-commit] r6844

[Matthew Fluet]

Avoid construction of duplicate edges in the graph to find (mutually)
recursive datatypes.  Thanks to Nicolas Bertolotti for the patch.

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U   mlton/trunk/mlton/ssa/ref-flatten.fun

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Modified: mlton/trunk/mlton/ssa/ref-flatten.fun
===================================================================
--- mlton/trunk/mlton/ssa/ref-flatten.fun	2008-09-08 13:55:24 UTC (rev 6843)
+++ mlton/trunk/mlton/ssa/ref-flatten.fun	2008-09-09 01:24:29 UTC (rev 6844)
@@ -774,8 +774,16 @@
                       case Type.dest t of
                          CPointer => ()
                        | Datatype tc => 
-                            (ignore o Graph.addEdge)
-                            (graph, {from = n, to = tyconNode tc})
+                            let
+                               val m = tyconNode tc
+                               val e = {from = n, to = m}
+                            in
+                               (* Avoid redundant edges. *)
+                               if Node.hasEdge e then ()
+                               else 
+                                  (ignore o Graph.addEdge)
+                                  (graph, {from = n, to = tyconNode tc})
+                            end
                        | IntInf => ()
                        | Object {args, ...} =>
                             Prod.foreach (args, loop)