X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Futils%2FDigraph.lhs;h=0eff6da6980e6d87e24d3fb45c506325e61c1ed0;hb=59c796f8e77325d35f29ddd3e724bfa780466d40;hp=d8f6220658945fa5a24cb2acf846f7096a802563;hpb=dbc254c3dcd64761015a3d1c191ac742caafbf4c;p=ghc-hetmet.git

diff --git a/ghc/compiler/utils/Digraph.lhs b/ghc/compiler/utils/Digraph.lhs
index d8f6220..0eff6da 100644
--- a/ghc/compiler/utils/Digraph.lhs
+++ b/ghc/compiler/utils/Digraph.lhs
@@ -32,9 +32,7 @@ module Digraph(
 ------------------------------------------------------------------------------
 
 
-#define ARR_ELT		(COMMA)
-
-import Util	( sortLt )
+import Util	( sortLe )
 
 -- Extensions
 import MONAD_ST
@@ -80,7 +78,8 @@ stronglyConnComp
 	=> [(node, key, [key])]		-- The graph; its ok for the
 					-- out-list to contain keys which arent
 					-- a vertex key, they are ignored
-	-> [SCC node]
+	-> [SCC node]	-- Returned in topologically sorted order
+			-- Later components depend on earlier ones, but not vice versa
 
 stronglyConnComp edges
   = map get_node (stronglyConnCompR edges)
@@ -101,8 +100,8 @@ stronglyConnCompR [] = []  -- added to avoid creating empty array in graphFromEd
 stronglyConnCompR edges
   = map decode forest
   where
-    (graph, vertex_fn) = graphFromEdges edges
-    forest	       = scc graph
+    (graph, vertex_fn) = _scc_ "graphFromEdges" graphFromEdges edges
+    forest	       = _scc_ "Digraph.scc" scc graph
     decode (Node v []) | mentions_itself v = CyclicSCC [vertex_fn v]
 		       | otherwise	   = AcyclicSCC (vertex_fn v)
     decode other = CyclicSCC (dec other [])
@@ -164,14 +163,16 @@ graphFromEdges edges
   where
     max_v      	    = length edges - 1
     bounds          = (0,max_v) :: (Vertex, Vertex)
-    sorted_edges    = sortLt lt edges
+    sorted_edges    = let
+			 (_,k1,_) `le` (_,k2,_) = case k1 `compare` k2 of { GT -> False; other -> True }
+		      in
+			sortLe le edges
     edges1	    = zipWith (,) [0..] sorted_edges
 
     graph	    = array bounds [(,) v (mapMaybe key_vertex ks) | (,) v (_,    _, ks) <- edges1]
     key_map	    = array bounds [(,) v k			   | (,) v (_,    k, _ ) <- edges1]
     vertex_map	    = array bounds edges1
 
-    (_,k1,_) `lt` (_,k2,_) = case k1 `compare` k2 of { LT -> True; other -> False }
 
     -- key_vertex :: key -> Maybe Vertex
     -- 	returns Nothing for non-interesting vertices
@@ -307,9 +308,6 @@ preorder (Node a ts) = a : preorderF ts
 preorderF           :: Forest a -> [a]
 preorderF ts         = concat (map preorder ts)
 
-preOrd :: Graph -> [Vertex]
-preOrd  = preorderF . dff
-
 tabulate        :: Bounds -> [Vertex] -> Table Int
 tabulate bnds vs = array bnds (zipWith (,) vs [1..])
 
@@ -363,12 +361,6 @@ scc g = dfs g (reverse (postOrd (transposeG g)))
 ------------------------------------------------------------
 
 \begin{code}
-tree              :: Bounds -> Forest Vertex -> Graph
-tree bnds ts       = buildG bnds (concat (map flat ts))
-		   where
-		     flat (Node v rs) = [ (v, w) | Node w us <- ts ] ++
-                    		        concat (map flat ts)
-
 back              :: Graph -> Table Int -> Graph
 back g post        = mapT select g
  where select v ws = [ w | w <- ws, post!v < post!w ]