X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Futils%2FDigraph.lhs;h=0eff6da6980e6d87e24d3fb45c506325e61c1ed0;hb=59c796f8e77325d35f29ddd3e724bfa780466d40;hp=1544c7b93386c90f15fd4ae646a73bbe99ea8215;hpb=00fe57d46c18e83674cc17c77643164289abdef5;p=ghc-hetmet.git

diff --git a/ghc/compiler/utils/Digraph.lhs b/ghc/compiler/utils/Digraph.lhs
index 1544c7b..0eff6da 100644
--- a/ghc/compiler/utils/Digraph.lhs
+++ b/ghc/compiler/utils/Digraph.lhs
@@ -32,18 +32,22 @@ module Digraph(
 ------------------------------------------------------------------------------
 
 
-#define ARR_ELT		(COMMA)
-
-import Util	( sortLt )
+import Util	( sortLe )
 
 -- Extensions
-import ST
+import MONAD_ST
 
 -- std interfaces
 import Maybe
 import Array
 import List
 import Outputable
+
+#if __GLASGOW_HASKELL__ >= 504
+import Data.Array.ST  hiding ( indices, bounds )
+#else
+import ST
+#endif
 \end{code}
 
 
@@ -74,7 +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)
@@ -89,14 +94,14 @@ stronglyConnCompR
 	=> [(node, key, [key])]		-- The graph; its ok for the
 					-- out-list to contain keys which arent
 					-- a vertex key, they are ignored
-	-> [SCC (node, key, [key])]
+	-> [SCC (node, key, [key])]	-- Topologically sorted
 
 stronglyConnCompR [] = []  -- added to avoid creating empty array in graphFromEdges -- SOF
 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 [])
@@ -158,14 +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
@@ -211,7 +218,7 @@ drawTree         = unlines . draw
 draw (Node x ts) = grp this (space (length this)) (stLoop ts)
  where this          = s1 ++ x ++ " "
 
-       space n       = take n (repeat ' ')
+       space n       = replicate n ' '
 
        stLoop []     = [""]
        stLoop [t]    = grp s2 "  " (draw t)
@@ -233,6 +240,17 @@ draw (Node x ts) = grp this (space (length this)) (stLoop ts)
 %************************************************************************
 
 \begin{code}
+#if __GLASGOW_HASKELL__ >= 504
+newSTArray :: Ix i => (i,i) -> e -> ST s (STArray s i e)
+newSTArray = newArray
+
+readSTArray :: Ix i => STArray s i e -> i -> ST s e
+readSTArray = readArray
+
+writeSTArray :: Ix i => STArray s i e -> i -> e -> ST s ()
+writeSTArray = writeArray
+#endif
+
 type Set s    = STArray s Vertex Bool
 
 mkEmpty      :: Bounds -> ST s (Set s)
@@ -290,9 +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..])
 
@@ -346,12 +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 ]