Bugfix to iterative coalescer

[ghc-hetmet.git] / compiler / utils / GraphOps.hs

diff --git a/compiler/utils/GraphOps.hs b/compiler/utils/GraphOps.hs
index ad5e18f..972dd07 100644 (file)
--- a/compiler/utils/GraphOps.hs
+++ b/compiler/utils/GraphOps.hs
@@ -273,7 +273,9 @@ coalesceGraph
                                --      less colorable (aggressive coalescing)
        -> Triv k cls color
        -> Graph k cls color
-       -> (Graph k cls color, [(k, k)])
+       -> ( Graph k cls color
+          , [(k, k)])          -- pairs of nodes that were coalesced, in the order that the
+                               --      coalescing was applied.
 
 coalesceGraph aggressive triv graph
        = coalesceGraph' aggressive triv graph []
@@ -301,8 +303,8 @@ coalesceGraph' aggressive triv graph kkPairsAcc
 
        -- keep running until there are no more coalesces can be found
    in  case catMaybes mPairs of
-        []     -> (graph', kkPairsAcc)
-        pairs  -> coalesceGraph' aggressive triv graph' (pairs ++ kkPairsAcc)
+        []     -> (graph', reverse kkPairsAcc)
+        pairs  -> coalesceGraph' aggressive triv graph' (reverse pairs ++ kkPairsAcc)
 
 
 -- | Coalesce this pair of nodes unconditionally / agressively.