comment wibbles

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

diff --git a/compiler/utils/GraphColor.hs b/compiler/utils/GraphColor.hs
index 307803a..10852d4 100644 (file)
--- a/compiler/utils/GraphColor.hs
+++ b/compiler/utils/GraphColor.hs
@@ -39,6 +39,7 @@ colorGraph
           , Eq color, Eq cls, Ord k
           , Outputable k, Outputable cls, Outputable color)
        => Bool                         -- ^ whether to do iterative coalescing
+       -> Int                          -- ^ how many times coloring has been called so far
        -> UniqFM (UniqSet color)       -- ^ map of (node class -> set of colors available for this class).
        -> Triv   k cls color           -- ^ fn to decide whether a node is trivially colorable.
        -> (Graph k cls color -> k)     -- ^ fn to choose a node to potentially leave uncolored if nothing is trivially colorable.
@@ -49,11 +50,10 @@ colorGraph
           , UniqFM  k )                -- map of regs (r1 -> r2) that were coaleced
                                        --       r1 should be replaced by r2 in the source
 
-colorGraph iterative colors triv spill graph0
+colorGraph iterative spinCount colors triv spill graph0
  = let
-       -- if we're not doing iterative coalescing, then just do a single coalescing
-       --      pass at the front. This won't be as good but should still eat up a
-       --      lot of the reg-reg moves.
+       -- If we're not doing iterative coalescing then just do a conservative
+       --      coalescing stage at the front.
        (graph_coalesced, kksCoalesce1)
                = if not iterative
                        then coalesceGraph False triv graph0
@@ -154,23 +154,23 @@ colorScan_spin iterative triv spill graph
                        $ graph
 
        , ksTrivFound   <- map nodeId nsTrivFound
-       , graph3        <- foldr (\k g -> let Just g' = delNode k g
+       , graph2        <- foldr (\k g -> let Just g' = delNode k g
                                          in  g')
                                graph ksTrivFound
 
-       = colorScan_spin iterative triv spill graph3
+       = colorScan_spin iterative triv spill graph2
                (ksTrivFound ++ ksTriv)
                ksSpill
                kksCoalesce
 
        -- Coalesce:
        --      If we're doing iterative coalescing and no triv nodes are avaliable
-       --      then it's type for a coalescing pass.
+       --      then it's time for a coalescing pass.
        | iterative
        = case coalesceGraph False triv graph of
 
                -- we were able to coalesce something
-               --      go back and see if this frees up more nodes to be trivially colorable.
+               --      go back to Simplify and see if this frees up more nodes to be trivially colorable.
                (graph2, kksCoalesceFound @(_:_))
                 -> colorScan_spin iterative triv spill graph2
                        ksTriv ksSpill (kksCoalesceFound ++ kksCoalesce)