-- | Basic operations on graphs.
--
+-- TODO: refine coalescing crieteria
+
{-# OPTIONS -fno-warn-missing-signatures #-}
module GraphOps (
addCoalesce, delCoalesce,
addExclusion,
addPreference,
- coalesceGraph,
- coalesceNodes,
+ coalesceNodes, coalesceGraph,
+ freezeNode, freezeOneInGraph, freezeAllInGraph,
+ scanGraph,
setColor,
validateGraph,
slurpNodeConflictCount
Nothing -> Nothing
+
-- | Get the size of the graph, O(n)
size :: Uniquable k
=> Graph k cls color -> Int
union graph1 graph2
= Graph
{ graphMap = plusUFM (graphMap graph1) (graphMap graph2) }
-
-
-- | Add a conflict between nodes to the graph, creating the nodes required.
--
coalesceGraph
:: (Uniquable k, Ord k, Eq cls, Outputable k)
- => Triv k cls color
+ => Bool -- ^ If True, coalesce nodes even if this might make the graph
+ -- less colorable (aggressive coalescing)
+ -> Triv k cls color
-> Graph k cls color
-> (Graph k cls color, [(k, k)])
-coalesceGraph triv graph
+coalesceGraph aggressive triv graph
+ = coalesceGraph' aggressive triv graph []
+
+coalesceGraph' aggressive triv graph kkPairsAcc
= let
-- find all the nodes that have coalescence edges
cNodes = filter (\node -> not $ isEmptyUniqSet (nodeCoalesce node))
-- do the coalescing, returning the new graph and a list of pairs of keys
-- that got coalesced together.
(graph', mPairs)
- = mapAccumL (coalesceNodes False triv) graph cList
+ = mapAccumL (coalesceNodes aggressive triv) graph cList
- in (graph', catMaybes mPairs)
+ -- 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)
-- | Coalesce this pair of nodes unconditionally / agressively.
else (k2, k1)
-- the nodes being coalesced must be in the graph
- , Just nMin <- lookupNode graph kMin
- , Just nMax <- lookupNode graph kMax
+ , Just nMin <- lookupNode graph kMin
+ , Just nMax <- lookupNode graph kMax
-- can't coalesce conflicting modes
, not $ elementOfUniqSet kMin (nodeConflicts nMax)
in (graph', Just (kMax, kMin))
-
+
+-- | Freeze a node
+-- This is for the iterative coalescer.
+-- By freezing a node we give up on ever coalescing it.
+-- Move all its coalesce edges into the frozen set - and update
+-- back edges from other nodes.
+--
+freezeNode
+ :: Uniquable k
+ => k -- ^ key of the node to freeze
+ -> Graph k cls color -- ^ the graph
+ -> Graph k cls color -- ^ graph with that node frozen
+
+freezeNode k
+ = graphMapModify
+ $ \fm ->
+ let
+ -- freeze all the edges in the node to be frozen
+ Just node = lookupUFM fm k
+ node' = node
+ { nodeCoalesce = emptyUniqSet }
+
+ fm1 = addToUFM fm k node'
+
+ -- update back edges pointing to this node
+ freezeEdge k node
+ = if elementOfUniqSet k (nodeCoalesce node)
+ then node
+ { nodeCoalesce = delOneFromUniqSet (nodeCoalesce node) k }
+ else panic "GraphOps.freezeNode: edge to freeze wasn't in the coalesce set"
+
+ fm2 = foldUniqSet (adjustUFM (freezeEdge k)) fm1
+ $ nodeCoalesce node
+
+ in fm2
+
+
+-- | Freeze one node in the graph
+-- This if for the iterative coalescer.
+-- Look for a move related node of low degree and freeze it.
+--
+-- We probably don't need to scan the whole graph looking for the node of absolute
+-- lowest degree. Just sample the first few and choose the one with the lowest
+-- degree out of those. Also, we don't make any distinction between conflicts of different
+-- classes.. this is just a heuristic, after all.
+--
+-- IDEA: freezing a node might free it up for Simplify.. would be good to check for triv
+-- right here, and add it to a worklist if known triv/non-move nodes.
+--
+freezeOneInGraph
+ :: (Uniquable k, Outputable k)
+ => Graph k cls color
+ -> ( Graph k cls color -- the new graph
+ , Bool ) -- whether we found a node to freeze
+
+freezeOneInGraph graph
+ = let compareNodeDegree n1 n2
+ = compare (sizeUniqSet $ nodeConflicts n1) (sizeUniqSet $ nodeConflicts n2)
+
+ candidates
+ = sortBy compareNodeDegree
+ $ take 5 -- 5 isn't special, it's just a small number.
+ $ scanGraph (\node -> not $ isEmptyUniqSet (nodeCoalesce node)) graph
+
+ in case candidates of
+
+ -- there wasn't anything available to freeze
+ [] -> (graph, False)
+
+ -- we found something to freeze
+ (n : _)
+ -> ( freezeNode (nodeId n) graph
+ , True)
+
+
+-- | Freeze all the nodes in the graph
+-- for debugging the iterative allocator.
+--
+freezeAllInGraph
+ :: (Uniquable k, Outputable k)
+ => Graph k cls color
+ -> Graph k cls color
+
+freezeAllInGraph graph
+ = foldr freezeNode graph
+ $ map nodeId
+ $ eltsUFM $ graphMap graph
+
+
+-- | Find all the nodes in the graph that meet some criteria
+--
+scanGraph
+ :: Uniquable k
+ => (Node k cls color -> Bool)
+ -> Graph k cls color
+ -> [Node k cls color]
+
+scanGraph match graph
+ = filter match $ eltsUFM $ graphMap graph
+
+
-- | validate the internal structure of a graph
-- all its edges should point to valid nodes
-- if they don't then throw an error
-> Graph k cls color
validateGraph doc graph
- = let edges = unionUniqSets
- (unionManyUniqSets
- (map nodeConflicts $ eltsUFM $ graphMap graph))
- (unionManyUniqSets
- (map nodeCoalesce $ eltsUFM $ graphMap graph))
-
+ = let edges = unionManyUniqSets
+ ( (map nodeConflicts $ eltsUFM $ graphMap graph)
+ ++ (map nodeCoalesce $ eltsUFM $ graphMap graph))
+
nodes = mkUniqSet $ map nodeId $ eltsUFM $ graphMap graph
badEdges = minusUniqSet edges nodes
projects / ghc-hetmet.git / blobdiff