diff options
Diffstat (limited to 'compiler/utils/UnVarGraph.hs')
| -rw-r--r-- | compiler/utils/UnVarGraph.hs | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/compiler/utils/UnVarGraph.hs b/compiler/utils/UnVarGraph.hs index 228f3b5220..a2f3c687bb 100644 --- a/compiler/utils/UnVarGraph.hs +++ b/compiler/utils/UnVarGraph.hs @@ -24,14 +24,16 @@ module UnVarGraph , unionUnVarGraph, unionUnVarGraphs , completeGraph, completeBipartiteGraph , neighbors + , hasLoopAt , delNode ) where +import GhcPrelude + import Id import VarEnv import UniqFM import Outputable -import Data.List import Bag import Unique @@ -119,6 +121,13 @@ neighbors (UnVarGraph g) v = unionUnVarSets $ concatMap go $ bagToList g go (CBPG s1 s2) = (if v `elemUnVarSet` s1 then [s2] else []) ++ (if v `elemUnVarSet` s2 then [s1] else []) +-- hasLoopAt G v <=> v--v ∈ G +hasLoopAt :: UnVarGraph -> Var -> Bool +hasLoopAt (UnVarGraph g) v = any go $ bagToList g + where go (CG s) = v `elemUnVarSet` s + go (CBPG s1 s2) = v `elemUnVarSet` s1 && v `elemUnVarSet` s2 + + delNode :: UnVarGraph -> Var -> UnVarGraph delNode (UnVarGraph g) v = prune $ UnVarGraph $ mapBag go g where go (CG s) = CG (s `delUnVarSet` v) |