1 files changed, 33 insertions, 0 deletions
diff --git a/compiler/GHC/CmmToAsm/Utils.hs b/compiler/GHC/CmmToAsm/Utils.hs
new file mode 100644
index 0000000000..648805f210
--- /dev/null
+++ b/compiler/GHC/CmmToAsm/Utils.hs
@@ -0,0 +1,33 @@
+module GHC.CmmToAsm.Utils
+   ( topInfoTable
+   , entryBlocks
+   )
+where
+
+import GHC.Prelude
+
+import GHC.Cmm.BlockId
+import GHC.Cmm.Dataflow.Collections
+import GHC.Cmm.Dataflow.Label
+import GHC.Cmm hiding (topInfoTable)
+
+-- | Returns the info table associated with the CmmDecl's entry point,
+-- if any.
+topInfoTable :: GenCmmDecl a (LabelMap i) (ListGraph b) -> Maybe i
+topInfoTable (CmmProc infos _ _ (ListGraph (b:_)))
+  = mapLookup (blockId b) infos
+topInfoTable _
+  = Nothing
+
+-- | Return the list of BlockIds in a CmmDecl that are entry points
+-- for this proc (i.e. they may be jumped to from outside this proc).
+entryBlocks :: GenCmmDecl a (LabelMap i) (ListGraph b) -> [BlockId]
+entryBlocks (CmmProc info _ _ (ListGraph code)) = entries
+  where
+        infos = mapKeys info
+        entries = case code of
+                    [] -> infos
+                    BasicBlock entry _ : _ -- first block is the entry point
+                       | entry `elem` infos -> infos
+                       | otherwise          -> entry : infos
+entryBlocks _ = []