cmm: Introduce blockConcat

compiler/GHC/Cmm/ContFlowOpt.hs

@@ -10,7 +10,7 @@ where
 
 import GHC.Prelude hiding (succ, unzip, zip)
 
-import GHC.Cmm.Dataflow.Block
+import GHC.Cmm.Dataflow.Block hiding (blockConcat)
 import GHC.Cmm.Dataflow.Collections
 import GHC.Cmm.Dataflow.Graph
 import GHC.Cmm.Dataflow.Label

compiler/GHC/Cmm/Dataflow/Block.hs

@@ -14,6 +14,7 @@ module GHC.Cmm.Dataflow.Block
     , IndexedCO
     , Block(..)
     , blockAppend
+    , blockConcat
     , blockCons
     , blockFromList
     , blockJoin
@@ -136,6 +137,8 @@ blockJoin f b t = BlockCC f b t
 blockAppend :: Block n e O -> Block n O x -> Block n e x
 blockAppend = cat
 
+blockConcat :: [Block n O O] -> Block n O O
+blockConcat = foldr blockAppend emptyBlock
 
 -- Taking apart