summaryrefslogtreecommitdiff
path: root/compiler/cmm/Hoopl
diff options
context:
space:
mode:
Diffstat (limited to 'compiler/cmm/Hoopl')
-rw-r--r--compiler/cmm/Hoopl/Block.hs327
-rw-r--r--compiler/cmm/Hoopl/Collections.hs87
-rw-r--r--compiler/cmm/Hoopl/Dataflow.hs12
-rw-r--r--compiler/cmm/Hoopl/Graph.hs199
-rw-r--r--compiler/cmm/Hoopl/Label.hs122
-rw-r--r--compiler/cmm/Hoopl/Unique.hs91
6 files changed, 834 insertions, 4 deletions
diff --git a/compiler/cmm/Hoopl/Block.hs b/compiler/cmm/Hoopl/Block.hs
new file mode 100644
index 0000000000..3623fcd242
--- /dev/null
+++ b/compiler/cmm/Hoopl/Block.hs
@@ -0,0 +1,327 @@
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeFamilies #-}
+module Hoopl.Block
+ ( C
+ , O
+ , MaybeO(..)
+ , IndexedCO
+ , Block(..)
+ , blockAppend
+ , blockCons
+ , blockFromList
+ , blockJoin
+ , blockJoinHead
+ , blockJoinTail
+ , blockSnoc
+ , blockSplit
+ , blockSplitHead
+ , blockSplitTail
+ , blockToList
+ , emptyBlock
+ , firstNode
+ , foldBlockNodesB
+ , foldBlockNodesB3
+ , foldBlockNodesF
+ , isEmptyBlock
+ , lastNode
+ , mapBlock
+ , mapBlock'
+ , mapBlock3'
+ , replaceFirstNode
+ , replaceLastNode
+ ) where
+
+
+-- -----------------------------------------------------------------------------
+-- Shapes: Open and Closed
+
+-- | Used at the type level to indicate an "open" structure with
+-- a unique, unnamed control-flow edge flowing in or out.
+-- "Fallthrough" and concatenation are permitted at an open point.
+data O
+
+-- | Used at the type level to indicate a "closed" structure which
+-- supports control transfer only through the use of named
+-- labels---no "fallthrough" is permitted. The number of control-flow
+-- edges is unconstrained.
+data C
+
+-- | Either type indexed by closed/open using type families
+type family IndexedCO ex a b :: *
+type instance IndexedCO C a _b = a
+type instance IndexedCO O _a b = b
+
+-- | Maybe type indexed by open/closed
+data MaybeO ex t where
+ JustO :: t -> MaybeO O t
+ NothingO :: MaybeO C t
+
+-- | Maybe type indexed by closed/open
+data MaybeC ex t where
+ JustC :: t -> MaybeC C t
+ NothingC :: MaybeC O t
+
+
+instance Functor (MaybeO ex) where
+ fmap _ NothingO = NothingO
+ fmap f (JustO a) = JustO (f a)
+
+instance Functor (MaybeC ex) where
+ fmap _ NothingC = NothingC
+ fmap f (JustC a) = JustC (f a)
+
+-- -----------------------------------------------------------------------------
+-- The Block type
+
+-- | A sequence of nodes. May be any of four shapes (O/O, O/C, C/O, C/C).
+-- Open at the entry means single entry, mutatis mutandis for exit.
+-- A closed/closed block is a /basic/ block and can't be extended further.
+-- Clients should avoid manipulating blocks and should stick to either nodes
+-- or graphs.
+data Block n e x where
+ BlockCO :: n C O -> Block n O O -> Block n C O
+ BlockCC :: n C O -> Block n O O -> n O C -> Block n C C
+ BlockOC :: Block n O O -> n O C -> Block n O C
+
+ BNil :: Block n O O
+ BMiddle :: n O O -> Block n O O
+ BCat :: Block n O O -> Block n O O -> Block n O O
+ BSnoc :: Block n O O -> n O O -> Block n O O
+ BCons :: n O O -> Block n O O -> Block n O O
+
+
+-- -----------------------------------------------------------------------------
+-- Simple operations on Blocks
+
+-- Predicates
+
+isEmptyBlock :: Block n e x -> Bool
+isEmptyBlock BNil = True
+isEmptyBlock (BCat l r) = isEmptyBlock l && isEmptyBlock r
+isEmptyBlock _ = False
+
+
+-- Building
+
+emptyBlock :: Block n O O
+emptyBlock = BNil
+
+blockCons :: n O O -> Block n O x -> Block n O x
+blockCons n b = case b of
+ BlockOC b l -> (BlockOC $! (n `blockCons` b)) l
+ BNil{} -> BMiddle n
+ BMiddle{} -> n `BCons` b
+ BCat{} -> n `BCons` b
+ BSnoc{} -> n `BCons` b
+ BCons{} -> n `BCons` b
+
+blockSnoc :: Block n e O -> n O O -> Block n e O
+blockSnoc b n = case b of
+ BlockCO f b -> BlockCO f $! (b `blockSnoc` n)
+ BNil{} -> BMiddle n
+ BMiddle{} -> b `BSnoc` n
+ BCat{} -> b `BSnoc` n
+ BSnoc{} -> b `BSnoc` n
+ BCons{} -> b `BSnoc` n
+
+blockJoinHead :: n C O -> Block n O x -> Block n C x
+blockJoinHead f (BlockOC b l) = BlockCC f b l
+blockJoinHead f b = BlockCO f BNil `cat` b
+
+blockJoinTail :: Block n e O -> n O C -> Block n e C
+blockJoinTail (BlockCO f b) t = BlockCC f b t
+blockJoinTail b t = b `cat` BlockOC BNil t
+
+blockJoin :: n C O -> Block n O O -> n O C -> Block n C C
+blockJoin f b t = BlockCC f b t
+
+blockAppend :: Block n e O -> Block n O x -> Block n e x
+blockAppend = cat
+
+
+-- Taking apart
+
+firstNode :: Block n C x -> n C O
+firstNode (BlockCO n _) = n
+firstNode (BlockCC n _ _) = n
+
+lastNode :: Block n x C -> n O C
+lastNode (BlockOC _ n) = n
+lastNode (BlockCC _ _ n) = n
+
+blockSplitHead :: Block n C x -> (n C O, Block n O x)
+blockSplitHead (BlockCO n b) = (n, b)
+blockSplitHead (BlockCC n b t) = (n, BlockOC b t)
+
+blockSplitTail :: Block n e C -> (Block n e O, n O C)
+blockSplitTail (BlockOC b n) = (b, n)
+blockSplitTail (BlockCC f b t) = (BlockCO f b, t)
+
+-- | Split a closed block into its entry node, open middle block, and
+-- exit node.
+blockSplit :: Block n C C -> (n C O, Block n O O, n O C)
+blockSplit (BlockCC f b t) = (f, b, t)
+
+blockToList :: Block n O O -> [n O O]
+blockToList b = go b []
+ where go :: Block n O O -> [n O O] -> [n O O]
+ go BNil r = r
+ go (BMiddle n) r = n : r
+ go (BCat b1 b2) r = go b1 $! go b2 r
+ go (BSnoc b1 n) r = go b1 (n:r)
+ go (BCons n b1) r = n : go b1 r
+
+blockFromList :: [n O O] -> Block n O O
+blockFromList = foldr BCons BNil
+
+-- Modifying
+
+replaceFirstNode :: Block n C x -> n C O -> Block n C x
+replaceFirstNode (BlockCO _ b) f = BlockCO f b
+replaceFirstNode (BlockCC _ b n) f = BlockCC f b n
+
+replaceLastNode :: Block n x C -> n O C -> Block n x C
+replaceLastNode (BlockOC b _) n = BlockOC b n
+replaceLastNode (BlockCC l b _) n = BlockCC l b n
+
+-- -----------------------------------------------------------------------------
+-- General concatenation
+
+cat :: Block n e O -> Block n O x -> Block n e x
+cat x y = case x of
+ BNil -> y
+
+ BlockCO l b1 -> case y of
+ BlockOC b2 n -> (BlockCC l $! (b1 `cat` b2)) n
+ BNil -> x
+ BMiddle _ -> BlockCO l $! (b1 `cat` y)
+ BCat{} -> BlockCO l $! (b1 `cat` y)
+ BSnoc{} -> BlockCO l $! (b1 `cat` y)
+ BCons{} -> BlockCO l $! (b1 `cat` y)
+
+ BMiddle n -> case y of
+ BlockOC b2 n2 -> (BlockOC $! (x `cat` b2)) n2
+ BNil -> x
+ BMiddle{} -> BCons n y
+ BCat{} -> BCons n y
+ BSnoc{} -> BCons n y
+ BCons{} -> BCons n y
+
+ BCat{} -> case y of
+ BlockOC b3 n2 -> (BlockOC $! (x `cat` b3)) n2
+ BNil -> x
+ BMiddle n -> BSnoc x n
+ BCat{} -> BCat x y
+ BSnoc{} -> BCat x y
+ BCons{} -> BCat x y
+
+ BSnoc{} -> case y of
+ BlockOC b2 n2 -> (BlockOC $! (x `cat` b2)) n2
+ BNil -> x
+ BMiddle n -> BSnoc x n
+ BCat{} -> BCat x y
+ BSnoc{} -> BCat x y
+ BCons{} -> BCat x y
+
+
+ BCons{} -> case y of
+ BlockOC b2 n2 -> (BlockOC $! (x `cat` b2)) n2
+ BNil -> x
+ BMiddle n -> BSnoc x n
+ BCat{} -> BCat x y
+ BSnoc{} -> BCat x y
+ BCons{} -> BCat x y
+
+
+-- -----------------------------------------------------------------------------
+-- Mapping
+
+-- | map a function over the nodes of a 'Block'
+mapBlock :: (forall e x. n e x -> n' e x) -> Block n e x -> Block n' e x
+mapBlock f (BlockCO n b ) = BlockCO (f n) (mapBlock f b)
+mapBlock f (BlockOC b n) = BlockOC (mapBlock f b) (f n)
+mapBlock f (BlockCC n b m) = BlockCC (f n) (mapBlock f b) (f m)
+mapBlock _ BNil = BNil
+mapBlock f (BMiddle n) = BMiddle (f n)
+mapBlock f (BCat b1 b2) = BCat (mapBlock f b1) (mapBlock f b2)
+mapBlock f (BSnoc b n) = BSnoc (mapBlock f b) (f n)
+mapBlock f (BCons n b) = BCons (f n) (mapBlock f b)
+
+-- | A strict 'mapBlock'
+mapBlock' :: (forall e x. n e x -> n' e x) -> (Block n e x -> Block n' e x)
+mapBlock' f = mapBlock3' (f, f, f)
+
+-- | map over a block, with different functions to apply to first nodes,
+-- middle nodes and last nodes respectively. The map is strict.
+--
+mapBlock3' :: forall n n' e x .
+ ( n C O -> n' C O
+ , n O O -> n' O O,
+ n O C -> n' O C)
+ -> Block n e x -> Block n' e x
+mapBlock3' (f, m, l) b = go b
+ where go :: forall e x . Block n e x -> Block n' e x
+ go (BlockOC b y) = (BlockOC $! go b) $! l y
+ go (BlockCO x b) = (BlockCO $! f x) $! (go b)
+ go (BlockCC x b y) = ((BlockCC $! f x) $! go b) $! (l y)
+ go BNil = BNil
+ go (BMiddle n) = BMiddle $! m n
+ go (BCat x y) = (BCat $! go x) $! (go y)
+ go (BSnoc x n) = (BSnoc $! go x) $! (m n)
+ go (BCons n x) = (BCons $! m n) $! (go x)
+
+-- -----------------------------------------------------------------------------
+-- Folding
+
+
+-- | Fold a function over every node in a block, forward or backward.
+-- The fold function must be polymorphic in the shape of the nodes.
+foldBlockNodesF3 :: forall n a b c .
+ ( n C O -> a -> b
+ , n O O -> b -> b
+ , n O C -> b -> c)
+ -> (forall e x . Block n e x -> IndexedCO e a b -> IndexedCO x c b)
+foldBlockNodesF :: forall n a .
+ (forall e x . n e x -> a -> a)
+ -> (forall e x . Block n e x -> IndexedCO e a a -> IndexedCO x a a)
+foldBlockNodesB3 :: forall n a b c .
+ ( n C O -> b -> c
+ , n O O -> b -> b
+ , n O C -> a -> b)
+ -> (forall e x . Block n e x -> IndexedCO x a b -> IndexedCO e c b)
+foldBlockNodesB :: forall n a .
+ (forall e x . n e x -> a -> a)
+ -> (forall e x . Block n e x -> IndexedCO x a a -> IndexedCO e a a)
+
+foldBlockNodesF3 (ff, fm, fl) = block
+ where block :: forall e x . Block n e x -> IndexedCO e a b -> IndexedCO x c b
+ block (BlockCO f b ) = ff f `cat` block b
+ block (BlockCC f b l) = ff f `cat` block b `cat` fl l
+ block (BlockOC b l) = block b `cat` fl l
+ block BNil = id
+ block (BMiddle node) = fm node
+ block (b1 `BCat` b2) = block b1 `cat` block b2
+ block (b1 `BSnoc` n) = block b1 `cat` fm n
+ block (n `BCons` b2) = fm n `cat` block b2
+ cat :: forall a b c. (a -> b) -> (b -> c) -> a -> c
+ cat f f' = f' . f
+
+foldBlockNodesF f = foldBlockNodesF3 (f, f, f)
+
+foldBlockNodesB3 (ff, fm, fl) = block
+ where block :: forall e x . Block n e x -> IndexedCO x a b -> IndexedCO e c b
+ block (BlockCO f b ) = ff f `cat` block b
+ block (BlockCC f b l) = ff f `cat` block b `cat` fl l
+ block (BlockOC b l) = block b `cat` fl l
+ block BNil = id
+ block (BMiddle node) = fm node
+ block (b1 `BCat` b2) = block b1 `cat` block b2
+ block (b1 `BSnoc` n) = block b1 `cat` fm n
+ block (n `BCons` b2) = fm n `cat` block b2
+ cat :: forall a b c. (b -> c) -> (a -> b) -> a -> c
+ cat f f' = f . f'
+
+foldBlockNodesB f = foldBlockNodesB3 (f, f, f)
+
diff --git a/compiler/cmm/Hoopl/Collections.hs b/compiler/cmm/Hoopl/Collections.hs
new file mode 100644
index 0000000000..679057626b
--- /dev/null
+++ b/compiler/cmm/Hoopl/Collections.hs
@@ -0,0 +1,87 @@
+{-# LANGUAGE TypeFamilies #-}
+module Hoopl.Collections
+ ( IsSet(..)
+ , setInsertList, setDeleteList, setUnions
+ , IsMap(..)
+ , mapInsertList, mapDeleteList, mapUnions
+ ) where
+
+import Data.List (foldl', foldl1')
+
+class IsSet set where
+ type ElemOf set
+
+ setNull :: set -> Bool
+ setSize :: set -> Int
+ setMember :: ElemOf set -> set -> Bool
+
+ setEmpty :: set
+ setSingleton :: ElemOf set -> set
+ setInsert :: ElemOf set -> set -> set
+ setDelete :: ElemOf set -> set -> set
+
+ setUnion :: set -> set -> set
+ setDifference :: set -> set -> set
+ setIntersection :: set -> set -> set
+ setIsSubsetOf :: set -> set -> Bool
+
+ setFold :: (ElemOf set -> b -> b) -> b -> set -> b
+
+ setElems :: set -> [ElemOf set]
+ setFromList :: [ElemOf set] -> set
+
+-- Helper functions for IsSet class
+setInsertList :: IsSet set => [ElemOf set] -> set -> set
+setInsertList keys set = foldl' (flip setInsert) set keys
+
+setDeleteList :: IsSet set => [ElemOf set] -> set -> set
+setDeleteList keys set = foldl' (flip setDelete) set keys
+
+setUnions :: IsSet set => [set] -> set
+setUnions [] = setEmpty
+setUnions sets = foldl1' setUnion sets
+
+
+class IsMap map where
+ type KeyOf map
+
+ mapNull :: map a -> Bool
+ mapSize :: map a -> Int
+ mapMember :: KeyOf map -> map a -> Bool
+ mapLookup :: KeyOf map -> map a -> Maybe a
+ mapFindWithDefault :: a -> KeyOf map -> map a -> a
+
+ mapEmpty :: map a
+ mapSingleton :: KeyOf map -> a -> map a
+ mapInsert :: KeyOf map -> a -> map a -> map a
+ mapInsertWith :: (a -> a -> a) -> KeyOf map -> a -> map a -> map a
+ mapDelete :: KeyOf map -> map a -> map a
+
+ mapUnion :: map a -> map a -> map a
+ mapUnionWithKey :: (KeyOf map -> a -> a -> a) -> map a -> map a -> map a
+ mapDifference :: map a -> map a -> map a
+ mapIntersection :: map a -> map a -> map a
+ mapIsSubmapOf :: Eq a => map a -> map a -> Bool
+
+ mapMap :: (a -> b) -> map a -> map b
+ mapMapWithKey :: (KeyOf map -> a -> b) -> map a -> map b
+ mapFold :: (a -> b -> b) -> b -> map a -> b
+ mapFoldWithKey :: (KeyOf map -> a -> b -> b) -> b -> map a -> b
+ mapFilter :: (a -> Bool) -> map a -> map a
+
+ mapElems :: map a -> [a]
+ mapKeys :: map a -> [KeyOf map]
+ mapToList :: map a -> [(KeyOf map, a)]
+ mapFromList :: [(KeyOf map, a)] -> map a
+ mapFromListWith :: (a -> a -> a) -> [(KeyOf map,a)] -> map a
+
+-- Helper functions for IsMap class
+mapInsertList :: IsMap map => [(KeyOf map, a)] -> map a -> map a
+mapInsertList assocs map = foldl' (flip (uncurry mapInsert)) map assocs
+
+mapDeleteList :: IsMap map => [KeyOf map] -> map a -> map a
+mapDeleteList keys map = foldl' (flip mapDelete) map keys
+
+mapUnions :: IsMap map => [map a] -> map a
+mapUnions [] = mapEmpty
+mapUnions maps = foldl1' mapUnion maps
diff --git a/compiler/cmm/Hoopl/Dataflow.hs b/compiler/cmm/Hoopl/Dataflow.hs
index 6b33cf146b..c2ace502b3 100644
--- a/compiler/cmm/Hoopl/Dataflow.hs
+++ b/compiler/cmm/Hoopl/Dataflow.hs
@@ -42,10 +42,14 @@ import Data.Maybe
import Data.IntSet (IntSet)
import qualified Data.IntSet as IntSet
--- Hide definitions from Hoopl's Dataflow module.
-import Compiler.Hoopl hiding ( DataflowLattice, OldFact, NewFact, JoinFun
- , fact_bot, fact_join, joinOutFacts, mkFactBase
- )
+import Hoopl.Block
+import Hoopl.Graph
+import Hoopl.Collections
+import Hoopl.Label
+
+type family Fact x f :: *
+type instance Fact C f = FactBase f
+type instance Fact O f = f
newtype OldFact a = OldFact a
diff --git a/compiler/cmm/Hoopl/Graph.hs b/compiler/cmm/Hoopl/Graph.hs
new file mode 100644
index 0000000000..87da072458
--- /dev/null
+++ b/compiler/cmm/Hoopl/Graph.hs
@@ -0,0 +1,199 @@
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeFamilies #-}
+module Hoopl.Graph
+ ( Body
+ , Graph
+ , Graph'(..)
+ , NonLocal(..)
+ , addBlock
+ , bodyList
+ , emptyBody
+ , labelsDefined
+ , mapGraph
+ , mapGraphBlocks
+ , postorder_dfs_from
+ ) where
+
+
+import Hoopl.Label
+import Hoopl.Block
+import Hoopl.Collections
+
+-- | A (possibly empty) collection of closed/closed blocks
+type Body n = LabelMap (Block n C C)
+
+-- | @Body@ abstracted over @block@
+type Body' block (n :: * -> * -> *) = LabelMap (block n C C)
+
+-------------------------------
+-- | Gives access to the anchor points for
+-- nonlocal edges as well as the edges themselves
+class NonLocal thing where
+ entryLabel :: thing C x -> Label -- ^ The label of a first node or block
+ successors :: thing e C -> [Label] -- ^ Gives control-flow successors
+
+instance NonLocal n => NonLocal (Block n) where
+ entryLabel (BlockCO f _) = entryLabel f
+ entryLabel (BlockCC f _ _) = entryLabel f
+
+ successors (BlockOC _ n) = successors n
+ successors (BlockCC _ _ n) = successors n
+
+
+emptyBody :: Body' block n
+emptyBody = mapEmpty
+
+bodyList :: Body' block n -> [(Label,block n C C)]
+bodyList body = mapToList body
+
+addBlock :: NonLocal thing
+ => thing C C -> LabelMap (thing C C)
+ -> LabelMap (thing C C)
+addBlock b body
+ | mapMember lbl body = error $ "duplicate label " ++ show lbl ++ " in graph"
+ | otherwise = mapInsert lbl b body
+ where lbl = entryLabel b
+
+
+-- ---------------------------------------------------------------------------
+-- Graph
+
+-- | A control-flow graph, which may take any of four shapes (O/O,
+-- O/C, C/O, C/C). A graph open at the entry has a single,
+-- distinguished, anonymous entry point; if a graph is closed at the
+-- entry, its entry point(s) are supplied by a context.
+type Graph = Graph' Block
+
+-- | @Graph'@ is abstracted over the block type, so that we can build
+-- graphs of annotated blocks for example (Compiler.Hoopl.Dataflow
+-- needs this).
+data Graph' block (n :: * -> * -> *) e x where
+ GNil :: Graph' block n O O
+ GUnit :: block n O O -> Graph' block n O O
+ GMany :: MaybeO e (block n O C)
+ -> Body' block n
+ -> MaybeO x (block n C O)
+ -> Graph' block n e x
+
+
+-- -----------------------------------------------------------------------------
+-- Mapping over graphs
+
+-- | Maps over all nodes in a graph.
+mapGraph :: (forall e x. n e x -> n' e x) -> Graph n e x -> Graph n' e x
+mapGraph f = mapGraphBlocks (mapBlock f)
+
+-- | Function 'mapGraphBlocks' enables a change of representation of blocks,
+-- nodes, or both. It lifts a polymorphic block transform into a polymorphic
+-- graph transform. When the block representation stabilizes, a similar
+-- function should be provided for blocks.
+mapGraphBlocks :: forall block n block' n' e x .
+ (forall e x . block n e x -> block' n' e x)
+ -> (Graph' block n e x -> Graph' block' n' e x)
+
+mapGraphBlocks f = map
+ where map :: Graph' block n e x -> Graph' block' n' e x
+ map GNil = GNil
+ map (GUnit b) = GUnit (f b)
+ map (GMany e b x) = GMany (fmap f e) (mapMap f b) (fmap f x)
+
+-- -----------------------------------------------------------------------------
+-- Extracting Labels from graphs
+
+labelsDefined :: forall block n e x . NonLocal (block n) => Graph' block n e x
+ -> LabelSet
+labelsDefined GNil = setEmpty
+labelsDefined (GUnit{}) = setEmpty
+labelsDefined (GMany _ body x) = mapFoldWithKey addEntry (exitLabel x) body
+ where addEntry :: forall a. ElemOf LabelSet -> a -> LabelSet -> LabelSet
+ addEntry label _ labels = setInsert label labels
+ exitLabel :: MaybeO x (block n C O) -> LabelSet
+ exitLabel NothingO = setEmpty
+ exitLabel (JustO b) = setSingleton (entryLabel b)
+
+
+----------------------------------------------------------------
+
+class LabelsPtr l where
+ targetLabels :: l -> [Label]
+
+instance NonLocal n => LabelsPtr (n e C) where
+ targetLabels n = successors n
+
+instance LabelsPtr Label where
+ targetLabels l = [l]
+
+instance LabelsPtr LabelSet where
+ targetLabels = setElems
+
+instance LabelsPtr l => LabelsPtr [l] where
+ targetLabels = concatMap targetLabels
+
+-- | This is the most important traversal over this data structure. It drops
+-- unreachable code and puts blocks in an order that is good for solving forward
+-- dataflow problems quickly. The reverse order is good for solving backward
+-- dataflow problems quickly. The forward order is also reasonably good for
+-- emitting instructions, except that it will not usually exploit Forrest
+-- Baskett's trick of eliminating the unconditional branch from a loop. For
+-- that you would need a more serious analysis, probably based on dominators, to
+-- identify loop headers.
+--
+-- The ubiquity of 'postorder_dfs' is one reason for the ubiquity of the 'LGraph'
+-- representation, when for most purposes the plain 'Graph' representation is
+-- more mathematically elegant (but results in more complicated code).
+--
+-- Here's an easy way to go wrong! Consider
+-- @
+-- A -> [B,C]
+-- B -> D
+-- C -> D
+-- @
+-- Then ordinary dfs would give [A,B,D,C] which has a back ref from C to D.
+-- Better to get [A,B,C,D]
+
+
+-- | Traversal: 'postorder_dfs' returns a list of blocks reachable
+-- from the entry of enterable graph. The entry and exit are *not* included.
+-- The list has the following property:
+--
+-- Say a "back reference" exists if one of a block's
+-- control-flow successors precedes it in the output list
+--
+-- Then there are as few back references as possible
+--
+-- The output is suitable for use in
+-- a forward dataflow problem. For a backward problem, simply reverse
+-- the list. ('postorder_dfs' is sufficiently tricky to implement that
+-- one doesn't want to try and maintain both forward and backward
+-- versions.)
+
+postorder_dfs_from_except :: forall block e . (NonLocal block, LabelsPtr e)
+ => LabelMap (block C C) -> e -> LabelSet -> [block C C]
+postorder_dfs_from_except blocks b visited =
+ vchildren (get_children b) (\acc _visited -> acc) [] visited
+ where
+ vnode :: block C C -> ([block C C] -> LabelSet -> a) -> [block C C] -> LabelSet -> a
+ vnode block cont acc visited =
+ if setMember id visited then
+ cont acc visited
+ else
+ let cont' acc visited = cont (block:acc) visited in
+ vchildren (get_children block) cont' acc (setInsert id visited)
+ where id = entryLabel block
+ vchildren :: forall a. [block C C] -> ([block C C] -> LabelSet -> a) -> [block C C] -> LabelSet -> a
+ vchildren bs cont acc visited = next bs acc visited
+ where next children acc visited =
+ case children of [] -> cont acc visited
+ (b:bs) -> vnode b (next bs) acc visited
+ get_children :: forall l. LabelsPtr l => l -> [block C C]
+ get_children block = foldr add_id [] $ targetLabels block
+ add_id id rst = case lookupFact id blocks of
+ Just b -> b : rst
+ Nothing -> rst
+
+postorder_dfs_from
+ :: (NonLocal block, LabelsPtr b) => LabelMap (block C C) -> b -> [block C C]
+postorder_dfs_from blocks b = postorder_dfs_from_except blocks b setEmpty
diff --git a/compiler/cmm/Hoopl/Label.hs b/compiler/cmm/Hoopl/Label.hs
new file mode 100644
index 0000000000..5ee4f72fc3
--- /dev/null
+++ b/compiler/cmm/Hoopl/Label.hs
@@ -0,0 +1,122 @@
+{-# LANGUAGE DeriveFoldable #-}
+{-# LANGUAGE DeriveFunctor #-}
+{-# LANGUAGE DeriveTraversable #-}
+{-# LANGUAGE TypeFamilies #-}
+module Hoopl.Label
+ ( Label
+ , LabelMap
+ , LabelSet
+ , FactBase
+ , lookupFact
+ , uniqueToLbl
+ ) where
+
+import Outputable
+
+import Hoopl.Collections
+-- TODO: This should really just use GHC's Unique and Uniq{Set,FM}
+import Hoopl.Unique
+
+import Unique (Uniquable(..))
+
+-----------------------------------------------------------------------------
+-- Label
+-----------------------------------------------------------------------------
+
+newtype Label = Label { lblToUnique :: Unique }
+ deriving (Eq, Ord)
+
+uniqueToLbl :: Unique -> Label
+uniqueToLbl = Label
+
+instance Show Label where
+ show (Label n) = "L" ++ show n
+
+instance Uniquable Label where
+ getUnique label = getUnique (lblToUnique label)
+
+instance Outputable Label where
+ ppr label = ppr (getUnique label)
+
+-----------------------------------------------------------------------------
+-- LabelSet
+
+newtype LabelSet = LS UniqueSet deriving (Eq, Ord, Show)
+
+instance IsSet LabelSet where
+ type ElemOf LabelSet = Label
+
+ setNull (LS s) = setNull s
+ setSize (LS s) = setSize s
+ setMember (Label k) (LS s) = setMember k s
+
+ setEmpty = LS setEmpty
+ setSingleton (Label k) = LS (setSingleton k)
+ setInsert (Label k) (LS s) = LS (setInsert k s)
+ setDelete (Label k) (LS s) = LS (setDelete k s)
+
+ setUnion (LS x) (LS y) = LS (setUnion x y)
+ setDifference (LS x) (LS y) = LS (setDifference x y)
+ setIntersection (LS x) (LS y) = LS (setIntersection x y)
+ setIsSubsetOf (LS x) (LS y) = setIsSubsetOf x y
+
+ setFold k z (LS s) = setFold (k . uniqueToLbl) z s
+
+ setElems (LS s) = map uniqueToLbl (setElems s)
+ setFromList ks = LS (setFromList (map lblToUnique ks))
+
+-----------------------------------------------------------------------------
+-- LabelMap
+
+newtype LabelMap v = LM (UniqueMap v)
+ deriving (Eq, Ord, Show, Functor, Foldable, Traversable)
+
+instance IsMap LabelMap where
+ type KeyOf LabelMap = Label
+
+ mapNull (LM m) = mapNull m
+ mapSize (LM m) = mapSize m
+ mapMember (Label k) (LM m) = mapMember k m
+ mapLookup (Label k) (LM m) = mapLookup k m
+ mapFindWithDefault def (Label k) (LM m) = mapFindWithDefault def k m
+
+ mapEmpty = LM mapEmpty
+ mapSingleton (Label k) v = LM (mapSingleton k v)
+ mapInsert (Label k) v (LM m) = LM (mapInsert k v m)
+ mapInsertWith f (Label k) v (LM m) = LM (mapInsertWith f k v m)
+ mapDelete (Label k) (LM m) = LM (mapDelete k m)
+
+ mapUnion (LM x) (LM y) = LM (mapUnion x y)
+ mapUnionWithKey f (LM x) (LM y) = LM (mapUnionWithKey (f . uniqueToLbl) x y)
+ mapDifference (LM x) (LM y) = LM (mapDifference x y)
+ mapIntersection (LM x) (LM y) = LM (mapIntersection x y)
+ mapIsSubmapOf (LM x) (LM y) = mapIsSubmapOf x y
+
+ mapMap f (LM m) = LM (mapMap f m)
+ mapMapWithKey f (LM m) = LM (mapMapWithKey (f . uniqueToLbl) m)
+ mapFold k z (LM m) = mapFold k z m
+ mapFoldWithKey k z (LM m) = mapFoldWithKey (k . uniqueToLbl) z m
+ mapFilter f (LM m) = LM (mapFilter f m)
+
+ mapElems (LM m) = mapElems m
+ mapKeys (LM m) = map uniqueToLbl (mapKeys m)
+ mapToList (LM m) = [(uniqueToLbl k, v) | (k, v) <- mapToList m]
+ mapFromList assocs = LM (mapFromList [(lblToUnique k, v) | (k, v) <- assocs])
+ mapFromListWith f assocs = LM (mapFromListWith f [(lblToUnique k, v) | (k, v) <- assocs])
+
+-----------------------------------------------------------------------------
+-- Instances
+
+instance Outputable LabelSet where
+ ppr = ppr . setElems
+
+instance Outputable a => Outputable (LabelMap a) where
+ ppr = ppr . mapToList
+
+-----------------------------------------------------------------------------
+-- FactBase
+
+type FactBase f = LabelMap f
+
+lookupFact :: Label -> FactBase f -> Maybe f
+lookupFact = mapLookup
diff --git a/compiler/cmm/Hoopl/Unique.hs b/compiler/cmm/Hoopl/Unique.hs
new file mode 100644
index 0000000000..f27961bb28
--- /dev/null
+++ b/compiler/cmm/Hoopl/Unique.hs
@@ -0,0 +1,91 @@
+{-# LANGUAGE DeriveFunctor #-}
+{-# LANGUAGE DeriveTraversable #-}
+{-# LANGUAGE DeriveFoldable #-}
+{-# LANGUAGE TypeFamilies #-}
+module Hoopl.Unique
+ ( Unique
+ , UniqueMap
+ , UniqueSet
+ , intToUnique
+ ) where
+
+import qualified Data.IntMap as M
+import qualified Data.IntSet as S
+
+import Hoopl.Collections
+
+
+-----------------------------------------------------------------------------
+-- Unique
+-----------------------------------------------------------------------------
+
+type Unique = Int
+
+intToUnique :: Int -> Unique
+intToUnique = id
+
+-----------------------------------------------------------------------------
+-- UniqueSet
+
+newtype UniqueSet = US S.IntSet deriving (Eq, Ord, Show)
+
+instance IsSet UniqueSet where
+ type ElemOf UniqueSet = Unique
+
+ setNull (US s) = S.null s
+ setSize (US s) = S.size s
+ setMember k (US s) = S.member k s
+
+ setEmpty = US S.empty
+ setSingleton k = US (S.singleton k)
+ setInsert k (US s) = US (S.insert k s)
+ setDelete k (US s) = US (S.delete k s)
+
+ setUnion (US x) (US y) = US (S.union x y)
+ setDifference (US x) (US y) = US (S.difference x y)
+ setIntersection (US x) (US y) = US (S.intersection x y)
+ setIsSubsetOf (US x) (US y) = S.isSubsetOf x y
+
+ setFold k z (US s) = S.foldr k z s
+
+ setElems (US s) = S.elems s
+ setFromList ks = US (S.fromList ks)
+
+-----------------------------------------------------------------------------
+-- UniqueMap
+
+newtype UniqueMap v = UM (M.IntMap v)
+ deriving (Eq, Ord, Show, Functor, Foldable, Traversable)
+
+instance IsMap UniqueMap where
+ type KeyOf UniqueMap = Unique
+
+ mapNull (UM m) = M.null m
+ mapSize (UM m) = M.size m
+ mapMember k (UM m) = M.member k m
+ mapLookup k (UM m) = M.lookup k m
+ mapFindWithDefault def k (UM m) = M.findWithDefault def k m
+
+ mapEmpty = UM M.empty
+ mapSingleton k v = UM (M.singleton k v)
+ mapInsert k v (UM m) = UM (M.insert k v m)
+ mapInsertWith f k v (UM m) = UM (M.insertWith f k v m)
+ mapDelete k (UM m) = UM (M.delete k m)
+
+ mapUnion (UM x) (UM y) = UM (M.union x y)
+ mapUnionWithKey f (UM x) (UM y) = UM (M.unionWithKey (f . intToUnique) x y)
+ mapDifference (UM x) (UM y) = UM (M.difference x y)
+ mapIntersection (UM x) (UM y) = UM (M.intersection x y)
+ mapIsSubmapOf (UM x) (UM y) = M.isSubmapOf x y
+
+ mapMap f (UM m) = UM (M.map f m)
+ mapMapWithKey f (UM m) = UM (M.mapWithKey (f . intToUnique) m)
+ mapFold k z (UM m) = M.foldr k z m
+ mapFoldWithKey k z (UM m) = M.foldrWithKey (k . intToUnique) z m
+ mapFilter f (UM m) = UM (M.filter f m)
+
+ mapElems (UM m) = M.elems m
+ mapKeys (UM m) = M.keys m
+ mapToList (UM m) = M.toList m
+ mapFromList assocs = UM (M.fromList assocs)
+ mapFromListWith f assocs = UM (M.fromListWith f assocs)