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|
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE TypeFamilies #-}
module GHC.Cmm.Dataflow.Block
( Extensibility (..)
, O
, C
, 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
import GHC.Prelude
-- -----------------------------------------------------------------------------
-- Shapes: Open and Closed
-- | Used at the type level to indicate "open" vs "closed" structure.
data Extensibility
-- | An "open" structure with a unique, unnamed control-flow edge flowing in
-- or out. "Fallthrough" and concatenation are permitted at an open point.
= Open
-- | 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.
| Closed
type O = 'Open
type C = 'Closed
-- | Either type indexed by closed/open using type families
type family IndexedCO (ex :: Extensibility) (a :: k) (b :: k) :: k
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
deriving instance Functor (MaybeO ex)
-- -----------------------------------------------------------------------------
-- 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)
|
