ghc-8.2.1: coreSyn/TrieMap.hs
{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE UndecidableInstances #-}
module TrieMap(
-- * Maps over Core expressions
CoreMap, emptyCoreMap, extendCoreMap, lookupCoreMap, foldCoreMap,
-- * Maps over 'Type's
TypeMap, emptyTypeMap, extendTypeMap, lookupTypeMap, foldTypeMap,
LooseTypeMap,
-- ** With explicit scoping
CmEnv, lookupCME, extendTypeMapWithScope, lookupTypeMapWithScope,
mkDeBruijnContext,
-- * Maps over 'Maybe' values
MaybeMap,
-- * Maps over 'List' values
ListMap,
-- * Maps over 'Literal's
LiteralMap,
-- * 'TrieMap' class
TrieMap(..), insertTM, deleteTM,
lkDFreeVar, xtDFreeVar,
lkDNamed, xtDNamed,
(>.>), (|>), (|>>),
) where
import CoreSyn
import Coercion
import Literal
import Name
import Type
import TyCoRep
import Var
import UniqDFM
import Unique( Unique )
import FastString(FastString)
import qualified Data.Map as Map
import qualified Data.IntMap as IntMap
import VarEnv
import NameEnv
import Outputable
import Control.Monad( (>=>) )
{-
This module implements TrieMaps, which are finite mappings
whose key is a structured value like a CoreExpr or Type.
The code is very regular and boilerplate-like, but there is
some neat handling of *binders*. In effect they are deBruijn
numbered on the fly.
The regular pattern for handling TrieMaps on data structures was first
described (to my knowledge) in Connelly and Morris's 1995 paper "A
generalization of the Trie Data Structure"; there is also an accessible
description of the idea in Okasaki's book "Purely Functional Data
Structures", Section 10.3.2
************************************************************************
* *
The TrieMap class
* *
************************************************************************
-}
type XT a = Maybe a -> Maybe a -- How to alter a non-existent elt (Nothing)
-- or an existing elt (Just)
class TrieMap m where
type Key m :: *
emptyTM :: m a
lookupTM :: forall b. Key m -> m b -> Maybe b
alterTM :: forall b. Key m -> XT b -> m b -> m b
mapTM :: (a->b) -> m a -> m b
foldTM :: (a -> b -> b) -> m a -> b -> b
-- The unusual argument order here makes
-- it easy to compose calls to foldTM;
-- see for example fdE below
insertTM :: TrieMap m => Key m -> a -> m a -> m a
insertTM k v m = alterTM k (\_ -> Just v) m
deleteTM :: TrieMap m => Key m -> m a -> m a
deleteTM k m = alterTM k (\_ -> Nothing) m
----------------------
-- Recall that
-- Control.Monad.(>=>) :: (a -> Maybe b) -> (b -> Maybe c) -> a -> Maybe c
(>.>) :: (a -> b) -> (b -> c) -> a -> c
-- Reverse function composition (do f first, then g)
infixr 1 >.>
(f >.> g) x = g (f x)
infixr 1 |>, |>>
(|>) :: a -> (a->b) -> b -- Reverse application
x |> f = f x
----------------------
(|>>) :: TrieMap m2
=> (XT (m2 a) -> m1 (m2 a) -> m1 (m2 a))
-> (m2 a -> m2 a)
-> m1 (m2 a) -> m1 (m2 a)
(|>>) f g = f (Just . g . deMaybe)
deMaybe :: TrieMap m => Maybe (m a) -> m a
deMaybe Nothing = emptyTM
deMaybe (Just m) = m
{-
************************************************************************
* *
IntMaps
* *
************************************************************************
-}
instance TrieMap IntMap.IntMap where
type Key IntMap.IntMap = Int
emptyTM = IntMap.empty
lookupTM k m = IntMap.lookup k m
alterTM = xtInt
foldTM k m z = IntMap.foldr k z m
mapTM f m = IntMap.map f m
xtInt :: Int -> XT a -> IntMap.IntMap a -> IntMap.IntMap a
xtInt k f m = IntMap.alter f k m
instance Ord k => TrieMap (Map.Map k) where
type Key (Map.Map k) = k
emptyTM = Map.empty
lookupTM = Map.lookup
alterTM k f m = Map.alter f k m
foldTM k m z = Map.foldr k z m
mapTM f m = Map.map f m
{-
Note [foldTM determinism]
~~~~~~~~~~~~~~~~~~~~~~~~~
We want foldTM to be deterministic, which is why we have an instance of
TrieMap for UniqDFM, but not for UniqFM. Here's an example of some things that
go wrong if foldTM is nondeterministic. Consider:
f a b = return (a <> b)
Depending on the order that the typechecker generates constraints you
get either:
f :: (Monad m, Monoid a) => a -> a -> m a
or:
f :: (Monoid a, Monad m) => a -> a -> m a
The generated code will be different after desugaring as the dictionaries
will be bound in different orders, leading to potential ABI incompatibility.
One way to solve this would be to notice that the typeclasses could be
sorted alphabetically.
Unfortunately that doesn't quite work with this example:
f a b = let x = a <> a; y = b <> b in x
where you infer:
f :: (Monoid m, Monoid m1) => m1 -> m -> m1
or:
f :: (Monoid m1, Monoid m) => m1 -> m -> m1
Here you could decide to take the order of the type variables in the type
according to depth first traversal and use it to order the constraints.
The real trouble starts when the user enables incoherent instances and
the compiler has to make an arbitrary choice. Consider:
class T a b where
go :: a -> b -> String
instance (Show b) => T Int b where
go a b = show a ++ show b
instance (Show a) => T a Bool where
go a b = show a ++ show b
f = go 10 True
GHC is free to choose either dictionary to implement f, but for the sake of
determinism we'd like it to be consistent when compiling the same sources
with the same flags.
inert_dicts :: DictMap is implemented with a TrieMap. In getUnsolvedInerts it
gets converted to a bag of (Wanted) Cts using a fold. Then in
solve_simple_wanteds it's merged with other WantedConstraints. We want the
conversion to a bag to be deterministic. For that purpose we use UniqDFM
instead of UniqFM to implement the TrieMap.
See Note [Deterministic UniqFM] in UniqDFM for more details on how it's made
deterministic.
-}
instance TrieMap UniqDFM where
type Key UniqDFM = Unique
emptyTM = emptyUDFM
lookupTM k m = lookupUDFM m k
alterTM k f m = alterUDFM f m k
foldTM k m z = foldUDFM k z m
mapTM f m = mapUDFM f m
{-
************************************************************************
* *
Maybes
* *
************************************************************************
If m is a map from k -> val
then (MaybeMap m) is a map from (Maybe k) -> val
-}
data MaybeMap m a = MM { mm_nothing :: Maybe a, mm_just :: m a }
instance TrieMap m => TrieMap (MaybeMap m) where
type Key (MaybeMap m) = Maybe (Key m)
emptyTM = MM { mm_nothing = Nothing, mm_just = emptyTM }
lookupTM = lkMaybe lookupTM
alterTM = xtMaybe alterTM
foldTM = fdMaybe
mapTM = mapMb
mapMb :: TrieMap m => (a->b) -> MaybeMap m a -> MaybeMap m b
mapMb f (MM { mm_nothing = mn, mm_just = mj })
= MM { mm_nothing = fmap f mn, mm_just = mapTM f mj }
lkMaybe :: (forall b. k -> m b -> Maybe b)
-> Maybe k -> MaybeMap m a -> Maybe a
lkMaybe _ Nothing = mm_nothing
lkMaybe lk (Just x) = mm_just >.> lk x
xtMaybe :: (forall b. k -> XT b -> m b -> m b)
-> Maybe k -> XT a -> MaybeMap m a -> MaybeMap m a
xtMaybe _ Nothing f m = m { mm_nothing = f (mm_nothing m) }
xtMaybe tr (Just x) f m = m { mm_just = mm_just m |> tr x f }
fdMaybe :: TrieMap m => (a -> b -> b) -> MaybeMap m a -> b -> b
fdMaybe k m = foldMaybe k (mm_nothing m)
. foldTM k (mm_just m)
{-
************************************************************************
* *
Lists
* *
************************************************************************
-}
data ListMap m a
= LM { lm_nil :: Maybe a
, lm_cons :: m (ListMap m a) }
instance TrieMap m => TrieMap (ListMap m) where
type Key (ListMap m) = [Key m]
emptyTM = LM { lm_nil = Nothing, lm_cons = emptyTM }
lookupTM = lkList lookupTM
alterTM = xtList alterTM
foldTM = fdList
mapTM = mapList
mapList :: TrieMap m => (a->b) -> ListMap m a -> ListMap m b
mapList f (LM { lm_nil = mnil, lm_cons = mcons })
= LM { lm_nil = fmap f mnil, lm_cons = mapTM (mapTM f) mcons }
lkList :: TrieMap m => (forall b. k -> m b -> Maybe b)
-> [k] -> ListMap m a -> Maybe a
lkList _ [] = lm_nil
lkList lk (x:xs) = lm_cons >.> lk x >=> lkList lk xs
xtList :: TrieMap m => (forall b. k -> XT b -> m b -> m b)
-> [k] -> XT a -> ListMap m a -> ListMap m a
xtList _ [] f m = m { lm_nil = f (lm_nil m) }
xtList tr (x:xs) f m = m { lm_cons = lm_cons m |> tr x |>> xtList tr xs f }
fdList :: forall m a b. TrieMap m
=> (a -> b -> b) -> ListMap m a -> b -> b
fdList k m = foldMaybe k (lm_nil m)
. foldTM (fdList k) (lm_cons m)
foldMaybe :: (a -> b -> b) -> Maybe a -> b -> b
foldMaybe _ Nothing b = b
foldMaybe k (Just a) b = k a b
{-
************************************************************************
* *
Basic maps
* *
************************************************************************
-}
lkDNamed :: NamedThing n => n -> DNameEnv a -> Maybe a
lkDNamed n env = lookupDNameEnv env (getName n)
xtDNamed :: NamedThing n => n -> XT a -> DNameEnv a -> DNameEnv a
xtDNamed tc f m = alterDNameEnv f m (getName tc)
------------------------
type LiteralMap a = Map.Map Literal a
emptyLiteralMap :: LiteralMap a
emptyLiteralMap = emptyTM
lkLit :: Literal -> LiteralMap a -> Maybe a
lkLit = lookupTM
xtLit :: Literal -> XT a -> LiteralMap a -> LiteralMap a
xtLit = alterTM
{-
************************************************************************
* *
GenMap
* *
************************************************************************
Note [Compressed TrieMap]
~~~~~~~~~~~~~~~~~~~~~~~~~
The GenMap constructor augments TrieMaps with leaf compression. This helps
solve the performance problem detailed in #9960: suppose we have a handful
H of entries in a TrieMap, each with a very large key, size K. If you fold over
such a TrieMap you'd expect time O(H). That would certainly be true of an
association list! But with TrieMap we actually have to navigate down a long
singleton structure to get to the elements, so it takes time O(K*H). This
can really hurt on many type-level computation benchmarks:
see for example T9872d.
The point of a TrieMap is that you need to navigate to the point where only one
key remains, and then things should be fast. So the point of a SingletonMap
is that, once we are down to a single (key,value) pair, we stop and
just use SingletonMap.
'EmptyMap' provides an even more basic (but essential) optimization: if there is
nothing in the map, don't bother building out the (possibly infinite) recursive
TrieMap structure!
-}
data GenMap m a
= EmptyMap
| SingletonMap (Key m) a
| MultiMap (m a)
instance (Outputable a, Outputable (m a)) => Outputable (GenMap m a) where
ppr EmptyMap = text "Empty map"
ppr (SingletonMap _ v) = text "Singleton map" <+> ppr v
ppr (MultiMap m) = ppr m
-- TODO undecidable instance
instance (Eq (Key m), TrieMap m) => TrieMap (GenMap m) where
type Key (GenMap m) = Key m
emptyTM = EmptyMap
lookupTM = lkG
alterTM = xtG
foldTM = fdG
mapTM = mapG
-- NB: Be careful about RULES and type families (#5821). So we should make sure
-- to specify @Key TypeMapX@ (and not @DeBruijn Type@, the reduced form)
{-# SPECIALIZE lkG :: Key TypeMapX -> TypeMapG a -> Maybe a #-}
{-# SPECIALIZE lkG :: Key CoercionMapX -> CoercionMapG a -> Maybe a #-}
{-# SPECIALIZE lkG :: Key CoreMapX -> CoreMapG a -> Maybe a #-}
lkG :: (Eq (Key m), TrieMap m) => Key m -> GenMap m a -> Maybe a
lkG _ EmptyMap = Nothing
lkG k (SingletonMap k' v') | k == k' = Just v'
| otherwise = Nothing
lkG k (MultiMap m) = lookupTM k m
{-# SPECIALIZE xtG :: Key TypeMapX -> XT a -> TypeMapG a -> TypeMapG a #-}
{-# SPECIALIZE xtG :: Key CoercionMapX -> XT a -> CoercionMapG a -> CoercionMapG a #-}
{-# SPECIALIZE xtG :: Key CoreMapX -> XT a -> CoreMapG a -> CoreMapG a #-}
xtG :: (Eq (Key m), TrieMap m) => Key m -> XT a -> GenMap m a -> GenMap m a
xtG k f EmptyMap
= case f Nothing of
Just v -> SingletonMap k v
Nothing -> EmptyMap
xtG k f m@(SingletonMap k' v')
| k' == k
-- The new key matches the (single) key already in the tree. Hence,
-- apply @f@ to @Just v'@ and build a singleton or empty map depending
-- on the 'Just'/'Nothing' response respectively.
= case f (Just v') of
Just v'' -> SingletonMap k' v''
Nothing -> EmptyMap
| otherwise
-- We've hit a singleton tree for a different key than the one we are
-- searching for. Hence apply @f@ to @Nothing@. If result is @Nothing@ then
-- we can just return the old map. If not, we need a map with *two*
-- entries. The easiest way to do that is to insert two items into an empty
-- map of type @m a@.
= case f Nothing of
Nothing -> m
Just v -> emptyTM |> alterTM k' (const (Just v'))
>.> alterTM k (const (Just v))
>.> MultiMap
xtG k f (MultiMap m) = MultiMap (alterTM k f m)
{-# SPECIALIZE mapG :: (a -> b) -> TypeMapG a -> TypeMapG b #-}
{-# SPECIALIZE mapG :: (a -> b) -> CoercionMapG a -> CoercionMapG b #-}
{-# SPECIALIZE mapG :: (a -> b) -> CoreMapG a -> CoreMapG b #-}
mapG :: TrieMap m => (a -> b) -> GenMap m a -> GenMap m b
mapG _ EmptyMap = EmptyMap
mapG f (SingletonMap k v) = SingletonMap k (f v)
mapG f (MultiMap m) = MultiMap (mapTM f m)
{-# SPECIALIZE fdG :: (a -> b -> b) -> TypeMapG a -> b -> b #-}
{-# SPECIALIZE fdG :: (a -> b -> b) -> CoercionMapG a -> b -> b #-}
{-# SPECIALIZE fdG :: (a -> b -> b) -> CoreMapG a -> b -> b #-}
fdG :: TrieMap m => (a -> b -> b) -> GenMap m a -> b -> b
fdG _ EmptyMap = \z -> z
fdG k (SingletonMap _ v) = \z -> k v z
fdG k (MultiMap m) = foldTM k m
{-
************************************************************************
* *
CoreMap
* *
************************************************************************
Note [Binders]
~~~~~~~~~~~~~~
* In general we check binders as late as possible because types are
less likely to differ than expression structure. That's why
cm_lam :: CoreMapG (TypeMapG a)
rather than
cm_lam :: TypeMapG (CoreMapG a)
* We don't need to look at the type of some binders, notalby
- the case binder in (Case _ b _ _)
- the binders in an alternative
because they are totally fixed by the context
Note [Empty case alternatives]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* For a key (Case e b ty (alt:alts)) we don't need to look the return type
'ty', because every alternative has that type.
* For a key (Case e b ty []) we MUST look at the return type 'ty', because
otherwise (Case (error () "urk") _ Int []) would compare equal to
(Case (error () "urk") _ Bool [])
which is utterly wrong (Trac #6097)
We could compare the return type regardless, but the wildly common case
is that it's unnecessary, so we have two fields (cm_case and cm_ecase)
for the two possibilities. Only cm_ecase looks at the type.
See also Note [Empty case alternatives] in CoreSyn.
-}
-- | @CoreMap a@ is a map from 'CoreExpr' to @a@. If you are a client, this
-- is the type you want.
newtype CoreMap a = CoreMap (CoreMapG a)
instance TrieMap CoreMap where
type Key CoreMap = CoreExpr
emptyTM = CoreMap emptyTM
lookupTM k (CoreMap m) = lookupTM (deBruijnize k) m
alterTM k f (CoreMap m) = CoreMap (alterTM (deBruijnize k) f m)
foldTM k (CoreMap m) = foldTM k m
mapTM f (CoreMap m) = CoreMap (mapTM f m)
-- | @CoreMapG a@ is a map from @DeBruijn CoreExpr@ to @a@. The extended
-- key makes it suitable for recursive traversal, since it can track binders,
-- but it is strictly internal to this module. If you are including a 'CoreMap'
-- inside another 'TrieMap', this is the type you want.
type CoreMapG = GenMap CoreMapX
-- | @CoreMapX a@ is the base map from @DeBruijn CoreExpr@ to @a@, but without
-- the 'GenMap' optimization.
data CoreMapX a
= CM { cm_var :: VarMap a
, cm_lit :: LiteralMap a
, cm_co :: CoercionMapG a
, cm_type :: TypeMapG a
, cm_cast :: CoreMapG (CoercionMapG a)
, cm_tick :: CoreMapG (TickishMap a)
, cm_app :: CoreMapG (CoreMapG a)
, cm_lam :: CoreMapG (BndrMap a) -- Note [Binders]
, cm_letn :: CoreMapG (CoreMapG (BndrMap a))
, cm_letr :: ListMap CoreMapG (CoreMapG (ListMap BndrMap a))
, cm_case :: CoreMapG (ListMap AltMap a)
, cm_ecase :: CoreMapG (TypeMapG a) -- Note [Empty case alternatives]
}
instance Eq (DeBruijn CoreExpr) where
D env1 e1 == D env2 e2 = go e1 e2 where
go (Var v1) (Var v2) = case (lookupCME env1 v1, lookupCME env2 v2) of
(Just b1, Just b2) -> b1 == b2
(Nothing, Nothing) -> v1 == v2
_ -> False
go (Lit lit1) (Lit lit2) = lit1 == lit2
go (Type t1) (Type t2) = D env1 t1 == D env2 t2
go (Coercion co1) (Coercion co2) = D env1 co1 == D env2 co2
go (Cast e1 co1) (Cast e2 co2) = D env1 co1 == D env2 co2 && go e1 e2
go (App f1 a1) (App f2 a2) = go f1 f2 && go a1 a2
-- This seems a bit dodgy, see 'eqTickish'
go (Tick n1 e1) (Tick n2 e2) = n1 == n2 && go e1 e2
go (Lam b1 e1) (Lam b2 e2)
= D env1 (varType b1) == D env2 (varType b2)
&& D (extendCME env1 b1) e1 == D (extendCME env2 b2) e2
go (Let (NonRec v1 r1) e1) (Let (NonRec v2 r2) e2)
= go r1 r2
&& D (extendCME env1 v1) e1 == D (extendCME env2 v2) e2
go (Let (Rec ps1) e1) (Let (Rec ps2) e2)
= length ps1 == length ps2
&& D env1' rs1 == D env2' rs2
&& D env1' e1 == D env2' e2
where
(bs1,rs1) = unzip ps1
(bs2,rs2) = unzip ps2
env1' = extendCMEs env1 bs1
env2' = extendCMEs env2 bs2
go (Case e1 b1 t1 a1) (Case e2 b2 t2 a2)
| null a1 -- See Note [Empty case alternatives]
= null a2 && go e1 e2 && D env1 t1 == D env2 t2
| otherwise
= go e1 e2 && D (extendCME env1 b1) a1 == D (extendCME env2 b2) a2
go _ _ = False
emptyE :: CoreMapX a
emptyE = CM { cm_var = emptyTM, cm_lit = emptyLiteralMap
, cm_co = emptyTM, cm_type = emptyTM
, cm_cast = emptyTM, cm_app = emptyTM
, cm_lam = emptyTM, cm_letn = emptyTM
, cm_letr = emptyTM, cm_case = emptyTM
, cm_ecase = emptyTM, cm_tick = emptyTM }
instance TrieMap CoreMapX where
type Key CoreMapX = DeBruijn CoreExpr
emptyTM = emptyE
lookupTM = lkE
alterTM = xtE
foldTM = fdE
mapTM = mapE
--------------------------
mapE :: (a->b) -> CoreMapX a -> CoreMapX b
mapE f (CM { cm_var = cvar, cm_lit = clit
, cm_co = cco, cm_type = ctype
, cm_cast = ccast , cm_app = capp
, cm_lam = clam, cm_letn = cletn
, cm_letr = cletr, cm_case = ccase
, cm_ecase = cecase, cm_tick = ctick })
= CM { cm_var = mapTM f cvar, cm_lit = mapTM f clit
, cm_co = mapTM f cco, cm_type = mapTM f ctype
, cm_cast = mapTM (mapTM f) ccast, cm_app = mapTM (mapTM f) capp
, cm_lam = mapTM (mapTM f) clam, cm_letn = mapTM (mapTM (mapTM f)) cletn
, cm_letr = mapTM (mapTM (mapTM f)) cletr, cm_case = mapTM (mapTM f) ccase
, cm_ecase = mapTM (mapTM f) cecase, cm_tick = mapTM (mapTM f) ctick }
--------------------------
lookupCoreMap :: CoreMap a -> CoreExpr -> Maybe a
lookupCoreMap cm e = lookupTM e cm
extendCoreMap :: CoreMap a -> CoreExpr -> a -> CoreMap a
extendCoreMap m e v = alterTM e (\_ -> Just v) m
foldCoreMap :: (a -> b -> b) -> b -> CoreMap a -> b
foldCoreMap k z m = foldTM k m z
emptyCoreMap :: CoreMap a
emptyCoreMap = emptyTM
instance Outputable a => Outputable (CoreMap a) where
ppr m = text "CoreMap elts" <+> ppr (foldTM (:) m [])
-------------------------
fdE :: (a -> b -> b) -> CoreMapX a -> b -> b
fdE k m
= foldTM k (cm_var m)
. foldTM k (cm_lit m)
. foldTM k (cm_co m)
. foldTM k (cm_type m)
. foldTM (foldTM k) (cm_cast m)
. foldTM (foldTM k) (cm_tick m)
. foldTM (foldTM k) (cm_app m)
. foldTM (foldTM k) (cm_lam m)
. foldTM (foldTM (foldTM k)) (cm_letn m)
. foldTM (foldTM (foldTM k)) (cm_letr m)
. foldTM (foldTM k) (cm_case m)
. foldTM (foldTM k) (cm_ecase m)
-- lkE: lookup in trie for expressions
lkE :: DeBruijn CoreExpr -> CoreMapX a -> Maybe a
lkE (D env expr) cm = go expr cm
where
go (Var v) = cm_var >.> lkVar env v
go (Lit l) = cm_lit >.> lkLit l
go (Type t) = cm_type >.> lkG (D env t)
go (Coercion c) = cm_co >.> lkG (D env c)
go (Cast e c) = cm_cast >.> lkG (D env e) >=> lkG (D env c)
go (Tick tickish e) = cm_tick >.> lkG (D env e) >=> lkTickish tickish
go (App e1 e2) = cm_app >.> lkG (D env e2) >=> lkG (D env e1)
go (Lam v e) = cm_lam >.> lkG (D (extendCME env v) e)
>=> lkBndr env v
go (Let (NonRec b r) e) = cm_letn >.> lkG (D env r)
>=> lkG (D (extendCME env b) e) >=> lkBndr env b
go (Let (Rec prs) e) = let (bndrs,rhss) = unzip prs
env1 = extendCMEs env bndrs
in cm_letr
>.> lkList (lkG . D env1) rhss
>=> lkG (D env1 e)
>=> lkList (lkBndr env1) bndrs
go (Case e b ty as) -- See Note [Empty case alternatives]
| null as = cm_ecase >.> lkG (D env e) >=> lkG (D env ty)
| otherwise = cm_case >.> lkG (D env e)
>=> lkList (lkA (extendCME env b)) as
xtE :: DeBruijn CoreExpr -> XT a -> CoreMapX a -> CoreMapX a
xtE (D env (Var v)) f m = m { cm_var = cm_var m
|> xtVar env v f }
xtE (D env (Type t)) f m = m { cm_type = cm_type m
|> xtG (D env t) f }
xtE (D env (Coercion c)) f m = m { cm_co = cm_co m
|> xtG (D env c) f }
xtE (D _ (Lit l)) f m = m { cm_lit = cm_lit m |> xtLit l f }
xtE (D env (Cast e c)) f m = m { cm_cast = cm_cast m |> xtG (D env e)
|>> xtG (D env c) f }
xtE (D env (Tick t e)) f m = m { cm_tick = cm_tick m |> xtG (D env e)
|>> xtTickish t f }
xtE (D env (App e1 e2)) f m = m { cm_app = cm_app m |> xtG (D env e2)
|>> xtG (D env e1) f }
xtE (D env (Lam v e)) f m = m { cm_lam = cm_lam m
|> xtG (D (extendCME env v) e)
|>> xtBndr env v f }
xtE (D env (Let (NonRec b r) e)) f m = m { cm_letn = cm_letn m
|> xtG (D (extendCME env b) e)
|>> xtG (D env r)
|>> xtBndr env b f }
xtE (D env (Let (Rec prs) e)) f m = m { cm_letr =
let (bndrs,rhss) = unzip prs
env1 = extendCMEs env bndrs
in cm_letr m
|> xtList (xtG . D env1) rhss
|>> xtG (D env1 e)
|>> xtList (xtBndr env1)
bndrs f }
xtE (D env (Case e b ty as)) f m
| null as = m { cm_ecase = cm_ecase m |> xtG (D env e)
|>> xtG (D env ty) f }
| otherwise = m { cm_case = cm_case m |> xtG (D env e)
|>> let env1 = extendCME env b
in xtList (xtA env1) as f }
-- TODO: this seems a bit dodgy, see 'eqTickish'
type TickishMap a = Map.Map (Tickish Id) a
lkTickish :: Tickish Id -> TickishMap a -> Maybe a
lkTickish = lookupTM
xtTickish :: Tickish Id -> XT a -> TickishMap a -> TickishMap a
xtTickish = alterTM
------------------------
data AltMap a -- A single alternative
= AM { am_deflt :: CoreMapG a
, am_data :: DNameEnv (CoreMapG a)
, am_lit :: LiteralMap (CoreMapG a) }
instance TrieMap AltMap where
type Key AltMap = CoreAlt
emptyTM = AM { am_deflt = emptyTM
, am_data = emptyDNameEnv
, am_lit = emptyLiteralMap }
lookupTM = lkA emptyCME
alterTM = xtA emptyCME
foldTM = fdA
mapTM = mapA
instance Eq (DeBruijn CoreAlt) where
D env1 a1 == D env2 a2 = go a1 a2 where
go (DEFAULT, _, rhs1) (DEFAULT, _, rhs2)
= D env1 rhs1 == D env2 rhs2
go (LitAlt lit1, _, rhs1) (LitAlt lit2, _, rhs2)
= lit1 == lit2 && D env1 rhs1 == D env2 rhs2
go (DataAlt dc1, bs1, rhs1) (DataAlt dc2, bs2, rhs2)
= dc1 == dc2 &&
D (extendCMEs env1 bs1) rhs1 == D (extendCMEs env2 bs2) rhs2
go _ _ = False
mapA :: (a->b) -> AltMap a -> AltMap b
mapA f (AM { am_deflt = adeflt, am_data = adata, am_lit = alit })
= AM { am_deflt = mapTM f adeflt
, am_data = mapTM (mapTM f) adata
, am_lit = mapTM (mapTM f) alit }
lkA :: CmEnv -> CoreAlt -> AltMap a -> Maybe a
lkA env (DEFAULT, _, rhs) = am_deflt >.> lkG (D env rhs)
lkA env (LitAlt lit, _, rhs) = am_lit >.> lkLit lit >=> lkG (D env rhs)
lkA env (DataAlt dc, bs, rhs) = am_data >.> lkDNamed dc
>=> lkG (D (extendCMEs env bs) rhs)
xtA :: CmEnv -> CoreAlt -> XT a -> AltMap a -> AltMap a
xtA env (DEFAULT, _, rhs) f m =
m { am_deflt = am_deflt m |> xtG (D env rhs) f }
xtA env (LitAlt l, _, rhs) f m =
m { am_lit = am_lit m |> xtLit l |>> xtG (D env rhs) f }
xtA env (DataAlt d, bs, rhs) f m =
m { am_data = am_data m |> xtDNamed d
|>> xtG (D (extendCMEs env bs) rhs) f }
fdA :: (a -> b -> b) -> AltMap a -> b -> b
fdA k m = foldTM k (am_deflt m)
. foldTM (foldTM k) (am_data m)
. foldTM (foldTM k) (am_lit m)
{-
************************************************************************
* *
Coercions
* *
************************************************************************
-}
-- We should really never care about the contents of a coercion. Instead,
-- just look up the coercion's type.
newtype CoercionMap a = CoercionMap (CoercionMapG a)
instance TrieMap CoercionMap where
type Key CoercionMap = Coercion
emptyTM = CoercionMap emptyTM
lookupTM k (CoercionMap m) = lookupTM (deBruijnize k) m
alterTM k f (CoercionMap m) = CoercionMap (alterTM (deBruijnize k) f m)
foldTM k (CoercionMap m) = foldTM k m
mapTM f (CoercionMap m) = CoercionMap (mapTM f m)
type CoercionMapG = GenMap CoercionMapX
newtype CoercionMapX a = CoercionMapX (TypeMapX a)
instance TrieMap CoercionMapX where
type Key CoercionMapX = DeBruijn Coercion
emptyTM = CoercionMapX emptyTM
lookupTM = lkC
alterTM = xtC
foldTM f (CoercionMapX core_tm) = foldTM f core_tm
mapTM f (CoercionMapX core_tm) = CoercionMapX (mapTM f core_tm)
instance Eq (DeBruijn Coercion) where
D env1 co1 == D env2 co2
= D env1 (coercionType co1) ==
D env2 (coercionType co2)
lkC :: DeBruijn Coercion -> CoercionMapX a -> Maybe a
lkC (D env co) (CoercionMapX core_tm) = lkT (D env $ coercionType co)
core_tm
xtC :: DeBruijn Coercion -> XT a -> CoercionMapX a -> CoercionMapX a
xtC (D env co) f (CoercionMapX m)
= CoercionMapX (xtT (D env $ coercionType co) f m)
{-
************************************************************************
* *
Types
* *
************************************************************************
-}
-- | @TypeMapG a@ is a map from @DeBruijn Type@ to @a@. The extended
-- key makes it suitable for recursive traversal, since it can track binders,
-- but it is strictly internal to this module. If you are including a 'TypeMap'
-- inside another 'TrieMap', this is the type you want. Note that this
-- lookup does not do a kind-check. Thus, all keys in this map must have
-- the same kind. Also note that this map respects the distinction between
-- @Type@ and @Constraint@, despite the fact that they are equivalent type
-- synonyms in Core.
type TypeMapG = GenMap TypeMapX
-- | @TypeMapX a@ is the base map from @DeBruijn Type@ to @a@, but without the
-- 'GenMap' optimization.
data TypeMapX a
= TM { tm_var :: VarMap a
, tm_app :: TypeMapG (TypeMapG a)
, tm_tycon :: DNameEnv a
, tm_forall :: TypeMapG (BndrMap a) -- See Note [Binders]
, tm_tylit :: TyLitMap a
, tm_coerce :: Maybe a
}
-- Note that there is no tyconapp case; see Note [Equality on AppTys] in Type
-- | Squeeze out any synonyms, and change TyConApps to nested AppTys. Why the
-- last one? See Note [Equality on AppTys] in Type
--
-- Note, however, that we keep Constraint and Type apart here, despite the fact
-- that they are both synonyms of TYPE 'LiftedRep (see #11715).
trieMapView :: Type -> Maybe Type
trieMapView ty
-- First check for TyConApps that need to be expanded to
-- AppTy chains.
| Just (tc, tys@(_:_)) <- tcSplitTyConApp_maybe ty
= Just $ foldl AppTy (TyConApp tc []) tys
-- Then resolve any remaining nullary synonyms.
| Just ty' <- tcView ty = Just ty'
trieMapView _ = Nothing
instance TrieMap TypeMapX where
type Key TypeMapX = DeBruijn Type
emptyTM = emptyT
lookupTM = lkT
alterTM = xtT
foldTM = fdT
mapTM = mapT
instance Eq (DeBruijn Type) where
env_t@(D env t) == env_t'@(D env' t')
| Just new_t <- tcView t = D env new_t == env_t'
| Just new_t' <- tcView t' = env_t == D env' new_t'
| otherwise
= case (t, t') of
(CastTy t1 _, _) -> D env t1 == D env t'
(_, CastTy t1' _) -> D env t == D env t1'
(TyVarTy v, TyVarTy v')
-> case (lookupCME env v, lookupCME env' v') of
(Just bv, Just bv') -> bv == bv'
(Nothing, Nothing) -> v == v'
_ -> False
-- See Note [Equality on AppTys] in Type
(AppTy t1 t2, s) | Just (t1', t2') <- repSplitAppTy_maybe s
-> D env t1 == D env' t1' && D env t2 == D env' t2'
(s, AppTy t1' t2') | Just (t1, t2) <- repSplitAppTy_maybe s
-> D env t1 == D env' t1' && D env t2 == D env' t2'
(FunTy t1 t2, FunTy t1' t2')
-> D env t1 == D env' t1' && D env t2 == D env' t2'
(TyConApp tc tys, TyConApp tc' tys')
-> tc == tc' && D env tys == D env' tys'
(LitTy l, LitTy l')
-> l == l'
(ForAllTy (TvBndr tv _) ty, ForAllTy (TvBndr tv' _) ty')
-> D env (tyVarKind tv) == D env' (tyVarKind tv') &&
D (extendCME env tv) ty == D (extendCME env' tv') ty'
(CoercionTy {}, CoercionTy {})
-> True
_ -> False
instance {-# OVERLAPPING #-}
Outputable a => Outputable (TypeMapG a) where
ppr m = text "TypeMap elts" <+> ppr (foldTM (:) m [])
emptyT :: TypeMapX a
emptyT = TM { tm_var = emptyTM
, tm_app = EmptyMap
, tm_tycon = emptyDNameEnv
, tm_forall = EmptyMap
, tm_tylit = emptyTyLitMap
, tm_coerce = Nothing }
mapT :: (a->b) -> TypeMapX a -> TypeMapX b
mapT f (TM { tm_var = tvar, tm_app = tapp, tm_tycon = ttycon
, tm_forall = tforall, tm_tylit = tlit
, tm_coerce = tcoerce })
= TM { tm_var = mapTM f tvar
, tm_app = mapTM (mapTM f) tapp
, tm_tycon = mapTM f ttycon
, tm_forall = mapTM (mapTM f) tforall
, tm_tylit = mapTM f tlit
, tm_coerce = fmap f tcoerce }
-----------------
lkT :: DeBruijn Type -> TypeMapX a -> Maybe a
lkT (D env ty) m = go ty m
where
go ty | Just ty' <- trieMapView ty = go ty'
go (TyVarTy v) = tm_var >.> lkVar env v
go (AppTy t1 t2) = tm_app >.> lkG (D env t1)
>=> lkG (D env t2)
go (TyConApp tc []) = tm_tycon >.> lkDNamed tc
go ty@(TyConApp _ (_:_)) = pprPanic "lkT TyConApp" (ppr ty)
go (LitTy l) = tm_tylit >.> lkTyLit l
go (ForAllTy (TvBndr tv _) ty) = tm_forall >.> lkG (D (extendCME env tv) ty)
>=> lkBndr env tv
go ty@(FunTy {}) = pprPanic "lkT FunTy" (ppr ty)
go (CastTy t _) = go t
go (CoercionTy {}) = tm_coerce
-----------------
xtT :: DeBruijn Type -> XT a -> TypeMapX a -> TypeMapX a
xtT (D env ty) f m | Just ty' <- trieMapView ty = xtT (D env ty') f m
xtT (D env (TyVarTy v)) f m = m { tm_var = tm_var m |> xtVar env v f }
xtT (D env (AppTy t1 t2)) f m = m { tm_app = tm_app m |> xtG (D env t1)
|>> xtG (D env t2) f }
xtT (D _ (TyConApp tc [])) f m = m { tm_tycon = tm_tycon m |> xtDNamed tc f }
xtT (D _ (LitTy l)) f m = m { tm_tylit = tm_tylit m |> xtTyLit l f }
xtT (D env (CastTy t _)) f m = xtT (D env t) f m
xtT (D _ (CoercionTy {})) f m = m { tm_coerce = tm_coerce m |> f }
xtT (D env (ForAllTy (TvBndr tv _) ty)) f m
= m { tm_forall = tm_forall m |> xtG (D (extendCME env tv) ty)
|>> xtBndr env tv f }
xtT (D _ ty@(TyConApp _ (_:_))) _ _ = pprPanic "xtT TyConApp" (ppr ty)
xtT (D _ ty@(FunTy {})) _ _ = pprPanic "xtT FunTy" (ppr ty)
fdT :: (a -> b -> b) -> TypeMapX a -> b -> b
fdT k m = foldTM k (tm_var m)
. foldTM (foldTM k) (tm_app m)
. foldTM k (tm_tycon m)
. foldTM (foldTM k) (tm_forall m)
. foldTyLit k (tm_tylit m)
. foldMaybe k (tm_coerce m)
------------------------
data TyLitMap a = TLM { tlm_number :: Map.Map Integer a
, tlm_string :: Map.Map FastString a
}
instance TrieMap TyLitMap where
type Key TyLitMap = TyLit
emptyTM = emptyTyLitMap
lookupTM = lkTyLit
alterTM = xtTyLit
foldTM = foldTyLit
mapTM = mapTyLit
emptyTyLitMap :: TyLitMap a
emptyTyLitMap = TLM { tlm_number = Map.empty, tlm_string = Map.empty }
mapTyLit :: (a->b) -> TyLitMap a -> TyLitMap b
mapTyLit f (TLM { tlm_number = tn, tlm_string = ts })
= TLM { tlm_number = Map.map f tn, tlm_string = Map.map f ts }
lkTyLit :: TyLit -> TyLitMap a -> Maybe a
lkTyLit l =
case l of
NumTyLit n -> tlm_number >.> Map.lookup n
StrTyLit n -> tlm_string >.> Map.lookup n
xtTyLit :: TyLit -> XT a -> TyLitMap a -> TyLitMap a
xtTyLit l f m =
case l of
NumTyLit n -> m { tlm_number = tlm_number m |> Map.alter f n }
StrTyLit n -> m { tlm_string = tlm_string m |> Map.alter f n }
foldTyLit :: (a -> b -> b) -> TyLitMap a -> b -> b
foldTyLit l m = flip (Map.foldr l) (tlm_string m)
. flip (Map.foldr l) (tlm_number m)
-------------------------------------------------
-- | @TypeMap a@ is a map from 'Type' to @a@. If you are a client, this
-- is the type you want. The keys in this map may have different kinds.
newtype TypeMap a = TypeMap (TypeMapG (TypeMapG a))
lkTT :: DeBruijn Type -> TypeMap a -> Maybe a
lkTT (D env ty) (TypeMap m) = lkG (D env $ typeKind ty) m
>>= lkG (D env ty)
xtTT :: DeBruijn Type -> XT a -> TypeMap a -> TypeMap a
xtTT (D env ty) f (TypeMap m)
= TypeMap (m |> xtG (D env $ typeKind ty)
|>> xtG (D env ty) f)
-- Below are some client-oriented functions which operate on 'TypeMap'.
instance TrieMap TypeMap where
type Key TypeMap = Type
emptyTM = TypeMap emptyTM
lookupTM k m = lkTT (deBruijnize k) m
alterTM k f m = xtTT (deBruijnize k) f m
foldTM k (TypeMap m) = foldTM (foldTM k) m
mapTM f (TypeMap m) = TypeMap (mapTM (mapTM f) m)
foldTypeMap :: (a -> b -> b) -> b -> TypeMap a -> b
foldTypeMap k z m = foldTM k m z
emptyTypeMap :: TypeMap a
emptyTypeMap = emptyTM
lookupTypeMap :: TypeMap a -> Type -> Maybe a
lookupTypeMap cm t = lookupTM t cm
extendTypeMap :: TypeMap a -> Type -> a -> TypeMap a
extendTypeMap m t v = alterTM t (const (Just v)) m
lookupTypeMapWithScope :: TypeMap a -> CmEnv -> Type -> Maybe a
lookupTypeMapWithScope m cm t = lkTT (D cm t) m
-- | Extend a 'TypeMap' with a type in the given context.
-- @extendTypeMapWithScope m (mkDeBruijnContext [a,b,c]) t v@ is equivalent to
-- @extendTypeMap m (forall a b c. t) v@, but allows reuse of the context over
-- multiple insertions.
extendTypeMapWithScope :: TypeMap a -> CmEnv -> Type -> a -> TypeMap a
extendTypeMapWithScope m cm t v = xtTT (D cm t) (const (Just v)) m
-- | Construct a deBruijn environment with the given variables in scope.
-- e.g. @mkDeBruijnEnv [a,b,c]@ constructs a context @forall a b c.@
mkDeBruijnContext :: [Var] -> CmEnv
mkDeBruijnContext = extendCMEs emptyCME
-- | A 'LooseTypeMap' doesn't do a kind-check. Thus, when lookup up (t |> g),
-- you'll find entries inserted under (t), even if (g) is non-reflexive.
newtype LooseTypeMap a
= LooseTypeMap (TypeMapG a)
instance TrieMap LooseTypeMap where
type Key LooseTypeMap = Type
emptyTM = LooseTypeMap emptyTM
lookupTM k (LooseTypeMap m) = lookupTM (deBruijnize k) m
alterTM k f (LooseTypeMap m) = LooseTypeMap (alterTM (deBruijnize k) f m)
foldTM f (LooseTypeMap m) = foldTM f m
mapTM f (LooseTypeMap m) = LooseTypeMap (mapTM f m)
{-
************************************************************************
* *
Variables
* *
************************************************************************
-}
type BoundVar = Int -- Bound variables are deBruijn numbered
type BoundVarMap a = IntMap.IntMap a
data CmEnv = CME { cme_next :: !BoundVar
, cme_env :: VarEnv BoundVar }
emptyCME :: CmEnv
emptyCME = CME { cme_next = 0, cme_env = emptyVarEnv }
extendCME :: CmEnv -> Var -> CmEnv
extendCME (CME { cme_next = bv, cme_env = env }) v
= CME { cme_next = bv+1, cme_env = extendVarEnv env v bv }
extendCMEs :: CmEnv -> [Var] -> CmEnv
extendCMEs env vs = foldl extendCME env vs
lookupCME :: CmEnv -> Var -> Maybe BoundVar
lookupCME (CME { cme_env = env }) v = lookupVarEnv env v
-- | @DeBruijn a@ represents @a@ modulo alpha-renaming. This is achieved
-- by equipping the value with a 'CmEnv', which tracks an on-the-fly deBruijn
-- numbering. This allows us to define an 'Eq' instance for @DeBruijn a@, even
-- if this was not (easily) possible for @a@. Note: we purposely don't
-- export the constructor. Make a helper function if you find yourself
-- needing it.
data DeBruijn a = D CmEnv a
-- | Synthesizes a @DeBruijn a@ from an @a@, by assuming that there are no
-- bound binders (an empty 'CmEnv'). This is usually what you want if there
-- isn't already a 'CmEnv' in scope.
deBruijnize :: a -> DeBruijn a
deBruijnize = D emptyCME
instance Eq (DeBruijn a) => Eq (DeBruijn [a]) where
D _ [] == D _ [] = True
D env (x:xs) == D env' (x':xs') = D env x == D env' x' &&
D env xs == D env' xs'
_ == _ = False
--------- Variable binders -------------
-- | A 'BndrMap' is a 'TypeMapG' which allows us to distinguish between
-- binding forms whose binders have different types. For example,
-- if we are doing a 'TrieMap' lookup on @\(x :: Int) -> ()@, we should
-- not pick up an entry in the 'TrieMap' for @\(x :: Bool) -> ()@:
-- we can disambiguate this by matching on the type (or kind, if this
-- a binder in a type) of the binder.
type BndrMap = TypeMapG
-- Note [Binders]
-- ~~~~~~~~~~~~~~
-- We need to use 'BndrMap' for 'Coercion', 'CoreExpr' AND 'Type', since all
-- of these data types have binding forms.
lkBndr :: CmEnv -> Var -> BndrMap a -> Maybe a
lkBndr env v m = lkG (D env (varType v)) m
xtBndr :: CmEnv -> Var -> XT a -> BndrMap a -> BndrMap a
xtBndr env v f = xtG (D env (varType v)) f
--------- Variable occurrence -------------
data VarMap a = VM { vm_bvar :: BoundVarMap a -- Bound variable
, vm_fvar :: DVarEnv a } -- Free variable
instance TrieMap VarMap where
type Key VarMap = Var
emptyTM = VM { vm_bvar = IntMap.empty, vm_fvar = emptyDVarEnv }
lookupTM = lkVar emptyCME
alterTM = xtVar emptyCME
foldTM = fdVar
mapTM = mapVar
mapVar :: (a->b) -> VarMap a -> VarMap b
mapVar f (VM { vm_bvar = bv, vm_fvar = fv })
= VM { vm_bvar = mapTM f bv, vm_fvar = mapTM f fv }
lkVar :: CmEnv -> Var -> VarMap a -> Maybe a
lkVar env v
| Just bv <- lookupCME env v = vm_bvar >.> lookupTM bv
| otherwise = vm_fvar >.> lkDFreeVar v
xtVar :: CmEnv -> Var -> XT a -> VarMap a -> VarMap a
xtVar env v f m
| Just bv <- lookupCME env v = m { vm_bvar = vm_bvar m |> alterTM bv f }
| otherwise = m { vm_fvar = vm_fvar m |> xtDFreeVar v f }
fdVar :: (a -> b -> b) -> VarMap a -> b -> b
fdVar k m = foldTM k (vm_bvar m)
. foldTM k (vm_fvar m)
lkDFreeVar :: Var -> DVarEnv a -> Maybe a
lkDFreeVar var env = lookupDVarEnv env var
xtDFreeVar :: Var -> XT a -> DVarEnv a -> DVarEnv a
xtDFreeVar v f m = alterDVarEnv f m v