liquidhaskell-0.8.10.1: src/Language/Haskell/Liquid/Transforms/ANF.hs
--------------------------------------------------------------------------------
-- | Convert GHC Core into Administrative Normal Form (ANF) --------------------
--------------------------------------------------------------------------------
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE NoMonomorphismRestriction #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE OverloadedStrings #-}
module Language.Haskell.Liquid.Transforms.ANF (anormalize) where
import Prelude hiding (error)
import CoreSyn hiding (mkTyArg)
import CoreUtils (exprType)
import qualified DsMonad
import DsMonad (initDsWithModGuts)
import GHC hiding (exprType)
import HscTypes
import Literal
import MkCore (mkCoreLets)
import Outputable (trace)
import Language.Haskell.Liquid.GHC.TypeRep
import Language.Haskell.Liquid.GHC.API hiding (exprType, mkTyArg)
import VarEnv (VarEnv, emptyVarEnv, extendVarEnv, lookupWithDefaultVarEnv)
import UniqSupply (MonadUnique, getUniqueM)
import Control.Monad.State.Lazy
import System.Console.CmdArgs.Verbosity (whenLoud)
import qualified Language.Fixpoint.Misc as F
import qualified Language.Fixpoint.Types as F
import Language.Haskell.Liquid.UX.Config as UX
import qualified Language.Haskell.Liquid.Misc as Misc
import Language.Haskell.Liquid.GHC.Misc as GM
import Language.Haskell.Liquid.Transforms.Rec
import Language.Haskell.Liquid.Transforms.Rewrite
import Language.Haskell.Liquid.Types.Errors
import qualified Language.Haskell.Liquid.GHC.SpanStack as Sp
import qualified Language.Haskell.Liquid.GHC.Resugar as Rs
import Data.Maybe (fromMaybe)
import Data.List (sortBy, (\\))
import Data.Function (on)
import qualified Text.Printf as Printf
--------------------------------------------------------------------------------
-- | A-Normalize a module ------------------------------------------------------
--------------------------------------------------------------------------------
anormalize :: UX.Config -> HscEnv -> ModGuts -> IO [CoreBind]
--------------------------------------------------------------------------------
anormalize cfg hscEnv modGuts = do
whenLoud $ do
putStrLn "***************************** GHC CoreBinds ***************************"
putStrLn $ GM.showCBs untidy (mg_binds modGuts)
putStrLn "***************************** REC CoreBinds ***************************"
putStrLn $ GM.showCBs untidy orig_cbs
putStrLn "***************************** RWR CoreBinds ***************************"
putStrLn $ GM.showCBs untidy rwr_cbs
(fromMaybe err . snd) <$> initDsWithModGuts hscEnv modGuts act -- hscEnv m grEnv tEnv emptyFamInstEnv act
where
err = panic Nothing "Oops, cannot A-Normalize GHC Core!"
act = Misc.concatMapM (normalizeTopBind γ0) rwr_cbs
γ0 = emptyAnfEnv cfg
rwr_cbs = rewriteBinds cfg orig_cbs
orig_cbs = transformRecExpr $ mg_binds modGuts
untidy = UX.untidyCore cfg
{-
m = mgi_module modGuts
grEnv = mgi_rdr_env modGuts
tEnv = modGutsTypeEnv modGuts
modGutsTypeEnv :: MGIModGuts -> TypeEnv
modGutsTypeEnv mg = typeEnvFromEntities ids tcs fis
where
ids = bindersOfBinds (mgi_binds mg)
tcs = mgi_tcs mg
fis = mgi_fam_insts mg
-}
--------------------------------------------------------------------------------
-- | A-Normalize a @CoreBind@ --------------------------------------------------
--------------------------------------------------------------------------------
-- Can't make the below default for normalizeBind as it
-- fails tests/pos/lets.hs due to GHCs odd let-bindings
normalizeTopBind :: AnfEnv -> Bind CoreBndr -> DsMonad.DsM [CoreBind]
normalizeTopBind γ (NonRec x e)
= do e' <- runDsM $ evalStateT (stitch γ e) (DsST [])
return [normalizeTyVars $ NonRec x e']
normalizeTopBind γ (Rec xes)
= do xes' <- runDsM $ execStateT (normalizeBind γ (Rec xes)) (DsST [])
return $ map normalizeTyVars (st_binds xes')
normalizeTyVars :: Bind Id -> Bind Id
normalizeTyVars (NonRec x e) = NonRec (setVarType x t') $ normalizeForAllTys e
where
t' = subst msg as as' bt
msg = "WARNING: unable to renameVars on " ++ GM.showPpr x
as' = fst $ splitForAllTys $ exprType e
(as, bt) = splitForAllTys (varType x)
normalizeTyVars (Rec xes) = Rec xes'
where
nrec = normalizeTyVars <$> ((\(x, e) -> NonRec x e) <$> xes)
xes' = (\(NonRec x e) -> (x, e)) <$> nrec
subst :: String -> [TyVar] -> [TyVar] -> Type -> Type
subst msg as as' bt
| length as == length as'
= mkForAllTys (mkTyArg <$> as') $ substTy su bt
| otherwise
= trace msg $ mkForAllTys (mkTyArg <$> as) bt
where su = mkTvSubstPrs $ zip as (mkTyVarTys as')
-- | eta-expand CoreBinds with quantified types
normalizeForAllTys :: CoreExpr -> CoreExpr
normalizeForAllTys e = case e of
Lam b _ | isTyVar b
-> e
_ -> mkLams tvs (mkTyApps e (map mkTyVarTy tvs))
where
(tvs, _) = splitForAllTys (exprType e)
newtype DsM a = DsM {runDsM :: DsMonad.DsM a}
deriving (Functor, Monad, MonadUnique, Applicative)
data DsST = DsST { st_binds :: [CoreBind] }
type DsMW = StateT DsST DsM
------------------------------------------------------------------
normalizeBind :: AnfEnv -> CoreBind -> DsMW ()
------------------------------------------------------------------
normalizeBind γ (NonRec x e)
= do e' <- normalize γ e
add [NonRec x e']
normalizeBind γ (Rec xes)
= do es' <- mapM (stitch γ) es
add [Rec (zip xs es')]
where
(xs, es) = unzip xes
--------------------------------------------------------------------
normalizeName :: AnfEnv -> CoreExpr -> DsMW CoreExpr
--------------------------------------------------------------------
-- normalizeNameDebug γ e
-- = liftM (tracePpr ("normalizeName" ++ showPpr e)) $ normalizeName γ e
normalizeName γ e@(Lit l)
| shouldNormalize l
= normalizeLiteral γ e
| otherwise
= return e
normalizeName γ (Var x)
= return $ Var (lookupAnfEnv γ x x)
normalizeName _ e@(Type _)
= return e
normalizeName γ e@(Coercion _)
= do x <- lift $ freshNormalVar γ $ exprType e
add [NonRec x e]
return $ Var x
normalizeName γ (Tick tt e)
= do e' <- normalizeName (γ `at` tt) e
return $ Tick tt e'
normalizeName γ e
= do e' <- normalize γ e
x <- lift $ freshNormalVar γ $ exprType e
add [NonRec x e']
return $ Var x
shouldNormalize :: Literal -> Bool
shouldNormalize (LitNumber {}) = True
shouldNormalize (LitString {}) = True
shouldNormalize _ = False
add :: [CoreBind] -> DsMW ()
add w = modify $ \s -> s { st_binds = st_binds s ++ w}
--------------------------------------------------------------------------------
normalizeLiteral :: AnfEnv -> CoreExpr -> DsMW CoreExpr
--------------------------------------------------------------------------------
normalizeLiteral γ e =
do x <- lift $ freshNormalVar γ $ exprType e
add [NonRec x e]
return $ Var x
--------------------------------------------------------------------------------
normalize :: AnfEnv -> CoreExpr -> DsMW CoreExpr
--------------------------------------------------------------------------------
normalize γ e
| UX.patternFlag γ
, Just p <- Rs.lift e
= normalizePattern γ p
normalize γ (Lam x e) | isTyVar x
= do e' <- normalize γ e
return $ Lam x e'
normalize γ (Lam x e)
= do e' <- stitch γ e
return $ Lam x e'
normalize γ (Let b e)
= do normalizeBind γ b
normalize γ e
-- Need to float bindings all the way up to the top
-- Due to GHCs odd let-bindings (see tests/pos/lets.hs)
normalize γ (Case e x t as)
= do n <- normalizeName γ e
x' <- lift $ freshNormalVar γ τx -- rename "wild" to avoid shadowing
let γ' = extendAnfEnv γ x x'
as' <- forM as $ \(c, xs, e') -> liftM (c, xs,) (stitch (incrCaseDepth c γ') e')
as'' <- lift $ expandDefaultCase γ τx as'
return $ Case n x' t as''
where τx = GM.expandVarType x
normalize γ (Var x)
= return $ Var (lookupAnfEnv γ x x)
normalize _ e@(Lit _)
= return e
normalize _ e@(Type _)
= return e
normalize γ (Cast e τ)
= do e' <- normalizeName γ e
return $ Cast e' τ
normalize γ (App e1 e2@(Type _))
= do e1' <- normalize γ e1
e2' <- normalize γ e2
return $ App e1' e2'
normalize γ (App e1 e2)
= do e1' <- normalize γ e1
n2 <- normalizeName γ e2
return $ App e1' n2
normalize γ (Tick tt e)
= do e' <- normalize (γ `at` tt) e
return $ Tick tt e'
normalize _ (Coercion c)
= return $ Coercion c
--------------------------------------------------------------------------------
stitch :: AnfEnv -> CoreExpr -> DsMW CoreExpr
--------------------------------------------------------------------------------
stitch γ e
= do bs' <- get
modify $ \s -> s { st_binds = [] }
e' <- normalize γ e
bs <- st_binds <$> get
put bs'
return $ mkCoreLets bs e'
_mkCoreLets' :: [CoreBind] -> CoreExpr -> CoreExpr
_mkCoreLets' bs e = mkCoreLets bs1 e1
where
(e1, bs1) = GM.tracePpr "MKCORELETS" (e, bs)
--------------------------------------------------------------------------------
normalizePattern :: AnfEnv -> Rs.Pattern -> DsMW CoreExpr
--------------------------------------------------------------------------------
normalizePattern γ p@(Rs.PatBind {}) = do
-- don't normalize the >>= itself, we have a special typing rule for it
e1' <- normalize γ (Rs.patE1 p)
e2' <- stitch γ (Rs.patE2 p)
return $ Rs.lower p { Rs.patE1 = e1', Rs.patE2 = e2' }
normalizePattern γ p@(Rs.PatReturn {}) = do
e' <- normalize γ (Rs.patE p)
return $ Rs.lower p { Rs.patE = e' }
normalizePattern _ p@(Rs.PatProject {}) =
return (Rs.lower p)
normalizePattern γ p@(Rs.PatSelfBind {}) = do
normalize γ (Rs.patE p)
normalizePattern γ p@(Rs.PatSelfRecBind {}) = do
e' <- normalize γ (Rs.patE p)
return $ Rs.lower p { Rs.patE = e' }
--------------------------------------------------------------------------------
expandDefault :: AnfEnv -> Bool
--------------------------------------------------------------------------------
expandDefault γ = aeCaseDepth γ <= maxCaseExpand γ
--------------------------------------------------------------------------------
expandDefaultCase :: AnfEnv
-> Type
-> [(AltCon, [Id], CoreExpr)]
-> DsM [(AltCon, [Id], CoreExpr)]
--------------------------------------------------------------------------------
expandDefaultCase γ tyapp zs@((DEFAULT, _ ,_) : _) | expandDefault γ
= expandDefaultCase' γ tyapp zs
expandDefaultCase γ tyapp@(TyConApp tc _) z@((DEFAULT, _ ,_):dcs)
= case tyConDataCons_maybe tc of
Just ds -> do let ds' = ds \\ [ d | (DataAlt d, _ , _) <- dcs]
let n = length ds'
if n == 1
then expandDefaultCase' γ tyapp z
else if maxCaseExpand γ /= 2
then return z
else return (trace (expandMessage False γ n) z)
Nothing -> return z --
expandDefaultCase _ _ z
= return z
expandDefaultCase'
:: AnfEnv -> Type -> [(AltCon, [Id], c)] -> DsM [(AltCon, [Id], c)]
expandDefaultCase' γ t ((DEFAULT, _, e) : dcs)
| Just dtss <- GM.defaultDataCons t (F.fst3 <$> dcs) = do
dcs' <- warnCaseExpand γ <$> forM dtss (cloneCase γ e)
return $ sortCases (dcs' ++ dcs)
expandDefaultCase' _ _ z
= return z
cloneCase :: AnfEnv -> e -> (DataCon, [TyVar], [Type]) -> DsM (AltCon, [Id], e)
cloneCase γ e (d, as, ts) = do
xs <- mapM (freshNormalVar γ) ts
return (DataAlt d, as ++ xs, e)
sortCases :: [(AltCon, b, c)] -> [(AltCon, b, c)]
sortCases = sortBy (cmpAltCon `on` F.fst3)
warnCaseExpand :: AnfEnv -> [a] -> [a]
warnCaseExpand γ xs
| 10 < n = trace (expandMessage True γ n) xs
| otherwise = xs
where
n = length xs
expandMessage :: Bool -> AnfEnv -> Int -> String
expandMessage expand γ n = unlines [msg1, msg2]
where
msg1 = Printf.printf "WARNING: (%s) %s DEFAULT with %d cases at depth %d" (showPpr sp) v1 n d
msg2 = Printf.printf "%s expansion with --max-case-expand=%d" v2 d'
(v1, v2, d')
| expand = ("Expanding" , "Disable", d-1) :: (String, String, Int)
| otherwise = ("Not expanding", "Enable" , d+1)
d = aeCaseDepth γ
sp = Sp.srcSpan (aeSrcSpan γ)
--------------------------------------------------------------------------------
-- | ANF Environments ----------------------------------------------------------
--------------------------------------------------------------------------------
freshNormalVar :: AnfEnv -> Type -> DsM Id
freshNormalVar γ t = do
u <- getUniqueM
let i = getKey u
let sp = Sp.srcSpan (aeSrcSpan γ)
return (mkUserLocal (anfOcc i) u t sp)
anfOcc :: Int -> OccName
anfOcc = mkVarOccFS . GM.symbolFastString . F.intSymbol F.anfPrefix
data AnfEnv = AnfEnv
{ aeVarEnv :: VarEnv Id
, aeSrcSpan :: Sp.SpanStack
, aeCfg :: UX.Config
, aeCaseDepth :: !Int
}
instance UX.HasConfig AnfEnv where
getConfig = aeCfg
emptyAnfEnv :: UX.Config -> AnfEnv
emptyAnfEnv cfg = AnfEnv
{ aeVarEnv = emptyVarEnv
, aeSrcSpan = Sp.empty
, aeCfg = cfg
, aeCaseDepth = 1
}
lookupAnfEnv :: AnfEnv -> Id -> Id -> Id
lookupAnfEnv γ x y = lookupWithDefaultVarEnv (aeVarEnv γ) x y
extendAnfEnv :: AnfEnv -> Id -> Id -> AnfEnv
extendAnfEnv γ x y = γ { aeVarEnv = extendVarEnv (aeVarEnv γ) x y }
incrCaseDepth :: AltCon -> AnfEnv -> AnfEnv
incrCaseDepth DEFAULT γ = γ { aeCaseDepth = 1 + aeCaseDepth γ }
incrCaseDepth _ γ = γ
at :: AnfEnv -> Tickish Id -> AnfEnv
at γ tt = γ { aeSrcSpan = Sp.push (Sp.Tick tt) (aeSrcSpan γ)}