X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FcoreSyn%2FCoreUtils.lhs;h=38e4a11759d74f49429881768a3f546f207fa0d6;hb=522c8ebea4546658b4a5ee6727a0cab64fd72e8b;hp=24d4d0292e1b8cd288e81d66d2248f30930da024;hpb=00a259f5e3ceca206b388d02495799dc1e974bf5;p=ghc-hetmet.git diff --git a/compiler/coreSyn/CoreUtils.lhs b/compiler/coreSyn/CoreUtils.lhs index 24d4d02..38e4a11 100644 --- a/compiler/coreSyn/CoreUtils.lhs +++ b/compiler/coreSyn/CoreUtils.lhs @@ -44,7 +44,7 @@ import GLAEXTS -- For `xori` import CoreSyn import CoreFVs ( exprFreeVars ) import PprCore ( pprCoreExpr ) -import Var ( Var, TyVar, CoVar, isCoVar, tyVarKind, mkCoVar, mkTyVar ) +import Var ( Var, TyVar, CoVar, tyVarKind, mkCoVar, mkTyVar ) import OccName ( mkVarOccFS ) import SrcLoc ( noSrcLoc ) import VarSet ( unionVarSet ) @@ -72,13 +72,12 @@ import Type ( Type, mkFunTy, mkForAllTy, splitFunTy_maybe, splitFunTy, tcEqTypeX, applyTys, isUnLiftedType, seqType, mkTyVarTy, splitForAllTy_maybe, isForAllTy, - splitTyConApp_maybe, coreEqType, funResultTy, applyTy, - substTyWith, mkPredTy + splitTyConApp_maybe, splitTyConApp, coreEqType, funResultTy, applyTy, + substTyWith, mkPredTy, zipOpenTvSubst, substTy, substTyVar ) import Coercion ( Coercion, mkTransCoercion, coercionKind, splitNewTypeRepCo_maybe, mkSymCoercion, - decomposeCo, coercionKindPredTy, - splitCoercionKind ) + decomposeCo, coercionKindPredTy ) import TyCon ( tyConArity ) import TysWiredIn ( boolTy, trueDataCon, falseDataCon ) import CostCentre ( CostCentre ) @@ -634,15 +633,15 @@ exprIsHNF (Var v) -- NB: There are no value args at this point -- A worry: what if an Id's unfolding is just itself: -- then we could get an infinite loop... -exprIsHNF (Lit l) = True -exprIsHNF (Type ty) = True -- Types are honorary Values; - -- we don't mind copying them -exprIsHNF (Lam b e) = isRuntimeVar b || exprIsHNF e -exprIsHNF (Note _ e) = exprIsHNF e -exprIsHNF (Cast e co) = exprIsHNF e +exprIsHNF (Lit l) = True +exprIsHNF (Type ty) = True -- Types are honorary Values; + -- we don't mind copying them +exprIsHNF (Lam b e) = isRuntimeVar b || exprIsHNF e +exprIsHNF (Note _ e) = exprIsHNF e +exprIsHNF (Cast e co) = exprIsHNF e exprIsHNF (App e (Type _)) = exprIsHNF e exprIsHNF (App e a) = app_is_value e [a] -exprIsHNF other = False +exprIsHNF other = False -- There is at least one value argument app_is_value (Var fun) args @@ -665,22 +664,6 @@ check_args fun_ty (arg : args) \end{code} \begin{code} --- deep applies a TyConApp coercion as a substitution to a reflexive coercion --- deepCast t [a1,...,an] co corresponds to deep(t, [a1,...,an], co) from --- FC paper -deepCast :: Type -> [TyVar] -> Coercion -> Coercion -deepCast ty tyVars co - = ASSERT( let {(lty, rty) = coercionKind co; - Just (tc1, lArgs) = splitTyConApp_maybe lty; - Just (tc2, rArgs) = splitTyConApp_maybe rty} - in - tc1 == tc2 && length lArgs == length rArgs && - length lArgs == length tyVars ) - substTyWith tyVars coArgs ty - where - -- coArgs = [right (left (left co)), right (left co), right co] - coArgs = decomposeCo (length tyVars) co - -- These InstPat functions go here to avoid circularity between DataCon and Id dataConRepInstPat = dataConInstPat dataConRepArgTys (repeat (FSLIT("ipv"))) dataConRepFSInstPat = dataConInstPat dataConRepArgTys @@ -742,97 +725,97 @@ dataConInstPat arg_fun fss uniqs con inst_tys (ex_fss, fss') = splitAt n_ex fss (co_fss, id_fss) = splitAt n_co fss' - -- make existential type variables + -- Make existential type variables + ex_bndrs = zipWith3 mk_ex_var ex_uniqs ex_fss ex_tvs mk_ex_var uniq fs var = mkTyVar new_name kind where new_name = mkSysTvName uniq fs kind = tyVarKind var - ex_bndrs = zipWith3 mk_ex_var ex_uniqs ex_fss ex_tvs - - -- make the instantiation substitution - inst_subst = substTyWith (univ_tvs ++ ex_tvs) (inst_tys ++ map mkTyVarTy ex_bndrs) + -- Make the instantiating substitution + subst = zipOpenTvSubst (univ_tvs ++ ex_tvs) (inst_tys ++ map mkTyVarTy ex_bndrs) - -- make new coercion vars, instantiating kind + -- Make new coercion vars, instantiating kind + co_bndrs = zipWith3 mk_co_var co_uniqs co_fss eq_preds mk_co_var uniq fs eq_pred = mkCoVar new_name co_kind where new_name = mkSysTvName uniq fs - co_kind = inst_subst (mkPredTy eq_pred) - - co_bndrs = zipWith3 mk_co_var co_uniqs co_fss eq_preds + co_kind = substTy subst (mkPredTy eq_pred) -- make value vars, instantiating types - mk_id_var uniq fs ty = mkUserLocal (mkVarOccFS fs) uniq (inst_subst ty) noSrcLoc + mk_id_var uniq fs ty = mkUserLocal (mkVarOccFS fs) uniq (substTy subst ty) noSrcLoc id_bndrs = zipWith3 mk_id_var id_uniqs id_fss arg_tys exprIsConApp_maybe :: CoreExpr -> Maybe (DataCon, [CoreExpr]) -- Returns (Just (dc, [x1..xn])) if the argument expression is -- a constructor application of the form (dc x1 .. xn) exprIsConApp_maybe (Cast expr co) - = -- Maybe this is over the top, but here we try to turn - -- coerce (S,T) ( x, y ) - -- effectively into - -- ( coerce S x, coerce T y ) - -- This happens in anger in PrelArrExts which has a coerce - -- case coerce memcpy a b of - -- (# r, s #) -> ... - -- where the memcpy is in the IO monad, but the call is in - -- the (ST s) monad + = -- Here we do the PushC reduction rule as described in the FC paper case exprIsConApp_maybe expr of { - Nothing -> Nothing ; - Just (dc, args) -> - - let (from_ty, to_ty) = coercionKind co in - + Nothing -> Nothing ; + Just (dc, dc_args) -> + + -- The transformation applies iff we have + -- (C e1 ... en) `cast` co + -- where co :: (T t1 .. tn) :=: (T s1 ..sn) + -- That is, with a T at the top of both sides + -- The left-hand one must be a T, because exprIsConApp returned True + -- but the right-hand one might not be. (Though it usually will.) + + let (from_ty, to_ty) = coercionKind co + (from_tc, from_tc_arg_tys) = splitTyConApp from_ty + -- The inner one must be a TyConApp + in case splitTyConApp_maybe to_ty of { Nothing -> Nothing ; - Just (tc, tc_arg_tys) | tc /= dataConTyCon dc -> Nothing - -- | not (isVanillaDataCon dc) -> Nothing - | otherwise -> - -- Type constructor must match datacon - - case splitTyConApp_maybe from_ty of { - Nothing -> Nothing ; - Just (tc', tc_arg_tys') | tc /= tc' -> Nothing - -- Both sides of coercion must have the same type constructor - | otherwise -> - + Just (to_tc, to_tc_arg_tys) + | from_tc /= to_tc -> Nothing + -- These two Nothing cases are possible; we might see + -- (C x y) `cast` (g :: T a ~ S [a]), + -- where S is a type function. In fact, exprIsConApp + -- will probably not be called in such circumstances, + -- but there't nothing wrong with it + + | otherwise -> let - -- here we do the PushC reduction rule as described in the FC paper - arity = tyConArity tc - n_ex_tvs = length dc_ex_tyvars + tc_arity = tyConArity from_tc - (_univ_args, rest) = splitAt arity args - (ex_args, val_args) = splitAt n_ex_tvs rest + (univ_args, rest1) = splitAt tc_arity dc_args + (ex_args, rest2) = splitAt n_ex_tvs rest1 + (co_args, val_args) = splitAt n_cos rest2 arg_tys = dataConRepArgTys dc - dc_tyvars = dataConUnivTyVars dc + dc_univ_tyvars = dataConUnivTyVars dc dc_ex_tyvars = dataConExTyVars dc - - deep arg_ty = deepCast arg_ty dc_tyvars co - - -- first we appropriately cast the value arguments - new_val_args = zipWith mkCoerce (map deep arg_tys) val_args - - -- then we cast the existential coercion arguments - orig_tvs = dc_tyvars ++ dc_ex_tyvars - gammas = decomposeCo arity co - new_tys = gammas ++ (map (\ (Type t) -> t) ex_args) - theta = substTyWith orig_tvs new_tys - cast_ty tv (Type ty) - | isCoVar tv - , (ty1, ty2) <- splitCoercionKind (tyVarKind tv) - = Type $ mkTransCoercion (mkSymCoercion (theta ty1)) - (mkTransCoercion ty (theta ty2)) - | otherwise - = Type ty - new_ex_args = zipWith cast_ty dc_ex_tyvars ex_args + dc_eq_spec = dataConEqSpec dc + dc_tyvars = dc_univ_tyvars ++ dc_ex_tyvars + n_ex_tvs = length dc_ex_tyvars + n_cos = length dc_eq_spec + + -- Make the "theta" from Fig 3 of the paper + gammas = decomposeCo tc_arity co + new_tys = gammas ++ map (\ (Type t) -> t) ex_args + theta = zipOpenTvSubst dc_tyvars new_tys + + -- First we cast the existential coercion arguments + cast_co (tv,ty) (Type co) = Type $ mkSymCoercion (substTyVar theta tv) + `mkTransCoercion` co + `mkTransCoercion` (substTy theta ty) + new_co_args = zipWith cast_co dc_eq_spec co_args + -- ...and now value arguments + new_val_args = zipWith cast_arg arg_tys val_args + cast_arg arg_ty arg = mkCoerce (substTy theta arg_ty) arg + in - ASSERT( all isTypeArg (take arity args) ) - ASSERT( equalLength val_args arg_tys ) - Just (dc, map Type tc_arg_tys ++ new_ex_args ++ new_val_args) - }}} + ASSERT( length univ_args == tc_arity ) + ASSERT( from_tc == dataConTyCon dc ) + ASSERT( and (zipWith coreEqType [t | Type t <- univ_args] from_tc_arg_tys) ) + ASSERT( all isTypeArg (univ_args ++ ex_args) ) + ASSERT2( equalLength val_args arg_tys, ppr dc $$ ppr dc_tyvars $$ ppr dc_ex_tyvars $$ ppr arg_tys $$ ppr dc_args $$ ppr univ_args $$ ppr ex_args $$ ppr val_args $$ ppr arg_tys ) + + Just (dc, map Type to_tc_arg_tys ++ ex_args ++ new_co_args ++ new_val_args) + }} exprIsConApp_maybe (Note _ expr) = exprIsConApp_maybe expr @@ -1257,6 +1240,7 @@ exprIsBig (Lit _) = False exprIsBig (Var v) = False exprIsBig (Type t) = False exprIsBig (App f a) = exprIsBig f || exprIsBig a +exprIsBig (Cast e _) = exprIsBig e -- Hopefully coercions are not too big! exprIsBig other = True \end{code}