X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcoreSyn%2FCoreUtils.lhs;h=bea8316a261d9fc3d1d7d5c6e1c1d900dc858f4e;hb=17fdd8ad14910060688239d99fa12968276d4095;hp=901bc4d29ac146b092b3da54d9ea0ad879b85f6e;hpb=f05b6981de4c1f76279e17a59d3c42e83ee8d244;p=ghc-hetmet.git diff --git a/ghc/compiler/coreSyn/CoreUtils.lhs b/ghc/compiler/coreSyn/CoreUtils.lhs index 901bc4d..bea8316 100644 --- a/ghc/compiler/coreSyn/CoreUtils.lhs +++ b/ghc/compiler/coreSyn/CoreUtils.lhs @@ -11,7 +11,7 @@ module CoreUtils ( mkPiType, -- Taking expressions apart - findDefault, findAlt, + findDefault, findAlt, hasDefault, -- Properties of expressions exprType, coreAltsType, @@ -19,7 +19,7 @@ module CoreUtils ( exprIsValue,exprOkForSpeculation, exprIsBig, exprIsConApp_maybe, exprIsAtom, idAppIsBottom, idAppIsCheap, - exprArity, + exprArity, -- Expr transformation etaReduce, etaExpand, @@ -49,11 +49,10 @@ import VarEnv import Name ( hashName ) import Literal ( hashLiteral, literalType, litIsDupable ) import DataCon ( DataCon, dataConRepArity ) -import PrimOp ( primOpOkForSpeculation, primOpIsCheap, - primOpIsDupable ) +import PrimOp ( primOpOkForSpeculation, primOpIsCheap ) import Id ( Id, idType, globalIdDetails, idStrictness, idLBVarInfo, mkWildId, idArity, idName, idUnfolding, idInfo, isOneShotLambda, - isDataConId_maybe, isPrimOpId_maybe, mkSysLocal, hasNoBinding + isDataConId_maybe, mkSysLocal, hasNoBinding ) import IdInfo ( LBVarInfo(..), GlobalIdDetails(..), @@ -61,12 +60,11 @@ import IdInfo ( LBVarInfo(..), import Demand ( appIsBottom ) import Type ( Type, mkFunTy, mkForAllTy, splitFunTy_maybe, applyTys, isUnLiftedType, seqType, mkUTy, mkTyVarTy, - splitForAllTy_maybe, splitNewType_maybe + splitForAllTy_maybe, isForAllTy, eqType ) import TysWiredIn ( boolTy, trueDataCon, falseDataCon ) import CostCentre ( CostCentre ) import UniqSupply ( UniqSupply, splitUniqSupply, uniqFromSupply ) -import Maybes ( maybeToBool ) import Outputable import TysPrim ( alphaTy ) -- Debugging only \end{code} @@ -187,23 +185,24 @@ mkInlineMe e = Note InlineMe e mkCoerce :: Type -> Type -> CoreExpr -> CoreExpr mkCoerce to_ty from_ty (Note (Coerce to_ty2 from_ty2) expr) - = ASSERT( from_ty == to_ty2 ) + = ASSERT( from_ty `eqType` to_ty2 ) mkCoerce to_ty from_ty2 expr mkCoerce to_ty from_ty expr - | to_ty == from_ty = expr - | otherwise = ASSERT( from_ty == exprType expr ) - Note (Coerce to_ty from_ty) expr + | to_ty `eqType` from_ty = expr + | otherwise = ASSERT( from_ty `eqType` exprType expr ) + Note (Coerce to_ty from_ty) expr \end{code} \begin{code} mkSCC :: CostCentre -> Expr b -> Expr b -- Note: Nested SCC's *are* preserved for the benefit of - -- cost centre stack profiling (Durham) - -mkSCC cc (Lit lit) = Lit lit -mkSCC cc (Lam x e) = Lam x (mkSCC cc e) -- Move _scc_ inside lambda -mkSCC cc expr = Note (SCC cc) expr + -- cost centre stack profiling +mkSCC cc (Lit lit) = Lit lit +mkSCC cc (Lam x e) = Lam x (mkSCC cc e) -- Move _scc_ inside lambda +mkSCC cc (Note (SCC cc') e) = Note (SCC cc) (Note (SCC cc') e) +mkSCC cc (Note n e) = Note n (mkSCC cc e) -- Move _scc_ inside notes +mkSCC cc expr = Note (SCC cc) expr \end{code} @@ -252,25 +251,31 @@ mkIfThenElse guard then_expr else_expr %* * %************************************************************************ +The default alternative must be first, if it exists at all. +This makes it easy to find, though it makes matching marginally harder. \begin{code} +hasDefault :: [CoreAlt] -> Bool +hasDefault ((DEFAULT,_,_) : alts) = True +hasDefault _ = False + findDefault :: [CoreAlt] -> ([CoreAlt], Maybe CoreExpr) -findDefault [] = ([], Nothing) -findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null alts && null args ) - ([], Just rhs) -findDefault (alt : alts) = case findDefault alts of - (alts', deflt) -> (alt : alts', deflt) +findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null args ) (alts, Just rhs) +findDefault alts = (alts, Nothing) findAlt :: AltCon -> [CoreAlt] -> CoreAlt findAlt con alts - = go alts + = case alts of + (deflt@(DEFAULT,_,_):alts) -> go alts deflt + other -> go alts panic_deflt + where - go [] = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts)) - go (alt : alts) | matches alt = alt - | otherwise = go alts + panic_deflt = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts)) - matches (DEFAULT, _, _) = True - matches (con1, _, _) = con == con1 + go [] deflt = deflt + go (alt@(con1,_,_) : alts) deflt | con == con1 = alt + | otherwise = ASSERT( not (con1 == DEFAULT) ) + go alts deflt \end{code} @@ -304,9 +309,9 @@ exprIsTrivial (Var v) | otherwise = True exprIsTrivial (Type _) = True exprIsTrivial (Lit lit) = True -exprIsTrivial (App e arg) = isTypeArg arg && exprIsTrivial e +exprIsTrivial (App e arg) = not (isRuntimeArg arg) && exprIsTrivial e exprIsTrivial (Note _ e) = exprIsTrivial e -exprIsTrivial (Lam b body) | isTyVar b = exprIsTrivial body +exprIsTrivial (Lam b body) = not (isRuntimeVar b) && exprIsTrivial body exprIsTrivial other = False exprIsAtom :: CoreExpr -> Bool @@ -386,7 +391,7 @@ exprIsCheap (Type _) = True exprIsCheap (Var _) = True exprIsCheap (Note InlineMe e) = True exprIsCheap (Note _ e) = exprIsCheap e -exprIsCheap (Lam x e) = if isId x then True else exprIsCheap e +exprIsCheap (Lam x e) = isRuntimeVar x || exprIsCheap e exprIsCheap (Case e _ alts) = exprIsCheap e && and [exprIsCheap rhs | (_,_,rhs) <- alts] -- Experimentally, treat (case x of ...) as cheap @@ -412,8 +417,8 @@ exprIsCheap other_expr -- because it certainly doesn't need to be shared! go (App f a) n_args args_cheap - | isTypeArg a = go f n_args args_cheap - | otherwise = go f (n_args + 1) (exprIsCheap a && args_cheap) + | not (isRuntimeArg a) = go f n_args args_cheap + | otherwise = go f (n_args + 1) (exprIsCheap a && args_cheap) go other n_args args_cheap = False @@ -482,8 +487,8 @@ exprOkForSpeculation other_expr other -> False go (App f a) n_args args_ok - | isTypeArg a = go f n_args args_ok - | otherwise = go f (n_args + 1) (exprOkForSpeculation a && args_ok) + | not (isRuntimeArg a) = go f n_args args_ok + | otherwise = go f (n_args + 1) (exprOkForSpeculation a && args_ok) go other n_args args_ok = False \end{code} @@ -507,7 +512,7 @@ idAppIsBottom id n_val_args = appIsBottom (idStrictness id) n_val_args \end{code} @exprIsValue@ returns true for expressions that are certainly *already* -evaluated to WHNF. This is used to decide wether it's ok to change +evaluated to WHNF. This is used to decide whether it's ok to change case x of _ -> e ===> e and to decide whether it's safe to discard a `seq` @@ -531,7 +536,7 @@ exprIsValue :: CoreExpr -> Bool -- True => Value-lambda, constructor, PAP exprIsValue (Type ty) = True -- Types are honorary Values; we don't mind -- copying them exprIsValue (Lit l) = True -exprIsValue (Lam b e) = isId b || exprIsValue e +exprIsValue (Lam b e) = isRuntimeVar b || exprIsValue e exprIsValue (Note _ e) = exprIsValue e exprIsValue other_expr = go other_expr 0 @@ -539,8 +544,8 @@ exprIsValue other_expr go (Var f) n_args = idAppIsValue f n_args go (App f a) n_args - | isTypeArg a = go f n_args - | otherwise = go f (n_args + 1) + | not (isRuntimeArg a) = go f n_args + | otherwise = go f (n_args + 1) go (Note _ f) n_args = go f n_args @@ -559,8 +564,13 @@ idAppIsValue id n_val_args \begin{code} exprIsConApp_maybe :: CoreExpr -> Maybe (DataCon, [CoreExpr]) -exprIsConApp_maybe expr - = analyse (collectArgs expr) +exprIsConApp_maybe (Note InlineMe expr) = exprIsConApp_maybe expr + -- We ignore InlineMe notes in case we have + -- x = __inline_me__ (a,b) + -- All part of making sure that INLINE pragmas never hurt + -- Marcin tripped on this one when making dictionaries more inlinable + +exprIsConApp_maybe expr = analyse (collectArgs expr) where analyse (Var fun, args) | Just con <- isDataConId_maybe fun, @@ -702,15 +712,6 @@ exprEtaExpandArity e -- giving just -- f = \x -> e -- A Bad Idea - -min_zero :: [Int] -> Int -- Find the minimum, but zero is the smallest -min_zero (x:xs) = go x xs - where - go 0 xs = 0 -- Nothing beats zero - go min [] = min - go min (x:xs) | x < min = go x xs - | otherwise = go min xs - \end{code} @@ -735,7 +736,16 @@ etaExpand :: Int -- Add this number of value args -- (/\b. coerce T (\y::A -> (coerce (A->B) (E b) y) etaExpand n us expr ty - | n == 0 -- Saturated, so nothing to do + | n == 0 && + -- The ILX code generator requires eta expansion for type arguments + -- too, but alas the 'n' doesn't tell us how many of them there + -- may be. So we eagerly eta expand any big lambdas, and just + -- cross our fingers about possible loss of sharing in the + -- ILX case. + -- The Right Thing is probably to make 'arity' include + -- type variables throughout the compiler. (ToDo.) + not (isForAllTy ty) + -- Saturated, so nothing to do = expr | otherwise -- An unsaturated constructor or primop; eta expand it @@ -751,13 +761,8 @@ etaExpand n us expr ty (us1, us2) = splitUniqSupply us uniq = uniqFromSupply us1 - ; Nothing -> - - case splitNewType_maybe ty of { - Just ty' -> mkCoerce ty ty' (etaExpand n us (mkCoerce ty' ty expr) ty') ; - - Nothing -> pprTrace "Bad eta expand" (ppr expr $$ ppr ty) expr - }}} + ; Nothing -> pprTrace "Bad eta expand" (ppr expr $$ ppr ty) expr + }} \end{code} @@ -787,13 +792,15 @@ And in any case it seems more robust to have exprArity be a bit more intelligent exprArity :: CoreExpr -> Int exprArity e = go e `max` 0 where - go (Lam x e) | isId x = go e + 1 - | otherwise = go e - go (Note _ e) = go e - go (App e (Type t)) = go e - go (App f a) = go f - 1 - go (Var v) = idArity v - go _ = 0 + go (Lam x e) | isId x = go e + 1 + | otherwise = go e + go (Note _ e) = go e + go (App e (Type t)) = go e + go (App f a) | exprIsCheap a = go f - 1 + -- Important! f (fac x) does not have arity 2, + -- even if f does! + go (Var v) = idArity v + go _ = 0 \end{code} @@ -812,7 +819,7 @@ cheapEqExpr :: Expr b -> Expr b -> Bool cheapEqExpr (Var v1) (Var v2) = v1==v2 cheapEqExpr (Lit lit1) (Lit lit2) = lit1 == lit2 -cheapEqExpr (Type t1) (Type t2) = t1 == t2 +cheapEqExpr (Type t1) (Type t2) = t1 `eqType` t2 cheapEqExpr (App f1 a1) (App f2 a2) = f1 `cheapEqExpr` f2 && a1 `cheapEqExpr` a2 @@ -832,6 +839,9 @@ exprIsBig other = True \begin{code} eqExpr :: CoreExpr -> CoreExpr -> Bool -- Works ok at more general type, but only needed at CoreExpr + -- Used in rule matching, so when we find a type we use + -- eqTcType, which doesn't look through newtypes + -- [And it doesn't risk falling into a black hole either.] eqExpr e1 e2 = eq emptyVarEnv e1 e2 where @@ -862,7 +872,7 @@ eqExpr e1 e2 env' = extendVarEnv env v1 v2 eq env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && eq env e1 e2 - eq env (Type t1) (Type t2) = t1 == t2 + eq env (Type t1) (Type t2) = t1 `eqType` t2 eq env e1 e2 = False eq_list env [] [] = True @@ -873,7 +883,7 @@ eqExpr e1 e2 eq (extendVarEnvList env (vs1 `zip` vs2)) r1 r2 eq_note env (SCC cc1) (SCC cc2) = cc1 == cc2 - eq_note env (Coerce t1 f1) (Coerce t2 f2) = t1==t2 && f1==f2 + eq_note env (Coerce t1 f1) (Coerce t2 f2) = t1 `eqType` t2 && f1 `eqType` f2 eq_note env InlineCall InlineCall = True eq_note env other1 other2 = False \end{code}