X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FcoreSyn%2FCoreUtils.lhs;h=44ca27a9ab2079b0c0691d7ac71084759e400358;hp=b5097d52f0e0290e07333670aa4419648bb81745;hb=e79c9ce01d0ce4412bd4bcd99c8c728a6a2ec569;hpb=7fc749a43b4b6b85d234fa95d4928648259584f4 diff --git a/compiler/coreSyn/CoreUtils.lhs b/compiler/coreSyn/CoreUtils.lhs index b5097d5..44ca27a 100644 --- a/compiler/coreSyn/CoreUtils.lhs +++ b/compiler/coreSyn/CoreUtils.lhs @@ -6,42 +6,45 @@ Utility functions on @Core@ syntax \begin{code} -{-# OPTIONS -w #-} +{-# OPTIONS -fno-warn-incomplete-patterns #-} -- The above warning supression flag is a temporary kludge. -- While working on this module you are encouraged to remove it and fix -- any warnings in the module. See -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings -- for details +-- | Commonly useful utilites for manipulating the Core language module CoreUtils ( - -- Construction + -- * Constructing expressions mkInlineMe, mkSCC, mkCoerce, mkCoerceI, bindNonRec, needsCaseBinding, - mkIfThenElse, mkAltExpr, mkPiType, mkPiTypes, + mkAltExpr, mkPiType, mkPiTypes, - -- Taking expressions apart + -- * Taking expressions apart findDefault, findAlt, isDefaultAlt, mergeAlts, trimConArgs, - -- Properties of expressions - exprType, coreAltType, + -- * Properties of expressions + exprType, coreAltType, coreAltsType, exprIsDupable, exprIsTrivial, exprIsCheap, exprIsHNF,exprOkForSpeculation, exprIsBig, exprIsConApp_maybe, exprIsBottom, rhsIsStatic, - -- Arity and eta expansion + -- * Arity and eta expansion manifestArity, exprArity, exprEtaExpandArity, etaExpand, - -- Size - coreBindsSize, + -- * Expression and bindings size + coreBindsSize, exprSize, - -- Hashing + -- * Hashing hashExpr, - -- Equality - cheapEqExpr, tcEqExpr, tcEqExprX, applyTypeToArgs, applyTypeToArg, + -- * Equality + cheapEqExpr, tcEqExpr, tcEqExprX, + -- * Manipulating data constructors and types + applyTypeToArgs, applyTypeToArg, dataConOrigInstPat, dataConRepInstPat, dataConRepFSInstPat ) where @@ -55,6 +58,7 @@ import SrcLoc import VarSet import VarEnv import Name +import Module #if mingw32_TARGET_OS import Packages #endif @@ -67,10 +71,8 @@ import NewDemand import Type import Coercion import TyCon -import TysWiredIn import CostCentre import BasicTypes -import PackageConfig import Unique import Outputable import DynFlags @@ -93,13 +95,15 @@ import GHC.Exts -- For `xori` \begin{code} exprType :: CoreExpr -> Type - +-- ^ Recover the type of a well-typed Core expression. Fails when +-- applied to the actual 'CoreSyn.Type' expression as it cannot +-- really be said to have a type exprType (Var var) = idType var exprType (Lit lit) = literalType lit exprType (Let _ body) = exprType body -exprType (Case _ _ ty alts) = ty -exprType (Cast e co) = snd (coercionKind co) -exprType (Note other_note e) = exprType e +exprType (Case _ _ ty _) = ty +exprType (Cast _ co) = snd (coercionKind co) +exprType (Note _ e) = exprType e exprType (Lam binder expr) = mkPiType binder (exprType expr) exprType e@(App _ _) = case collectArgs e of @@ -108,35 +112,39 @@ exprType e@(App _ _) exprType other = pprTrace "exprType" (pprCoreExpr other) alphaTy coreAltType :: CoreAlt -> Type +-- ^ Returns the type of the alternatives right hand side coreAltType (_,_,rhs) = exprType rhs -\end{code} -@mkPiType@ makes a (->) type or a forall type, depending on whether -it is given a type variable or a term variable. We cleverly use the -lbvarinfo field to figure out the right annotation for the arrove in -case of a term variable. +coreAltsType :: [CoreAlt] -> Type +-- ^ Returns the type of the first alternative, which should be the same as for all alternatives +coreAltsType (alt:_) = coreAltType alt +coreAltsType [] = panic "corAltsType" +\end{code} \begin{code} -mkPiType :: Var -> Type -> Type -- The more polymorphic version -mkPiTypes :: [Var] -> Type -> Type -- doesn't work... - -mkPiTypes vs ty = foldr mkPiType ty vs +mkPiType :: Var -> Type -> Type +-- ^ Makes a @(->)@ type or a forall type, depending +-- on whether it is given a type variable or a term variable. +mkPiTypes :: [Var] -> Type -> Type +-- ^ 'mkPiType' for multiple type or value arguments mkPiType v ty | isId v = mkFunTy (idType v) ty | otherwise = mkForAllTy v ty + +mkPiTypes vs ty = foldr mkPiType ty vs \end{code} \begin{code} applyTypeToArg :: Type -> CoreExpr -> Type +-- ^ Determines the type resulting from applying an expression to a function with the given type applyTypeToArg fun_ty (Type arg_ty) = applyTy fun_ty arg_ty -applyTypeToArg fun_ty other_arg = funResultTy fun_ty +applyTypeToArg fun_ty _ = funResultTy fun_ty applyTypeToArgs :: CoreExpr -> Type -> [CoreExpr] -> Type --- A more efficient version of applyTypeToArg --- when we have several args --- The first argument is just for debugging -applyTypeToArgs e op_ty [] = op_ty +-- ^ A more efficient version of 'applyTypeToArg' when we have several arguments. +-- The first argument is just for debugging, and gives some context +applyTypeToArgs _ op_ty [] = op_ty applyTypeToArgs e op_ty (Type ty : args) = -- Accumulate type arguments so we can instantiate all at once @@ -145,15 +153,18 @@ applyTypeToArgs e op_ty (Type ty : args) go rev_tys (Type ty : args) = go (ty:rev_tys) args go rev_tys rest_args = applyTypeToArgs e op_ty' rest_args where - op_ty' = applyTys op_ty (reverse rev_tys) + op_ty' = applyTysD msg op_ty (reverse rev_tys) + msg = ptext (sLit "applyTypeToArgs") <+> + panic_msg e op_ty -applyTypeToArgs e op_ty (other_arg : args) +applyTypeToArgs e op_ty (_ : args) = case (splitFunTy_maybe op_ty) of Just (_, res_ty) -> applyTypeToArgs e res_ty args - Nothing -> pprPanic "applyTypeToArgs" (pprCoreExpr e $$ ppr op_ty) -\end{code} - + Nothing -> pprPanic "applyTypeToArgs" (panic_msg e op_ty) +panic_msg :: CoreExpr -> Type -> SDoc +panic_msg e op_ty = pprCoreExpr e $$ ppr op_ty +\end{code} %************************************************************************ %* * @@ -194,17 +205,20 @@ its rhs is trivial) and *then* we could get rid of the inline_me. But it hardly seems worth it, so I don't bother. \begin{code} +-- | Wraps the given expression in an inlining hint unless the expression +-- is trivial in some sense, so that doing so would usually hurt us +mkInlineMe :: CoreExpr -> CoreExpr mkInlineMe (Var v) = Var v mkInlineMe e = Note InlineMe e \end{code} - - \begin{code} +-- | Wrap the given expression in the coercion, dropping identity coercions and coalescing nested coercions mkCoerceI :: CoercionI -> CoreExpr -> CoreExpr mkCoerceI IdCo e = e mkCoerceI (ACo co) e = mkCoerce co e +-- | Wrap the given expression in the coercion safely, coalescing nested coercions mkCoerce :: Coercion -> CoreExpr -> CoreExpr mkCoerce co (Cast expr co2) = ASSERT(let { (from_ty, _to_ty) = coercionKind co; @@ -213,7 +227,7 @@ mkCoerce co (Cast expr co2) mkCoerce (mkTransCoercion co2 co) expr mkCoerce co expr - = let (from_ty, to_ty) = coercionKind co in + = let (from_ty, _to_ty) = coercionKind co in -- if to_ty `coreEqType` from_ty -- then expr -- else @@ -222,10 +236,12 @@ mkCoerce co expr \end{code} \begin{code} +-- | Wraps the given expression in the cost centre unless +-- in a way that maximises their utility to the user mkSCC :: CostCentre -> Expr b -> Expr b -- Note: Nested SCC's *are* preserved for the benefit of -- cost centre stack profiling -mkSCC cc (Lit lit) = Lit lit +mkSCC _ (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 @@ -242,20 +258,27 @@ mkSCC cc expr = Note (SCC cc) expr \begin{code} bindNonRec :: Id -> CoreExpr -> CoreExpr -> CoreExpr --- (bindNonRec x r b) produces either --- let x = r in b --- or --- case r of x { _DEFAULT_ -> b } +-- ^ @bindNonRec x r b@ produces either: +-- +-- > let x = r in b +-- +-- or: -- --- depending on whether x is unlifted or not +-- > case r of x { _DEFAULT_ -> b } +-- +-- depending on whether we have to use a @case@ or @let@ +-- binding for the expression (see 'needsCaseBinding'). -- It's used by the desugarer to avoid building bindings --- that give Core Lint a heart attack. Actually the simplifier --- deals with them perfectly well. - +-- that give Core Lint a heart attack, although actually +-- the simplifier deals with them perfectly well. See +-- also 'MkCore.mkCoreLet' bindNonRec bndr rhs body - | needsCaseBinding (idType bndr) rhs = Case rhs bndr (exprType body) [(DEFAULT,[],body)] + | needsCaseBinding (idType bndr) rhs = Case rhs bndr (exprType body) [(DEFAULT, [], body)] | otherwise = Let (NonRec bndr rhs) body +-- | Tests whether we have to use a @case@ rather than @let@ binding for this expression +-- as per the invariants of 'CoreExpr': see "CoreSyn#let_app_invariant" +needsCaseBinding :: Type -> CoreExpr -> Bool needsCaseBinding ty rhs = isUnLiftedType ty && not (exprOkForSpeculation rhs) -- Make a case expression instead of a let -- These can arise either from the desugarer, @@ -263,22 +286,18 @@ needsCaseBinding ty rhs = isUnLiftedType ty && not (exprOkForSpeculation rhs) \end{code} \begin{code} -mkAltExpr :: AltCon -> [CoreBndr] -> [Type] -> CoreExpr - -- This guy constructs the value that the scrutinee must have - -- when you are in one particular branch of a case +mkAltExpr :: AltCon -- ^ Case alternative constructor + -> [CoreBndr] -- ^ Things bound by the pattern match + -> [Type] -- ^ The type arguments to the case alternative + -> CoreExpr +-- ^ This guy constructs the value that the scrutinee must have +-- given that you are in one particular branch of a case mkAltExpr (DataAlt con) args inst_tys = mkConApp con (map Type inst_tys ++ varsToCoreExprs args) mkAltExpr (LitAlt lit) [] [] = Lit lit mkAltExpr (LitAlt _) _ _ = panic "mkAltExpr LitAlt" mkAltExpr DEFAULT _ _ = panic "mkAltExpr DEFAULT" - -mkIfThenElse :: CoreExpr -> CoreExpr -> CoreExpr -> CoreExpr -mkIfThenElse guard then_expr else_expr --- Not going to be refining, so okay to take the type of the "then" clause - = Case guard (mkWildId boolTy) (exprType then_expr) - [ (DataAlt falseDataCon, [], else_expr), -- Increasing order of tag! - (DataAlt trueDataCon, [], then_expr) ] \end{code} @@ -292,15 +311,18 @@ 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} +-- | Extract the default case alternative findDefault :: [CoreAlt] -> ([CoreAlt], Maybe CoreExpr) findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null args ) (alts, Just rhs) findDefault alts = (alts, Nothing) +-- | Find the case alternative corresponding to a particular +-- constructor: panics if no such constructor exists findAlt :: AltCon -> [CoreAlt] -> CoreAlt findAlt con alts = case alts of (deflt@(DEFAULT,_,_):alts) -> go alts deflt - other -> go alts panic_deflt + _ -> go alts panic_deflt where panic_deflt = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts)) @@ -313,12 +335,12 @@ findAlt con alts isDefaultAlt :: CoreAlt -> Bool isDefaultAlt (DEFAULT, _, _) = True -isDefaultAlt other = False +isDefaultAlt _ = False --------------------------------- mergeAlts :: [CoreAlt] -> [CoreAlt] -> [CoreAlt] --- Merge preserving order; alternatives in the first arg --- shadow ones in the second +-- ^ Merge alternatives preserving order; alternatives in +-- the first argument shadow ones in the second mergeAlts [] as2 = as2 mergeAlts as1 [] = as1 mergeAlts (a1:as1) (a2:as2) @@ -330,13 +352,16 @@ mergeAlts (a1:as1) (a2:as2) --------------------------------- trimConArgs :: AltCon -> [CoreArg] -> [CoreArg] --- Given case (C a b x y) of --- C b x y -> ... --- we want to drop the leading type argument of the scrutinee +-- ^ Given: +-- +-- > case (C a b x y) of +-- > C b x y -> ... +-- +-- We want to drop the leading type argument of the scrutinee -- leaving the arguments to match agains the pattern trimConArgs DEFAULT args = ASSERT( null args ) [] -trimConArgs (LitAlt lit) args = ASSERT( null args ) [] +trimConArgs (LitAlt _) args = ASSERT( null args ) [] trimConArgs (DataAlt dc) args = dropList (dataConUnivTyVars dc) args \end{code} @@ -352,14 +377,11 @@ trimConArgs (DataAlt dc) args = dropList (dataConUnivTyVars dc) args applications. Note that primop Ids aren't considered trivial unless -@exprIsBottom@ is true of expressions that are guaranteed to diverge - - There used to be a gruesome test for (hasNoBinding v) in the Var case: exprIsTrivial (Var v) | hasNoBinding v = idArity v == 0 -The idea here is that a constructor worker, like $wJust, is -really short for (\x -> $wJust x), becuase $wJust has no binding. +The idea here is that a constructor worker, like \$wJust, is +really short for (\x -> \$wJust x), becuase \$wJust has no binding. So it should be treated like a lambda. Ditto unsaturated primops. But now constructor workers are not "have-no-binding" Ids. And completely un-applied primops and foreign-call Ids are sufficiently @@ -372,15 +394,16 @@ SCC notes. We do not treat (_scc_ "foo" x) as trivial, because b) see the note [SCC-and-exprIsTrivial] in Simplify.simplLazyBind \begin{code} -exprIsTrivial (Var v) = True -- See notes above -exprIsTrivial (Type _) = True -exprIsTrivial (Lit lit) = litIsTrivial lit -exprIsTrivial (App e arg) = not (isRuntimeArg arg) && exprIsTrivial e -exprIsTrivial (Note (SCC _) e) = False -- See notes above +exprIsTrivial :: CoreExpr -> Bool +exprIsTrivial (Var _) = True -- See notes above +exprIsTrivial (Type _) = True +exprIsTrivial (Lit lit) = litIsTrivial lit +exprIsTrivial (App e arg) = not (isRuntimeArg arg) && exprIsTrivial e +exprIsTrivial (Note (SCC _) _) = False -- See notes above exprIsTrivial (Note _ e) = exprIsTrivial e -exprIsTrivial (Cast e co) = exprIsTrivial e -exprIsTrivial (Lam b body) = not (isRuntimeVar b) && exprIsTrivial body -exprIsTrivial other = False +exprIsTrivial (Cast e _) = exprIsTrivial e +exprIsTrivial (Lam b body) = not (isRuntimeVar b) && exprIsTrivial body +exprIsTrivial _ = False \end{code} @@ -396,20 +419,21 @@ exprIsTrivial other = False \begin{code} -exprIsDupable (Type _) = True -exprIsDupable (Var v) = True -exprIsDupable (Lit lit) = litIsDupable lit -exprIsDupable (Note InlineMe e) = True +exprIsDupable :: CoreExpr -> Bool +exprIsDupable (Type _) = True +exprIsDupable (Var _) = True +exprIsDupable (Lit lit) = litIsDupable lit +exprIsDupable (Note InlineMe _) = True exprIsDupable (Note _ e) = exprIsDupable e -exprIsDupable (Cast e co) = exprIsDupable e -exprIsDupable expr +exprIsDupable (Cast e _) = exprIsDupable e +exprIsDupable expr = go expr 0 where - go (Var v) n_args = True + go (Var _) _ = True go (App f a) n_args = n_args < dupAppSize && exprIsDupable a && go f (n_args+1) - go other n_args = False + go _ _ = False dupAppSize :: Int dupAppSize = 4 -- Size of application we are prepared to duplicate @@ -445,12 +469,12 @@ because sharing will make sure it is only evaluated once. \begin{code} exprIsCheap :: CoreExpr -> Bool -exprIsCheap (Lit lit) = True +exprIsCheap (Lit _) = True exprIsCheap (Type _) = True exprIsCheap (Var _) = True -exprIsCheap (Note InlineMe e) = True +exprIsCheap (Note InlineMe _) = True exprIsCheap (Note _ e) = exprIsCheap e -exprIsCheap (Cast e co) = exprIsCheap e +exprIsCheap (Cast e _) = exprIsCheap e exprIsCheap (Lam x e) = isRuntimeVar x || exprIsCheap e exprIsCheap (Case e _ _ alts) = exprIsCheap e && and [exprIsCheap rhs | (_,_,rhs) <- alts] @@ -471,7 +495,7 @@ exprIsCheap other_expr -- Applications and variables go (App f a) val_args | isRuntimeArg a = go f (a:val_args) | otherwise = go f val_args - go (Var f) [] = True -- Just a type application of a variable + go (Var _) [] = True -- Just a type application of a variable -- (f t1 t2 t3) counts as WHNF go (Var f) args = case globalIdDetails f of @@ -480,14 +504,14 @@ exprIsCheap other_expr -- Applications and variables PrimOpId op -> go_primop op args DataConWorkId _ -> go_pap args - other | length args < idArity f -> go_pap args + _ | length args < idArity f -> go_pap args - other -> isBottomingId f + _ -> isBottomingId f -- Application of a function which -- always gives bottom; we treat this as cheap -- because it certainly doesn't need to be shared! - go other args = False + go _ _ = False -------------- go_pap args = all exprIsTrivial args @@ -505,41 +529,45 @@ exprIsCheap other_expr -- Applications and variables -------------- go_sel [arg] = exprIsCheap arg -- I'm experimenting with making record selection - go_sel other = False -- look cheap, so we will substitute it inside a + go_sel _ = False -- look cheap, so we will substitute it inside a -- lambda. Particularly for dictionary field selection. -- BUT: Take care with (sel d x)! The (sel d) might be cheap, but -- there's no guarantee that (sel d x) will be too. Hence (n_val_args == 1) \end{code} -exprOkForSpeculation returns True of an expression that it is - - * safe to evaluate even if normal order eval might not - evaluate the expression at all, or - - * safe *not* to evaluate even if normal order would do so - -It returns True iff - - the expression guarantees to terminate, - soon, - without raising an exception, - without causing a side effect (e.g. writing a mutable variable) - -NB: if exprIsHNF e, then exprOkForSpecuation e - -E.G. - let x = case y# +# 1# of { r# -> I# r# } - in E -==> - case y# +# 1# of { r# -> - let x = I# r# - in E - } - -We can only do this if the (y+1) is ok for speculation: it has no -side effects, and can't diverge or raise an exception. - \begin{code} +-- | 'exprOkForSpeculation' returns True of an expression that is: +-- +-- * Safe to evaluate even if normal order eval might not +-- evaluate the expression at all, or +-- +-- * Safe /not/ to evaluate even if normal order would do so +-- +-- Precisely, it returns @True@ iff: +-- +-- * The expression guarantees to terminate, +-- +-- * soon, +-- +-- * without raising an exception, +-- +-- * without causing a side effect (e.g. writing a mutable variable) +-- +-- Note that if @exprIsHNF e@, then @exprOkForSpecuation e@. +-- As an example of the considerations in this test, consider: +-- +-- > let x = case y# +# 1# of { r# -> I# r# } +-- > in E +-- +-- being translated to: +-- +-- > case y# +# 1# of { r# -> +-- > let x = I# r# +-- > in E +-- > } +-- +-- We can only do this if the @y + 1@ is ok for speculation: it has no +-- side effects, and can't diverge or raise an exception. exprOkForSpeculation :: CoreExpr -> Bool exprOkForSpeculation (Lit _) = True exprOkForSpeculation (Type _) = True @@ -547,14 +575,14 @@ exprOkForSpeculation (Type _) = True exprOkForSpeculation (Var v) = isUnLiftedType (idType v) && not (isTickBoxOp v) exprOkForSpeculation (Note _ e) = exprOkForSpeculation e -exprOkForSpeculation (Cast e co) = exprOkForSpeculation e +exprOkForSpeculation (Cast e _) = exprOkForSpeculation e exprOkForSpeculation other_expr = case collectArgs other_expr of (Var f, args) -> spec_ok (globalIdDetails f) args - other -> False + _ -> False where - spec_ok (DataConWorkId _) args + spec_ok (DataConWorkId _) _ = True -- The strictness of the constructor has already -- been expressed by its "wrapper", so we don't need -- to take the arguments into account @@ -572,11 +600,10 @@ exprOkForSpeculation other_expr -- A bit conservative: we don't really need -- to care about lazy arguments, but this is easy - spec_ok other args = False + spec_ok _ _ = False +-- | True of dyadic operators that can fail only if the second arg is zero! isDivOp :: PrimOp -> Bool --- True of dyadic operators that can fail --- only if the second arg is zero -- This function probably belongs in PrimOp, or even in -- an automagically generated file.. but it's such a -- special case I thought I'd leave it here for now. @@ -588,53 +615,59 @@ isDivOp IntegerQuotRemOp = True isDivOp IntegerDivModOp = True isDivOp FloatDivOp = True isDivOp DoubleDivOp = True -isDivOp other = False +isDivOp _ = False \end{code} - \begin{code} -exprIsBottom :: CoreExpr -> Bool -- True => definitely bottom +-- | True of expressions that are guaranteed to diverge upon execution +exprIsBottom :: CoreExpr -> Bool exprIsBottom e = go 0 e - where - -- n is the number of args - go n (Note _ e) = go n e - go n (Cast e co) = go n e - go n (Let _ e) = go n e - go n (Case e _ _ _) = go 0 e -- Just check the scrut - go n (App e _) = go (n+1) e - go n (Var v) = idAppIsBottom v n - go n (Lit _) = False - go n (Lam _ _) = False - go n (Type _) = False + where + -- n is the number of args + go n (Note _ e) = go n e + go n (Cast e _) = go n e + go n (Let _ e) = go n e + go _ (Case e _ _ _) = go 0 e -- Just check the scrut + go n (App e _) = go (n+1) e + go n (Var v) = idAppIsBottom v n + go _ (Lit _) = False + go _ (Lam _ _) = False + go _ (Type _) = False idAppIsBottom :: Id -> Int -> Bool idAppIsBottom id n_val_args = appIsBottom (idNewStrictness id) n_val_args \end{code} -@exprIsHNF@ returns true for expressions that are certainly *already* -evaluated to *head* normal form. 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` - -So, it does *not* treat variables as evaluated, unless they say they are. - -But it *does* treat partial applications and constructor applications -as values, even if their arguments are non-trivial, provided the argument -type is lifted; - e.g. (:) (f x) (map f xs) is a value - map (...redex...) is a value -Because `seq` on such things completes immediately - -For unlifted argument types, we have to be careful: - C (f x :: Int#) -Suppose (f x) diverges; then C (f x) is not a value. However this can't -happen: see CoreSyn Note [CoreSyn let/app invariant]. Args of unboxed -type must be ok-for-speculation (or trivial). - \begin{code} + +-- | This returns true for expressions that are certainly /already/ +-- evaluated to /head/ normal form. This is used to decide whether it's ok +-- to change: +-- +-- > case x of _ -> e +-- +-- into: +-- +-- > e +-- +-- and to decide whether it's safe to discard a 'seq'. +-- So, it does /not/ treat variables as evaluated, unless they say they are. +-- However, it /does/ treat partial applications and constructor applications +-- as values, even if their arguments are non-trivial, provided the argument +-- type is lifted. For example, both of these are values: +-- +-- > (:) (f x) (map f xs) +-- > map (...redex...) +-- +-- Because 'seq' on such things completes immediately. +-- +-- For unlifted argument types, we have to be careful: +-- +-- > C (f x :: Int#) +-- +-- Suppose @f x@ diverges; then @C (f x)@ is not a value. However this can't +-- happen: see "CoreSyn#let_app_invariant". This invariant states that arguments of +-- unboxed type must be ok-for-speculation (or trivial). exprIsHNF :: CoreExpr -> Bool -- True => Value-lambda, constructor, PAP exprIsHNF (Var v) -- NB: There are no value args at this point = isDataConWorkId v -- Catches nullary constructors, @@ -645,31 +678,36 @@ 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 _) = True +exprIsHNF (Type _) = 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 _) = exprIsHNF e exprIsHNF (App e (Type _)) = exprIsHNF e exprIsHNF (App e a) = app_is_value e [a] -exprIsHNF other = False +exprIsHNF _ = False -- There is at least one value argument +app_is_value :: CoreExpr -> [CoreArg] -> Bool app_is_value (Var fun) args = idArity fun > valArgCount args -- Under-applied function || isDataConWorkId fun -- or data constructor -app_is_value (Note n f) as = app_is_value f as +app_is_value (Note _ f) as = app_is_value f as app_is_value (Cast f _) as = app_is_value f as app_is_value (App f a) as = app_is_value f (a:as) -app_is_value other as = False +app_is_value _ _ = False \end{code} +These InstPat functions go here to avoid circularity between DataCon and Id + \begin{code} --- These InstPat functions go here to avoid circularity between DataCon and Id -dataConRepInstPat = dataConInstPat dataConRepArgTys (repeat (FSLIT("ipv"))) +dataConRepInstPat, dataConOrigInstPat :: [Unique] -> DataCon -> [Type] -> ([TyVar], [CoVar], [Id]) +dataConRepFSInstPat :: [FastString] -> [Unique] -> DataCon -> [Type] -> ([TyVar], [CoVar], [Id]) + +dataConRepInstPat = dataConInstPat dataConRepArgTys (repeat ((fsLit "ipv"))) dataConRepFSInstPat = dataConInstPat dataConRepArgTys -dataConOrigInstPat = dataConInstPat dc_arg_tys (repeat (FSLIT("ipv"))) +dataConOrigInstPat = dataConInstPat dc_arg_tys (repeat ((fsLit "ipv"))) where dc_arg_tys dc = map mkPredTy (dataConEqTheta dc) ++ map mkPredTy (dataConDictTheta dc) ++ dataConOrigArgTys dc -- Remember to include the existential dictionaries @@ -703,12 +741,12 @@ dataConInstPat :: (DataCon -> [Type]) -- function used to find arg tys -- ... -- -- has representation type --- forall a. forall a1. forall b. (a :=: (a1,b)) => +-- forall a. forall a1. forall b. (a ~ (a1,b)) => -- Int -> b -> T a -- -- dataConInstPat fss us T1 (a1',b') will return -- --- ([a1'', b''], [c :: (a1', b'):=:(a1'', b'')], [x :: Int, y :: b'']) +-- ([a1'', b''], [c :: (a1', b')~(a1'', b'')], [x :: Int, y :: b'']) -- -- where the double-primed variables are created with the FastStrings and -- Uniques given as fss and us @@ -753,18 +791,18 @@ dataConInstPat arg_fun fss uniqs con inst_tys mk_id_var uniq fs ty = mkUserLocal (mkVarOccFS fs) uniq (substTy subst ty) noSrcSpan arg_ids = zipWith3 mk_id_var id_uniqs id_fss arg_tys +-- | Returns @Just (dc, [x1..xn])@ if the argument expression is +-- a constructor application of the form @dc x1 .. xn@ 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) - = -- Here we do the PushC reduction rule as described in the FC paper + = -- Here we do the KPush reduction rule as described in the FC paper case exprIsConApp_maybe expr of { 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) + -- 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.) @@ -787,17 +825,20 @@ exprIsConApp_maybe (Cast expr co) let tc_arity = tyConArity from_tc - (univ_args, rest1) = splitAt tc_arity dc_args - (ex_args, rest2) = splitAt n_ex_tvs rest1 - (co_args, val_args) = splitAt n_cos rest2 + (univ_args, rest1) = splitAt tc_arity dc_args + (ex_args, rest2) = splitAt n_ex_tvs rest1 + (co_args_spec, rest3) = splitAt n_cos_spec rest2 + (co_args_theta, val_args) = splitAt n_cos_theta rest3 arg_tys = dataConRepArgTys dc dc_univ_tyvars = dataConUnivTyVars dc dc_ex_tyvars = dataConExTyVars dc dc_eq_spec = dataConEqSpec dc + dc_eq_theta = dataConEqTheta dc dc_tyvars = dc_univ_tyvars ++ dc_ex_tyvars n_ex_tvs = length dc_ex_tyvars - n_cos = length dc_eq_spec + n_cos_spec = length dc_eq_spec + n_cos_theta = length dc_eq_theta -- Make the "theta" from Fig 3 of the paper gammas = decomposeCo tc_arity co @@ -805,10 +846,15 @@ exprIsConApp_maybe (Cast expr co) 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 + cast_co_spec (tv, ty) co + = cast_co_theta (mkEqPred (mkTyVarTy tv, ty)) co + cast_co_theta eqPred (Type co) + | (ty1, ty2) <- getEqPredTys eqPred + = Type $ mkSymCoercion (substTy theta ty1) + `mkTransCoercion` co + `mkTransCoercion` (substTy theta ty2) + new_co_args = zipWith cast_co_spec dc_eq_spec co_args_spec ++ + zipWith cast_co_theta dc_eq_theta co_args_theta -- ...and now value arguments new_val_args = zipWith cast_arg arg_tys val_args @@ -862,7 +908,7 @@ exprIsConApp_maybe expr = analyse (collectArgs expr) isCheapUnfolding unf = exprIsConApp_maybe (unfoldingTemplate unf) - analyse other = Nothing + analyse _ = Nothing \end{code} @@ -874,10 +920,10 @@ exprIsConApp_maybe expr = analyse (collectArgs expr) %************************************************************************ \begin{code} +-- ^ The Arity returned is the number of value args the +-- expression can be applied to without doing much work exprEtaExpandArity :: DynFlags -> CoreExpr -> Arity -{- The Arity returned is the number of value args the - thing can be applied to without doing much work - +{- exprEtaExpandArity is used when eta expanding e ==> \xy -> e x y @@ -963,26 +1009,27 @@ data ArityType = AFun Bool ArityType -- True <=> one-shot arityDepth :: ArityType -> Arity arityDepth (AFun _ ty) = 1 + arityDepth ty -arityDepth ty = 0 +arityDepth _ = 0 -andArityType ABot at2 = at2 -andArityType ATop at2 = ATop +andArityType :: ArityType -> ArityType -> ArityType +andArityType ABot at2 = at2 +andArityType ATop _ = ATop andArityType (AFun t1 at1) (AFun t2 at2) = AFun (t1 && t2) (andArityType at1 at2) -andArityType at1 at2 = andArityType at2 at1 +andArityType at1 at2 = andArityType at2 at1 arityType :: DynFlags -> CoreExpr -> ArityType -- (go1 e) = [b1,..,bn] -- means expression can be rewritten \x_b1 -> ... \x_bn -> body -- where bi is True <=> the lambda is one-shot -arityType dflags (Note n e) = arityType dflags e +arityType dflags (Note _ e) = arityType dflags e -- Not needed any more: etaExpand is cleverer --- | ok_note n = arityType dflags e --- | otherwise = ATop +-- removed: | ok_note n = arityType dflags e +-- removed: | otherwise = ATop -arityType dflags (Cast e co) = arityType dflags e +arityType dflags (Cast e _) = arityType dflags e -arityType dflags (Var v) +arityType _ (Var v) = mk (idArity v) (arg_tys (idType v)) where mk :: Arity -> [Type] -> ArityType @@ -992,9 +1039,9 @@ arityType dflags (Var v) -- False -> \(s:RealWorld) -> e -- where foo has arity 1. Then we want the state hack to -- apply to foo too, so we can eta expand the case. - mk 0 tys | isBottomingId v = ABot - | (ty:tys) <- tys, isStateHackType ty = AFun True ATop - | otherwise = ATop + mk 0 tys | isBottomingId v = ABot + | (ty:_) <- tys, isStateHackType ty = AFun True ATop + | otherwise = ATop mk n (ty:tys) = AFun (isStateHackType ty) (mk (n-1) tys) mk n [] = AFun False (mk (n-1) []) @@ -1011,9 +1058,13 @@ arityType dflags (Lam x e) -- Applications; decrease arity arityType dflags (App f (Type _)) = arityType dflags f -arityType dflags (App f a) = case arityType dflags f of - AFun one_shot xs | exprIsCheap a -> xs - other -> ATop +arityType dflags (App f a) + = case arityType dflags f of + ABot -> ABot -- If function diverges, ignore argument + ATop -> ATop -- No no info about function + AFun _ xs + | exprIsCheap a -> xs + | otherwise -> ATop -- Case/Let; keep arity if either the expression is cheap -- or it's a 1-shot lambda @@ -1024,15 +1075,15 @@ arityType dflags (App f a) = case arityType dflags f of -- The difference is observable using 'seq' arityType dflags (Case scrut _ _ alts) = case foldr1 andArityType [arityType dflags rhs | (_,_,rhs) <- alts] of - xs | exprIsCheap scrut -> xs - xs@(AFun one_shot _) | one_shot -> AFun True ATop - other -> ATop + xs | exprIsCheap scrut -> xs + AFun one_shot _ | one_shot -> AFun True ATop + _ -> ATop arityType dflags (Let b e) = case arityType dflags e of - xs | cheap_bind b -> xs - xs@(AFun one_shot _) | one_shot -> AFun True ATop - other -> ATop + xs | cheap_bind b -> xs + AFun one_shot _ | one_shot -> AFun True ATop + _ -> ATop where cheap_bind (NonRec b e) = is_cheap (b,e) cheap_bind (Rec prs) = all is_cheap prs @@ -1055,7 +1106,7 @@ arityType dflags (Let b e) -- One could go further and make exprIsCheap reply True to any -- dictionary-typed expression, but that's more work. -arityType dflags other = ATop +arityType _ _ = ATop {- NOT NEEDED ANY MORE: etaExpand is cleverer ok_note InlineMe = False @@ -1074,17 +1125,21 @@ ok_note other = True \begin{code} -etaExpand :: Arity -- Result should have this number of value args - -> [Unique] - -> CoreExpr -> Type -- Expression and its type - -> CoreExpr --- (etaExpand n us e ty) returns an expression with --- the same meaning as 'e', but with arity 'n'. +-- | @etaExpand n us e ty@ returns an expression with +-- the same meaning as @e@, but with arity @n@. +-- +-- Given: +-- +-- > e' = etaExpand n us e ty -- --- Given e' = etaExpand n us e ty --- We should have --- ty = exprType e = exprType e' +-- We should have that: -- +-- > ty = exprType e = exprType e' +etaExpand :: Arity -- ^ Result should have this number of value args + -> [Unique] -- ^ Uniques to assign to the new binders + -> CoreExpr -- ^ Expression to expand + -> Type -- ^ Type of expression to expand + -> CoreExpr -- Note that SCCs are not treated specially. If we have -- etaExpand 2 (\x -> scc "foo" e) -- = (\xy -> (scc "foo" e) y) @@ -1094,7 +1149,6 @@ etaExpand n us expr ty | manifestArity expr >= n = expr -- The no-op case | otherwise = eta_expand n us expr ty - where -- manifestArity sees how many leading value lambdas there are manifestArity :: CoreExpr -> Arity @@ -1102,7 +1156,7 @@ manifestArity (Lam v e) | isId v = 1 + manifestArity e | otherwise = manifestArity e manifestArity (Note _ e) = manifestArity e manifestArity (Cast e _) = manifestArity e -manifestArity e = 0 +manifestArity _ = 0 -- etaExpand deals with for-alls. For example: -- etaExpand 1 E @@ -1112,8 +1166,9 @@ manifestArity e = 0 -- -- It deals with coerces too, though they are now rare -- so perhaps the extra code isn't worth it +eta_expand :: Int -> [Unique] -> CoreExpr -> Type -> CoreExpr -eta_expand n us expr ty +eta_expand n _ expr ty | 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 @@ -1154,7 +1209,7 @@ eta_expand n us expr ty Lam lam_tv (eta_expand n us2 (App expr (Type (mkTyVarTy lam_tv))) (substTyWith [tv] [mkTyVarTy lam_tv] ty')) where - lam_tv = setVarName tv (mkSysTvName uniq FSLIT("etaT")) + lam_tv = setVarName tv (mkSysTvName uniq (fsLit "etaT")) -- Using tv as a base retains its tyvar/covar-ness (uniq:us2) = us ; Nothing -> @@ -1162,7 +1217,7 @@ eta_expand n us expr ty case splitFunTy_maybe ty of { Just (arg_ty, res_ty) -> Lam arg1 (eta_expand (n-1) us2 (App expr (Var arg1)) res_ty) where - arg1 = mkSysLocal FSLIT("eta") uniq arg_ty + arg1 = mkSysLocal (fsLit "eta") uniq arg_ty (uniq:us2) = us ; Nothing -> @@ -1183,6 +1238,7 @@ eta_expand n us expr ty -- This *can* legitmately happen: e.g. coerce Int (\x. x) -- Essentially the programmer is playing fast and loose with types -- (Happy does this a lot). So we simply decline to eta-expand. + -- Otherwise we'd end up with an explicit lambda having a non-function type expr }}} \end{code} @@ -1211,23 +1267,52 @@ And in any case it seems more robust to have exprArity be a bit more intelligent But note that (\x y z -> f x y z) should have arity 3, regardless of f's arity. +Note [exprArity invariant] +~~~~~~~~~~~~~~~~~~~~~~~~~~ +exprArity has the following invariant: + (exprArity e) = n, then manifestArity (etaExpand e n) = n + +That is, if exprArity says "the arity is n" then etaExpand really can get +"n" manifest lambdas to the top. + +Why is this important? Because + - In TidyPgm we use exprArity to fix the *final arity* of + each top-level Id, and in + - In CorePrep we use etaExpand on each rhs, so that the visible lambdas + actually match that arity, which in turn means + that the StgRhs has the right number of lambdas + +An alternative would be to do the eta-expansion in TidyPgm, at least +for top-level bindings, in which case we would not need the trim_arity +in exprArity. That is a less local change, so I'm going to leave it for today! + + \begin{code} +-- | An approximate, fast, version of 'exprEtaExpandArity' exprArity :: CoreExpr -> Arity exprArity e = go e - where - go (Var v) = idArity v - go (Lam x e) | isId x = go e + 1 - | otherwise = go e - go (Note n e) = go e - go (Cast e _) = go e - go (App e (Type t)) = go e - go (App f a) | exprIsCheap a = (go f - 1) `max` 0 - -- NB: exprIsCheap a! - -- f (fac x) does not have arity 2, - -- even if f has arity 3! - -- NB: `max 0`! (\x y -> f x) has arity 2, even if f is - -- unknown, hence arity 0 - go _ = 0 + where + go (Var v) = idArity v + go (Lam x e) | isId x = go e + 1 + | otherwise = go e + go (Note _ e) = go e + go (Cast e co) = trim_arity (go e) 0 (snd (coercionKind co)) + go (App e (Type _)) = go e + go (App f a) | exprIsCheap a = (go f - 1) `max` 0 + -- NB: exprIsCheap a! + -- f (fac x) does not have arity 2, + -- even if f has arity 3! + -- NB: `max 0`! (\x y -> f x) has arity 2, even if f is + -- unknown, hence arity 0 + go _ = 0 + + -- Note [exprArity invariant] + trim_arity n a ty + | n==a = a + | Just (_, ty') <- splitForAllTy_maybe ty = trim_arity n a ty' + | Just (_, ty') <- splitFunTy_maybe ty = trim_arity n (a+1) ty' + | Just (ty',_) <- splitNewTypeRepCo_maybe ty = trim_arity n a ty' + | otherwise = a \end{code} %************************************************************************ @@ -1236,11 +1321,12 @@ exprArity e = go e %* * %************************************************************************ -@cheapEqExpr@ is a cheap equality test which bales out fast! - True => definitely equal - False => may or may not be equal - \begin{code} +-- | A cheap equality test which bales out fast! +-- If it returns @True@ the arguments are definitely equal, +-- otherwise, they may or may not be equal. +-- +-- See also 'exprIsBig' cheapEqExpr :: Expr b -> Expr b -> Bool cheapEqExpr (Var v1) (Var v2) = v1==v2 @@ -1250,23 +1336,26 @@ cheapEqExpr (Type t1) (Type t2) = t1 `coreEqType` t2 cheapEqExpr (App f1 a1) (App f2 a2) = f1 `cheapEqExpr` f2 && a1 `cheapEqExpr` a2 +cheapEqExpr (Cast e1 t1) (Cast e2 t2) + = e1 `cheapEqExpr` e2 && t1 `coreEqCoercion` t2 + cheapEqExpr _ _ = False exprIsBig :: Expr b -> Bool --- Returns True of expressions that are too big to be compared by cheapEqExpr +-- ^ Returns @True@ of expressions that are too big to be compared by 'cheapEqExpr' exprIsBig (Lit _) = False -exprIsBig (Var v) = False -exprIsBig (Type t) = False +exprIsBig (Var _) = False +exprIsBig (Type _) = False exprIsBig (App f a) = exprIsBig f || exprIsBig a exprIsBig (Cast e _) = exprIsBig e -- Hopefully coercions are not too big! -exprIsBig other = True +exprIsBig _ = True \end{code} \begin{code} tcEqExpr :: CoreExpr -> CoreExpr -> Bool --- Used in rule matching, so does *not* look through --- newtypes, predicate types; hence tcEqExpr +-- ^ A kind of shallow equality used in rule matching, so does +-- /not/ look through newtypes or predicate types tcEqExpr e1 e2 = tcEqExprX rn_env e1 e2 where @@ -1274,7 +1363,7 @@ tcEqExpr e1 e2 = tcEqExprX rn_env e1 e2 tcEqExprX :: RnEnv2 -> CoreExpr -> CoreExpr -> Bool tcEqExprX env (Var v1) (Var v2) = rnOccL env v1 == rnOccR env v2 -tcEqExprX env (Lit lit1) (Lit lit2) = lit1 == lit2 +tcEqExprX _ (Lit lit1) (Lit lit2) = lit1 == lit2 tcEqExprX env (App f1 a1) (App f2 a2) = tcEqExprX env f1 f2 && tcEqExprX env a1 a2 tcEqExprX env (Lam v1 e1) (Lam v2 e2) = tcEqExprX (rnBndr2 env v1 v2) e1 e2 tcEqExprX env (Let (NonRec v1 r1) e1) @@ -1296,16 +1385,18 @@ tcEqExprX env (Case e1 v1 t1 a1) where env' = rnBndr2 env v1 v2 -tcEqExprX env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && tcEqExprX env e1 e2 +tcEqExprX env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && tcEqExprX env e1 e2 tcEqExprX env (Cast e1 co1) (Cast e2 co2) = tcEqTypeX env co1 co2 && tcEqExprX env e1 e2 -tcEqExprX env (Type t1) (Type t2) = tcEqTypeX env t1 t2 -tcEqExprX env e1 e2 = False - +tcEqExprX env (Type t1) (Type t2) = tcEqTypeX env t1 t2 +tcEqExprX _ _ _ = False + +eq_alt :: RnEnv2 -> CoreAlt -> CoreAlt -> Bool eq_alt env (c1,vs1,r1) (c2,vs2,r2) = c1==c2 && tcEqExprX (rnBndrs2 env vs1 vs2) r1 r2 -eq_note env (SCC cc1) (SCC cc2) = cc1 == cc2 -eq_note env (CoreNote s1) (CoreNote s2) = s1 == s2 -eq_note env other1 other2 = False +eq_note :: RnEnv2 -> Note -> Note -> Bool +eq_note _ (SCC cc1) (SCC cc2) = cc1 == cc2 +eq_note _ (CoreNote s1) (CoreNote s2) = s1 == s2 +eq_note _ _ _ = False \end{code} @@ -1320,8 +1411,8 @@ coreBindsSize :: [CoreBind] -> Int coreBindsSize bs = foldr ((+) . bindSize) 0 bs exprSize :: CoreExpr -> Int - -- A measure of the size of the expressions - -- It also forces the expression pretty drastically as a side effect +-- ^ A measure of the size of the expressions, strictly greater than 0 +-- It also forces the expression pretty drastically as a side effect exprSize (Var v) = v `seq` 1 exprSize (Lit lit) = lit `seq` 1 exprSize (App f a) = exprSize f + exprSize a @@ -1332,6 +1423,7 @@ exprSize (Cast e co) = (seqType co `seq` 1) + exprSize e exprSize (Note n e) = noteSize n + exprSize e exprSize (Type t) = seqType t `seq` 1 +noteSize :: Note -> Int noteSize (SCC cc) = cc `seq` 1 noteSize InlineMe = 1 noteSize (CoreNote s) = s `seq` 1 -- hdaume: core annotations @@ -1342,13 +1434,17 @@ varSize b | isTyVar b = 1 megaSeqIdInfo (idInfo b) `seq` 1 -varsSize = foldr ((+) . varSize) 0 +varsSize :: [Var] -> Int +varsSize = sum . map varSize +bindSize :: CoreBind -> Int bindSize (NonRec b e) = varSize b + exprSize e bindSize (Rec prs) = foldr ((+) . pairSize) 0 prs +pairSize :: (Var, CoreExpr) -> Int pairSize (b,e) = varSize b + exprSize e +altSize :: CoreAlt -> Int altSize (c,bs,e) = c `seq` varsSize bs + exprSize e \end{code} @@ -1361,45 +1457,46 @@ altSize (c,bs,e) = c `seq` varsSize bs + exprSize e \begin{code} hashExpr :: CoreExpr -> Int --- Two expressions that hash to the same Int may be equal (but may not be) --- Two expressions that hash to the different Ints are definitely unequal --- --- But "unequal" here means "not identical"; two alpha-equivalent --- expressions may hash to the different Ints +-- ^ Two expressions that hash to the same @Int@ may be equal (but may not be) +-- Two expressions that hash to the different Ints are definitely unequal. -- --- The emphasis is on a crude, fast hash, rather than on high precision +-- The emphasis is on a crude, fast hash, rather than on high precision. +-- +-- But unequal here means \"not identical\"; two alpha-equivalent +-- expressions may hash to the different Ints. -- --- We must be careful that \x.x and \y.y map to the same hash code, --- (at least if we want the above invariant to be true) +-- We must be careful that @\\x.x@ and @\\y.y@ map to the same hash code, +-- (at least if we want the above invariant to be true). hashExpr e = fromIntegral (hash_expr (1,emptyVarEnv) e .&. 0x7fffffff) -- UniqFM doesn't like negative Ints -type HashEnv = (Int, VarEnv Int) -- Hash code for bound variables +type HashEnv = (Int, VarEnv Int) -- Hash code for bound variables hash_expr :: HashEnv -> CoreExpr -> Word32 -- Word32, because we're expecting overflows here, and overflowing -- signed types just isn't cool. In C it's even undefined. hash_expr env (Note _ e) = hash_expr env e -hash_expr env (Cast e co) = hash_expr env e +hash_expr env (Cast e _) = hash_expr env e hash_expr env (Var v) = hashVar env v -hash_expr env (Lit lit) = fromIntegral (hashLiteral lit) +hash_expr _ (Lit lit) = fromIntegral (hashLiteral lit) hash_expr env (App f e) = hash_expr env f * fast_hash_expr env e hash_expr env (Let (NonRec b r) e) = hash_expr (extend_env env b) e * fast_hash_expr env r -hash_expr env (Let (Rec ((b,r):_)) e) = hash_expr (extend_env env b) e +hash_expr env (Let (Rec ((b,_):_)) e) = hash_expr (extend_env env b) e hash_expr env (Case e _ _ _) = hash_expr env e hash_expr env (Lam b e) = hash_expr (extend_env env b) e -hash_expr env (Type t) = WARN(True, text "hash_expr: type") 1 +hash_expr _ (Type _) = WARN(True, text "hash_expr: type") 1 -- Shouldn't happen. Better to use WARN than trace, because trace -- prevents the CPR optimisation kicking in for hash_expr. +fast_hash_expr :: HashEnv -> CoreExpr -> Word32 fast_hash_expr env (Var v) = hashVar env v fast_hash_expr env (Type t) = fast_hash_type env t -fast_hash_expr env (Lit lit) = fromIntegral (hashLiteral lit) -fast_hash_expr env (Cast e co) = fast_hash_expr env e -fast_hash_expr env (Note n e) = fast_hash_expr env e -fast_hash_expr env (App f a) = fast_hash_expr env a -- A bit idiosyncratic ('a' not 'f')! -fast_hash_expr env other = 1 +fast_hash_expr _ (Lit lit) = fromIntegral (hashLiteral lit) +fast_hash_expr env (Cast e _) = fast_hash_expr env e +fast_hash_expr env (Note _ e) = fast_hash_expr env e +fast_hash_expr env (App _ a) = fast_hash_expr env a -- A bit idiosyncratic ('a' not 'f')! +fast_hash_expr _ _ = 1 fast_hash_type :: HashEnv -> Type -> Word32 fast_hash_type env ty @@ -1428,17 +1525,17 @@ arguments, come from another DLL (because we can't refer to static labels in other DLLs). If this happens we simply make the RHS into an updatable thunk, -and 'exectute' it rather than allocating it statically. +and 'execute' it rather than allocating it statically. \begin{code} +-- | This function is called only on *top-level* right-hand sides. +-- Returns @True@ if the RHS can be allocated statically in the output, +-- with no thunks involved at all. rhsIsStatic :: PackageId -> CoreExpr -> Bool --- This function is called only on *top-level* right-hand sides --- Returns True if the RHS can be allocated statically, with --- no thunks involved at all. --- -- It's called (i) in TidyPgm.hasCafRefs to decide if the rhs is, or --- refers to, CAFs; and (ii) in CoreToStg to decide whether to put an --- update flag on it. +-- refers to, CAFs; (ii) in CoreToStg to decide whether to put an +-- update flag on it and (iii) in DsExpr to decide how to expand +-- list literals -- -- The basic idea is that rhsIsStatic returns True only if the RHS is -- (a) a value lambda @@ -1488,25 +1585,22 @@ rhsIsStatic :: PackageId -> CoreExpr -> Bool -- dynamic -- -- c) don't look through unfolding of f in (f x). --- --- When opt_RuntimeTypes is on, we keep type lambdas and treat --- them as making the RHS re-entrant (non-updatable). -rhsIsStatic this_pkg rhs = is_static False rhs +rhsIsStatic _this_pkg rhs = is_static False rhs where is_static :: Bool -- True <=> in a constructor argument; must be atomic -> CoreExpr -> Bool is_static False (Lam b e) = isRuntimeVar b || is_static False e - is_static in_arg (Note (SCC _) e) = False + is_static _ (Note (SCC _) _) = False is_static in_arg (Note _ e) = is_static in_arg e - is_static in_arg (Cast e co) = is_static in_arg e + is_static in_arg (Cast e _) = is_static in_arg e - is_static in_arg (Lit lit) + is_static _ (Lit lit) = case lit of MachLabel _ _ -> False - other -> True + _ -> True -- A MachLabel (foreign import "&foo") in an argument -- prevents a constructor application from being static. The -- reason is that it might give rise to unresolvable symbols @@ -1520,7 +1614,7 @@ rhsIsStatic this_pkg rhs = is_static False rhs where go (Var f) n_val_args #if mingw32_TARGET_OS - | not (isDllName this_pkg (idName f)) + | not (isDllName _this_pkg (idName f)) #endif = saturated_data_con f n_val_args || (in_arg && n_val_args == 0) @@ -1542,11 +1636,11 @@ rhsIsStatic this_pkg rhs = is_static False rhs -- x = D# (1.0## /## 2.0##) -- can't float because /## can fail. - go (Note (SCC _) f) n_val_args = False - go (Note _ f) n_val_args = go f n_val_args - go (Cast e co) n_val_args = go e n_val_args + go (Note (SCC _) _) _ = False + go (Note _ f) n_val_args = go f n_val_args + go (Cast e _) n_val_args = go e n_val_args - go other n_val_args = False + go _ _ = False saturated_data_con f n_val_args = case isDataConWorkId_maybe f of