\begin{code}
+-- | Utility functions for constructing Core syntax, principally for desugaring
module DsUtils (
EquationInfo(..),
firstPat, shiftEqns,
-
- mkDsLet, mkDsLets, mkDsApp, mkDsApps,
MatchResult(..), CanItFail(..),
cantFailMatchResult, alwaysFailMatchResult,
mkCoPrimCaseMatchResult, mkCoAlgCaseMatchResult,
wrapBind, wrapBinds,
- mkErrorAppDs, mkNilExpr, mkConsExpr, mkListExpr,
- mkIntExpr, mkCharExpr,
- mkStringExpr, mkStringExprFS, mkIntegerExpr,
- mkBuildExpr, mkFoldrExpr,
-
- seqVar,
-
- -- Core tuples
- mkCoreVarTup, mkCoreTup, mkCoreVarTupTy, mkCoreTupTy,
- mkBigCoreVarTup, mkBigCoreTup, mkBigCoreVarTupTy, mkBigCoreTupTy,
-
- -- LHs tuples
- mkLHsVarTup, mkLHsTup, mkLHsVarPatTup, mkLHsPatTup,
- mkBigLHsVarTup, mkBigLHsTup, mkBigLHsVarPatTup, mkBigLHsPatTup,
-
- -- Tuple bindings
- mkSelectorBinds, mkTupleSelector,
- mkSmallTupleCase, mkTupleCase,
-
- dsSyntaxTable, lookupEvidence,
+ mkErrorAppDs,
+
+ seqVar,
+
+ -- LHs tuples
+ mkLHsVarTup, mkLHsTup, mkLHsVarPatTup, mkLHsPatTup,
+ mkBigLHsVarTup, mkBigLHsTup, mkBigLHsVarPatTup, mkBigLHsPatTup,
+
+ mkSelectorBinds,
+
+ dsSyntaxTable, lookupEvidence,
selectSimpleMatchVarL, selectMatchVars, selectMatchVar,
mkTickBox, mkOptTickBox, mkBinaryTickBox
import HsSyn
import TcHsSyn
import CoreSyn
-import Constants
import DsMonad
import CoreUtils
+import MkCore
import MkId
import Id
import Var
import StaticFlags
import Data.Char
-
-infixl 4 `mkDsApp`, `mkDsApps`
\end{code}
mk_panic std_name = pprPanic "dsSyntaxTable" (ptext (sLit "Not found:") <+> ppr std_name)
\end{code}
-
-%************************************************************************
-%* *
-\subsection{Building lets}
-%* *
-%************************************************************************
-
-Use case, not let for unlifted types. The simplifier will turn some
-back again.
-
-\begin{code}
-mkDsLet :: CoreBind -> CoreExpr -> CoreExpr
-mkDsLet (NonRec bndr rhs) body -- See Note [CoreSyn let/app invariant]
- | isUnLiftedType (idType bndr) && not (exprOkForSpeculation rhs)
- = Case rhs bndr (exprType body) [(DEFAULT,[],body)]
-mkDsLet bind body
- = Let bind body
-
-mkDsLets :: [CoreBind] -> CoreExpr -> CoreExpr
-mkDsLets binds body = foldr mkDsLet body binds
-
------------
-mkDsApp :: CoreExpr -> CoreExpr -> CoreExpr
--- Check the invariant that the arg of an App is ok-for-speculation if unlifted
--- See CoreSyn Note [CoreSyn let/app invariant]
-mkDsApp fun (Type ty) = App fun (Type ty)
-mkDsApp fun arg = mk_val_app fun arg arg_ty res_ty
- where
- (arg_ty, res_ty) = splitFunTy (exprType fun)
-
------------
-mkDsApps :: CoreExpr -> [CoreExpr] -> CoreExpr
--- Slightly more efficient version of (foldl mkDsApp)
-mkDsApps fun args
- = go fun (exprType fun) args
- where
- go fun _ [] = fun
- go fun fun_ty (Type ty : args) = go (App fun (Type ty)) (applyTy fun_ty ty) args
- go fun fun_ty (arg : args) = go (mk_val_app fun arg arg_ty res_ty) res_ty args
- where
- (arg_ty, res_ty) = splitFunTy fun_ty
------------
-mk_val_app :: CoreExpr -> CoreExpr -> Type -> Type -> CoreExpr
-mk_val_app (Var f `App` Type ty1 `App` Type _ `App` arg1) arg2 _ res_ty
- | f == seqId -- Note [Desugaring seq (1), (2)]
- = Case arg1 case_bndr res_ty [(DEFAULT,[],arg2)]
- where
- case_bndr = case arg1 of
- Var v1 | isLocalId v1 -> v1 -- Note [Desugaring seq (2) and (3)]
- _ -> mkWildId ty1
-
-mk_val_app fun arg arg_ty _ -- See Note [CoreSyn let/app invariant]
- | not (isUnLiftedType arg_ty) || exprOkForSpeculation arg
- = App fun arg -- The vastly common case
-
-mk_val_app fun arg arg_ty res_ty
- = Case arg (mkWildId arg_ty) res_ty [(DEFAULT,[],App fun (Var arg_id))]
- where
- arg_id = mkWildId arg_ty -- Lots of shadowing, but it doesn't matter,
- -- because 'fun ' should not have a free wild-id
-\end{code}
-
-Note [Desugaring seq (1)] cf Trac #1031
-~~~~~~~~~~~~~~~~~~~~~~~~~
- f x y = x `seq` (y `seq` (# x,y #))
-
-The [CoreSyn let/app invariant] means that, other things being equal, because
-the argument to the outer 'seq' has an unlifted type, we'll use call-by-value thus:
-
- f x y = case (y `seq` (# x,y #)) of v -> x `seq` v
-
-But that is bad for two reasons:
- (a) we now evaluate y before x, and
- (b) we can't bind v to an unboxed pair
-
-Seq is very, very special! So we recognise it right here, and desugar to
- case x of _ -> case y of _ -> (# x,y #)
-
-Note [Desugaring seq (2)] cf Trac #2231
-~~~~~~~~~~~~~~~~~~~~~~~~~
-Consider
- let chp = case b of { True -> fst x; False -> 0 }
- in chp `seq` ...chp...
-Here the seq is designed to plug the space leak of retaining (snd x)
-for too long.
-
-If we rely on the ordinary inlining of seq, we'll get
- let chp = case b of { True -> fst x; False -> 0 }
- case chp of _ { I# -> ...chp... }
-
-But since chp is cheap, and the case is an alluring contet, we'll
-inline chp into the case scrutinee. Now there is only one use of chp,
-so we'll inline a second copy. Alas, we've now ruined the purpose of
-the seq, by re-introducing the space leak:
- case (case b of {True -> fst x; False -> 0}) of
- I# _ -> ...case b of {True -> fst x; False -> 0}...
-
-We can try to avoid doing this by ensuring that the binder-swap in the
-case happens, so we get his at an early stage:
- case chp of chp2 { I# -> ...chp2... }
-But this is fragile. The real culprit is the source program. Perhaps we
-should have said explicitly
- let !chp2 = chp in ...chp2...
-
-But that's painful. So the code here does a little hack to make seq
-more robust: a saturated application of 'seq' is turned *directly* into
-the case expression. So we desugar to:
- let chp = case b of { True -> fst x; False -> 0 }
- case chp of chp { I# -> ...chp... }
-Notice the shadowing of the case binder! And now all is well.
-
-The reason it's a hack is because if you define mySeq=seq, the hack
-won't work on mySeq.
-
-Note [Desugaring seq (3)] cf Trac #2409
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The isLocalId ensures that we don't turn
- True `seq` e
-into
- case True of True { ... }
-which stupidly tries to bind the datacon 'True'.
-
-
%************************************************************************
%* *
\subsection{ Selecting match variables}
extractMatchResult (MatchResult CanFail match_fn) fail_expr = do
(fail_bind, if_it_fails) <- mkFailurePair fail_expr
body <- match_fn if_it_fails
- return (mkDsLet fail_bind body)
+ return (mkCoreLet fail_bind body)
combineMatchResults :: MatchResult -> MatchResult -> MatchResult
[(DEFAULT, [], body)]
mkCoLetMatchResult :: CoreBind -> MatchResult -> MatchResult
-mkCoLetMatchResult bind = adjustMatchResult (mkDsLet bind)
+mkCoLetMatchResult bind = adjustMatchResult (mkCoreLet bind)
-- (mkViewMatchResult var' viewExpr var mr) makes the expression
-- let var' = viewExpr var in mr
mkViewMatchResult :: Id -> CoreExpr -> Id -> MatchResult -> MatchResult
mkViewMatchResult var' viewExpr var =
- adjustMatchResult (mkDsLet (NonRec var' (mkDsApp viewExpr (Var var))))
+ adjustMatchResult (mkCoreLet (NonRec var' (mkCoreApp viewExpr (Var var))))
mkEvalMatchResult :: Id -> Type -> MatchResult -> MatchResult
mkEvalMatchResult var ty
--
mkAlt indexP (con, args, MatchResult _ bodyFun) = do
body <- bodyFun fail
- return (LitAlt lit, [], mkDsLets binds body)
+ return (LitAlt lit, [], mkCoreLets binds body)
where
lit = MachInt $ toInteger (dataConSourceArity con)
binds = [NonRec arg (indexExpr i) | (i, arg) <- zip [1..] args]
indexExpr i = mkApps (Var indexP) [Type elemTy, Var var, mkIntExpr i]
\end{code}
-
%************************************************************************
%* *
\subsection{Desugarer's versions of some Core functions}
src_loc <- getSrcSpanDs
let
full_msg = showSDoc (hcat [ppr src_loc, text "|", text msg])
- core_msg = Lit (mkStringLit full_msg)
- -- mkStringLit returns a result of type String#
+ core_msg = Lit (mkMachString full_msg)
+ -- mkMachString returns a result of type String#
return (mkApps (Var err_id) [Type ty, core_msg])
\end{code}
-
-%************************************************************************
-%* *
-\subsection{Making literals}
-%* *
-%************************************************************************
-
-\begin{code}
-mkCharExpr :: Char -> CoreExpr -- Returns @C# c :: Int@
-mkIntExpr :: Integer -> CoreExpr -- Returns @I# i :: Int@
-mkIntegerExpr :: Integer -> DsM CoreExpr -- Result :: Integer
-mkStringExpr :: String -> DsM CoreExpr -- Result :: String
-mkStringExprFS :: FastString -> DsM CoreExpr -- Result :: String
-
-mkIntExpr i = mkConApp intDataCon [mkIntLit i]
-mkCharExpr c = mkConApp charDataCon [mkLit (MachChar c)]
-
-mkIntegerExpr i
- | inIntRange i -- Small enough, so start from an Int
- = do integer_id <- dsLookupGlobalId smallIntegerName
- return (mkSmallIntegerLit integer_id i)
-
--- Special case for integral literals with a large magnitude:
--- They are transformed into an expression involving only smaller
--- integral literals. This improves constant folding.
-
- | otherwise = do -- Big, so start from a string
- plus_id <- dsLookupGlobalId plusIntegerName
- times_id <- dsLookupGlobalId timesIntegerName
- integer_id <- dsLookupGlobalId smallIntegerName
- let
- lit i = mkSmallIntegerLit integer_id i
- plus a b = Var plus_id `App` a `App` b
- times a b = Var times_id `App` a `App` b
-
- -- Transform i into (x1 + (x2 + (x3 + (...) * b) * b) * b) with abs xi <= b
- horner :: Integer -> Integer -> CoreExpr
- horner b i | abs q <= 1 = if r == 0 || r == i
- then lit i
- else lit r `plus` lit (i-r)
- | r == 0 = horner b q `times` lit b
- | otherwise = lit r `plus` (horner b q `times` lit b)
- where
- (q,r) = i `quotRem` b
-
- return (horner tARGET_MAX_INT i)
-
-mkSmallIntegerLit :: Id -> Integer -> CoreExpr
-mkSmallIntegerLit small_integer i = mkApps (Var small_integer) [mkIntLit i]
-
-mkStringExpr str = mkStringExprFS (mkFastString str)
-
-mkStringExprFS str
- | nullFS str
- = return (mkNilExpr charTy)
-
- | lengthFS str == 1
- = do let the_char = mkCharExpr (headFS str)
- return (mkConsExpr charTy the_char (mkNilExpr charTy))
-
- | all safeChar chars
- = do unpack_id <- dsLookupGlobalId unpackCStringName
- return (App (Var unpack_id) (Lit (MachStr str)))
-
- | otherwise
- = do unpack_id <- dsLookupGlobalId unpackCStringUtf8Name
- return (App (Var unpack_id) (Lit (MachStr str)))
-
- where
- chars = unpackFS str
- safeChar c = ord c >= 1 && ord c <= 0x7F
-\end{code}
-
-
%************************************************************************
%* *
\subsection[mkSelectorBind]{Make a selector bind}
is_triv_pat (WildPat _) = True
is_triv_pat (ParPat p) = is_triv_lpat p
is_triv_pat _ = False
-\end{code}
-
-
-%************************************************************************
-%* *
- Big Tuples
-%* *
-%************************************************************************
-
-Nesting policy. Better a 2-tuple of 10-tuples (3 objects) than
-a 10-tuple of 2-tuples (11 objects). So we want the leaves to be big.
-
-\begin{code}
-
-mkBigTuple :: ([a] -> a) -> [a] -> a
-mkBigTuple small_tuple as = mk_big_tuple (chunkify as)
- where
- -- Each sub-list is short enough to fit in a tuple
- mk_big_tuple [as] = small_tuple as
- mk_big_tuple as_s = mk_big_tuple (chunkify (map small_tuple as_s))
-
-chunkify :: [a] -> [[a]]
--- The sub-lists of the result all have length <= mAX_TUPLE_SIZE
--- But there may be more than mAX_TUPLE_SIZE sub-lists
-chunkify xs
- | n_xs <= mAX_TUPLE_SIZE = {- pprTrace "Small" (ppr n_xs) -} [xs]
- | otherwise = {- pprTrace "Big" (ppr n_xs) -} (split xs)
- where
- n_xs = length xs
- split [] = []
- split xs = take mAX_TUPLE_SIZE xs : split (drop mAX_TUPLE_SIZE xs)
-
-\end{code}
-
-Creating tuples and their types for Core expressions
-
-@mkBigCoreVarTup@ builds a tuple; the inverse to @mkTupleSelector@.
-
-* If it has only one element, it is the identity function.
-
-* If there are more elements than a big tuple can have, it nests
- the tuples.
-
-\begin{code}
-
--- Small tuples: build exactly the specified tuple
-mkCoreVarTup :: [Id] -> CoreExpr
-mkCoreVarTup ids = mkCoreTup (map Var ids)
-
-mkCoreVarTupTy :: [Id] -> Type
-mkCoreVarTupTy ids = mkCoreTupTy (map idType ids)
-
-
-mkCoreTup :: [CoreExpr] -> CoreExpr
-mkCoreTup [] = Var unitDataConId
-mkCoreTup [c] = c
-mkCoreTup cs = mkConApp (tupleCon Boxed (length cs))
- (map (Type . exprType) cs ++ cs)
-
-mkCoreTupTy :: [Type] -> Type
-mkCoreTupTy [ty] = ty
-mkCoreTupTy tys = mkTupleTy Boxed (length tys) tys
-
-
-
--- Big tuples
-mkBigCoreVarTup :: [Id] -> CoreExpr
-mkBigCoreVarTup ids = mkBigCoreTup (map Var ids)
-
-mkBigCoreVarTupTy :: [Id] -> Type
-mkBigCoreVarTupTy ids = mkBigCoreTupTy (map idType ids)
-
-
-mkBigCoreTup :: [CoreExpr] -> CoreExpr
-mkBigCoreTup = mkBigTuple mkCoreTup
-
-mkBigCoreTupTy :: [Type] -> Type
-mkBigCoreTupTy = mkBigTuple mkCoreTupTy
\end{code}
mkBigLHsVarTup ids = mkBigLHsTup (map nlHsVar ids)
mkBigLHsTup :: [LHsExpr Id] -> LHsExpr Id
-mkBigLHsTup = mkBigTuple mkLHsTup
+mkBigLHsTup = mkChunkified mkLHsTup
-- The Big equivalents for the source tuple patterns
mkBigLHsVarPatTup bs = mkBigLHsPatTup (map nlVarPat bs)
mkBigLHsPatTup :: [LPat Id] -> LPat Id
-mkBigLHsPatTup = mkBigTuple mkLHsPatTup
-\end{code}
-
-
-@mkTupleSelector@ builds a selector which scrutises the given
-expression and extracts the one name from the list given.
-If you want the no-shadowing rule to apply, the caller
-is responsible for making sure that none of these names
-are in scope.
-
-If there is just one id in the ``tuple'', then the selector is
-just the identity.
-
-If it's big, it does nesting
- mkTupleSelector [a,b,c,d] b v e
- = case e of v {
- (p,q) -> case p of p {
- (a,b) -> b }}
-We use 'tpl' vars for the p,q, since shadowing does not matter.
-
-In fact, it's more convenient to generate it innermost first, getting
-
- case (case e of v
- (p,q) -> p) of p
- (a,b) -> b
-
-\begin{code}
-mkTupleSelector :: [Id] -- The tuple args
- -> Id -- The selected one
- -> Id -- A variable of the same type as the scrutinee
- -> CoreExpr -- Scrutinee
- -> CoreExpr
-
-mkTupleSelector vars the_var scrut_var scrut
- = mk_tup_sel (chunkify vars) the_var
- where
- mk_tup_sel [vars] the_var = mkCoreSel vars the_var scrut_var scrut
- mk_tup_sel vars_s the_var = mkCoreSel group the_var tpl_v $
- mk_tup_sel (chunkify tpl_vs) tpl_v
- where
- tpl_tys = [mkCoreTupTy (map idType gp) | gp <- vars_s]
- tpl_vs = mkTemplateLocals tpl_tys
- [(tpl_v, group)] = [(tpl,gp) | (tpl,gp) <- zipEqual "mkTupleSelector" tpl_vs vars_s,
- the_var `elem` gp ]
-\end{code}
-
-A generalization of @mkTupleSelector@, allowing the body
-of the case to be an arbitrary expression.
-
-If the tuple is big, it is nested:
-
- mkTupleCase uniqs [a,b,c,d] body v e
- = case e of v { (p,q) ->
- case p of p { (a,b) ->
- case q of q { (c,d) ->
- body }}}
-
-To avoid shadowing, we use uniqs to invent new variables p,q.
-
-ToDo: eliminate cases where none of the variables are needed.
-
-\begin{code}
-mkTupleCase
- :: UniqSupply -- for inventing names of intermediate variables
- -> [Id] -- the tuple args
- -> CoreExpr -- body of the case
- -> Id -- a variable of the same type as the scrutinee
- -> CoreExpr -- scrutinee
- -> CoreExpr
-
-mkTupleCase uniqs vars body scrut_var scrut
- = mk_tuple_case uniqs (chunkify vars) body
- where
- -- This is the case where don't need any nesting
- mk_tuple_case _ [vars] body
- = mkSmallTupleCase vars body scrut_var scrut
-
- -- This is the case where we must make nest tuples at least once
- mk_tuple_case us vars_s body
- = let (us', vars', body') = foldr one_tuple_case (us, [], body) vars_s
- in mk_tuple_case us' (chunkify vars') body'
-
- one_tuple_case chunk_vars (us, vs, body)
- = let (us1, us2) = splitUniqSupply us
- scrut_var = mkSysLocal (fsLit "ds") (uniqFromSupply us1)
- (mkCoreTupTy (map idType chunk_vars))
- body' = mkSmallTupleCase chunk_vars body scrut_var (Var scrut_var)
- in (us2, scrut_var:vs, body')
-\end{code}
-
-The same, but with a tuple small enough not to need nesting.
-
-\begin{code}
-mkSmallTupleCase
- :: [Id] -- the tuple args
- -> CoreExpr -- body of the case
- -> Id -- a variable of the same type as the scrutinee
- -> CoreExpr -- scrutinee
- -> CoreExpr
-
-mkSmallTupleCase [var] body _scrut_var scrut
- = bindNonRec var scrut body
-mkSmallTupleCase vars body scrut_var scrut
--- One branch no refinement?
- = Case scrut scrut_var (exprType body) [(DataAlt (tupleCon Boxed (length vars)), vars, body)]
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[mkFailurePair]{Code for pattern-matching and other failures}
-%* *
-%************************************************************************
-
-Call the constructor Ids when building explicit lists, so that they
-interact well with rules.
-
-\begin{code}
-mkNilExpr :: Type -> CoreExpr
-mkNilExpr ty = mkConApp nilDataCon [Type ty]
-
-mkConsExpr :: Type -> CoreExpr -> CoreExpr -> CoreExpr
-mkConsExpr ty hd tl = mkConApp consDataCon [Type ty, hd, tl]
-
-mkListExpr :: Type -> [CoreExpr] -> CoreExpr
-mkListExpr ty xs = foldr (mkConsExpr ty) (mkNilExpr ty) xs
-
-mkFoldrExpr :: PostTcType -> PostTcType -> CoreExpr -> CoreExpr -> CoreExpr -> DsM CoreExpr
-mkFoldrExpr elt_ty result_ty c n list = do
- foldr_id <- dsLookupGlobalId foldrName
- return (Var foldr_id `App` Type elt_ty
- `App` Type result_ty
- `App` c
- `App` n
- `App` list)
-
-mkBuildExpr :: Type -> ((Id, Type) -> (Id, Type) -> DsM CoreExpr) -> DsM CoreExpr
-mkBuildExpr elt_ty mk_build_inside = do
- [n_tyvar] <- newTyVarsDs [alphaTyVar]
- let n_ty = mkTyVarTy n_tyvar
- c_ty = mkFunTys [elt_ty, n_ty] n_ty
- [c, n] <- newSysLocalsDs [c_ty, n_ty]
-
- build_inside <- mk_build_inside (c, c_ty) (n, n_ty)
-
- build_id <- dsLookupGlobalId buildName
- return $ Var build_id `App` Type elt_ty `App` mkLams [n_tyvar, c, n] build_inside
-
-mkCoreSel :: [Id] -- The tuple args
- -> Id -- The selected one
- -> Id -- A variable of the same type as the scrutinee
- -> CoreExpr -- Scrutinee
- -> CoreExpr
-
--- mkCoreSel [x] x v e
--- ===> e
-mkCoreSel [var] should_be_the_same_var _ scrut
- = ASSERT(var == should_be_the_same_var)
- scrut
-
--- mkCoreSel [x,y,z] x v e
--- ===> case e of v { (x,y,z) -> x
-mkCoreSel vars the_var scrut_var scrut
- = ASSERT( notNull vars )
- Case scrut scrut_var (idType the_var)
- [(DataAlt (tupleCon Boxed (length vars)), vars, Var the_var)]
+mkBigLHsPatTup = mkChunkified mkLHsPatTup
\end{code}
%************************************************************************
projects / ghc-hetmet.git / commitdiff