X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FbasicTypes%2FMkId.lhs;h=1eacea9938a66d96effb06f4a1a0e6f771d59718;hb=59300a7161f44b3a2afe381a6ccd914043a32c4f;hp=1fe712b285e14012085c39e53c05d4fbb0e845be;hpb=9ffadf219cbc4f8ec57264786df936a3cee88aec;p=ghc-hetmet.git diff --git a/compiler/basicTypes/MkId.lhs b/compiler/basicTypes/MkId.lhs index 1fe712b..1eacea9 100644 --- a/compiler/basicTypes/MkId.lhs +++ b/compiler/basicTypes/MkId.lhs @@ -33,9 +33,9 @@ module MkId ( -- And some particular Ids; see below for why they are wired in wiredInIds, ghcPrimIds, unsafeCoerceId, realWorldPrimId, voidArgId, nullAddrId, seqId, - lazyId, lazyIdUnfolding, lazyIdKey, + lazyId, lazyIdKey, - mkRuntimeErrorApp, + mkRuntimeErrorApp, mkImpossibleExpr, rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID, rUNTIME_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID, nO_METHOD_BINDING_ERROR_ID, pAT_ERROR_ID, eRROR_ID, rEC_SEL_ERROR_ID, @@ -50,27 +50,24 @@ import TysPrim import TysWiredIn import PrelRules import Type -import TypeRep import Coercion import TcType -import CoreUtils +import CoreUtils ( exprType, mkCoerce ) import CoreUnfold import Literal import TyCon import Class import VarSet import Name -import OccName import PrimOp import ForeignCall import DataCon import Id import Var ( Var, TyVar, mkCoVar, mkExportedLocalVar ) import IdInfo -import NewDemand +import Demand import CoreSyn import Unique -import Maybes import PrelNames import BasicTypes hiding ( SuccessFlag(..) ) import Util @@ -86,17 +83,42 @@ import Module %* * %************************************************************************ +Note [Wired-in Ids] +~~~~~~~~~~~~~~~~~~~ +There are several reasons why an Id might appear in the wiredInIds: + +(1) The ghcPrimIds are wired in because they can't be defined in + Haskell at all, although the can be defined in Core. They have + compulsory unfoldings, so they are always inlined and they have + no definition site. Their home module is GHC.Prim, so they + also have a description in primops.txt.pp, where they are called + 'pseudoops'. + +(2) The 'error' function, eRROR_ID, is wired in because we don't yet have + a way to express in an interface file that the result type variable + is 'open'; that is can be unified with an unboxed type + + [The interface file format now carry such information, but there's + no way yet of expressing at the definition site for these + error-reporting functions that they have an 'open' + result type. -- sof 1/99] + +(3) Other error functions (rUNTIME_ERROR_ID) are wired in (a) because + the desugarer generates code that mentiones them directly, and + (b) for the same reason as eRROR_ID + +(4) lazyId is wired in because the wired-in version overrides the + strictness of the version defined in GHC.Base + +In cases (2-4), the function has a definition in a library module, and +can be called; but the wired-in version means that the details are +never read from that module's interface file; instead, the full definition +is right here. + \begin{code} wiredInIds :: [Id] wiredInIds - = [ -- These error-y things are wired in because we don't yet have - -- a way to express in an interface file that the result type variable - -- is 'open'; that is can be unified with an unboxed type - -- - -- [The interface file format now carry such information, but there's - -- no way yet of expressing at the definition site for these - -- error-reporting functions that they have an 'open' - -- result type. -- sof 1/99] + = [ eRROR_ID, -- This one isn't used anywhere else in the compiler -- But we still need it in wiredInIds so that when GHC @@ -243,7 +265,7 @@ mkDataConIds wrap_name wkr_name data_con wkr_arity = dataConRepArity data_con wkr_info = noCafIdInfo `setArityInfo` wkr_arity - `setAllStrictnessInfo` Just wkr_sig + `setStrictnessInfo` Just wkr_sig `setUnfoldingInfo` evaldUnfolding -- Record that it's evaluated, -- even if arity = 0 @@ -307,7 +329,7 @@ mkDataConIds wrap_name wkr_name data_con -- It's important to specify the arity, so that partial -- applications are treated as values `setUnfoldingInfo` wrap_unf - `setAllStrictnessInfo` Just wrap_sig + `setStrictnessInfo` Just wrap_sig all_strict_marks = dataConExStricts data_con ++ dataConStrictMarks data_con wrap_sig = mkStrictSig (mkTopDmdType arg_dmds cpr_info) @@ -323,8 +345,8 @@ mkDataConIds wrap_name wkr_name data_con -- ...(let w = C x in ...(w p q)...)... -- we want to see that w is strict in its two arguments - wrap_unf = mkImplicitUnfolding $ Note InlineMe $ - mkLams wrap_tvs $ + wrap_unf = mkInlineRule InlSat wrap_rhs (length dict_args + length id_args) + wrap_rhs = mkLams wrap_tvs $ mkLams eq_args $ mkLams dict_args $ mkLams id_args $ foldr mk_case con_app @@ -435,34 +457,57 @@ mkDictSelId no_unf name clas -- But it's type must expose the representation of the dictionary -- to get (say) C a -> (a -> a) - info = noCafIdInfo - `setArityInfo` 1 - `setAllStrictnessInfo` Just strict_sig - `setUnfoldingInfo` (if no_unf then noUnfolding - else mkImplicitUnfolding rhs) - - -- We no longer use 'must-inline' on record selectors. They'll - -- inline like crazy if they scrutinise a constructor + base_info = noCafIdInfo + `setArityInfo` 1 + `setStrictnessInfo` Just strict_sig + `setUnfoldingInfo` (if no_unf then noUnfolding + else mkImplicitUnfolding rhs) + -- In module where class op is defined, we must add + -- the unfolding, even though it'll never be inlined + -- becuase we use that to generate a top-level binding + -- for the ClassOp + + info | new_tycon = base_info + -- For newtype dictionaries, just inline the class op + -- See Note [Single-method classes] in TcInstDcls + | otherwise = base_info + `setSpecInfo` mkSpecInfo [rule] + `setInlinePragInfo` neverInlinePragma + -- Otherwise add a magic BuiltinRule, and never inline it + -- so that the rule is always available to fire. + -- See Note [ClassOp/DFun selection] in TcInstDcls + + n_ty_args = length tyvars + + -- This is the built-in rule that goes + -- op (dfT d1 d2) ---> opT d1 d2 + rule = BuiltinRule { ru_name = fsLit "Class op " `appendFS` + occNameFS (getOccName name) + , ru_fn = name + , ru_nargs = n_ty_args + 1 + , ru_try = dictSelRule index n_ty_args } -- The strictness signature is of the form U(AAAVAAAA) -> T -- where the V depends on which item we are selecting -- It's worth giving one, so that absence info etc is generated -- even if the selector isn't inlined strict_sig = mkStrictSig (mkTopDmdType [arg_dmd] TopRes) - arg_dmd | isNewTyCon tycon = evalDmd - | otherwise = Eval (Prod [ if the_arg_id == id then evalDmd else Abs - | id <- arg_ids ]) + arg_dmd | new_tycon = evalDmd + | otherwise = Eval (Prod [ if the_arg_id == id then evalDmd else Abs + | id <- arg_ids ]) tycon = classTyCon clas + new_tycon = isNewTyCon tycon [data_con] = tyConDataCons tycon tyvars = dataConUnivTyVars data_con arg_tys = {- ASSERT( isVanillaDataCon data_con ) -} dataConRepArgTys data_con eq_theta = dataConEqTheta data_con - the_arg_id = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` arg_ids) name + index = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` [0..]) name + the_arg_id = arg_ids !! index pred = mkClassPred clas (mkTyVarTys tyvars) - dict_id = mkTemplateLocal 1 $ mkPredTy pred - (eq_ids,n) = mkCoVarLocals 2 $ mkPredTys eq_theta + dict_id = mkTemplateLocal 1 $ mkPredTy pred + (eq_ids,n) = mkCoVarLocals 2 $ mkPredTys eq_theta arg_ids = mkTemplateLocalsNum n arg_tys mkCoVarLocals i [] = ([],i) @@ -471,9 +516,23 @@ mkDictSelId no_unf name clas in (y:ys,j) rhs = mkLams tyvars (Lam dict_id rhs_body) - rhs_body | isNewTyCon tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id) - | otherwise = Case (Var dict_id) dict_id (idType the_arg_id) - [(DataAlt data_con, eq_ids ++ arg_ids, Var the_arg_id)] + rhs_body | new_tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id) + | otherwise = Case (Var dict_id) dict_id (idType the_arg_id) + [(DataAlt data_con, eq_ids ++ arg_ids, Var the_arg_id)] + +dictSelRule :: Int -> Arity -> [CoreExpr] -> Maybe CoreExpr +-- Oh, very clever +-- op_i t1..tk (df s1..sn d1..dm) = op_i_helper s1..sn d1..dm +-- op_i t1..tk (D t1..tk op1 ... opm) = opi +-- +-- NB: the data constructor has the same number of type args as the class op + +dictSelRule index n_ty_args args + | (dict_arg : _) <- drop n_ty_args args + , Just (_, _, val_args) <- exprIsConApp_maybe dict_arg + = Just (val_args !! index) + | otherwise + = Nothing \end{code} @@ -704,7 +763,7 @@ mkPrimOpId prim_op info = noCafIdInfo `setSpecInfo` mkSpecInfo (primOpRules prim_op name) `setArityInfo` arity - `setAllStrictnessInfo` Just strict_sig + `setStrictnessInfo` Just strict_sig -- For each ccall we manufacture a separate CCallOpId, giving it -- a fresh unique, a type that is correct for this particular ccall, @@ -730,7 +789,7 @@ mkFCallId uniq fcall ty info = noCafIdInfo `setArityInfo` arity - `setAllStrictnessInfo` Just strict_sig + `setStrictnessInfo` Just strict_sig (_, tau) = tcSplitForAllTys ty (arg_tys, _) = tcSplitFunTys tau @@ -803,8 +862,9 @@ mkDictFunId :: Name -- Name to use for the dict fun; -> Id mkDictFunId dfun_name inst_tyvars dfun_theta clas inst_tys - = mkExportedLocalVar DFunId dfun_name dfun_ty vanillaIdInfo + = mkExportedLocalVar (DFunId is_nt) dfun_name dfun_ty vanillaIdInfo where + is_nt = isNewTyCon (classTyCon clas) dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys) \end{code} @@ -879,14 +939,11 @@ nullAddrId = pcMiscPrelId nullAddrName addrPrimTy info mkCompulsoryUnfolding (Lit nullAddrLit) ------------------------------------------------ -seqId :: Id --- 'seq' is very special. See notes with --- See DsUtils.lhs Note [Desugaring seq (1)] and --- Note [Desugaring seq (2)] and --- Fixity is set in LoadIface.ghcPrimIface +seqId :: Id -- See Note [seqId magic] seqId = pcMiscPrelId seqName ty info where info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs + `setSpecInfo` mkSpecInfo [seq_cast_rule] ty = mkForAllTys [alphaTyVar,openBetaTyVar] @@ -894,30 +951,101 @@ seqId = pcMiscPrelId seqName ty info [x,y] = mkTemplateLocals [alphaTy, openBetaTy] rhs = mkLams [alphaTyVar,openBetaTyVar,x,y] (Case (Var x) x openBetaTy [(DEFAULT, [], Var y)]) + -- See Note [Built-in RULES for seq] + seq_cast_rule = BuiltinRule { ru_name = fsLit "seq of cast" + , ru_fn = seqName + , ru_nargs = 4 + , ru_try = match_seq_of_cast + } + +match_seq_of_cast :: [CoreExpr] -> Maybe CoreExpr + -- See Note [Built-in RULES for seq] +match_seq_of_cast [Type _, Type res_ty, Cast scrut co, expr] + = Just (Var seqId `mkApps` [Type (fst (coercionKind co)), Type res_ty, + scrut, expr]) +match_seq_of_cast _ = Nothing + ------------------------------------------------ -lazyId :: Id --- lazy :: forall a?. a? -> a? (i.e. works for unboxed types too) --- Used to lazify pseq: pseq a b = a `seq` lazy b --- --- Also, no strictness: by being a built-in Id, all the info about lazyId comes from here, --- not from GHC.Base.hi. This is important, because the strictness --- analyser will spot it as strict! --- --- Also no unfolding in lazyId: it gets "inlined" by a HACK in the worker/wrapperpass --- (see WorkWrap.wwExpr) --- We could use inline phases to do this, but that would be vulnerable to changes in --- phase numbering....we must inline precisely after strictness analysis. +lazyId :: Id -- See Note [lazyId magic] lazyId = pcMiscPrelId lazyIdName ty info where info = noCafIdInfo ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy alphaTy) - -lazyIdUnfolding :: CoreExpr -- Used to expand 'lazyId' after strictness anal -lazyIdUnfolding = mkLams [openAlphaTyVar,x] (Var x) - where - [x] = mkTemplateLocals [openAlphaTy] \end{code} +Note [seqId magic] +~~~~~~~~~~~~~~~~~~ +'GHC.Prim.seq' is special in several ways. + +a) Its second arg can have an unboxed type + x `seq` (v +# w) + +b) Its fixity is set in LoadIface.ghcPrimIface + +c) It has quite a bit of desugaring magic. + See DsUtils.lhs Note [Desugaring seq (1)] and (2) and (3) + +d) There is some special rule handing: Note [User-defined RULES for seq] + +Note [User-defined RULES for seq] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Roman found situations where he had + case (f n) of _ -> e +where he knew that f (which was strict in n) would terminate if n did. +Notice that the result of (f n) is discarded. So it makes sense to +transform to + case n of _ -> e + +Rather than attempt some general analysis to support this, I've added +enough support that you can do this using a rewrite rule: + + RULE "f/seq" forall n. seq (f n) e = seq n e + +You write that rule. When GHC sees a case expression that discards +its result, it mentally transforms it to a call to 'seq' and looks for +a RULE. (This is done in Simplify.rebuildCase.) As usual, the +correctness of the rule is up to you. + +To make this work, we need to be careful that the magical desugaring +done in Note [seqId magic] item (c) is *not* done on the LHS of a rule. +Or rather, we arrange to un-do it, in DsBinds.decomposeRuleLhs. + +Note [Built-in RULES for seq] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +We also have the following built-in rule for seq + + seq (x `cast` co) y = seq x y + +This eliminates unnecessary casts and also allows other seq rules to +match more often. Notably, + + seq (f x `cast` co) y --> seq (f x) y + +and now a user-defined rule for seq (see Note [User-defined RULES for seq]) +may fire. + + +Note [lazyId magic] +~~~~~~~~~~~~~~~~~~~ + lazy :: forall a?. a? -> a? (i.e. works for unboxed types too) + +Used to lazify pseq: pseq a b = a `seq` lazy b + +Also, no strictness: by being a built-in Id, all the info about lazyId comes from here, +not from GHC.Base.hi. This is important, because the strictness +analyser will spot it as strict! + +Also no unfolding in lazyId: it gets "inlined" by a HACK in CorePrep. +It's very important to do this inlining *after* unfoldings are exposed +in the interface file. Otherwise, the unfolding for (say) pseq in the +interface file will not mention 'lazy', so if we inline 'pseq' we'll totally +miss the very thing that 'lazy' was there for in the first place. +See Trac #3259 for a real world example. + +lazyId is defined in GHC.Base, so we don't *have* to inline it. If it +appears un-applied, we'll end up just calling it. + +------------------------------------------------------------- @realWorld#@ used to be a magic literal, \tr{void#}. If things get nasty as-is, change it back to a literal (@Literal@). @@ -977,6 +1105,10 @@ mkRuntimeErrorApp err_id res_ty err_msg where err_string = Lit (mkMachString err_msg) +mkImpossibleExpr :: Type -> CoreExpr +mkImpossibleExpr res_ty + = mkRuntimeErrorApp rUNTIME_ERROR_ID res_ty "Impossible case alternative" + rEC_SEL_ERROR_ID = mkRuntimeErrorId recSelErrorName rUNTIME_ERROR_ID = mkRuntimeErrorId runtimeErrorName iRREFUT_PAT_ERROR_ID = mkRuntimeErrorId irrefutPatErrorName @@ -1026,7 +1158,7 @@ pc_bottoming_Id :: Name -> Type -> Id pc_bottoming_Id name ty = pcMiscPrelId name ty bottoming_info where - bottoming_info = vanillaIdInfo `setAllStrictnessInfo` Just strict_sig + bottoming_info = vanillaIdInfo `setStrictnessInfo` Just strict_sig `setArityInfo` 1 -- Make arity and strictness agree