X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Frename%2FRnIfaces.lhs;h=7cab59c01dc89237fadedd0d5ab796029ca0551b;hb=c7e7bc25c21e28651194d9d37a53a8820932fba7;hp=bb279370e23ac463b13605a00030366160c137af;hpb=51a571c0f5b0201ea53bec60fcaafb78c01c017e;p=ghc-hetmet.git diff --git a/ghc/compiler/rename/RnIfaces.lhs b/ghc/compiler/rename/RnIfaces.lhs index bb27937..7cab59c 100644 --- a/ghc/compiler/rename/RnIfaces.lhs +++ b/ghc/compiler/rename/RnIfaces.lhs @@ -34,9 +34,13 @@ import RnHiFiles ( tryLoadInterface, loadHomeInterface, import RnSource ( rnTyClDecl, rnInstDecl, rnIfaceRuleDecl ) import RnEnv import RnMonad -import Id ( idType ) +import Id ( idType, idName, globalIdDetails ) +import IdInfo ( GlobalIdDetails(..) ) import Type ( namesOfType ) -import TyCon ( isSynTyCon, getSynTyConDefn ) +import FieldLabel ( fieldLabelTyCon ) +import DataCon ( dataConTyCon ) +import TyCon ( isSynTyCon, getSynTyConDefn, tyConClass_maybe, tyConName ) +import Class ( className ) import Name ( Name {-instance NamedThing-}, nameOccName, nameModule, isLocalName, NamedThing(..) ) @@ -49,8 +53,9 @@ import Module ( Module, ModuleEnv, extendModuleEnv_C, foldModuleEnv, lookupModuleEnv, elemModuleSet, extendModuleSet ) -import PrelInfo ( wiredInThingEnv ) -import Maybes ( orElse ) +import PrelInfo ( wiredInThingEnv, hasKey, fractionalClassKey, numClassKey, + integerTyConName, doubleTyConName ) +import Maybes ( maybeToBool ) import FiniteMap import Outputable import Bag @@ -64,18 +69,64 @@ import Util ( sortLt ) %* * %********************************************************* -mkImportInof figures out what the ``usage information'' for this +mkImportInfo figures out what the ``usage information'' for this moudule is; that is, what it must record in its interface file as the things it uses. We produce a line for every module B below the module, A, currently being compiled: import B ; -to record the fact that A does import B indireclty. This is used to decide +to record the fact that A does import B indirectly. This is used to decide to look to look for B.hi rather than B.hi-boot when compiling a module that imports A. This line says that A imports B, but uses nothing in it. So we'll get an early bale-out when compiling A if B's version changes. +The usage information records: + +\begin{itemize} +\item (a) anything reachable from its body code +\item (b) any module exported with a @module Foo@ +\item (c) anything reachable from an exported item +\end{itemize} + +Why (b)? Because if @Foo@ changes then this module's export list +will change, so we must recompile this module at least as far as +making a new interface file --- but in practice that means complete +recompilation. + +Why (c)? Consider this: +\begin{verbatim} + module A( f, g ) where | module B( f ) where + import B( f ) | f = h 3 + g = ... | h = ... +\end{verbatim} + +Here, @B.f@ isn't used in A. Should we nevertheless record @B.f@ in +@A@'s usages? Our idea is that we aren't going to touch A.hi if it is +*identical* to what it was before. If anything about @B.f@ changes +than anyone who imports @A@ should be recompiled in case they use +@B.f@ (they'll get an early exit if they don't). So, if anything +about @B.f@ changes we'd better make sure that something in A.hi +changes, and the convenient way to do that is to record the version +number @B.f@ in A.hi in the usage list. If B.f changes that'll force a +complete recompiation of A, which is overkill but it's the only way to +write a new, slightly different, A.hi. + +But the example is tricker. Even if @B.f@ doesn't change at all, +@B.h@ may do so, and this change may not be reflected in @f@'s version +number. But with -O, a module that imports A must be recompiled if +@B.h@ changes! So A must record a dependency on @B.h@. So we treat +the occurrence of @B.f@ in the export list *just as if* it were in the +code of A, and thereby haul in all the stuff reachable from it. + + *** Conclusion: if A mentions B.f in its export list, + behave just as if A mentioned B.f in its source code, + and slurp in B.f and all its transitive closure *** + +[NB: If B was compiled with -O, but A isn't, we should really *still* +haul in all the unfoldings for B, in case the module that imports A *is* +compiled with -O. I think this is the case.] + \begin{code} mkImportInfo :: ModuleName -- Name of this module -> [ImportDecl n] -- The import decls @@ -128,9 +179,14 @@ mkImportInfo this_mod imports import_info0 = foldModuleEnv mk_imp_info [] pit import_info1 = foldModuleEnv mk_imp_info import_info0 hit - import_info = [ (mod_name, orphans, is_boot, NothingAtAll) - | (mod_name, (orphans, is_boot)) <- fmToList (iImpModInfo ifaces) ] ++ - import_info1 + import_info = not_even_opened_imports ++ import_info1 + + -- Recall that iImpModInfo describes modules that have been mentioned + -- in the import lists of interfaces we have opened, but which we have + -- not even opened when compiling this module + not_even_opened_imports = [ (mod_name, orphans, is_boot, NothingAtAll) + | (mod_name, (orphans, is_boot)) <- fmToList (iImpModInfo ifaces) ] + mk_imp_info :: ModIface -> [ImportVersion Name] -> [ImportVersion Name] mk_imp_info iface so_far @@ -145,6 +201,8 @@ mkImportInfo this_mod imports | import_all_mod -- Case (a) and (b); the import-all part = if is_home_pkg_mod then go_for_it (Specifically mod_vers (Just export_vers) [] rules_vers) + -- Since the module isn't in the mv_map, presumably we + -- didn't actually import anything at all from it else go_for_it (Everything mod_vers) @@ -214,6 +272,15 @@ slurpSourceRefs source_fvs -- and the instance decls -- The outer loop is needed because consider + -- instance Foo a => Baz (Maybe a) where ... + -- It may be that Baz and Maybe are used in the source module, + -- but not Foo; so we need to chase Foo too. + -- + -- We also need to follow superclass refs. In particular, 'chasing Foo' must + -- include actually getting in Foo's class decl + -- class Wib a => Foo a where .. + -- so that its superclasses are discovered. The point is that Wib is a gate too. + -- We do this for tycons too, so that we look through type synonyms. go_outer decls fvs all_gates [] = returnRn (decls, fvs) @@ -227,6 +294,7 @@ slurpSourceRefs source_fvs (nameSetToList (gates2 `minusNameSet` all_gates)) -- Knock out the all_gates because even if we don't slurp any new -- decls we can get some apparently-new gates from wired-in names + -- and we get an infinite loop go_inner (decls, fvs, gates) wanted_name = importDecl wanted_name `thenRn` \ import_result -> @@ -312,7 +380,28 @@ recordDeclSlurp ifaces@(Ifaces { iDecls = (decls_map, n_slurped), new_decls_map = foldl delFromNameEnv decls_map (availNames avail) new_slurped_names = addAvailToNameSet slurped_names avail -recordVSlurp ifaces name = ifaces { iVSlurp = updateVSlurp (iVSlurp ifaces) name } + +-- recordTypeEnvSlurp is used when we slurp something that's +-- already in the type environment, that was not slurped in an earlier compilation. +-- We record it in the iVSlurp set, because that's used to +-- generate usage information + +recordTypeEnvSlurp ifaces ty_thing + = ifaces { iVSlurp = updateVSlurp (iVSlurp ifaces) (get_main_name ty_thing) } + where + -- Tiresomely, we must get the "main" name for the + -- thing, because that's what VSlurp contains, and what + -- is recorded in the usage information + get_main_name (AClass cl) = className cl + get_main_name (ATyCon tc) + | Just clas <- tyConClass_maybe tc = get_main_name (AClass clas) + | otherwise = tyConName tc + get_main_name (AnId id) + = case globalIdDetails id of + DataConId dc -> get_main_name (ATyCon (dataConTyCon dc)) + DataConWrapId dc -> get_main_name (ATyCon (dataConTyCon dc)) + RecordSelId lbl -> get_main_name (ATyCon (fieldLabelTyCon lbl)) + other -> idName id updateVSlurp (imp_mods, imp_names) main_name | isHomeModule mod = (imp_mods, addOneToNameSet imp_names main_name) @@ -403,11 +492,11 @@ getGates source_fvs decl get_gates is_used (IfaceSig {tcdType = ty}) = extractHsTyNames ty get_gates is_used (ClassDecl { tcdCtxt = ctxt, tcdName = cls, tcdTyVars = tvs, tcdSigs = sigs}) - = (delListFromNameSet (foldr (plusFV . get) (extractHsCtxtTyNames ctxt) sigs) - (hsTyVarNames tvs) - `addOneToNameSet` cls) - `plusFV` implicitGates cls + = (super_cls_and_sigs `addOneToNameSet` cls) `unionNameSets` + implicitClassGates cls where + super_cls_and_sigs = delListFromNameSet (foldr (plusFV . get) (extractHsCtxtTyNames ctxt) sigs) + (hsTyVarNames tvs) get (ClassOpSig n _ ty _) | is_used n = extractHsTyNames ty | otherwise = emptyFVs @@ -444,6 +533,22 @@ get_gates is_used (TyData {tcdCtxt = ctxt, tcdName = tycon, tcdTyVars = tvs, tcd | otherwise = emptyFVs get_bang bty = extractHsTyNames (getBangType bty) + +implicitClassGates :: Name -> FreeVars +implicitClassGates cls + -- If we load class Num, add Integer to the free gates + -- This takes account of the fact that Integer might be needed for + -- defaulting, but we don't want to load Integer (and all its baggage) + -- if there's no numeric stuff needed. + -- Similarly for class Fractional and Double + -- + -- NB: adding T to the gates will force T to be loaded + -- + -- NB: If we load (say) Floating, we'll end up loading Fractional too, + -- since Fractional is a superclass of Floating + | cls `hasKey` numClassKey = unitFV integerTyConName + | cls `hasKey` fractionalClassKey = unitFV doubleTyConName + | otherwise = emptyFVs \end{code} @getWiredInGates@ is just like @getGates@, but it sees a previously-loaded @@ -461,8 +566,11 @@ getWiredInGates :: TyThing -> FreeVars -- mentioned in other modules, and hence are in the type environment getWiredInGates (AnId the_id) = namesOfType (idType the_id) -getWiredInGates (AClass cl) = emptyFVs -- The superclasses must also be previously - -- loaded, and hence are automatically gates +getWiredInGates (AClass cl) = implicitClassGates (getName cl) + -- The superclasses must also be previously + -- loaded, and hence are automatically gates + -- All previously-loaded classes are automatically gates + -- See "The gating story" above getWiredInGates (ATyCon tc) | isSynTyCon tc = delListFromNameSet (namesOfType ty) (map getName tyvars) | otherwise = unitFV (getName tc) @@ -490,7 +598,12 @@ getImportedInstDecls gates getIfacesRn `thenRn` \ ifaces -> getTypeEnvRn `thenRn` \ lookup -> let - (decls, new_insts) = selectGated gates lookup (iInsts ifaces) + available n + | n `elemNameSet` gates = True + | otherwise = case lookup n of { Just (AClass c) -> True; other -> False } + -- See "The gating story" above for the AClass thing + + (decls, new_insts) = selectGated available (iInsts ifaces) in setIfacesRn (ifaces { iInsts = new_insts }) `thenRn_` @@ -514,9 +627,11 @@ getImportedRules = getIfacesRn `thenRn` \ ifaces -> getTypeEnvRn `thenRn` \ lookup -> let - gates = iSlurp ifaces -- Anything at all that's been slurped - rules = iRules ifaces - (decls, new_rules) = selectGated gates lookup rules + -- Slurp rules for anything that is slurped, + -- either now or previously + gates = iSlurp ifaces + available n = n `elemNameSet` gates || maybeToBool (lookup n) + (decls, new_rules) = selectGated available (iRules ifaces) in if null decls then returnRn [] @@ -526,9 +641,10 @@ getImportedRules text "Slurped" <+> int (length decls) <+> text "rules"]) `thenRn_` returnRn decls -selectGated gates lookup (decl_bag, n_slurped) - -- Select only those decls whose gates are *all* in 'gates' - -- or are a class in 'lookup' +selectGated :: (Name->Bool) -> GatedDecls d + -> ([(Module,d)], GatedDecls d) +selectGated available (decl_bag, n_slurped) + -- Select only those decls whose gates are *all* available #ifdef DEBUG | opt_NoPruneDecls -- Just to try the effect of not gating at all = let @@ -541,9 +657,6 @@ selectGated gates lookup (decl_bag, n_slurped) = case foldrBag select ([], emptyBag) decl_bag of (decls, new_bag) -> (decls, (new_bag, n_slurped + length decls)) where - available n = n `elemNameSet` gates - || case lookup n of { Just (AClass c) -> True; other -> False } - select (reqd, decl) (yes, no) | all available reqd = (decl:yes, no) | otherwise = (yes, (reqd,decl) `consBag` no) @@ -576,19 +689,16 @@ importDecl name getTypeEnvRn `thenRn` \ lookup -> case lookup name of { Just ty_thing - | name `elemNameEnv` wiredInThingEnv - -> -- When we find a wired-in name we must load its home + | name `elemNameEnv` wiredInThingEnv + -> -- When we find a wired-in name we must load its home -- module so that we find any instance decls lurking therein loadHomeInterface wi_doc name `thenRn_` returnRn (InTypeEnv ty_thing) - | otherwise - -> -- Record that we use this thing. We must do this - -- regardless of whether we need to demand-slurp it in - -- or we already have it in the type environment. Why? - -- because the slurp information is used to generate usage - -- information in the interface. - setIfacesRn (recordVSlurp ifaces (getName ty_thing)) `thenRn_` + | otherwise + -> -- Very important: record that we've seen it + -- See comments with recordTypeEnvSlurp + setIfacesRn (recordTypeEnvSlurp ifaces ty_thing) `thenRn_` returnRn (InTypeEnv ty_thing) ; Nothing ->