X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FdeSugar%2FDesugar.lhs;h=1ba877ae1cf821b2161bbbcc79225cb1a493e3a9;hp=8387146f17a89bcead7809cef9456f5547d3de27;hb=da9d10064c084fed395e6030b1cb82bee2b140ed;hpb=9bcd95bad83ee937c178970e8b729732e680fe1e diff --git a/compiler/deSugar/Desugar.lhs b/compiler/deSugar/Desugar.lhs index 8387146..1ba877a 100644 --- a/compiler/deSugar/Desugar.lhs +++ b/compiler/deSugar/Desugar.lhs @@ -15,8 +15,11 @@ import HsSyn import TcRnTypes import MkIface import Id +import Pair import Name import CoreSyn +import CoreSubst +import CoqPass ( coqPassCoreToString, coqPassCoreToCore ) import PprCore import DsMonad import DsExpr @@ -27,18 +30,24 @@ import DsExpr () -- Forces DsExpr to be compiled; DsBinds only import Module import RdrName import NameSet -import VarSet +import NameEnv import Rules -import CoreLint -import CoreFVs +import CoreMonad ( endPass, CoreToDo(..) ) import ErrUtils import Outputable import SrcLoc -import Maybes -import FastString import Coverage - +import Util +import MonadUtils +import OrdList +import Data.List import Data.IORef +import PrelNames +import UniqSupply +import UniqFM +import CoreFVs +import Type +import Coercion \end{code} %************************************************************************ @@ -48,6 +57,8 @@ import Data.IORef %************************************************************************ \begin{code} + +-- | Main entry point to the desugarer. deSugar :: HscEnv -> ModLocation -> TcGblEnv -> IO (Messages, Maybe ModGuts) -- Can modify PCS by faulting in more declarations @@ -66,63 +77,247 @@ deSugar hsc_env tcg_warns = warns, tcg_anns = anns, tcg_binds = binds, - tcg_fords = fords, - tcg_rules = rules, - tcg_insts = insts, - tcg_fam_insts = fam_insts, - tcg_hpc = other_hpc_info }) + tcg_imp_specs = imp_specs, + tcg_ev_binds = ev_binds, + tcg_fords = fords, + tcg_rules = rules, + tcg_vects = vects, + tcg_insts = insts, + tcg_fam_insts = fam_insts, + tcg_hpc = other_hpc_info }) = do { let dflags = hsc_dflags hsc_env ; showPass dflags "Desugar" -- Desugar the program ; let export_set = availsToNameSet exports - ; let auto_scc = mkAutoScc mod export_set + ; let auto_scc = mkAutoScc dflags mod export_set ; let target = hscTarget dflags ; let hpcInfo = emptyHpcInfo other_hpc_info ; (msgs, mb_res) <- case target of HscNothing -> return (emptyMessages, - Just ([], [], NoStubs, hpcInfo, emptyModBreaks)) + Just ([], nilOL, [], [], NoStubs, hpcInfo, emptyModBreaks, undefined, undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + , undefined + )) _ -> do (binds_cvr,ds_hpc_info, modBreaks) <- if (opt_Hpc || target == HscInterpreted) && (not (isHsBoot hsc_src)) - then addCoverageTicksToBinds dflags mod mod_loc (typeEnvTyCons type_env) binds + then addCoverageTicksToBinds dflags mod mod_loc + (typeEnvTyCons type_env) binds else return (binds, hpcInfo, emptyModBreaks) initDs hsc_env mod rdr_env type_env $ do - core_prs <- dsTopLHsBinds auto_scc binds_cvr - (ds_fords, foreign_prs) <- dsForeigns fords - let all_prs = foreign_prs ++ core_prs - ds_rules <- mapM dsRule rules - return (all_prs, catMaybes ds_rules, ds_fords, ds_hpc_info, modBreaks) - - ; case mb_res of { - Nothing -> return (msgs, Nothing) ; - Just (all_prs, ds_rules, ds_fords,ds_hpc_info, modBreaks) -> do - - { -- Add export flags to bindings - keep_alive <- readIORef keep_var - ; let final_prs = addExportFlags target export_set - keep_alive all_prs ds_rules - ds_binds = [Rec final_prs] - -- Notice that we put the whole lot in a big Rec, even the foreign binds - -- When compiling PrelFloat, which defines data Float = F# Float# - -- we want F# to be in scope in the foreign marshalling code! - -- You might think it doesn't matter, but the simplifier brings all top-level - -- things into the in-scope set before simplifying; so we get no unfolding for F#! - - -- Lint result if necessary - ; endPass dflags "Desugar" Opt_D_dump_ds ds_binds - - -- Dump output - ; doIfSet (dopt Opt_D_dump_ds dflags) - (printDump (ppr_ds_rules ds_rules)) - - ; used_names <- mkUsedNames tcg_env - ; deps <- mkDependencies tcg_env + do { ds_ev_binds <- dsEvBinds ev_binds + ; core_prs <- dsTopLHsBinds auto_scc binds_cvr + ; (spec_prs, spec_rules) <- dsImpSpecs imp_specs + ; (ds_fords, foreign_prs) <- dsForeigns fords + ; ds_rules <- mapMaybeM dsRule rules + ; ds_vects <- mapM dsVect vects + ; hetmet_brak <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_brak_name else return undefined + ; hetmet_esc <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_esc_name else return undefined + ; hetmet_flatten <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_flatten_name else return undefined + ; hetmet_unflatten <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_unflatten_name else return undefined + ; hetmet_flattened_id <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_flattened_id_name else return undefined + ; hetmet_PGArrow <- if dopt Opt_F_coqpass dflags then dsLookupTyCon hetmet_PGArrow_name else return undefined + ; hetmet_PGArrow_unit <- if dopt Opt_F_coqpass dflags then dsLookupTyCon hetmet_PGArrow_unit_name else return undefined + ; hetmet_PGArrow_tensor <- if dopt Opt_F_coqpass dflags then dsLookupTyCon hetmet_PGArrow_tensor_name else return undefined + ; hetmet_PGArrow_exponent <- if dopt Opt_F_coqpass dflags then dsLookupTyCon hetmet_PGArrow_exponent_name else return undefined + ; hetmet_pga_id <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_id_name else return undefined + ; hetmet_pga_comp <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_comp_name else return undefined + ; hetmet_pga_first <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_first_name else return undefined + ; hetmet_pga_second <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_second_name else return undefined + ; hetmet_pga_cancell <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_cancell_name else return undefined + ; hetmet_pga_cancelr <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_cancelr_name else return undefined + ; hetmet_pga_uncancell <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_uncancell_name else return undefined + ; hetmet_pga_uncancelr <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_uncancelr_name else return undefined + ; hetmet_pga_assoc <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_assoc_name else return undefined + ; hetmet_pga_unassoc <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_unassoc_name else return undefined + ; hetmet_pga_copy <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_copy_name else return undefined + ; hetmet_pga_drop <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_drop_name else return undefined + ; hetmet_pga_swap <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_swap_name else return undefined + ; hetmet_pga_applyl <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_applyl_name else return undefined + ; hetmet_pga_applyr <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_applyr_name else return undefined + ; hetmet_pga_curryl <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_curryl_name else return undefined + ; hetmet_pga_curryr <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_curryr_name else return undefined + ; hetmet_pga_loopl <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_loopl_name else return undefined + ; hetmet_pga_loopr <- if dopt Opt_F_coqpass dflags then dsLookupGlobalId hetmet_pga_loopr_name else return undefined + ; let hpc_init + | opt_Hpc = hpcInitCode mod ds_hpc_info + | otherwise = empty + ; return ( ds_ev_binds + , foreign_prs `appOL` core_prs `appOL` spec_prs + , spec_rules ++ ds_rules, ds_vects + , ds_fords `appendStubC` hpc_init + , ds_hpc_info, modBreaks, hetmet_brak, hetmet_esc + , hetmet_flatten + , hetmet_unflatten + , hetmet_flattened_id + , hetmet_PGArrow + , hetmet_PGArrow_unit + , hetmet_PGArrow_tensor + , hetmet_PGArrow_exponent + , hetmet_pga_id + , hetmet_pga_comp + , hetmet_pga_first + , hetmet_pga_second + , hetmet_pga_cancell + , hetmet_pga_cancelr + , hetmet_pga_uncancell + , hetmet_pga_uncancelr + , hetmet_pga_assoc + , hetmet_pga_unassoc + , hetmet_pga_copy + , hetmet_pga_drop + , hetmet_pga_swap + , hetmet_pga_applyl + , hetmet_pga_applyr + , hetmet_pga_curryl + , hetmet_pga_curryr + , hetmet_pga_loopl + , hetmet_pga_loopr + ) } + + ; case mb_res of { + Nothing -> return (msgs, Nothing) ; + Just (ds_ev_binds, all_prs, all_rules, vects0, ds_fords, ds_hpc_info, modBreaks + , hetmet_brak, hetmet_esc + , hetmet_flatten + , hetmet_unflatten + , hetmet_flattened_id + , hetmet_PGArrow + , hetmet_PGArrow_unit + , hetmet_PGArrow_tensor + , hetmet_PGArrow_exponent + , hetmet_pga_id + , hetmet_pga_comp + , hetmet_pga_first + , hetmet_pga_second + , hetmet_pga_cancell + , hetmet_pga_cancelr + , hetmet_pga_uncancell + , hetmet_pga_uncancelr + , hetmet_pga_assoc + , hetmet_pga_unassoc + , hetmet_pga_copy + , hetmet_pga_drop + , hetmet_pga_swap + , hetmet_pga_applyl + , hetmet_pga_applyr + , hetmet_pga_curryl + , hetmet_pga_curryr + , hetmet_pga_loopl + , hetmet_pga_loopr + ) -> do + + { -- Add export flags to bindings + keep_alive <- readIORef keep_var + ; let (rules_for_locals, rules_for_imps) + = partition isLocalRule all_rules + final_prs = addExportFlagsAndRules target + export_set keep_alive rules_for_locals (fromOL all_prs) + + final_pgm = let comb = combineEvBinds ds_ev_binds final_prs + in if dopt Opt_F_simpleopt_before_flatten dflags + then comb + else simplifyBinds comb + -- Notice that we put the whole lot in a big Rec, even the foreign binds + -- When compiling PrelFloat, which defines data Float = F# Float# + -- we want F# to be in scope in the foreign marshalling code! + -- You might think it doesn't matter, but the simplifier brings all top-level + -- things into the in-scope set before simplifying; so we get no unfolding for F#! + + ; (final_pgm1, rules_for_imps1, ds_vects1) <- if dopt Opt_F_simpleopt_before_flatten dflags + then simpleOptPgm dflags final_pgm rules_for_imps vects0 + else return (final_pgm, rules_for_imps, vects0) + + ; ds_binds1 <- if dopt Opt_F_coqpass dflags + then do { us <- mkSplitUniqSupply '~' + ; let do_flatten = dopt Opt_F_flatten dflags + ; let do_skolemize = dopt Opt_F_skolemize dflags + ; return (coqPassCoreToCore + do_flatten + do_skolemize + hetmet_brak + hetmet_esc + hetmet_flatten + hetmet_unflatten + hetmet_flattened_id + us + final_pgm1 + hetmet_PGArrow + hetmet_PGArrow_unit + hetmet_PGArrow_tensor + hetmet_PGArrow_exponent + hetmet_pga_id + hetmet_pga_comp + hetmet_pga_first + hetmet_pga_second + hetmet_pga_cancell + hetmet_pga_cancelr + hetmet_pga_uncancell + hetmet_pga_uncancelr + hetmet_pga_assoc + hetmet_pga_unassoc + hetmet_pga_copy + hetmet_pga_drop + hetmet_pga_swap + hetmet_pga_applyl + hetmet_pga_applyr + hetmet_pga_curryl + hetmet_pga_curryr + hetmet_pga_loopl + hetmet_pga_loopr + ) + } + else return final_pgm + + ; (ds_binds2, ds_rules_for_imps2, ds_vects2) <- if dopt Opt_F_simpleopt_before_flatten dflags + then return (ds_binds1, rules_for_imps1, ds_vects1) + else simpleOptPgm dflags ds_binds1 rules_for_imps1 ds_vects1 + -- The simpleOptPgm gets rid of type + -- bindings plus any stupid dead code + + ; dumpIfSet_dyn dflags Opt_D_dump_proofs "Coq Pass Output" $ text $ coqPassCoreToString ds_binds1 + + ; dumpIfSet_dyn dflags Opt_D_coqpass "After Coq Pass" (text $ showSDoc $ pprCoreBindings ds_binds1) + + ; (ds_binds3, ds_rules_for_imps3, ds_vects3) + <- simpleOptPgm dflags ds_binds2 ds_rules_for_imps2 ds_vects2 + -- The simpleOptPgm gets rid of type + -- bindings plus any stupid dead code + + ; endPass dflags CoreDesugar ds_binds3 ds_rules_for_imps3 + + ; let used_names = mkUsedNames tcg_env + ; deps <- mkDependencies tcg_env ; let mod_guts = ModGuts { mg_module = mod, @@ -140,26 +335,61 @@ deSugar hsc_env mg_fam_insts = fam_insts, mg_inst_env = inst_env, mg_fam_inst_env = fam_inst_env, - mg_rules = ds_rules, - mg_binds = ds_binds, + mg_rules = ds_rules_for_imps3, + mg_binds = ds_binds3, mg_foreign = ds_fords, mg_hpc_info = ds_hpc_info, mg_modBreaks = modBreaks, + mg_vect_decls = ds_vects2, mg_vect_info = noVectInfo } ; return (msgs, Just mod_guts) }}} -mkAutoScc :: Module -> NameSet -> AutoScc -mkAutoScc mod exports +dsImpSpecs :: [LTcSpecPrag] -> DsM (OrdList (Id,CoreExpr), [CoreRule]) +dsImpSpecs imp_specs + = do { spec_prs <- mapMaybeM (dsSpec Nothing) imp_specs + ; let (spec_binds, spec_rules) = unzip spec_prs + ; return (concatOL spec_binds, spec_rules) } + +combineEvBinds :: [DsEvBind] -> [(Id,CoreExpr)] -> [CoreBind] +-- Top-level bindings can include coercion bindings, but not via superclasses +-- See Note [Top-level evidence] +combineEvBinds [] val_prs + = [Rec val_prs] +combineEvBinds (LetEvBind (NonRec b r) : bs) val_prs + | isId b = combineEvBinds bs ((b,r):val_prs) + | otherwise = NonRec b r : combineEvBinds bs val_prs +combineEvBinds (LetEvBind (Rec prs) : bs) val_prs + = combineEvBinds bs (prs ++ val_prs) +combineEvBinds (CaseEvBind x _ _ : _) _ + = pprPanic "topEvBindPairs" (ppr x) +\end{code} + +Note [Top-level evidence] +~~~~~~~~~~~~~~~~~~~~~~~~~ +Top-level evidence bindings may be mutually recursive with the top-level value +bindings, so we must put those in a Rec. But we can't put them *all* in a Rec +because the occurrence analyser doesn't teke account of type/coercion variables +when computing dependencies. + +So we pull out the type/coercion variables (which are in dependency order), +and Rec the rest. + + +\begin{code} +mkAutoScc :: DynFlags -> Module -> NameSet -> AutoScc +mkAutoScc dflags mod exports | not opt_SccProfilingOn -- No profiling = NoSccs - | opt_AutoSccsOnAllToplevs -- Add auto-scc on all top-level things + -- Add auto-scc on all top-level things + | dopt Opt_AutoSccsOnAllToplevs dflags = AddSccs mod (\id -> not $ isDerivedOccName $ getOccName id) -- See #1641. This is pretty yucky, but I can't see a better way -- to identify compiler-generated Ids, and at least this should -- catch them all. - | opt_AutoSccsOnExportedToplevs -- Only on exported things + -- Only on exported things + | dopt Opt_AutoSccsOnExportedToplevs dflags = AddSccs mod (\id -> idName id `elemNameSet` exports) | otherwise = NoSccs @@ -186,45 +416,45 @@ deSugarExpr hsc_env this_mod rdr_env type_env tc_expr = do dumpIfSet_dyn dflags Opt_D_dump_ds "Desugared" (pprCoreExpr expr) return (msgs, Just expr) +\end{code} --- addExportFlags --- Set the no-discard flag if either --- a) the Id is exported --- b) it's mentioned in the RHS of an orphan rule --- c) it's in the keep-alive set --- --- It means that the binding won't be discarded EVEN if the binding --- ends up being trivial (v = w) -- the simplifier would usually just --- substitute w for v throughout, but we don't apply the substitution to --- the rules (maybe we should?), so this substitution would make the rule --- bogus. - --- You might wonder why exported Ids aren't already marked as such; --- it's just because the type checker is rather busy already and --- I didn't want to pass in yet another mapping. - -addExportFlags :: HscTarget -> NameSet -> NameSet -> [(Id, t)] -> [CoreRule] - -> [(Id, t)] -addExportFlags target exports keep_alive prs rules - = [(add_export bndr, rhs) | (bndr,rhs) <- prs] +%************************************************************************ +%* * +%* Add rules and export flags to binders +%* * +%************************************************************************ + +\begin{code} +addExportFlagsAndRules + :: HscTarget -> NameSet -> NameSet -> [CoreRule] + -> [(Id, t)] -> [(Id, t)] +addExportFlagsAndRules target exports keep_alive rules prs + = mapFst add_one prs where - add_export bndr - | dont_discard bndr = setIdExported bndr + add_one bndr = add_rules name (add_export name bndr) + where + name = idName bndr + + ---------- Rules -------- + -- See Note [Attach rules to local ids] + -- NB: the binder might have some existing rules, + -- arising from specialisation pragmas + add_rules name bndr + | Just rules <- lookupNameEnv rule_base name + = bndr `addIdSpecialisations` rules + | otherwise + = bndr + rule_base = extendRuleBaseList emptyRuleBase rules + + ---------- Export flag -------- + -- See Note [Adding export flags] + add_export name bndr + | dont_discard name = setIdExported bndr | otherwise = bndr - orph_rhs_fvs = unionVarSets [ ruleRhsFreeVars rule - | rule <- rules, - not (isLocalRule rule) ] - -- A non-local rule keeps alive the free vars of its right-hand side. - -- (A "non-local" is one whose head function is not locally defined.) - -- Local rules are (later, after gentle simplification) - -- attached to the Id, and that keeps the rhs free vars alive. - - dont_discard bndr = is_exported name + dont_discard :: Name -> Bool + dont_discard name = is_exported name || name `elemNameSet` keep_alive - || bndr `elemVarSet` orph_rhs_fvs - where - name = idName bndr -- In interactive mode, we don't want to discard any top-level -- entities at all (eg. do not inline them away during @@ -236,15 +466,44 @@ addExportFlags target exports keep_alive prs rules is_exported :: Name -> Bool is_exported | target == HscInterpreted = isExternalName | otherwise = (`elemNameSet` exports) - -ppr_ds_rules :: [CoreRule] -> SDoc -ppr_ds_rules [] = empty -ppr_ds_rules rules - = text "" $$ text "-------------- DESUGARED RULES -----------------" $$ - pprRules rules \end{code} +Note [Adding export flags] +~~~~~~~~~~~~~~~~~~~~~~~~~~ +Set the no-discard flag if either + a) the Id is exported + b) it's mentioned in the RHS of an orphan rule + c) it's in the keep-alive set + +It means that the binding won't be discarded EVEN if the binding +ends up being trivial (v = w) -- the simplifier would usually just +substitute w for v throughout, but we don't apply the substitution to +the rules (maybe we should?), so this substitution would make the rule +bogus. + +You might wonder why exported Ids aren't already marked as such; +it's just because the type checker is rather busy already and +I didn't want to pass in yet another mapping. + +Note [Attach rules to local ids] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Find the rules for locally-defined Ids; then we can attach them +to the binders in the top-level bindings + +Reason + - It makes the rules easier to look up + - It means that transformation rules and specialisations for + locally defined Ids are handled uniformly + - It keeps alive things that are referred to only from a rule + (the occurrence analyser knows about rules attached to Ids) + - It makes sure that, when we apply a rule, the free vars + of the RHS are more likely to be in scope + - The imported rules are carried in the in-scope set + which is extended on each iteration by the new wave of + local binders; any rules which aren't on the binding will + thereby get dropped + %************************************************************************ %* * @@ -257,28 +516,94 @@ dsRule :: LRuleDecl Id -> DsM (Maybe CoreRule) dsRule (L loc (HsRule name act vars lhs _tv_lhs rhs _fv_rhs)) = putSrcSpanDs loc $ do { let bndrs' = [var | RuleBndr (L _ var) <- vars] - ; lhs' <- dsLExpr lhs - ; rhs' <- dsLExpr rhs + + ; lhs' <- unsetOptM Opt_EnableRewriteRules $ + unsetOptM Opt_WarnIdentities $ + dsLExpr lhs -- Note [Desugaring RULE left hand sides] + + ; rhs' <- dsLExpr rhs -- Substitute the dict bindings eagerly, -- and take the body apart into a (f args) form - ; case decomposeRuleLhs (mkLams bndrs' lhs') of { - Nothing -> do { warnDs msg; return Nothing } ; - Just (bndrs, fn_id, args) -> do + ; case decomposeRuleLhs bndrs' lhs' of { + Left msg -> do { warnDs msg; return Nothing } ; + Right (final_bndrs, fn_id, args) -> do - { let local_rule = isLocalId fn_id + { let is_local = isLocalId fn_id -- NB: isLocalId is False of implicit Ids. This is good becuase -- we don't want to attach rules to the bindings of implicit Ids, -- because they don't show up in the bindings until just before code gen fn_name = idName fn_id - - rule = Rule { ru_name = name, ru_fn = fn_name, ru_act = act, - ru_bndrs = bndrs, ru_args = args, ru_rhs = rhs', - ru_rough = roughTopNames args, - ru_local = local_rule } + final_rhs = simpleOptExpr rhs' -- De-crap it + rule = mkRule False {- Not auto -} is_local + name act fn_name final_bndrs args final_rhs ; return (Just rule) } } } - where - msg = hang (ptext (sLit "RULE left-hand side too complicated to desugar; ignored")) - 2 (ppr lhs) +\end{code} + +Note [Desugaring RULE left hand sides] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +For the LHS of a RULE we do *not* want to desugar + [x] to build (\cn. x `c` n) +We want to leave explicit lists simply as chains +of cons's. We can achieve that slightly indirectly by +switching off EnableRewriteRules. See DsExpr.dsExplicitList. + +That keeps the desugaring of list comprehensions simple too. + + + +Nor do we want to warn of conversion identities on the LHS; +the rule is precisly to optimise them: + {-# RULES "fromRational/id" fromRational = id :: Rational -> Rational #-} + + +%************************************************************************ +%* * +%* Desugaring vectorisation declarations +%* * +%************************************************************************ + +\begin{code} +dsVect :: LVectDecl Id -> DsM CoreVect +dsVect (L loc (HsVect (L _ v) rhs)) + = putSrcSpanDs loc $ + do { rhs' <- fmapMaybeM dsLExpr rhs + ; return $ Vect v rhs' + } +dsVect (L _loc (HsNoVect (L _ v))) + = return $ NoVect v +\end{code} + + + +\begin{code} +-- +-- Simplification routines run before the flattener. We can't use +-- simpleOptPgm -- it doesn't preserve the order of subexpressions or +-- let-binding groups. +-- +simplify :: Expr CoreBndr -> Expr CoreBndr +simplify (Var v) = Var v +simplify (App e1 e2) = App (simplify e1) (simplify e2) +simplify (Lit lit) = Lit lit +simplify (Note note e) = Note note (simplify e) +simplify (Cast e co) = if eqType (fst $ unPair $ coercionKind co) (snd $ unPair $ coercionKind co) + then simplify e + else Cast (simplify e) co +simplify (Lam v e) = Lam v (simplify e) +simplify (Case e b ty as) = Case (simplify e) b ty (map (\(a,b,e) -> (a,b,simplify e)) as) +simplify (Let bind body) = foldr Let (simplify body) (simplifyBind bind) +simplify (Type t) = Type t +simplify (Coercion co) = Coercion co + +simplifyBind :: Bind CoreBndr -> [Bind CoreBndr] +simplifyBind (NonRec b e) = [NonRec b (simplify e)] +simplifyBind (Rec []) = [] +simplifyBind (Rec (rbs@((b,e):rbs'))) = + if or $ map (\x -> elemUFM x (exprFreeIds e)) (map fst rbs) + then [Rec (map (\(v,e) -> (v,simplify e)) rbs)] + else (NonRec b (simplify e)):(simplifyBind $ Rec rbs') + +simplifyBinds = concatMap simplifyBind \end{code}