X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplify.lhs;h=17a7969e74da1ddc0a3c19c9803d514786a983da;hb=9d7da331989abcd1844e9d03b8d1e4163796fa85;hp=15bd6123db1eb61e7a581c492af1a5c3cff1f2ba;hpb=c45a0ac5fdc6a931c3bc1a45fd4967f54c2983ca;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/Simplify.lhs b/ghc/compiler/simplCore/Simplify.lhs index 15bd612..17a7969 100644 --- a/ghc/compiler/simplCore/Simplify.lhs +++ b/ghc/compiler/simplCore/Simplify.lhs @@ -8,25 +8,26 @@ module Simplify ( simplTopBinds, simplExpr ) where #include "HsVersions.h" -import CmdLineOpts ( dopt, DynFlag(Opt_D_dump_inlinings), +import DynFlags ( dopt, DynFlag(Opt_D_dump_inlinings), SimplifierSwitch(..) ) import SimplMonad -import SimplUtils ( mkCase, mkLam, newId, prepareAlts, - simplBinder, simplBinders, simplLamBndrs, simplRecBndrs, simplLetBndr, +import SimplEnv +import SimplUtils ( mkCase, mkLam, prepareAlts, SimplCont(..), DupFlag(..), LetRhsFlag(..), mkRhsStop, mkBoringStop, pushContArgs, contResultType, countArgs, contIsDupable, contIsRhsOrArg, - getContArgs, interestingCallContext, interestingArg, isStrictType + getContArgs, interestingCallContext, interestingArg, isStrictType, + preInlineUnconditionally, postInlineUnconditionally, + inlineMode, activeInline, activeRule ) import Id ( Id, idType, idInfo, idArity, isDataConWorkId, setIdUnfolding, isDeadBinder, idNewDemandInfo, setIdInfo, - setIdOccInfo, zapLamIdInfo, setOneShotLambda, + setIdOccInfo, zapLamIdInfo, setOneShotLambda ) import MkId ( eRROR_ID ) import Literal ( mkStringLit ) -import OccName ( encodeFS ) import IdInfo ( OccInfo(..), isLoopBreaker, setArityInfo, zapDemandInfo, setUnfoldingInfo, @@ -34,14 +35,14 @@ import IdInfo ( OccInfo(..), isLoopBreaker, ) import NewDemand ( isStrictDmd ) import Unify ( coreRefineTys ) -import DataCon ( dataConTyCon, dataConRepStrictness, isVanillaDataCon, dataConResTy ) +import DataCon ( dataConTyCon, dataConRepStrictness, isVanillaDataCon ) import TyCon ( tyConArity ) import CoreSyn import PprCore ( pprParendExpr, pprCoreExpr ) -import CoreUnfold ( mkOtherCon, mkUnfolding, callSiteInline ) +import CoreUnfold ( mkUnfolding, callSiteInline ) import CoreUtils ( exprIsDupable, exprIsTrivial, needsCaseBinding, exprIsConApp_maybe, mkPiTypes, findAlt, - exprType, exprIsValue, + exprType, exprIsHNF, exprOkForSpeculation, exprArity, mkCoerce, mkCoerce2, mkSCC, mkInlineMe, applyTypeToArg ) @@ -49,22 +50,19 @@ import Rules ( lookupRule ) import BasicTypes ( isMarkedStrict ) import CostCentre ( currentCCS ) import Type ( TvSubstEnv, isUnLiftedType, seqType, tyConAppArgs, funArgTy, - splitFunTy_maybe, splitFunTy, coreEqType, substTy, - mkTyVarTys, mkTyConApp + splitFunTy_maybe, splitFunTy, coreEqType ) -import VarEnv ( elemVarEnv ) -import Subst ( SubstResult(..), emptySubst, substExpr, - substId, simplIdInfo ) +import VarEnv ( elemVarEnv, emptyVarEnv ) import TysPrim ( realWorldStatePrimTy ) import PrelInfo ( realWorldPrimId ) import BasicTypes ( TopLevelFlag(..), isTopLevel, RecFlag(..), isNonRec ) +import StaticFlags ( opt_PprStyle_Debug ) import OrdList -import Maybe ( Maybe ) import Maybes ( orElse ) import Outputable -import Util ( notNull, equalLength ) +import Util ( notNull ) \end{code} @@ -235,7 +233,7 @@ simplTopBinds env binds -- so that if a transformation rule has unexpectedly brought -- anything into scope, then we don't get a complaint about that. -- It's rather as if the top-level binders were imported. - simplRecBndrs env (bindersOfBinds binds) `thenSmpl` \ (env, bndrs') -> + simplLetBndrs env (bindersOfBinds binds) `thenSmpl` \ (env, bndrs') -> simpl_binds env binds bndrs' `thenSmpl` \ (floats, _) -> freeTick SimplifierDone `thenSmpl_` returnSmpl (floatBinds floats) @@ -300,12 +298,14 @@ simplNonRecBind env bndr rhs rhs_se cont_ty thing_inside #endif simplNonRecBind env bndr rhs rhs_se cont_ty thing_inside - | preInlineUnconditionally env NotTopLevel bndr - = tick (PreInlineUnconditionally bndr) `thenSmpl_` - thing_inside (extendIdSubst env bndr (ContEx (getSubst rhs_se) rhs)) + = simplNonRecBind' env bndr rhs rhs_se cont_ty thing_inside +simplNonRecBind' env bndr rhs rhs_se cont_ty thing_inside + | preInlineUnconditionally env NotTopLevel bndr rhs + = tick (PreInlineUnconditionally bndr) `thenSmpl_` + thing_inside (extendIdSubst env bndr (mkContEx rhs_se rhs)) - | isStrictDmd (idNewDemandInfo bndr) || isStrictType (idType bndr) -- A strict let + | isStrictDmd (idNewDemandInfo bndr) || isStrictType bndr_ty -- A strict let = -- Don't use simplBinder because that doesn't keep -- fragile occurrence info in the substitution simplLetBndr env bndr `thenSmpl` \ (env, bndr1) -> @@ -315,10 +315,16 @@ simplNonRecBind env bndr rhs rhs_se cont_ty thing_inside let -- simplLetBndr doesn't deal with the IdInfo, so we must -- do so here (c.f. simplLazyBind) - bndr2 = bndr1 `setIdInfo` simplIdInfo (getSubst env) (idInfo bndr) + bndr2 = bndr1 `setIdInfo` simplIdInfo env (idInfo bndr) env2 = modifyInScope env1 bndr2 bndr2 in - completeNonRecX env2 True {- strict -} bndr bndr2 rhs1 thing_inside + if needsCaseBinding bndr_ty rhs1 + then + thing_inside env2 `thenSmpl` \ (floats, body) -> + returnSmpl (emptyFloats env2, Case rhs1 bndr2 (exprType body) + [(DEFAULT, [], wrapFloats floats body)]) + else + completeNonRecX env2 True {- strict -} bndr bndr2 rhs1 thing_inside | otherwise -- Normal, lazy case = -- Don't use simplBinder because that doesn't keep @@ -327,6 +333,9 @@ simplNonRecBind env bndr rhs rhs_se cont_ty thing_inside simplLazyBind env NotTopLevel NonRecursive bndr bndr' rhs rhs_se `thenSmpl` \ (floats, env) -> addFloats env floats thing_inside + + where + bndr_ty = idType bndr \end{code} A specialised variant of simplNonRec used when the RHS is already simplified, notably @@ -350,11 +359,10 @@ simplNonRecX env bndr new_rhs thing_inside -- because quotInt# can fail. = simplBinder env bndr `thenSmpl` \ (env, bndr') -> thing_inside env `thenSmpl` \ (floats, body) -> --- gaw 2004 let body' = wrapFloats floats body in returnSmpl (emptyFloats env, Case new_rhs bndr' (exprType body') [(DEFAULT, [], body')]) - | preInlineUnconditionally env NotTopLevel bndr + | preInlineUnconditionally env NotTopLevel bndr new_rhs -- This happens; for example, the case_bndr during case of -- known constructor: case (a,b) of x { (p,q) -> ... } -- Here x isn't mentioned in the RHS, so we don't want to @@ -363,7 +371,7 @@ simplNonRecX env bndr new_rhs thing_inside -- Similarly, single occurrences can be inlined vigourously -- e.g. case (f x, g y) of (a,b) -> .... -- If a,b occur once we can avoid constructing the let binding for them. - = thing_inside (extendIdSubst env bndr (ContEx emptySubst new_rhs)) + = thing_inside (extendIdSubst env bndr (DoneEx new_rhs)) | otherwise = simplBinder env bndr `thenSmpl` \ (env, bndr') -> @@ -423,9 +431,9 @@ simplRecOrTopPair :: SimplEnv -> SimplM (FloatsWith SimplEnv) simplRecOrTopPair env top_lvl bndr bndr' rhs - | preInlineUnconditionally env top_lvl bndr -- Check for unconditional inline - = tick (PreInlineUnconditionally bndr) `thenSmpl_` - returnSmpl (emptyFloats env, extendIdSubst env bndr (ContEx (getSubst env) rhs)) + | preInlineUnconditionally env top_lvl bndr rhs -- Check for unconditional inline + = tick (PreInlineUnconditionally bndr) `thenSmpl_` + returnSmpl (emptyFloats env, extendIdSubst env bndr (mkContEx env rhs)) | otherwise = simplLazyBind env top_lvl Recursive bndr bndr' rhs env @@ -488,7 +496,7 @@ simplLazyBind env top_lvl is_rec bndr bndr1 rhs rhs_se -- NB 4: does no harm for non-recursive bindings - bndr2 = bndr1 `setIdInfo` simplIdInfo (getSubst env) (idInfo bndr) + bndr2 = bndr1 `setIdInfo` simplIdInfo env (idInfo bndr) env1 = modifyInScope env bndr2 bndr2 rhs_env = setInScope rhs_se env1 is_top_level = isTopLevel top_lvl @@ -515,24 +523,24 @@ simplLazyBind env top_lvl is_rec bndr bndr1 rhs rhs_se if isEmptyFloats floats && isNilOL aux_binds then -- Shortcut a common case completeLazyBind env1 top_lvl bndr bndr2 rhs2 - else if is_top_level || exprIsTrivial rhs2 || exprIsValue rhs2 then + else if is_top_level || exprIsTrivial rhs2 || exprIsHNF rhs2 then -- WARNING: long dodgy argument coming up -- WANTED: a better way to do this -- - -- We can't use "exprIsCheap" instead of exprIsValue, + -- We can't use "exprIsCheap" instead of exprIsHNF, -- because that causes a strictness bug. -- x = let y* = E in case (scc y) of { T -> F; F -> T} -- The case expression is 'cheap', but it's wrong to transform to -- y* = E; x = case (scc y) of {...} -- Either we must be careful not to float demanded non-values, or - -- we must use exprIsValue for the test, which ensures that the - -- thing is non-strict. So exprIsValue => bindings are non-strict + -- we must use exprIsHNF for the test, which ensures that the + -- thing is non-strict. So exprIsHNF => bindings are non-strict -- I think. The WARN below tests for this. -- -- We use exprIsTrivial here because we want to reveal lone variables. -- E.g. let { x = letrec { y = E } in y } in ... -- Here we definitely want to float the y=E defn. - -- exprIsValue definitely isn't right for that. + -- exprIsHNF definitely isn't right for that. -- -- Again, the floated binding can't be strict; if it's recursive it'll -- be non-strict; if it's non-recursive it'd be inlined. @@ -606,7 +614,7 @@ completeLazyBind :: SimplEnv -- (as usual) use the in-scope-env from the floats completeLazyBind env top_lvl old_bndr new_bndr new_rhs - | postInlineUnconditionally env new_bndr occ_info new_rhs + | postInlineUnconditionally env top_lvl new_bndr occ_info new_rhs unfolding = -- Drop the binding tick (PostInlineUnconditionally old_bndr) `thenSmpl_` returnSmpl (emptyFloats env, extendIdSubst env old_bndr (DoneEx new_rhs)) @@ -637,7 +645,6 @@ completeLazyBind env top_lvl old_bndr new_bndr new_rhs -- After inling f at some of its call sites the original binding may -- (for example) be no longer strictly demanded. -- The solution here is a bit ad hoc... - unfolding = mkUnfolding (isTopLevel top_lvl) new_rhs info_w_unf = new_bndr_info `setUnfoldingInfo` unfolding final_info | loop_breaker = new_bndr_info | isEvaldUnfolding unfolding = zapDemandInfo info_w_unf `orElse` info_w_unf @@ -651,6 +658,7 @@ completeLazyBind env top_lvl old_bndr new_bndr new_rhs returnSmpl (unitFloat env final_id new_rhs, env) where + unfolding = mkUnfolding (isTopLevel top_lvl) new_rhs loop_breaker = isLoopBreaker occ_info old_info = idInfo old_bndr occ_info = occInfo old_info @@ -706,7 +714,7 @@ might do the same again. simplExpr :: SimplEnv -> CoreExpr -> SimplM CoreExpr simplExpr env expr = simplExprC env expr (mkBoringStop expr_ty') where - expr_ty' = substTy (getTvSubst env) (exprType expr) + expr_ty' = substTy env (exprType expr) -- The type in the Stop continuation, expr_ty', is usually not used -- It's only needed when discarding continuations after finding -- a function that returns bottom. @@ -733,7 +741,6 @@ simplExprF env (Type ty) cont simplType env ty `thenSmpl` \ ty' -> rebuild env (Type ty') cont --- gaw 2004 simplExprF env (Case scrut bndr case_ty alts) cont | not (switchIsOn (getSwitchChecker env) NoCaseOfCase) = -- Simplify the scrutinee with a Select continuation @@ -746,10 +753,10 @@ simplExprF env (Case scrut bndr case_ty alts) cont rebuild env case_expr' cont where case_cont = Select NoDup bndr alts env (mkBoringStop case_ty') - case_ty' = substTy (getTvSubst env) case_ty -- c.f. defn of simplExpr + case_ty' = substTy env case_ty -- c.f. defn of simplExpr simplExprF env (Let (Rec pairs) body) cont - = simplRecBndrs env (map fst pairs) `thenSmpl` \ (env, bndrs') -> + = simplLetBndrs env (map fst pairs) `thenSmpl` \ (env, bndrs') -> -- NB: bndrs' don't have unfoldings or rules -- We add them as we go down @@ -769,7 +776,7 @@ simplType :: SimplEnv -> InType -> SimplM OutType simplType env ty = seqType new_ty `seq` returnSmpl new_ty where - new_ty = substTy (getTvSubst env) ty + new_ty = substTy env ty \end{code} @@ -836,6 +843,11 @@ mkLamBndrZapper fun n_args \begin{code} simplNote env (Coerce to from) body cont = let + addCoerce s1 k1 cont -- Drop redundant coerces. This can happen if a polymoprhic + -- (coerce a b e) is instantiated with a=ty1 b=ty2 and the + -- two are the same. This happens a lot in Happy-generated parsers + | s1 `coreEqType` k1 = cont + addCoerce s1 k1 (CoerceIt t1 cont) -- coerce T1 S1 (coerce S1 K1 e) -- ==> @@ -846,9 +858,9 @@ simplNote env (Coerce to from) body cont -- we may find (coerce T (coerce S (\x.e))) y -- and we'd like it to simplify to e[y/x] in one round -- of simplification - | t1 `coreEqType` k1 = cont -- The coerces cancel out - | otherwise = CoerceIt t1 cont -- They don't cancel, but - -- the inner one is redundant + | t1 `coreEqType` k1 = cont -- The coerces cancel out + | otherwise = CoerceIt t1 cont -- They don't cancel, but + -- the inner one is redundant addCoerce t1t2 s1s2 (ApplyTo dup arg arg_se cont) | not (isTypeArg arg), -- This whole case only works for value args @@ -867,8 +879,8 @@ simplNote env (Coerce to from) body cont -- But it isn't a common case. = let (t1,t2) = splitFunTy t1t2 - new_arg = mkCoerce2 s1 t1 (substExpr subst arg) - subst = getSubst (setInScope arg_se env) + new_arg = mkCoerce2 s1 t1 (substExpr arg_env arg) + arg_env = setInScope arg_se env in ApplyTo dup new_arg (zapSubstEnv env) (addCoerce t2 s2 cont) @@ -914,10 +926,10 @@ simplNote env (CoreNote s) e cont \begin{code} simplVar env var cont - = case substId (getSubst env) var of - DoneEx e -> simplExprF (zapSubstEnv env) e cont - ContEx se e -> simplExprF (setSubstEnv env se) e cont - DoneId var1 occ -> completeCall (zapSubstEnv env) var1 occ cont + = case substId env var of + DoneEx e -> simplExprF (zapSubstEnv env) e cont + ContEx tvs ids e -> simplExprF (setSubstEnv env tvs ids) e cont + DoneId var1 occ -> completeCall (zapSubstEnv env) var1 occ cont -- Note [zapSubstEnv] -- The template is already simplified, so don't re-substitute. -- This is VITAL. Consider @@ -969,9 +981,10 @@ completeCall env var occ_info cont let in_scope = getInScope env + rules = getRules env maybe_rule = case activeRule env of Nothing -> Nothing -- No rules apply - Just act_fn -> lookupRule act_fn in_scope var args + Just act_fn -> lookupRule act_fn in_scope rules var args in case maybe_rule of { Just (rule_name, rule_rhs) -> @@ -1003,6 +1016,13 @@ completeCall env var occ_info cont case maybe_inline of { Just unfolding -- There is an inlining! -> tick (UnfoldingDone var) `thenSmpl_` + (if dopt Opt_D_dump_inlinings dflags then + pprTrace "Inlining done" (vcat [ + text "Before:" <+> ppr var <+> sep (map pprParendExpr args), + text "Inlined fn: " <+> ppr unfolding, + text "Cont: " <+> ppr call_cont]) + else + id) $ makeThatCall env var unfolding args call_cont ; @@ -1290,7 +1310,7 @@ Blob of helper functions for the "case-of-something-else" situation. rebuildCase :: SimplEnv -> OutExpr -- Scrutinee -> InId -- Case binder - -> [InAlt] -- Alternatives + -> [InAlt] -- Alternatives (inceasing order) -> SimplCont -> SimplM FloatsWithExpr @@ -1305,9 +1325,10 @@ rebuildCase env scrut case_bndr alts cont = knownCon env (LitAlt lit) [] case_bndr alts cont | otherwise - = prepareAlts scrut case_bndr alts `thenSmpl` \ (better_alts, handled_cons) -> + = -- Prepare the alternatives. + prepareAlts scrut case_bndr alts `thenSmpl` \ (better_alts, handled_cons) -> - -- Deal with the case binder, and prepare the continuation; + -- Prepare the continuation; -- The new subst_env is in place prepareCaseCont env better_alts cont `thenSmpl` \ (floats, (dup_cont, nondup_cont)) -> addFloats env floats $ \ env -> @@ -1324,7 +1345,7 @@ rebuildCase env scrut case_bndr alts cont res_ty' = contResultType dup_cont in - -- Deal with variable scrutinee + -- Deal with case binder simplCaseBinder env scrut case_bndr `thenSmpl` \ (alt_env, case_bndr') -> -- Deal with the case alternatives @@ -1451,20 +1472,22 @@ simplAlts :: SimplEnv -> SimplM [OutAlt] -- Includes the continuation simplAlts env handled_cons case_bndr' alts cont' - = mapSmpl simpl_alt alts + = do { mb_alts <- mapSmpl simpl_alt alts + ; return [alt' | Just (_, alt') <- mb_alts] } + -- Filter out the alternatives that are inaccessible where - simpl_alt alt = simplAlt env handled_cons case_bndr' alt cont' `thenSmpl` \ (_, alt') -> - returnSmpl alt' + simpl_alt alt = simplAlt env handled_cons case_bndr' alt cont' simplAlt :: SimplEnv -> [AltCon] -> OutId -> InAlt -> SimplCont - -> SimplM (Maybe TvSubstEnv, OutAlt) + -> SimplM (Maybe (TvSubstEnv, OutAlt)) -- Simplify an alternative, returning the type refinement for the -- alternative, if the alternative does any refinement at all +-- Nothing => the alternative is inaccessible simplAlt env handled_cons case_bndr' (DEFAULT, bndrs, rhs) cont' = ASSERT( null bndrs ) simplExprC env' rhs cont' `thenSmpl` \ rhs' -> - returnSmpl (Nothing, (DEFAULT, [], rhs')) + returnSmpl (Just (emptyVarEnv, (DEFAULT, [], rhs'))) where env' = mk_rhs_env env case_bndr' (mkOtherCon handled_cons) -- Record the constructors that the case-binder *can't* be. @@ -1472,7 +1495,7 @@ simplAlt env handled_cons case_bndr' (DEFAULT, bndrs, rhs) cont' simplAlt env handled_cons case_bndr' (LitAlt lit, bndrs, rhs) cont' = ASSERT( null bndrs ) simplExprC env' rhs cont' `thenSmpl` \ rhs' -> - returnSmpl (Nothing, (LitAlt lit, [], rhs')) + returnSmpl (Just (emptyVarEnv, (LitAlt lit, [], rhs'))) where env' = mk_rhs_env env case_bndr' (mkUnfolding False (Lit lit)) @@ -1493,34 +1516,35 @@ simplAlt env handled_cons case_bndr' (DataAlt con, vs, rhs) cont' env' = mk_rhs_env env case_bndr' unf in simplExprC env' rhs cont' `thenSmpl` \ rhs' -> - returnSmpl (Nothing, (DataAlt con, vs', rhs')) + returnSmpl (Just (emptyVarEnv, (DataAlt con, vs', rhs'))) | otherwise -- GADT case = let (tvs,ids) = span isTyVar vs in simplBinders env tvs `thenSmpl` \ (env1, tvs') -> - let - pat_res_ty = dataConResTy con (mkTyVarTys tvs') - tv_subst = getTvSubst env1 - in - case coreRefineTys tvs' tv_subst pat_res_ty (idType case_bndr') of { - Nothing -- Dead code; for now, I'm just going to put in an - -- error case so I can see them + case coreRefineTys (getInScope env1) con tvs' (idType case_bndr') of { + Nothing -- Inaccessible + | opt_PprStyle_Debug -- Hack: if debugging is on, generate an error case + -- so we can see it -> let rhs' = mkApps (Var eRROR_ID) - [Type (substTy tv_subst (exprType rhs)), + [Type (substTy env (exprType rhs)), Lit (mkStringLit "Impossible alternative (GADT)")] in simplBinders env1 ids `thenSmpl` \ (env2, ids') -> - returnSmpl (Nothing, (DataAlt con, tvs' ++ ids', rhs')) ; + returnSmpl (Just (emptyVarEnv, (DataAlt con, tvs' ++ ids', rhs'))) - Just tv_subst_env -> -- The normal case + | otherwise -- Filter out the inaccessible branch + -> return Nothing ; + + Just refine@(tv_subst_env, _) -> -- The normal case let - env2 = setTvSubstEnv env1 tv_subst_env + env2 = refineSimplEnv env1 refine -- Simplify the Ids in the refined environment, so their types -- reflect the refinement. Usually this doesn't matter, but it helps -- in mkDupableAlt, when we want to float a lambda that uses these binders + -- Furthermore, it means the binders contain maximal type information in simplBinders env2 (add_evals con ids) `thenSmpl` \ (env3, ids') -> let unf = mkUnfolding False con_app @@ -1530,7 +1554,7 @@ simplAlt env handled_cons case_bndr' (DataAlt con, vs, rhs) cont' vs' = tvs' ++ ids' in simplExprC env_w_unf rhs cont' `thenSmpl` \ rhs' -> - returnSmpl (Just tv_subst_env, (DataAlt con, vs', rhs')) } + returnSmpl (Just (tv_subst_env, (DataAlt con, vs', rhs'))) } where -- add_evals records the evaluated-ness of the bound variables of @@ -1553,7 +1577,7 @@ simplAlt env handled_cons case_bndr' (DataAlt con, vs, rhs) cont' | otherwise = zapped_v : go vs strs where zapped_v = zap_occ_info v - evald_v = zapped_v `setIdUnfolding` mkOtherCon [] + evald_v = zapped_v `setIdUnfolding` evaldUnfolding go _ _ = pprPanic "cat_evals" (ppr dc $$ ppr vs $$ ppr strs) -- If the case binder is alive, then we add the unfolding @@ -1614,7 +1638,7 @@ knownCon env con args bndr alts cont bind_args env bs (drop n_drop_tys args) $ \ env -> let con_app = mkConApp dc (take n_drop_tys args ++ con_args) - con_args = [substExpr (getSubst env) (varToCoreExpr b) | b <- bs] + con_args = [substExpr env (varToCoreExpr b) | b <- bs] -- args are aready OutExprs, but bs are InIds in simplNonRecX env bndr con_app $ \ env -> @@ -1727,7 +1751,6 @@ mkDupableCont env (ApplyTo _ arg se cont) -- This has been this way for a long time, so I'll leave it, -- but I can't convince myself that it's right. --- gaw 2004 mkDupableCont env (Select _ case_bndr alts se cont) = -- e.g. (case [...hole...] of { pi -> ei }) -- ===> @@ -1766,17 +1789,24 @@ mkDupableAlts env case_bndr' alts dupable_cont where go env [] = returnSmpl (emptyFloats env, []) go env (alt:alts) - = mkDupableAlt env case_bndr' dupable_cont alt `thenSmpl` \ (floats1, alt') -> - addFloats env floats1 $ \ env -> - go env alts `thenSmpl` \ (floats2, alts') -> - returnSmpl (floats2, alt' : alts') + = do { (floats1, mb_alt') <- mkDupableAlt env case_bndr' dupable_cont alt + ; addFloats env floats1 $ \ env -> do + { (floats2, alts') <- go env alts + ; returnSmpl (floats2, case mb_alt' of + Just alt' -> alt' : alts' + Nothing -> alts' + )}} mkDupableAlt env case_bndr' cont alt - = simplAlt env [] case_bndr' alt cont `thenSmpl` \ (mb_reft, (con, bndrs', rhs')) -> + = simplAlt env [] case_bndr' alt cont `thenSmpl` \ mb_stuff -> + case mb_stuff of { + Nothing -> returnSmpl (emptyFloats env, Nothing) ; + + Just (reft, (con, bndrs', rhs')) -> -- Safe to say that there are no handled-cons for the DEFAULT case if exprIsDupable rhs' then - returnSmpl (emptyFloats env, (con, bndrs', rhs')) + returnSmpl (emptyFloats env, Just (con, bndrs', rhs')) -- It is worth checking for a small RHS because otherwise we -- get extra let bindings that may cause an extra iteration of the simplifier to -- inline back in place. Quite often the rhs is just a variable or constructor. @@ -1798,13 +1828,11 @@ mkDupableAlt env case_bndr' cont alt rhs_ty' = exprType rhs' used_bndrs' = filter abstract_over (case_bndr' : bndrs') abstract_over bndr - | isTyVar bndr = not (mb_reft `refines` bndr) + | isTyVar bndr = not (bndr `elemVarEnv` reft) -- Don't abstract over tyvar binders which are refined away + -- See Note [Refinement] below | otherwise = not (isDeadBinder bndr) -- The deadness info on the new Ids is preserved by simplBinders - refines Nothing bndr = False - refines (Just tv_subst) bndr = bndr `elemVarEnv` tv_subst - -- See Note [Refinement] below in -- If we try to lift a primitive-typed something out -- for let-binding-purposes, we will *caseify* it (!), @@ -1846,7 +1874,7 @@ mkDupableAlt env case_bndr' cont alt ) `thenSmpl` \ (final_bndrs', final_args) -> -- See comment about "$j" name above - newId (encodeFS FSLIT("$j")) (mkPiTypes final_bndrs' rhs_ty') `thenSmpl` \ join_bndr -> + newId FSLIT("$j") (mkPiTypes final_bndrs' rhs_ty') `thenSmpl` \ join_bndr -> -- Notice the funky mkPiTypes. If the contructor has existentials -- it's possible that the join point will be abstracted over -- type varaibles as well as term variables. @@ -1872,7 +1900,7 @@ mkDupableAlt env case_bndr' cont alt join_rhs = mkLams really_final_bndrs rhs' join_call = mkApps (Var join_bndr) final_args in - returnSmpl (unitFloat env join_bndr join_rhs, (con, bndrs', join_call)) + returnSmpl (unitFloat env join_bndr join_rhs, Just (con, bndrs', join_call)) } \end{code} Note [Refinement]