X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FcoreSyn%2FCoreSubst.lhs;h=3578037f301b132357e08f4f7d11ea42b8e102ee;hb=635952097df211953c4bd0456b37eba64c485f60;hp=216b6364a45db2a87f940ead9477273d7ac8ffa1;hpb=3545603ca61d81093151307477bdecb7910cb1b7;p=ghc-hetmet.git diff --git a/compiler/coreSyn/CoreSubst.lhs b/compiler/coreSyn/CoreSubst.lhs index 216b636..3578037 100644 --- a/compiler/coreSyn/CoreSubst.lhs +++ b/compiler/coreSyn/CoreSubst.lhs @@ -12,7 +12,8 @@ module CoreSubst ( -- ** Substituting into expressions and related types deShadowBinds, substSpec, substRulesForImportedIds, - substTy, substExpr, substBind, substUnfolding, + substTy, substExpr, substExprSC, substBind, substBindSC, + substUnfolding, substUnfoldingSC, substUnfoldingSource, lookupIdSubst, lookupTvSubst, substIdOcc, -- ** Operations on substitutions @@ -39,7 +40,7 @@ import OccurAnal( occurAnalyseExpr ) import qualified Type import Type ( Type, TvSubst(..), TvSubstEnv ) -import Coercion ( optCoercion ) +import OptCoercion ( optCoercion ) import VarSet import VarEnv import Id @@ -212,13 +213,13 @@ extendSubstList subst [] = subst extendSubstList subst ((var,rhs):prs) = extendSubstList (extendSubst subst var rhs) prs -- | Find the substitution for an 'Id' in the 'Subst' -lookupIdSubst :: Subst -> Id -> CoreExpr -lookupIdSubst (Subst in_scope ids _) v +lookupIdSubst :: SDoc -> Subst -> Id -> CoreExpr +lookupIdSubst doc (Subst in_scope ids _) v | not (isLocalId v) = Var v | Just e <- lookupVarEnv ids v = e | Just v' <- lookupInScope in_scope v = Var v' -- Vital! See Note [Extending the Subst] - | otherwise = WARN( True, ptext (sLit "CoreSubst.lookupIdSubst") <+> ppr v $$ ppr in_scope ) + | otherwise = WARN( True, ptext (sLit "CoreSubst.lookupIdSubst") <+> ppr v $$ ppr in_scope $$ doc) Var v -- | Find the substitution for a 'TyVar' in the 'Subst' @@ -282,11 +283,20 @@ instance Outputable Subst where -- -- Do *not* attempt to short-cut in the case of an empty substitution! -- See Note [Extending the Subst] -substExpr :: Subst -> CoreExpr -> CoreExpr -substExpr subst expr +substExprSC :: SDoc -> Subst -> CoreExpr -> CoreExpr +substExprSC _doc subst orig_expr + | isEmptySubst subst = orig_expr + | otherwise = -- pprTrace "enter subst-expr" (doc $$ ppr orig_expr) $ + subst_expr subst orig_expr + +substExpr :: SDoc -> Subst -> CoreExpr -> CoreExpr +substExpr _doc subst orig_expr = subst_expr subst orig_expr + +subst_expr :: Subst -> CoreExpr -> CoreExpr +subst_expr subst expr = go expr where - go (Var v) = lookupIdSubst subst v + go (Var v) = lookupIdSubst (text "subst_expr") subst v go (Type ty) = Type (substTy subst ty) go (Lit lit) = Lit lit go (App fun arg) = App (go fun) (go arg) @@ -295,11 +305,11 @@ substExpr subst expr -- Optimise coercions as we go; this is good, for example -- in the RHS of rules, which are only substituted in - go (Lam bndr body) = Lam bndr' (substExpr subst' body) + go (Lam bndr body) = Lam bndr' (subst_expr subst' body) where (subst', bndr') = substBndr subst bndr - go (Let bind body) = Let bind' (substExpr subst' body) + go (Let bind body) = Let bind' (subst_expr subst' body) where (subst', bind') = substBind subst bind @@ -307,7 +317,7 @@ substExpr subst expr where (subst', bndr') = substBndr subst bndr - go_alt subst (con, bndrs, rhs) = (con, bndrs', substExpr subst' rhs) + go_alt subst (con, bndrs, rhs) = (con, bndrs', subst_expr subst' rhs) where (subst', bndrs') = substBndrs subst bndrs @@ -315,16 +325,32 @@ substExpr subst expr -- | Apply a substititon to an entire 'CoreBind', additionally returning an updated 'Subst' -- that should be used by subsequent substitutons. -substBind :: Subst -> CoreBind -> (Subst, CoreBind) -substBind subst (NonRec bndr rhs) = (subst', NonRec bndr' (substExpr subst rhs)) +substBind, substBindSC :: Subst -> CoreBind -> (Subst, CoreBind) + +substBindSC subst bind -- Short-cut if the substitution is empty + | not (isEmptySubst subst) + = substBind subst bind + | otherwise + = case bind of + NonRec bndr rhs -> (subst', NonRec bndr' rhs) + where + (subst', bndr') = substBndr subst bndr + Rec pairs -> (subst', Rec (bndrs' `zip` rhss')) + where + (bndrs, rhss) = unzip pairs + (subst', bndrs') = substRecBndrs subst bndrs + rhss' | isEmptySubst subst' = rhss + | otherwise = map (subst_expr subst') rhss + +substBind subst (NonRec bndr rhs) = (subst', NonRec bndr' (subst_expr subst rhs)) where (subst', bndr') = substBndr subst bndr -substBind subst (Rec pairs) = (subst', Rec pairs') +substBind subst (Rec pairs) = (subst', Rec (bndrs' `zip` rhss')) where - (subst', bndrs') = substRecBndrs subst (map fst pairs) - pairs' = bndrs' `zip` rhss' - rhss' = map (substExpr subst' . snd) pairs + (bndrs, rhss) = unzip pairs + (subst', bndrs') = substRecBndrs subst bndrs + rhss' = map (subst_expr subst') rhss \end{code} \begin{code} @@ -360,7 +386,7 @@ preserve occ info in rules. substBndr :: Subst -> Var -> (Subst, Var) substBndr subst bndr | isTyVar bndr = substTyVarBndr subst bndr - | otherwise = substIdBndr subst subst bndr + | otherwise = substIdBndr (text "var-bndr") subst subst bndr -- | Applies 'substBndr' to a number of 'Var's, accumulating a new 'Subst' left-to-right substBndrs :: Subst -> [Var] -> (Subst, [Var]) @@ -371,18 +397,20 @@ substRecBndrs :: Subst -> [Id] -> (Subst, [Id]) substRecBndrs subst bndrs = (new_subst, new_bndrs) where -- Here's the reason we need to pass rec_subst to subst_id - (new_subst, new_bndrs) = mapAccumL (substIdBndr new_subst) subst bndrs + (new_subst, new_bndrs) = mapAccumL (substIdBndr (text "rec-bndr") new_subst) subst bndrs \end{code} \begin{code} -substIdBndr :: Subst -- ^ Substitution to use for the IdInfo +substIdBndr :: SDoc + -> Subst -- ^ Substitution to use for the IdInfo -> Subst -> Id -- ^ Substitition and Id to transform -> (Subst, Id) -- ^ Transformed pair -- NB: unfolding may be zapped -substIdBndr rec_subst subst@(Subst in_scope env tvs) old_id - = (Subst (in_scope `extendInScopeSet` new_id) new_env tvs, new_id) +substIdBndr _doc rec_subst subst@(Subst in_scope env tvs) old_id + = -- pprTrace "substIdBndr" (doc $$ ppr old_id $$ ppr in_scope) $ + (Subst (in_scope `extendInScopeSet` new_id) new_env tvs, new_id) where id1 = uniqAway in_scope old_id -- id1 is cloned if necessary id2 | no_type_change = id1 @@ -414,7 +442,7 @@ It also unconditionally zaps the OccInfo. \begin{code} -- | Very similar to 'substBndr', but it always allocates a new 'Unique' for --- each variable in its output and removes all 'IdInfo' +-- each variable in its output. It substitutes the IdInfo though. cloneIdBndr :: Subst -> UniqSupply -> Id -> (Subst, Id) cloneIdBndr subst us old_id = clone_id subst subst (old_id, uniqFromSupply us) @@ -507,11 +535,16 @@ substIdInfo subst new_id info ------------------ -- | Substitutes for the 'Id's within an unfolding -substUnfolding :: Subst -> Unfolding -> Unfolding +substUnfolding, substUnfoldingSC :: Subst -> Unfolding -> Unfolding -- Seq'ing on the returned Unfolding is enough to cause -- all the substitutions to happen completely -substUnfolding subst (DFunUnfolding con args) - = DFunUnfolding con (map (substExpr subst) args) + +substUnfoldingSC subst unf -- Short-cut version + | isEmptySubst subst = unf + | otherwise = substUnfolding subst unf + +substUnfolding subst (DFunUnfolding ar con args) + = DFunUnfolding ar con (map (substExpr (text "dfun-unf") subst) args) substUnfolding subst unf@(CoreUnfolding { uf_tmpl = tmpl, uf_src = src }) -- Retain an InlineRule! @@ -522,7 +555,7 @@ substUnfolding subst unf@(CoreUnfolding { uf_tmpl = tmpl, uf_src = src }) new_src `seq` unf { uf_tmpl = new_tmpl, uf_src = new_src } where - new_tmpl = substExpr subst tmpl + new_tmpl = substExpr (text "subst-unf") subst tmpl new_src = substUnfoldingSource subst src substUnfolding _ unf = unf -- NoUnfolding, OtherCon @@ -533,13 +566,13 @@ substUnfoldingSource (Subst in_scope ids _) (InlineWrapper wkr) | Just wkr_expr <- lookupVarEnv ids wkr = case wkr_expr of Var w1 -> InlineWrapper w1 - _other -> WARN( True, text "Interesting! CoreSubst.substWorker1:" <+> ppr wkr - <+> ifPprDebug (equals <+> ppr wkr_expr) ) + _other -> -- WARN( True, text "Interesting! CoreSubst.substWorker1:" <+> ppr wkr + -- <+> ifPprDebug (equals <+> ppr wkr_expr) ) -- Note [Worker inlining] InlineRule -- It's not a wrapper any more, but still inline it! | Just w1 <- lookupInScope in_scope wkr = InlineWrapper w1 - | otherwise = WARN( True, text "Interesting! CoreSubst.substWorker2:" <+> ppr wkr ) + | otherwise = -- WARN( True, text "Interesting! CoreSubst.substWorker2:" <+> ppr wkr ) -- This can legitimately happen. The worker has been inlined and -- dropped as dead code, because we don't treat the UnfoldingSource -- as an "occurrence". @@ -551,7 +584,7 @@ substUnfoldingSource _ src = src ------------------ substIdOcc :: Subst -> Id -> Id -- These Ids should not be substituted to non-Ids -substIdOcc subst v = case lookupIdSubst subst v of +substIdOcc subst v = case lookupIdSubst (text "substIdOcc") subst v of Var v' -> v' other -> pprPanic "substIdOcc" (vcat [ppr v <+> ppr other, ppr subst]) @@ -585,8 +618,8 @@ substRule subst subst_ru_fn rule@(Rule { ru_bndrs = bndrs, ru_args = args , ru_fn = fn_name, ru_rhs = rhs }) = rule { ru_bndrs = bndrs', ru_fn = subst_ru_fn fn_name, - ru_args = map (substExpr subst') args, - ru_rhs = substExpr subst' rhs } + ru_args = map (substExpr (text "subst-rule" <+> ppr fn_name) subst') args, + ru_rhs = substExpr (text "subst-rule" <+> ppr fn_name) subst' rhs } where (subst', bndrs') = substBndrs subst bndrs @@ -596,7 +629,7 @@ substVarSet subst fvs = foldVarSet (unionVarSet . subst_fv subst) emptyVarSet fvs where subst_fv subst fv - | isId fv = exprFreeVars (lookupIdSubst subst fv) + | isId fv = exprFreeVars (lookupIdSubst (text "substVarSet") subst fv) | otherwise = Type.tyVarsOfType (lookupTvSubst subst fv) \end{code} @@ -630,7 +663,8 @@ simpleOptExpr :: CoreExpr -> CoreExpr -- may change radically simpleOptExpr expr - = go init_subst (occurAnalyseExpr expr) + = -- pprTrace "simpleOptExpr" (ppr init_subst $$ ppr expr) + go init_subst (occurAnalyseExpr expr) where init_subst = mkEmptySubst (mkInScopeSet (exprFreeVars expr)) -- It's potentially important to make a proper in-scope set @@ -643,7 +677,7 @@ simpleOptExpr expr -- It's a bit painful to call exprFreeVars, because it makes -- three passes instead of two (occ-anal, and go) - go subst (Var v) = lookupIdSubst subst v + go subst (Var v) = lookupIdSubst (text "simpleOptExpr") subst v go subst (App e1 e2) = App (go subst e1) (go subst e2) go subst (Type ty) = Type (substTy subst ty) go _ (Lit lit) = Lit lit