\begin{code}
module SimplUtils (
- simplBinder, simplBinders, simplIds,
+ simplBinder, simplBinders, simplRecIds, simplLetId,
tryRhsTyLam, tryEtaExpansion,
- mkCase, findAlt, findDefault,
+ mkCase,
-- The continuation type
SimplCont(..), DupFlag(..), contIsDupable, contResultType,
opt_UF_UpdateInPlace
)
import CoreSyn
-import CoreUtils ( exprIsTrivial, cheapEqExpr, exprType, exprIsCheap, etaExpand, exprEtaExpandArity, bindNonRec )
-import Subst ( InScopeSet, mkSubst, substBndrs, substBndr, substIds, substExpr )
+import CoreUtils ( exprIsTrivial, cheapEqExpr, exprType, exprIsCheap,
+ etaExpand, exprEtaExpandArity, bindNonRec, mkCoerce,
+ findDefault
+ )
+import Subst ( InScopeSet, mkSubst, substExpr )
+import qualified Subst ( simplBndrs, simplBndr, simplLetId )
import Id ( idType, idName,
idUnfolding, idStrictness,
- mkVanillaId, idInfo
+ mkLocalId, idInfo
)
import IdInfo ( StrictnessInfo(..) )
import Maybes ( maybeToBool, catMaybes )
import TyCon ( tyConDataConsIfAvailable )
import DataCon ( dataConRepArity )
import VarEnv ( SubstEnv )
-import Util ( lengthExceeds )
+import Util ( lengthExceeds, mapAccumL )
import Outputable
\end{code}
simplBinders bndrs thing_inside
= getSubst `thenSmpl` \ subst ->
let
- (subst', bndrs') = substBndrs subst bndrs
+ (subst', bndrs') = Subst.simplBndrs subst bndrs
in
seqBndrs bndrs' `seq`
setSubst subst' (thing_inside bndrs')
simplBinder bndr thing_inside
= getSubst `thenSmpl` \ subst ->
let
- (subst', bndr') = substBndr subst bndr
+ (subst', bndr') = Subst.simplBndr subst bndr
in
seqBndr bndr' `seq`
setSubst subst' (thing_inside bndr')
--- Same semantics as simplBinders, but a little less
--- plumbing and hence a little more efficient.
--- Maybe not worth the candle?
-simplIds :: [InBinder] -> ([OutBinder] -> SimplM a) -> SimplM a
-simplIds ids thing_inside
+simplRecIds :: [InBinder] -> ([OutBinder] -> SimplM a) -> SimplM a
+simplRecIds ids thing_inside
= getSubst `thenSmpl` \ subst ->
let
- (subst', bndrs') = substIds subst ids
+ (subst', ids') = mapAccumL Subst.simplLetId subst ids
in
- seqBndrs bndrs' `seq`
- setSubst subst' (thing_inside bndrs')
+ seqBndrs ids' `seq`
+ setSubst subst' (thing_inside ids')
+
+simplLetId :: InBinder -> (OutBinder -> SimplM a) -> SimplM a
+simplLetId id thing_inside
+ = getSubst `thenSmpl` \ subst ->
+ let
+ (subst', id') = Subst.simplLetId subst id
+ in
+ seqBndr id' `seq`
+ setSubst subst' (thing_inside id')
seqBndrs [] = ()
seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs
tryRhsTyLam :: OutExpr -> SimplM ([OutBind], OutExpr)
tryRhsTyLam rhs -- Only does something if there's a let
- | null tyvars || not (worth_it body) -- inside a type lambda, and a WHNF inside that
- = returnSmpl ([], rhs)
+ | null tyvars || not (worth_it body) -- inside a type lambda,
+ = returnSmpl ([], rhs) -- and a WHNF inside that
| otherwise
= go (\x -> x) body `thenSmpl` \ (binds, body') ->
where
(tyvars, body) = collectTyBinders rhs
- worth_it (Let _ e) = whnf_in_middle e
- worth_it other = False
+ worth_it e@(Let _ _) = whnf_in_middle e
+ worth_it e = False
+
+ whnf_in_middle (Let (NonRec x rhs) e) | isUnLiftedType (idType x) = False
whnf_in_middle (Let _ e) = whnf_in_middle e
whnf_in_middle e = exprIsCheap e
let
poly_name = setNameUnique (idName var) uniq -- Keep same name
poly_ty = mkForAllTys tyvars_here (idType var) -- But new type of course
- poly_id = mkVanillaId poly_name poly_ty
+ poly_id = mkLocalId poly_name poly_ty
-- In the olden days, it was crucial to copy the occInfo of the original var,
-- because we were looking at occurrence-analysed but as yet unsimplified code!
mkCase scrut case_bndr alts
| all identity_alt alts
= tick (CaseIdentity case_bndr) `thenSmpl_`
- returnSmpl scrut
+ returnSmpl (re_note scrut)
where
- identity_alt (DEFAULT, [], Var v) = v == case_bndr
- identity_alt (DataAlt con, args, rhs) = cheapEqExpr rhs
- (mkConApp con (map Type arg_tys ++ map varToCoreExpr args))
- identity_alt other = False
-
- arg_tys = tyConAppArgs (idType case_bndr)
+ identity_alt (con, args, rhs) = de_note rhs `cheapEqExpr` identity_rhs con args
+
+ identity_rhs (DataAlt con) args = mkConApp con (arg_tys ++ map varToCoreExpr args)
+ identity_rhs (LitAlt lit) _ = Lit lit
+ identity_rhs DEFAULT _ = Var case_bndr
+
+ arg_tys = map Type (tyConAppArgs (idType case_bndr))
+
+ -- We've seen this:
+ -- case coerce T e of x { _ -> coerce T' x }
+ -- And we definitely want to eliminate this case!
+ -- So we throw away notes from the RHS, and reconstruct
+ -- (at least an approximation) at the other end
+ de_note (Note _ e) = de_note e
+ de_note e = e
+
+ -- re_note wraps a coerce if it might be necessary
+ re_note scrut = case head alts of
+ (_,_,rhs1@(Note _ _)) -> mkCoerce (exprType rhs1) (idType case_bndr) scrut
+ other -> scrut
\end{code}
The catch-all case
\end{code}
-\begin{code}
-findDefault :: [CoreAlt] -> ([CoreAlt], Maybe CoreExpr)
-findDefault [] = ([], Nothing)
-findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null alts && null args )
- ([], Just rhs)
-findDefault (alt : alts) = case findDefault alts of
- (alts', deflt) -> (alt : alts', deflt)
-
-findAlt :: AltCon -> [CoreAlt] -> CoreAlt
-findAlt con alts
- = go alts
- where
- go [] = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts))
- go (alt : alts) | matches alt = alt
- | otherwise = go alts
-
- matches (DEFAULT, _, _) = True
- matches (con1, _, _) = con == con1
-\end{code}