lower levels it is preserved with @let@/@letrec@s).
\begin{code}
-{-# OPTIONS -w #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
--- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
--- for details
-
module DsBinds ( dsTopLHsBinds, dsLHsBinds, decomposeRuleLhs,
dsCoercion,
AutoScc(..)
import HsSyn -- lots of things
import CoreSyn -- lots of things
import CoreUtils
+import CoreFVs
import TcHsSyn ( mkArbitraryType ) -- Mis-placed?
import TcType
import Module
import Id
import Var ( TyVar )
+import VarSet
import Rules
import VarEnv
import Type
-> HsBind Id
-> DsM [(Id,CoreExpr)] -- Result
-dsHsBind auto_scc rest (VarBind var expr)
- = dsLExpr expr `thenDs` \ core_expr ->
+dsHsBind _ rest (VarBind var expr) = do
+ core_expr <- dsLExpr expr
- -- Dictionary bindings are always VarMonoBinds, so
- -- we only need do this here
- addDictScc var core_expr `thenDs` \ core_expr' ->
- returnDs ((var, core_expr') : rest)
+ -- Dictionary bindings are always VarMonoBinds, so
+ -- we only need do this here
+ core_expr' <- addDictScc var core_expr
+ return ((var, core_expr') : rest)
-dsHsBind auto_scc rest (FunBind { fun_id = L _ fun, fun_matches = matches,
- fun_co_fn = co_fn, fun_tick = tick, fun_infix = inf })
- = matchWrapper (FunRhs (idName fun) inf) matches `thenDs` \ (args, body) ->
- mkOptTickBox tick body `thenDs` \ body' ->
- dsCoercion co_fn (return (mkLams args body')) `thenDs` \ rhs ->
- returnDs ((fun,rhs) : rest)
+dsHsBind _ rest (FunBind { fun_id = L _ fun, fun_matches = matches,
+ fun_co_fn = co_fn, fun_tick = tick, fun_infix = inf }) = do
+ (args, body) <- matchWrapper (FunRhs (idName fun) inf) matches
+ body' <- mkOptTickBox tick body
+ rhs <- dsCoercion co_fn (return (mkLams args body'))
+ return ((fun,rhs) : rest)
-dsHsBind auto_scc rest (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty })
- = dsGuarded grhss ty `thenDs` \ body_expr ->
- mkSelectorBinds pat body_expr `thenDs` \ sel_binds ->
- returnDs (sel_binds ++ rest)
+dsHsBind _ rest (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty }) = do
+ body_expr <- dsGuarded grhss ty
+ sel_binds <- mkSelectorBinds pat body_expr
+ return (sel_binds ++ rest)
-- Note [Rules and inlining]
-- Common special case: no type or dictionary abstraction
-- Another common case: one exported variable
-- Non-recursive bindings come through this way
dsHsBind auto_scc rest
- (AbsBinds all_tyvars dicts exports@[(tyvars, global, local, prags)] binds)
- = ASSERT( all (`elem` tyvars) all_tyvars )
- ds_lhs_binds NoSccs binds `thenDs` \ core_prs ->
- let
- -- Always treat the binds as recursive, because the typechecker
- -- makes rather mixed-up dictionary bindings
- core_bind = Rec core_prs
- in
- mappM (dsSpec all_tyvars dicts tyvars global local core_bind)
- prags `thenDs` \ mb_specs ->
+ (AbsBinds all_tyvars dicts [(tyvars, global, local, prags)] binds)
+ = ASSERT( all (`elem` tyvars) all_tyvars ) do
+ core_prs <- ds_lhs_binds NoSccs binds
+ let
+ -- Always treat the binds as recursive, because the typechecker
+ -- makes rather mixed-up dictionary bindings
+ core_bind = Rec core_prs
+
+ mb_specs <- mapM (dsSpec all_tyvars dicts tyvars global local core_bind) prags
let
- (spec_binds, rules) = unzip (catMaybes mb_specs)
- global' = addIdSpecialisations global rules
- rhs' = mkLams tyvars $ mkLams dicts $ Let core_bind (Var local)
- bind = addInlinePrags prags global' $ addAutoScc auto_scc global' rhs'
- in
- returnDs (bind : spec_binds ++ rest)
+ (spec_binds, rules) = unzip (catMaybes mb_specs)
+ global' = addIdSpecialisations global rules
+ rhs' = mkLams tyvars $ mkLams dicts $ Let core_bind (Var local)
+ bind = addInlinePrags prags global' $ addAutoScc auto_scc global' rhs'
+
+ return (bind : spec_binds ++ rest)
dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds)
= do { core_prs <- ds_lhs_binds NoSccs binds
rhs = mkLams tyvars $ mkLams dicts $
mkTupleSelector locals' (locals' !! n) tup_id $
mkApps (mkTyApps (Var poly_tup_id) ty_args) dict_args
- ; returnDs ((global', rhs) : spec_binds) }
+ ; return ((global', rhs) : spec_binds) }
where
mk_ty_arg all_tyvar
| all_tyvar `elem` tyvars = return (mkTyVarTy all_tyvar)
| otherwise = dsMkArbitraryType all_tyvar
- ; export_binds_s <- mappM mk_bind (exports `zip` [0..])
+ ; export_binds_s <- mapM mk_bind (exports `zip` [0..])
-- don't scc (auto-)annotate the tuple itself.
- ; returnDs ((poly_tup_id, poly_tup_expr) :
+ ; return ((poly_tup_id, poly_tup_expr) :
(concat export_binds_s ++ rest)) }
mkABEnv :: [([TyVar], Id, Id, [LPrag])] -> VarEnv (Id, [LPrag])
-- inlined and specialised
--
-- Given SpecPrag (/\as.\ds. f es) t, we have
--- the defn f_spec as ds = f es
--- and the RULE f es = f_spec as ds
+-- the defn f_spec as ds = let-nonrec f = /\fas\fds. let f_mono = <f-rhs> in f_mono
+-- in f es
+-- and the RULE forall as, ds. f es = f_spec as ds
--
-- It is *possible* that 'es' does not mention all of the dictionaries 'ds'
-- (a bit silly, because then the
-dsSpec all_tvs dicts tvs poly_id mono_id mono_bind (L _ (InlinePrag {}))
+dsSpec _ _ _ _ _ _ (L _ (InlinePrag {}))
= return Nothing
dsSpec all_tvs dicts tvs poly_id mono_id mono_bind
- (L loc (SpecPrag spec_expr spec_ty _const_dicts inl))
- -- See Note [Const rule dicts]
+ (L loc (SpecPrag spec_expr spec_ty inl))
= putSrcSpanDs loc $
do { let poly_name = idName poly_id
; spec_name <- newLocalName poly_name
case mb_lhs of
Nothing -> do { warnDs decomp_msg; return Nothing }
- Just (var, args) -> do
+ Just (_, args) -> do
{ f_body <- fix_up (Let mono_bind (Var mono_id))
spec_rhs = Let (NonRec local_poly poly_f_body) ds_spec_expr
poly_f_body = mkLams (tvs ++ dicts) f_body
+ extra_dict_bndrs = filter isDictId (varSetElems (exprFreeVars ds_spec_expr))
+ -- Note [Const rule dicts]
+
rule = mkLocalRule (mkFastString ("SPEC " ++ showSDoc (ppr poly_name)))
AlwaysActive poly_name
- bndrs args
+ (extra_dict_bndrs ++ bndrs) args
(mkVarApps (Var spec_id) bndrs)
; return (Just (addInlineInfo inl spec_id spec_rhs, rule))
} } }
void_tvs = all_tvs \\ tvs
- dead_msg bs = vcat [ sep [ptext SLIT("Useless constraint") <> plural bs
- <+> ptext SLIT("in specialied type:"),
+ dead_msg bs = vcat [ sep [ptext (sLit "Useless constraint") <> plural bs
+ <+> ptext (sLit "in specialied type:"),
nest 2 (pprTheta (map get_pred bs))]
- , ptext SLIT("SPECIALISE pragma ignored")]
+ , ptext (sLit "SPECIALISE pragma ignored")]
get_pred b = ASSERT( isId b ) expectJust "dsSpec" (tcSplitPredTy_maybe (idType b))
- decomp_msg = hang (ptext SLIT("Specialisation too complicated to desugar; ignored"))
+ decomp_msg = hang (ptext (sLit "Specialisation too complicated to desugar; ignored"))
2 (ppr spec_expr)
+dsMkArbitraryType :: TcTyVar -> DsM Type
dsMkArbitraryType tv = mkArbitraryType warn tv
where
warn span msg = putSrcSpanDs span (warnDs msg)
Note [Const rule dicts]
~~~~~~~~~~~~~~~~~~~~~~~
-A SpecPrag has a field for "constant dicts" in the RULE, but I think
-it's pretty useless. See the place where it's generated in TcBinds.
-TcSimplify will discharge a constraint by binding it to, say,
-GHC.Base.$f2 :: Eq Int, withour putting anything in the LIE, so this
-dict won't show up in the const-dicts field. It probably doesn't matter,
-because the rule will end up being something like
- f Int GHC.Base.$f2 = ...
-rather than
- forall d. f Int d = ...
-The latter is more general, but in practice I think it won't make any
-difference.
+When the LHS of a specialisation rule, (/\as\ds. f es) has a free dict,
+which is presumably in scope at the function definition site, we can quantify
+over it too. *Any* dict with that type will do.
+
+So for example when you have
+ f :: Eq a => a -> a
+ f = <rhs>
+ {-# SPECIALISE f :: Int -> Int #-}
+
+Then we get the SpecPrag
+ SpecPrag (f Int dInt) Int
+
+And from that we want the rule
+
+ RULE forall dInt. f Int dInt = f_spec
+ f_spec = let f = <rhs> in f Int dInt
+
%************************************************************************
= go emptyVarEnv (occurAnalyseExpr lhs) -- Occurrence analysis sorts out the dict
-- bindings so we know if they are recursive
where
- -- Substitute dicts in the LHS args, so that there
- -- aren't any lets getting in the way
- -- Note that we substitute the function too; we might have this as
- -- a LHS: let f71 = M.f Int in f71
+ -- Substitute dicts in the LHS args, so that there
+ -- aren't any lets getting in the way
+ -- Note that we substitute the function too; we might have this as
+ -- a LHS: let f71 = M.f Int in f71
go env (Let (NonRec dict rhs) body)
- = go (extendVarEnv env dict (simpleSubst env rhs)) body
+ = go (extendVarEnv env dict (simpleSubst env rhs)) body
go env body
- = case collectArgs (simpleSubst env body) of
- (Var fn, args) -> Just (fn, args)
- other -> Nothing
+ = case collectArgs (simpleSubst env body) of
+ (Var fn, args) -> Just (fn, args)
+ _ -> Nothing
simpleSubst :: IdEnv CoreExpr -> CoreExpr -> CoreExpr
-- Similar to CoreSubst.substExpr, except that
wrap the dict in @_scc_ DICT <dict>@:
\begin{code}
-addDictScc var rhs = returnDs rhs
+addDictScc :: Id -> CoreExpr -> DsM CoreExpr
+addDictScc _ rhs = return rhs
{- DISABLED for now (need to somehow make up a name for the scc) -- SDM
| not ( opt_SccProfilingOn && opt_AutoSccsOnDicts)
|| not (isDictId var)
- = returnDs rhs -- That's easy: do nothing
+ = return rhs -- That's easy: do nothing
| otherwise
- = getModuleAndGroupDs `thenDs` \ (mod, grp) ->
+ = do (mod, grp) <- getModuleAndGroupDs
-- ToDo: do -dicts-all flag (mark dict things with individual CCs)
- returnDs (Note (SCC (mkAllDictsCC mod grp False)) rhs)
+ return (Note (SCC (mkAllDictsCC mod grp False)) rhs)
-}
\end{code}
dsCoercion :: HsWrapper -> DsM CoreExpr -> DsM CoreExpr
dsCoercion WpHole thing_inside = thing_inside
dsCoercion (WpCompose c1 c2) thing_inside = dsCoercion c1 (dsCoercion c2 thing_inside)
-dsCoercion (WpCo co) thing_inside = do { expr <- thing_inside
+dsCoercion (WpCast co) thing_inside = do { expr <- thing_inside
; return (Cast expr co) }
dsCoercion (WpLam id) thing_inside = do { expr <- thing_inside
; return (Lam id expr) }