import DsMonad
import DsGRHSs
import DsUtils
+import OccurAnal
import HsSyn -- lots of things
import CoreSyn -- lots of things
import MkCore
import CoreUtils
+import CoreUnfold
import CoreFVs
import TcHsSyn ( mkArbitraryType ) -- Mis-placed?
import TcType
-import OccurAnal
import CostCentre
import Module
import Id
-import Name ( localiseName )
-import Var ( TyVar )
+import Var ( Var, TyVar )
import VarSet
import Rules
import VarEnv
import BasicTypes hiding ( TopLevel )
import FastString
import StaticFlags ( opt_DsMultiTyVar )
-import Util ( mapSnd, mapAndUnzip, lengthExceeds )
+import Util ( mapSnd, count, mapAndUnzip, lengthExceeds )
import Control.Monad
import Data.List
------------------------
ds_lhs_binds :: AutoScc -> LHsBinds Id -> DsM [(Id,CoreExpr)]
+
-- scc annotation policy (see below)
ds_lhs_binds auto_scc binds = foldM (dsLHsBind auto_scc) [] (bagToList binds)
-> HsBind Id
-> DsM [(Id,CoreExpr)] -- Result
-dsHsBind _ rest (VarBind var expr) = do
- core_expr <- dsLExpr expr
+dsHsBind _ rest (VarBind var expr inline_regardless)
+ = do { core_expr <- dsLExpr expr
- -- Dictionary bindings are always VarMonoBinds, so
- -- we only need do this here
- core_expr' <- addDictScc var core_expr
- return ((var, core_expr') : rest)
+ -- Dictionary bindings are always VarBinds,
+ -- so we only need do this here
+ ; core_expr' <- addDictScc var core_expr
+ ; let var' | inline_regardless = var `setIdUnfolding` mkCompulsoryUnfolding core_expr'
+ | otherwise = var
-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)
+ ; return ((var', core_expr') : 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)
+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 _ 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]
~~~~~~~~~~~~~~~~~~~~~~~~~
dsHsBind auto_scc rest (AbsBinds [] [] exports binds)
= do { core_prs <- ds_lhs_binds NoSccs binds
; let env = mkABEnv exports
- do_one (lcl_id, rhs) | Just (_, gbl_id, _, prags) <- lookupVarEnv env lcl_id
- = addInlinePrags prags gbl_id $
- addAutoScc auto_scc gbl_id rhs
- | otherwise = (lcl_id, rhs)
+ ar_env = mkArityEnv binds
+ do_one (lcl_id, rhs)
+ | Just (_, gbl_id, _, prags) <- lookupVarEnv env lcl_id
+ = makeCorePair gbl_id (lookupArity ar_env lcl_id) prags $
+ addAutoScc auto_scc gbl_id rhs
+
+ | otherwise = (lcl_id, rhs)
+
locals' = [(lcl_id, Var gbl_id) | (_, gbl_id, lcl_id, _) <- exports]
-- Note [Rules and inlining]
; return (map do_one core_prs ++ locals' ++ rest) }
where B is the *non-recursive* binding
fl = fg a b
gl = gg b
- h = h a b
+ h = h a b -- See (b); note shadowing!
Notice (a) g has a different number of type variables to f, so we must
use the mkArbitraryType thing to fill in the gaps.
We use a type-let to do that.
(b) The local variable h isn't in the exports, and rather than
- clone a fresh copy we simply replace h by (h a b).
+ clone a fresh copy we simply replace h by (h a b), where
+ the two h's have different types! Shadowing happens here,
+ which looks confusing but works fine.
(c) The result is *still* quadratic-sized if there are a lot of
small bindings. So if there are more than some small
where
fvs = exprSomeFreeVars (`elemVarSet` bndrs) rhs
+ ar_env = mkArityEnv binds
env = mkABEnv exports
do_one (lcl_id, rhs)
| Just (id_tvs, gbl_id, _, prags) <- lookupVarEnv env lcl_id
- = (NonRec lcl_id (mkTyApps (Var gbl_id) (mkTyVarTys id_tvs)),
- addInlinePrags prags gbl_id $
- addAutoScc auto_scc gbl_id $
- mkLams id_tvs $
- mkLets [ NonRec tv (Type (lookupVarEnv_NF arby_env tv))
- | tv <- tyvars, not (tv `elem` id_tvs)] $
- add_lets rhs)
+ = let rhs' = addAutoScc auto_scc gbl_id $
+ mkLams id_tvs $
+ mkLets [ NonRec tv (Type (lookupVarEnv_NF arby_env tv))
+ | tv <- tyvars, not (tv `elem` id_tvs)] $
+ add_lets rhs
+ in (NonRec lcl_id (mkTyApps (Var gbl_id) (mkTyVarTys id_tvs)),
+ makeCorePair gbl_id (lookupArity ar_env lcl_id) prags rhs')
| otherwise
= (NonRec lcl_id (mkTyApps (Var non_exp_gbl_id) (mkTyVarTys tyvars)),
(non_exp_gbl_id, mkLams tyvars (add_lets rhs)))
-- Another common case: one exported variable
-- Non-recursive bindings come through this way
+ -- So do self-recursive bindings, and recursive bindings
+ -- that have been chopped up with type signatures
dsHsBind auto_scc rest
(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
+ = 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
+ inl_arity = lookupArity (mkArityEnv binds) local
- 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'
+ ; mb_specs <- mapM (dsSpec all_tyvars dicts tyvars global
+ local inl_arity core_bind) prags
+
+ ; let (spec_binds, rules) = unzip (catMaybes mb_specs)
+ global' = addIdSpecialisations global rules
+ rhs = addAutoScc auto_scc global $
+ mkLams tyvars $ mkLams dicts $ Let core_bind (Var local)
+ main_bind = makeCorePair global' (inl_arity + length dicts) prags rhs
- return (bind : spec_binds ++ rest)
+ ; return (main_bind : spec_binds ++ rest) }
dsHsBind auto_scc rest (AbsBinds all_tyvars dicts exports binds)
= do { core_prs <- ds_lhs_binds NoSccs binds
; let env = mkABEnv exports
- do_one (lcl_id,rhs) | Just (_, gbl_id, _, prags) <- lookupVarEnv env lcl_id
- = addInlinePrags prags lcl_id $
- addAutoScc auto_scc gbl_id rhs
+ ar_env = mkArityEnv binds
+ do_one (lcl_id,rhs) | Just (_, gbl_id, _, _prags) <- lookupVarEnv env lcl_id
+ = (lcl_id, addAutoScc auto_scc gbl_id rhs)
| otherwise = (lcl_id,rhs)
-- Rec because of mixed-up dictionary bindings
locals = [local | (_, _, local, _) <- exports]
local_tys = map idType locals
+ inl_prags :: [(Id, SrcSpan)]
+ inl_prags = [(id, loc) | (_, id, _, prags) <- exports
+ , L loc (InlinePrag {}) <- prags ]
+
+ ; mapM_ discardedInlineWarning inl_prags
+
; poly_tup_id <- newSysLocalDs (exprType poly_tup_expr)
; let dict_args = map Var dicts
; let substitute = substTyWith all_tyvars ty_args
; locals' <- newSysLocalsDs (map substitute local_tys)
; tup_id <- newSysLocalDs (substitute tup_ty)
- ; mb_specs <- mapM (dsSpec all_tyvars dicts tyvars global local core_bind)
+ ; mb_specs <- mapM (dsSpec all_tyvars dicts tyvars global local
+ (lookupArity ar_env local) core_bind)
prags
; let (spec_binds, rules) = unzip (catMaybes mb_specs)
global' = addIdSpecialisations global rules
| otherwise = dsMkArbitraryType all_tyvar
; export_binds_s <- mapM mk_bind (exports `zip` [0..])
- -- don't scc (auto-)annotate the tuple itself.
+ -- Don't scc (auto-)annotate the tuple itself.
; return ((poly_tup_id, poly_tup_expr) :
(concat export_binds_s ++ rest)) }
-mkABEnv :: [([TyVar], Id, Id, [LPrag])] -> VarEnv ([TyVar], Id, Id, [LPrag])
+------------------------
+makeCorePair :: Id-> Arity -> [LPrag] -> CoreExpr -> (Id, CoreExpr)
+makeCorePair gbl_id arity prags rhs
+ = (addInline gbl_id arity rhs prags, rhs)
+
+------------------------
+discardedInlineWarning :: (Id, SrcSpan) -> DsM ()
+discardedInlineWarning (id, loc)
+ = putSrcSpanDs loc $
+ warnDs $ sep [ ptext (sLit "Discarding INLINE pragma for") <+> ppr id
+ , ptext (sLit "because it is bound by a pattern, or a mutual recursion") ]
+
+------------------------
+type AbsBindEnv = VarEnv ([TyVar], Id, Id, [LPrag])
+ -- Maps the "lcl_id" for an AbsBind to
+ -- its "gbl_id" and associated pragmas, if any
+
+mkABEnv :: [([TyVar], Id, Id, [LPrag])] -> AbsBindEnv
-- Takes the exports of a AbsBinds, and returns a mapping
-- lcl_id -> (tyvars, gbl_id, lcl_id, prags)
mkABEnv exports = mkVarEnv [ (lcl_id, export) | export@(_, _, lcl_id, _) <- exports]
+mkArityEnv :: LHsBinds Id -> IdEnv Arity
+ -- Maps a local to the arity of its definition
+mkArityEnv binds = mkVarEnv (mapCatMaybes get_arity (bagToList binds))
+ where
+ get_arity (L _ (FunBind { fun_id = id, fun_matches = ms })) = Just (unLoc id, matchGroupArity ms)
+ get_arity _ = Nothing
+
+lookupArity :: IdEnv Arity -> Id -> Arity
+lookupArity ar_env id = lookupVarEnv ar_env id `orElse` 0
+
+addInline :: Id -> Arity -> CoreExpr -> [LPrag] -> Id
+addInline id arity rhs prags
+ = case [inl | L _ (InlinePrag inl) <- prags] of
+ [] -> id
+ (inl_spec : _) -> addInlineToId id arity rhs inl_spec
+
+addInlineToId :: Id -> Arity -> CoreExpr -> InlineSpec -> Id
+addInlineToId id inl_arity rhs (Inline phase is_inline)
+ = id `setInlinePragma` phase
+ `setIdUnfolding` inline_rule
+ where
+ inline_rule | is_inline = mkInlineRule rhs inl_arity
+ | otherwise = noUnfolding
+------------------------
dsSpec :: [TyVar] -> [DictId] -> [TyVar]
- -> Id -> Id -- Global, local
+ -> Id -> Id -> Arity -- Global, local, arity of local
-> CoreBind -> LPrag
-> DsM (Maybe ((Id,CoreExpr), -- Binding for specialised Id
CoreRule)) -- Rule for the Global Id
--
-- It is *possible* that 'es' does not mention all of the dictionaries 'ds'
-- (a bit silly, because then the
-dsSpec _ _ _ _ _ _ (L _ (InlinePrag {}))
+dsSpec _ _ _ _ _ _ _ (L _ (InlinePrag {}))
= return Nothing
-dsSpec all_tvs dicts tvs poly_id mono_id mono_bind
+dsSpec all_tvs dicts tvs poly_id mono_id inl_arity mono_bind
(L loc (SpecPrag spec_expr spec_ty inl))
= putSrcSpanDs loc $
do { let poly_name = idName poly_id
; spec_name <- newLocalName poly_name
; ds_spec_expr <- dsExpr spec_expr
- ; let (bndrs, body) = collectBinders (occurAnalyseExpr ds_spec_expr)
- -- ds_spec_expr may look like
- -- /\a. f a Int dOrdInt
- -- or /\a.\d:Ord a. let { dl::Ord [a] = dOrdList a d } in f [a] dl
- -- The occurrence-analysis does two things
- -- (a) identifies unused binders: Note [Unused spec binders]
- -- (b) sorts dict bindings into NonRecs
- -- so they can be inlined by decomposeRuleLhs
- mb_lhs = decomposeRuleLhs body
+ ; case (decomposeRuleLhs ds_spec_expr) of {
+ Nothing -> do { warnDs decomp_msg; return Nothing } ;
- -- Check for dead binders: Note [Unused spec binders]
- ; case filter isDeadBinder bndrs of {
- bs | not (null bs) -> do { warnDs (dead_msg bs); return Nothing }
- | otherwise ->
+ Just (bndrs, _fn, args) ->
- case mb_lhs of
- Nothing -> do { warnDs decomp_msg; return Nothing }
-
- Just (_, args) -> do {
+ -- Check for dead binders: Note [Unused spec binders]
+ case filter isDeadBinder bndrs of {
+ bs | not (null bs) -> do { warnDs (dead_msg bs); return Nothing }
+ | otherwise -> do
- f_body <- fix_up (Let mono_bind (Var mono_id))
+ { f_body <- fix_up (Let mono_bind (Var mono_id))
; let local_poly = setIdNotExported poly_id
-- Very important to make the 'f' non-exported,
-- else it won't be inlined!
spec_id = mkLocalId spec_name spec_ty
+ spec_id1 = addInlineToId spec_id (inl_arity + count isDictId bndrs)
+ spec_rhs inl
spec_rhs = Let (NonRec local_poly poly_f_body) ds_spec_expr
poly_f_body = mkLams (tvs ++ dicts) f_body
- extra_dict_bndrs = [localise d
+ extra_dict_bndrs = [localiseId d -- See Note [Constant rule dicts]
| d <- varSetElems (exprFreeVars ds_spec_expr)
, isDictId d]
-- Note [Const rule dicts]
AlwaysActive poly_name
(extra_dict_bndrs ++ bndrs) args
(mkVarApps (Var spec_id) bndrs)
- ; return (Just (addInlineInfo inl spec_id spec_rhs, rule))
- } } }
+ ; return (Just ((spec_id1, spec_rhs), rule))
+ } } } }
where
-- Bind to Any any of all_ptvs that aren't
-- relevant for this particular function
decomp_msg = hang (ptext (sLit "Specialisation too complicated to desugar; ignored"))
2 (ppr spec_expr)
-
- localise d = mkLocalId (localiseName (idName d)) (idType d)
- -- See Note [Constant rule dicts]
+
mkArbitraryTypeEnv :: [TyVar] -> [([TyVar], a, b, c)] -> DsM (TyVarEnv Type)
-- If any of the tyvars is missing from any of the lists in
But be careful! That dInt might be GHC.Base.$fOrdInt, which is an External
Name, and you can't bind them in a lambda or forall without getting things
-confused. Hence the use of 'localise' to make it Internal.
+confused. Hence the use of 'localiseId' to make it Internal.
%************************************************************************
%************************************************************************
\begin{code}
-decomposeRuleLhs :: CoreExpr -> Maybe (Id, [CoreExpr])
+decomposeRuleLhs :: CoreExpr -> Maybe ([Var], Id, [CoreExpr])
+-- Take apart the LHS of a RULE. It's suuposed to look like
+-- /\a. f a Int dOrdInt
+-- or /\a.\d:Ord a. let { dl::Ord [a] = dOrdList a d } in f [a] dl
+-- That is, the RULE binders are lambda-bound
-- Returns Nothing if the LHS isn't of the expected shape
decomposeRuleLhs lhs
- = go emptyVarEnv (occurAnalyseExpr lhs) -- Occurrence analysis sorts out the dict
- -- bindings so we know if they are recursive
+ = case (decomp emptyVarEnv body) of
+ Nothing -> Nothing
+ Just (fn, args) -> Just (bndrs, fn, args)
where
+ occ_lhs = occurAnalyseExpr lhs
+ -- The occurrence-analysis does two things
+ -- (a) identifies unused binders: Note [Unused spec binders]
+ -- (b) sorts dict bindings into NonRecs
+ -- so they can be inlined by 'decomp'
+ (bndrs, body) = collectBinders occ_lhs
+
-- 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 env body
+ decomp env (Let (NonRec dict rhs) body)
+ = decomp (extendVarEnv env dict (simpleSubst env rhs)) body
+ decomp env body
= case collectArgs (simpleSubst env body) of
(Var fn, args) -> Just (fn, args)
_ -> Nothing
go (Let (Rec pairs) body) = Let (Rec (mapSnd go pairs)) (go body)
go (Case scrut bndr ty alts) = Case (go scrut) bndr ty
[(c,bs,go r) | (c,bs,r) <- alts]
-
-addInlinePrags :: [LPrag] -> Id -> CoreExpr -> (Id,CoreExpr)
-addInlinePrags prags bndr rhs
- = case [inl | L _ (InlinePrag inl) <- prags] of
- [] -> (bndr, rhs)
- (inl:_) -> addInlineInfo inl bndr rhs
-
-addInlineInfo :: InlineSpec -> Id -> CoreExpr -> (Id,CoreExpr)
-addInlineInfo (Inline phase is_inline) bndr rhs
- = (attach_phase bndr phase, wrap_inline is_inline rhs)
- where
- attach_phase bndr phase
- | isAlwaysActive phase = bndr -- Default phase
- | otherwise = bndr `setInlinePragma` phase
-
- wrap_inline True body = mkInlineMe body
- wrap_inline False body = body
\end{code}
; return (Lam id expr) }
dsCoercion (WpTyLam tv) thing_inside = do { expr <- thing_inside
; return (Lam tv expr) }
-dsCoercion (WpApp id) thing_inside = do { expr <- thing_inside
- ; return (App expr (Var id)) }
+dsCoercion (WpApp v) thing_inside
+ | isTyVar v = do { expr <- thing_inside
+ {- Probably a coercion var -} ; return (App expr (Type (mkTyVarTy v))) }
+ | otherwise = do { expr <- thing_inside
+ {- An Id -} ; return (App expr (Var v)) }
dsCoercion (WpTyApp ty) thing_inside = do { expr <- thing_inside
; return (App expr (Type ty)) }
-dsCoercion WpInline thing_inside = do { expr <- thing_inside
- ; return (mkInlineMe expr) }
dsCoercion (WpLet bs) thing_inside = do { prs <- dsLHsBinds bs
; expr <- thing_inside
; return (Let (Rec prs) expr) }
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