2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[DsBinds]{Pattern-matching bindings (HsBinds and MonoBinds)}
6 Handles @HsBinds@; those at the top level require different handling,
7 in that the @Rec@/@NonRec@/etc structure is thrown away (whereas at
8 lower levels it is preserved with @let@/@letrec@s).
11 module DsBinds ( dsMonoBinds, AutoScc(..) ) where
13 #include "HsVersions.h"
16 import {-# SOURCE #-} DsExpr( dsExpr )
18 import HsSyn -- lots of things
19 import CoreSyn -- lots of things
20 import CoreUtils ( exprType, mkInlineMe, mkSCC )
21 import TcHsSyn ( TypecheckedMonoBinds )
23 import DsGRHSs ( dsGuarded )
25 import Match ( matchWrapper )
27 import CmdLineOpts ( opt_SccProfilingOn, opt_AutoSccsOnAllToplevs,
28 opt_AutoSccsOnExportedToplevs, opt_AutoSccsOnDicts
30 import CostCentre ( CostCentre, mkAutoCC, IsCafCC(..) )
31 import Id ( idType, idName, isUserExportedId, isSpecPragmaId, Id )
34 import Type ( mkTyVarTy, isDictTy )
35 import Subst ( mkTyVarSubst, substTy )
36 import TysWiredIn ( voidTy )
38 import Maybe ( isJust )
41 %************************************************************************
43 \subsection[dsMonoBinds]{Desugaring a @MonoBinds@}
45 %************************************************************************
48 dsMonoBinds :: AutoScc -- scc annotation policy (see below)
49 -> TypecheckedMonoBinds
50 -> [(Id,CoreExpr)] -- Put this on the end (avoid quadratic append)
51 -> DsM [(Id,CoreExpr)] -- Result
53 dsMonoBinds _ EmptyMonoBinds rest = returnDs rest
55 dsMonoBinds auto_scc (AndMonoBinds binds_1 binds_2) rest
56 = dsMonoBinds auto_scc binds_2 rest `thenDs` \ rest' ->
57 dsMonoBinds auto_scc binds_1 rest'
59 dsMonoBinds _ (CoreMonoBind var core_expr) rest
60 = returnDs ((var, core_expr) : rest)
62 dsMonoBinds _ (VarMonoBind var expr) rest
63 = dsExpr expr `thenDs` \ core_expr ->
65 -- Dictionary bindings are always VarMonoBinds, so
66 -- we only need do this here
67 addDictScc var core_expr `thenDs` \ core_expr' ->
70 -- Gross hack to prevent inlining into SpecPragmaId rhss
71 -- Consider fromIntegral = fromInteger . toInteger
72 -- spec1 = fromIntegral Int Float
73 -- Even though fromIntegral is small we don't want to inline
74 -- it inside spec1, so that we collect the specialised call
75 -- Solution: make spec1 an INLINE thing.
76 core_expr'' = mkInline (isSpecPragmaId var) core_expr'
79 returnDs ((var, core_expr'') : rest)
81 dsMonoBinds auto_scc (FunMonoBind fun _ matches locn) rest
83 matchWrapper (FunMatch fun) matches error_string `thenDs` \ (args, body) ->
84 addAutoScc auto_scc (fun, mkLams args body) `thenDs` \ pair ->
85 returnDs (pair : rest)
87 error_string = "function " ++ showSDoc (ppr fun)
89 dsMonoBinds auto_scc (PatMonoBind pat grhss locn) rest
91 dsGuarded grhss `thenDs` \ body_expr ->
92 mkSelectorBinds pat body_expr `thenDs` \ sel_binds ->
93 mapDs (addAutoScc auto_scc) sel_binds `thenDs` \ sel_binds ->
94 returnDs (sel_binds ++ rest)
96 -- Common special case: no type or dictionary abstraction
97 dsMonoBinds auto_scc (AbsBinds [] [] exports inlines binds) rest
98 = dsMonoBinds (addSccs auto_scc exports) binds []`thenDs` \ core_prs ->
100 exports' = [(global, Var local) | (_, global, local) <- exports]
102 returnDs (addLocalInlines exports inlines core_prs ++ exports' ++ rest)
104 -- Another common case: one exported variable
105 -- Non-recursive bindings come through this way
107 (AbsBinds all_tyvars dicts exps@[(tyvars, global, local)] inlines binds) rest
108 = ASSERT( all (`elem` tyvars) all_tyvars )
109 dsMonoBinds (addSccs auto_scc exps) binds [] `thenDs` \ core_prs ->
111 -- Always treat the binds as recursive, because the typechecker
112 -- makes rather mixed-up dictionary bindings
113 core_binds = [Rec core_prs]
114 global' = (global, mkInline (idName global `elemNameSet` inlines) $
115 mkLams tyvars $ mkLams dicts $
116 mkDsLets core_binds (Var local))
118 returnDs (global' : rest)
120 dsMonoBinds auto_scc (AbsBinds all_tyvars dicts exports inlines binds) rest
121 = dsMonoBinds (addSccs auto_scc exports) binds []`thenDs` \ core_prs ->
123 core_binds = [Rec (addLocalInlines exports inlines core_prs)]
125 tup_expr = mkTupleExpr locals
126 tup_ty = exprType tup_expr
127 poly_tup_expr = mkLams all_tyvars $ mkLams dicts $
128 mkDsLets core_binds tup_expr
129 locals = [local | (_, _, local) <- exports]
130 local_tys = map idType locals
132 newSysLocalDs (exprType poly_tup_expr) `thenDs` \ poly_tup_id ->
134 dict_args = map Var dicts
136 mk_bind (tyvars, global, local) n -- locals !! n == local
137 = -- Need to make fresh locals to bind in the selector, because
138 -- some of the tyvars will be bound to voidTy
139 newSysLocalsDs (map (substTy env) local_tys) `thenDs` \ locals' ->
140 newSysLocalDs (substTy env tup_ty) `thenDs` \ tup_id ->
141 returnDs (global, mkLams tyvars $ mkLams dicts $
142 mkTupleSelector locals' (locals' !! n) tup_id $
143 mkApps (mkTyApps (Var poly_tup_id) ty_args) dict_args)
145 mk_ty_arg all_tyvar | all_tyvar `elem` tyvars = mkTyVarTy all_tyvar
147 ty_args = map mk_ty_arg all_tyvars
148 env = mkTyVarSubst all_tyvars ty_args
150 zipWithDs mk_bind exports [0..] `thenDs` \ export_binds ->
151 -- don't scc (auto-)annotate the tuple itself.
152 returnDs ((poly_tup_id, poly_tup_expr) : (export_binds ++ rest))
156 %************************************************************************
158 \subsection{Adding inline pragmas}
160 %************************************************************************
163 mkInline :: Bool -> CoreExpr -> CoreExpr
164 mkInline True body = mkInlineMe body
165 mkInline False body = body
167 addLocalInlines :: [(a, Id, Id)] -> NameSet -> [(Id,CoreExpr)] -> [(Id,CoreExpr)]
168 addLocalInlines exports inlines pairs
169 = [(bndr, mkInline (bndr `elemVarSet` local_inlines) rhs) | (bndr,rhs) <- pairs]
171 local_inlines = mkVarSet [l | (_,g,l) <- exports, idName g `elemNameSet` inlines]
175 %************************************************************************
177 \subsection[addAutoScc]{Adding automatic sccs}
179 %************************************************************************
184 | TopLevelAddSccs (Id -> Maybe Id)
187 addSccs :: AutoScc -> [(a,Id,Id)] -> AutoScc
188 addSccs auto_scc@(TopLevelAddSccs _) exports = auto_scc
189 addSccs NoSccs exports = NoSccs
190 addSccs TopLevel exports
191 = TopLevelAddSccs (\id -> case [ exp | (_,exp,loc) <- exports, loc == id ] of
192 (exp:_) | opt_AutoSccsOnAllToplevs ||
193 (isUserExportedId exp &&
194 opt_AutoSccsOnExportedToplevs)
198 addAutoScc :: AutoScc -- if needs be, decorate toplevs?
200 -> DsM (Id, CoreExpr)
202 addAutoScc (TopLevelAddSccs auto_scc_fn) pair@(bndr, core_expr)
203 | do_auto_scc && worthSCC core_expr
204 = getModuleDs `thenDs` \ mod ->
205 returnDs (bndr, mkSCC (mkAutoCC top_bndr mod NotCafCC) core_expr)
206 where do_auto_scc = isJust maybe_auto_scc
207 maybe_auto_scc = auto_scc_fn bndr
208 (Just top_bndr) = maybe_auto_scc
213 noUserSCC (Note (SCC _) _) = False
214 worthSCC core_expr = True
217 If profiling and dealing with a dict binding,
218 wrap the dict in @_scc_ DICT <dict>@:
221 addDictScc var rhs = returnDs rhs
223 {- DISABLED for now (need to somehow make up a name for the scc) -- SDM
224 | not ( opt_SccProfilingOn && opt_AutoSccsOnDicts)
225 || not (isDictTy (idType var))
226 = returnDs rhs -- That's easy: do nothing
229 = getModuleAndGroupDs `thenDs` \ (mod, grp) ->
230 -- ToDo: do -dicts-all flag (mark dict things with individual CCs)
231 returnDs (Note (SCC (mkAllDictsCC mod grp False)) rhs)