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 ( coreExprType )
21 import TcHsSyn ( TypecheckedMonoBinds )
23 import DsGRHSs ( dsGuarded )
25 import Match ( matchWrapper )
27 import BasicTypes ( RecFlag(..) )
28 import CmdLineOpts ( opt_SccProfilingOn, opt_AutoSccsOnAllToplevs,
29 opt_AutoSccsOnExportedToplevs, opt_AutoSccsOnDicts
31 import CostCentre ( CostCentre, mkAutoCC, IsCafCC(..) )
32 import Id ( idType, idName, isUserExportedId, Id )
36 import Type ( mkTyVarTy, isDictTy )
37 import Subst ( mkTyVarSubst, substTy )
38 import TysWiredIn ( voidTy )
45 %************************************************************************
47 \subsection[dsMonoBinds]{Desugaring a @MonoBinds@}
49 %************************************************************************
52 dsMonoBinds :: AutoScc -- scc annotation policy (see below)
53 -> TypecheckedMonoBinds
54 -> [(Id,CoreExpr)] -- Put this on the end (avoid quadratic append)
55 -> DsM [(Id,CoreExpr)] -- Result
57 dsMonoBinds _ EmptyMonoBinds rest = returnDs rest
59 dsMonoBinds auto_scc (AndMonoBinds binds_1 binds_2) rest
60 = dsMonoBinds auto_scc binds_2 rest `thenDs` \ rest' ->
61 dsMonoBinds auto_scc binds_1 rest'
63 dsMonoBinds _ (CoreMonoBind var core_expr) rest
64 = returnDs ((var, core_expr) : rest)
66 dsMonoBinds _ (VarMonoBind var expr) rest
67 = dsExpr expr `thenDs` \ core_expr ->
69 -- Dictionary bindings are always VarMonoBinds, so
70 -- we only need do this here
71 addDictScc var core_expr `thenDs` \ core_expr' ->
73 returnDs ((var, core_expr') : rest)
75 dsMonoBinds auto_scc (FunMonoBind fun _ matches locn) rest
77 matchWrapper (FunMatch fun) matches error_string `thenDs` \ (args, body) ->
78 addAutoScc auto_scc (fun, mkLams args body) `thenDs` \ pair ->
79 returnDs (pair : rest)
81 error_string = "function " ++ showSDoc (ppr fun)
83 dsMonoBinds auto_scc (PatMonoBind pat grhss locn) rest
85 dsGuarded grhss `thenDs` \ body_expr ->
86 mkSelectorBinds pat body_expr `thenDs` \ sel_binds ->
87 mapDs (addAutoScc auto_scc) sel_binds `thenDs` \ sel_binds ->
88 returnDs (sel_binds ++ rest)
90 -- Common case: one exported variable
91 -- All non-recursive bindings come through this way
93 (AbsBinds all_tyvars dicts exps@[(tyvars, global, local)] inlines binds) rest
94 = ASSERT( all (`elem` tyvars) all_tyvars )
95 dsMonoBinds (addSccs auto_scc exps) binds [] `thenDs` \ core_prs ->
97 -- Always treat the binds as recursive, because the typechecker
98 -- makes rather mixed-up dictionary bindings
99 core_binds = [Rec core_prs]
100 global' = (global, mkInline (idName global `elemNameSet` inlines) $
101 mkLams tyvars $ mkLams dicts $
102 mkDsLets core_binds (Var local))
104 returnDs (global' : rest)
106 -- Another common special case: no type or dictionary abstraction
107 dsMonoBinds auto_scc (AbsBinds [] [] exports inlines binds) rest
108 = dsMonoBinds (addSccs auto_scc exports) binds []`thenDs` \ core_prs ->
110 exports' = [(global, Var local) | (_, global, local) <- exports]
112 returnDs (addLocalInlines exports inlines core_prs ++ exports' ++ rest)
114 dsMonoBinds auto_scc (AbsBinds all_tyvars dicts exports inlines binds) rest
115 = dsMonoBinds (addSccs auto_scc exports) binds []`thenDs` \ core_prs ->
117 core_binds = [Rec (addLocalInlines exports inlines core_prs)]
119 tup_expr = mkTupleExpr locals
120 tup_ty = coreExprType tup_expr
121 poly_tup_expr = mkLams all_tyvars $ mkLams dicts $
122 mkDsLets core_binds tup_expr
123 locals = [local | (_, _, local) <- exports]
124 local_tys = map idType locals
126 newSysLocalDs (coreExprType poly_tup_expr) `thenDs` \ poly_tup_id ->
128 dict_args = map Var dicts
130 mk_bind (tyvars, global, local) n -- locals !! n == local
131 = -- Need to make fresh locals to bind in the selector, because
132 -- some of the tyvars will be bound to voidTy
133 newSysLocalsDs (map (substTy env) local_tys) `thenDs` \ locals' ->
134 newSysLocalDs (substTy env tup_ty) `thenDs` \ tup_id ->
135 returnDs (global, mkLams tyvars $ mkLams dicts $
136 mkTupleSelector locals' (locals' !! n) tup_id $
137 mkApps (mkTyApps (Var poly_tup_id) ty_args) dict_args)
139 mk_ty_arg all_tyvar | all_tyvar `elem` tyvars = mkTyVarTy all_tyvar
141 ty_args = map mk_ty_arg all_tyvars
142 env = mkTyVarSubst all_tyvars ty_args
144 zipWithDs mk_bind exports [0..] `thenDs` \ export_binds ->
145 -- don't scc (auto-)annotate the tuple itself.
146 returnDs ((poly_tup_id, poly_tup_expr) : (export_binds ++ rest))
150 %************************************************************************
152 \subsection{Adding inline pragmas}
154 %************************************************************************
157 mkInline :: Bool -> CoreExpr -> CoreExpr
158 mkInline True body = Note InlineMe body
159 mkInline False body = body
161 addLocalInlines :: [(a, Id, Id)] -> NameSet -> [(Id,CoreExpr)] -> [(Id,CoreExpr)]
162 addLocalInlines exports inlines pairs
163 = [(bndr, mkInline (bndr `elemVarSet` local_inlines) rhs) | (bndr,rhs) <- pairs]
165 local_inlines = mkVarSet [l | (_,g,l) <- exports, idName g `elemNameSet` inlines]
169 %************************************************************************
171 \subsection[addAutoScc]{Adding automatic sccs}
173 %************************************************************************
178 | TopLevelAddSccs (Id -> Maybe Id)
181 addSccs :: AutoScc -> [(a,Id,Id)] -> AutoScc
182 addSccs auto_scc@(TopLevelAddSccs _) exports = auto_scc
183 addSccs NoSccs exports = NoSccs
184 addSccs TopLevel exports
185 = TopLevelAddSccs (\id -> case [ exp | (_,exp,loc) <- exports, loc == id ] of
186 (exp:_) | opt_AutoSccsOnAllToplevs ||
187 (isUserExportedId exp &&
188 opt_AutoSccsOnExportedToplevs)
192 addAutoScc :: AutoScc -- if needs be, decorate toplevs?
194 -> DsM (Id, CoreExpr)
196 addAutoScc (TopLevelAddSccs auto_scc_fn) pair@(bndr, core_expr)
197 | do_auto_scc && worthSCC core_expr
198 = getModuleAndGroupDs `thenDs` \ (mod,grp) ->
199 returnDs (bndr, Note (SCC (mkAutoCC top_bndr mod grp NotCafCC)) core_expr)
200 where do_auto_scc = isJust maybe_auto_scc
201 maybe_auto_scc = auto_scc_fn bndr
202 (Just top_bndr) = maybe_auto_scc
206 worthSCC (Note (SCC _) _) = False
207 worthSCC (Con _ _) = False
208 worthSCC core_expr = True
211 If profiling and dealing with a dict binding,
212 wrap the dict in @_scc_ DICT <dict>@:
215 addDictScc var rhs = returnDs rhs
217 {- DISABLED for now (need to somehow make up a name for the scc) -- SDM
218 | not ( opt_SccProfilingOn && opt_AutoSccsOnDicts)
219 || not (isDictTy (idType var))
220 = returnDs rhs -- That's easy: do nothing
223 = getModuleAndGroupDs `thenDs` \ (mod, grp) ->
224 -- ToDo: do -dicts-all flag (mark dict things with individual CCs)
225 returnDs (Note (SCC (mkAllDictsCC mod grp False)) rhs)