2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
5 \section{@Vars@: Variables}
10 varName, varUnique, varType,
11 setVarName, setVarUnique,
14 TyVar, mkTyVar, mkTcTyVar, mkWildCoVar,
16 setTyVarName, setTyVarUnique, setTyVarKind,
20 CoVar, coVarName, setCoVarUnique, setCoVarName, mkCoVar, isCoVar,
24 idName, idType, idUnique, idInfo, modifyIdInfo, maybeModifyIdInfo,
25 setIdName, setIdUnique, setIdType, setIdInfo, lazySetIdInfo,
26 setIdExported, setIdNotExported,
28 globalIdDetails, globaliseId,
30 mkLocalId, mkExportedLocalId, mkGlobalId,
32 isTyVar, isTcTyVar, isId, isLocalVar, isLocalId,
33 isGlobalId, isExportedId,
37 #include "HsVersions.h"
39 import {-# SOURCE #-} TypeRep( Type, Kind )
40 import {-# SOURCE #-} TcType( TcTyVarDetails, pprTcTyVarDetails )
41 import {-# SOURCE #-} IdInfo( GlobalIdDetails, notGlobalId,
44 import {-# SOURCE #-} TypeRep( isCoercionKind )
47 import Name hiding (varName)
55 %************************************************************************
57 \subsection{The main data type declarations}
59 %************************************************************************
62 Every @Var@ has a @Unique@, to uniquify it and for fast comparison, a
63 @Type@, and an @IdInfo@ (non-essential info about it, e.g.,
64 strictness). The essential info about different kinds of @Vars@ is
71 realUnique :: FastInt, -- Key for fast comparison
72 -- Identical to the Unique in the name,
73 -- cached here for speed
78 | TcTyVar { -- Used only during type inference
79 -- Used for kind variables during
82 realUnique :: FastInt,
84 tcTyVarDetails :: TcTyVarDetails }
86 | GlobalId { -- Used for imported Ids, dict selectors etc
87 -- See Note [GlobalId/LocalId] below
88 varName :: !Name, -- Always an External or WiredIn Name
89 realUnique :: FastInt,
92 gblDetails :: GlobalIdDetails }
94 | LocalId { -- Used for locally-defined Ids
95 -- See Note [GlobalId/LocalId] below
97 realUnique :: FastInt,
100 lclDetails :: LocalIdDetails }
103 = NotExported -- Not exported
104 | Exported -- Exported
105 -- Exported Ids are kept alive;
106 -- NotExported things may be discarded as dead code.
109 Note [GlobalId/LocalId]
110 ~~~~~~~~~~~~~~~~~~~~~~~
112 * always a constant (top-level)
113 * imported, or data constructor, or primop, or record selector
114 * has a Unique that is globally unique across the whole
115 GHC invocation (a single invocation may compile multiple modules)
116 * never treated as a candidate by the free-variable finder;
120 * bound within an expression (lambda, case, local let(rec))
121 * or defined at top level in the module being compiled
122 * always treated as a candidate by the free-variable finder
124 After CoreTidy, top-level LocalIds are turned into GlobalIds
128 instance Outputable Var where
129 ppr var = ppr (varName var) <+> ifPprDebug (brackets extra)
132 GlobalId {} -> ptext SLIT("gid")
133 LocalId {} -> ptext SLIT("lid")
134 TyVar {} -> ptext SLIT("tv")
135 TcTyVar {tcTyVarDetails = details} -> pprTcTyVarDetails details
137 instance Show Var where
138 showsPrec p var = showsPrecSDoc p (ppr var)
140 instance NamedThing Var where
143 instance Uniquable Var where
144 getUnique = varUnique
146 instance Eq Var where
147 a == b = realUnique a ==# realUnique b
149 instance Ord Var where
150 a <= b = realUnique a <=# realUnique b
151 a < b = realUnique a <# realUnique b
152 a >= b = realUnique a >=# realUnique b
153 a > b = realUnique a ># realUnique b
154 a `compare` b = varUnique a `compare` varUnique b
159 varUnique :: Var -> Unique
160 varUnique var = mkUniqueGrimily (iBox (realUnique var))
162 setVarUnique :: Var -> Unique -> Var
163 setVarUnique var uniq
164 = var { realUnique = getKey# uniq,
165 varName = setNameUnique (varName var) uniq }
167 setVarName :: Var -> Name -> Var
168 setVarName var new_name
169 = var { realUnique = getKey# (getUnique new_name),
174 %************************************************************************
176 \subsection{Type variables}
178 %************************************************************************
186 setTyVarUnique = setVarUnique
187 setTyVarName = setVarName
189 setTyVarKind :: TyVar -> Kind -> TyVar
190 setTyVarKind tv k = tv {varType = k}
194 mkTyVar :: Name -> Kind -> TyVar
195 mkTyVar name kind = ASSERT( not (isCoercionKind kind ) )
196 TyVar { varName = name
197 , realUnique = getKey# (nameUnique name)
199 , isCoercionVar = False
202 mkTcTyVar :: Name -> Kind -> TcTyVarDetails -> TyVar
203 mkTcTyVar name kind details
204 = ASSERT( not (isCoercionKind kind) )
205 TcTyVar { varName = name,
206 realUnique = getKey# (nameUnique name),
208 tcTyVarDetails = details
212 %************************************************************************
214 \subsection{Coercion variables}
216 %************************************************************************
219 type CoVar = Var -- A coercion variable is simply a type
220 -- variable of kind (ty1 :=: ty2)
223 setCoVarUnique = setVarUnique
224 setCoVarName = setVarName
226 mkCoVar :: Name -> Kind -> CoVar
227 mkCoVar name kind = ASSERT( isCoercionKind kind )
228 TyVar { varName = name
229 , realUnique = getKey# (nameUnique name)
231 , isCoercionVar = True
234 mkWildCoVar :: Kind -> TyVar
235 -- A type variable that is never referred to,
236 -- so its unique doesn't matter
238 = ASSERT( isCoercionKind kind )
239 TyVar { varName = mkSysTvName wild_uniq FSLIT("co_wild"),
240 realUnique = _ILIT(1),
242 isCoercionVar = True }
244 wild_uniq = mkBuiltinUnique 1
247 %************************************************************************
249 \subsection{Id Construction}
251 %************************************************************************
253 Most Id-related functions are in Id.lhs and MkId.lhs
265 setIdUnique :: Id -> Unique -> Id
266 setIdUnique = setVarUnique
268 setIdName :: Id -> Name -> Id
269 setIdName = setVarName
271 setIdType :: Id -> Type -> Id
272 setIdType id ty = id {varType = ty}
274 setIdExported :: Id -> Id
275 -- Can be called on GlobalIds, such as data cons and class ops,
276 -- which are "born" as GlobalIds and automatically exported
277 setIdExported id@(LocalId {}) = id { lclDetails = Exported }
278 setIdExported other_id = ASSERT( isId other_id ) other_id
280 setIdNotExported :: Id -> Id
281 -- We can only do this to LocalIds
282 setIdNotExported id = ASSERT( isLocalId id ) id { lclDetails = NotExported }
284 globaliseId :: GlobalIdDetails -> Id -> Id
285 -- If it's a local, make it global
286 globaliseId details id = GlobalId { varName = varName id,
287 realUnique = realUnique id,
288 varType = varType id,
290 gblDetails = details }
292 idInfo :: Id -> IdInfo
293 idInfo (GlobalId {idInfo_ = info}) = info
294 idInfo (LocalId {idInfo_ = info}) = info
295 idInfo other_var = pprPanic "idInfo" (ppr other_var)
297 lazySetIdInfo :: Id -> IdInfo -> Id
298 lazySetIdInfo id info = id {idInfo_ = info}
300 setIdInfo :: Id -> IdInfo -> Id
301 setIdInfo id info = seqIdInfo info `seq` id {idInfo_ = info}
302 -- Try to avoid spack leaks by seq'ing
304 modifyIdInfo :: (IdInfo -> IdInfo) -> Id -> Id
306 = seqIdInfo new_info `seq` id {idInfo_ = new_info}
308 new_info = fn (idInfo id)
310 -- maybeModifyIdInfo tries to avoid unnecesary thrashing
311 maybeModifyIdInfo :: Maybe IdInfo -> Id -> Id
312 maybeModifyIdInfo (Just new_info) id = id {idInfo_ = new_info}
313 maybeModifyIdInfo Nothing id = id
316 %************************************************************************
318 \subsection{Predicates over variables
320 %************************************************************************
323 mkGlobalId :: GlobalIdDetails -> Name -> Type -> IdInfo -> Id
324 mkGlobalId details name ty info
325 = GlobalId { varName = name,
326 realUnique = getKey# (nameUnique name), -- Cache the unique
328 gblDetails = details,
331 mk_local_id :: Name -> Type -> LocalIdDetails -> IdInfo -> Id
332 mk_local_id name ty details info
333 = LocalId { varName = name,
334 realUnique = getKey# (nameUnique name), -- Cache the unique
336 lclDetails = details,
339 mkLocalId :: Name -> Type -> IdInfo -> Id
340 mkLocalId name ty info = mk_local_id name ty NotExported info
342 mkExportedLocalId :: Name -> Type -> IdInfo -> Id
343 mkExportedLocalId name ty info = mk_local_id name ty Exported info
347 isTyVar, isTcTyVar :: Var -> Bool
348 isId, isLocalVar, isLocalId :: Var -> Bool
349 isGlobalId, isExportedId :: Var -> Bool
350 mustHaveLocalBinding :: Var -> Bool
352 isTyVar (TyVar {}) = True
353 isTyVar (TcTyVar {}) = True
354 isTyVar other = False
356 isTcTyVar (TcTyVar {}) = True
357 isTcTyVar other = False
359 isId (LocalId {}) = True
360 isId (GlobalId {}) = True
363 isLocalId (LocalId {}) = True
364 isLocalId other = False
366 isCoVar (v@(TyVar {})) = isCoercionVar v
367 isCoVar other = False
369 -- isLocalVar returns True for type variables as well as local Ids
370 -- These are the variables that we need to pay attention to when finding free
371 -- variables, or doing dependency analysis.
372 isLocalVar (GlobalId {}) = False
373 isLocalVar other = True
375 -- mustHaveLocalBinding returns True of Ids and TyVars
376 -- that must have a binding in this module. The converse
377 -- is not quite right: there are some GlobalIds that must have
378 -- bindings, such as record selectors. But that doesn't matter,
379 -- because it's only used for assertions
380 mustHaveLocalBinding var = isLocalVar var
382 isGlobalId (GlobalId {}) = True
383 isGlobalId other = False
385 -- isExportedId means "don't throw this away"
386 isExportedId (GlobalId {}) = True
387 isExportedId (LocalId {lclDetails = details})
391 isExportedId other = False
395 globalIdDetails :: Var -> GlobalIdDetails
396 -- Works OK on local Ids too, returning notGlobalId
397 globalIdDetails (GlobalId {gblDetails = details}) = details
398 globalIdDetails other = notGlobalId