Id.lhs 13.9 KB
Newer Older
1 2
%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
3 4 5 6
%
\section[Id]{@Ids@: Value and constructor identifiers}

\begin{code}
7
module Id (
8
	Id, DictId,
9

10
	-- Simple construction
11 12
	mkGlobalId, mkLocalId, mkSpecPragmaId, mkLocalIdWithInfo,
	mkSysLocal, mkUserLocal, mkVanillaGlobal,
13
	mkTemplateLocals, mkTemplateLocalsNum, mkWildId, mkTemplateLocal,
14
	mkWorkerId,
15 16

	-- Taking an Id apart
17
	idName, idType, idUnique, idInfo,
18
	idPrimRep, isId, globalIdDetails,
19
	recordSelectorFieldLabel,
20

21
	-- Modifying an Id
22
	setIdName, setIdUnique, setIdType, setIdNoDiscard, setGlobalIdDetails,
23
	setIdInfo, lazySetIdInfo, modifyIdInfo, maybeModifyIdInfo,
24
	zapLamIdInfo, zapDemandIdInfo, 
25 26

	-- Predicates
27
	isImplicitId, isDeadBinder,
28 29 30
	isSpecPragmaId,	isExportedId, isLocalId, isGlobalId,
	isRecordSelector,
	isPrimOpId, isPrimOpId_maybe, 
31 32
	isDataConId, isDataConId_maybe, 
	isDataConWrapId, isDataConWrapId_maybe,
33
	isBottomingId,
34 35 36 37 38
	hasNoBinding,

	-- Inline pragma stuff
	idInlinePragma, setInlinePragma, modifyInlinePragma, 

39

40
	-- One shot lambda stuff
41
	isOneShotLambda, setOneShotLambda, clearOneShotLambda,
42

43 44
	-- IdInfo stuff
	setIdUnfolding,
45
	setIdArityInfo,
46 47
	setIdDemandInfo,
	setIdStrictness,
48
        setIdTyGenInfo,
49
	setIdWorkerInfo,
50
	setIdSpecialisation,
51
	setIdCgInfo,
52
	setIdCprInfo,
53
	setIdOccInfo,
54

55 56 57
	idArity, idArityInfo, 
	idDemandInfo,
	idStrictness,
58
        idTyGenInfo,
59 60 61
	idWorkerInfo,
	idUnfolding,
	idSpecialisation,
62
	idCgInfo,
63
	idCafInfo,
64
	idCgArity,
65 66
	idCprInfo,
	idLBVarInfo,
67
	idOccInfo,
68

69
    ) where
70

71
#include "HsVersions.h"
sof's avatar
sof committed
72 73


74
import CoreSyn		( Unfolding, CoreRules )
75
import BasicTypes	( Arity )
76
import Var		( Id, DictId,
77 78 79
			  isId, isExportedId, isSpecPragmaId, isLocalId,
			  idName, idType, idUnique, idInfo, isGlobalId,
			  setIdName, setVarType, setIdUnique, setIdNoDiscard,
80 81
			  setIdInfo, lazySetIdInfo, modifyIdInfo, 
			  maybeModifyIdInfo,
82
			  globalIdDetails, setGlobalIdDetails
83
			)
84
import qualified Var	( mkLocalId, mkGlobalId, mkSpecPragmaId )
85
import Type		( Type, typePrimRep, addFreeTyVars, 
86
                          usOnce, seqType, splitTyConApp_maybe )
87 88 89

import IdInfo 

90
import Demand		( Demand )
sof's avatar
sof committed
91
import Name	 	( Name, OccName,
92
			  mkSysLocalName, mkLocalName,
93
			  getOccName, getSrcLoc
sof's avatar
sof committed
94
			) 
95
import OccName		( UserFS, mkWorkerOcc )
96
import PrimRep		( PrimRep )
97
import TysPrim		( statePrimTyCon )
98
import FieldLabel	( FieldLabel )
99
import SrcLoc		( SrcLoc )
100
import Outputable
101 102
import Unique		( Unique, mkBuiltinUnique, getBuiltinUniques, 
			  getNumBuiltinUniques )
103

104
infixl 	1 `setIdUnfolding`,
105
	  `setIdArityInfo`,
106 107
	  `setIdDemandInfo`,
	  `setIdStrictness`,
108
	  `setIdTyGenInfo`,
109
	  `setIdWorkerInfo`,
110
	  `setIdSpecialisation`,
111
	  `setInlinePragma`,
112 113
	  `idCafInfo`,
	  `idCprInfo`
114

115
	-- infixl so you can say (id `set` a `set` b)
116 117 118
\end{code}


119

120 121
%************************************************************************
%*									*
122
\subsection{Simple Id construction}
123 124 125
%*									*
%************************************************************************

126 127 128
Absolutely all Ids are made by mkId.  It is just like Var.mkId,
but in addition it pins free-tyvar-info onto the Id's type, 
where it can easily be found.
129

130
\begin{code}
131 132 133 134 135 136
mkLocalIdWithInfo :: Name -> Type -> IdInfo -> Id
mkLocalIdWithInfo name ty info = Var.mkLocalId name (addFreeTyVars ty) info

mkSpecPragmaId :: OccName -> Unique -> Type -> SrcLoc -> Id
mkSpecPragmaId occ uniq ty loc = Var.mkSpecPragmaId (mkLocalName uniq occ loc)
						    (addFreeTyVars ty)
137
						    vanillaIdInfo
138 139 140

mkGlobalId :: GlobalIdDetails -> Name -> Type -> IdInfo -> Id
mkGlobalId details name ty info = Var.mkGlobalId details name (addFreeTyVars ty) info
141
\end{code}
142

143
\begin{code}
144
mkLocalId :: Name -> Type -> Id
145
mkLocalId name ty = mkLocalIdWithInfo name ty vanillaIdInfo
146 147 148

-- SysLocal: for an Id being created by the compiler out of thin air...
-- UserLocal: an Id with a name the user might recognize...
149 150
mkUserLocal :: OccName -> Unique -> Type -> SrcLoc -> Id
mkSysLocal  :: UserFS  -> Unique -> Type -> Id
151
mkVanillaGlobal :: Name -> Type -> IdInfo -> Id
152

153 154 155
mkSysLocal  fs uniq ty      = mkLocalId (mkSysLocalName uniq fs)      ty
mkUserLocal occ uniq ty loc = mkLocalId (mkLocalName    uniq occ loc) ty
mkVanillaGlobal 	    = mkGlobalId VanillaGlobal
156
\end{code}
157 158 159 160

Make some local @Ids@ for a template @CoreExpr@.  These have bogus
@Uniques@, but that's OK because the templates are supposed to be
instantiated before use.
161
 
162
\begin{code}
163 164
-- "Wild Id" typically used when you need a binder that you don't expect to use
mkWildId :: Type -> Id
165
mkWildId ty = mkSysLocal SLIT("wild") (mkBuiltinUnique 1) ty
166

167 168 169 170 171 172 173
mkWorkerId :: Unique -> Id -> Type -> Id
-- A worker gets a local name.  CoreTidy will globalise it if necessary.
mkWorkerId uniq unwrkr ty
  = mkLocalId wkr_name ty
  where
    wkr_name = mkLocalName uniq (mkWorkerOcc (getOccName unwrkr)) (getSrcLoc unwrkr)

174
-- "Template locals" typically used in unfoldings
175
mkTemplateLocals :: [Type] -> [Id]
176
mkTemplateLocals tys = zipWith (mkSysLocal SLIT("tpl"))
177 178
			       (getBuiltinUniques (length tys))
			       tys
179

180
mkTemplateLocalsNum :: Int -> [Type] -> [Id]
181
-- The Int gives the starting point for unique allocation
182
mkTemplateLocalsNum n tys = zipWith (mkSysLocal SLIT("tpl"))
183 184
			    	    (getNumBuiltinUniques n (length tys))
			       	    tys
185

186 187
mkTemplateLocal :: Int -> Type -> Id
mkTemplateLocal i ty = mkSysLocal SLIT("tpl") (mkBuiltinUnique i) ty
188 189 190
\end{code}


191 192 193 194 195 196 197
%************************************************************************
%*									*
\subsection[Id-general-funs]{General @Id@-related functions}
%*									*
%************************************************************************

\begin{code}
198
setIdType :: Id -> Type -> Id
199
	-- Add free tyvar info to the type
200
setIdType id ty = seqType ty `seq` setVarType id (addFreeTyVars ty)
sof's avatar
sof committed
201

202 203
idPrimRep :: Id -> PrimRep
idPrimRep id = typePrimRep (idType id)
204 205 206 207 208
\end{code}


%************************************************************************
%*									*
209
\subsection{Special Ids}
210 211 212
%*									*
%************************************************************************

213 214 215 216 217 218 219 220 221
The @SpecPragmaId@ exists only to make Ids that are
on the *LHS* of bindings created by SPECIALISE pragmas; 
eg:		s = f Int d
The SpecPragmaId is never itself mentioned; it
exists solely so that the specialiser will find
the call to f, and make specialised version of it.
The SpecPragmaId binding is discarded by the specialiser
when it gathers up overloaded calls.
Meanwhile, it is not discarded as dead code.
222 223


224
\begin{code}
225
recordSelectorFieldLabel :: Id -> FieldLabel
226 227
recordSelectorFieldLabel id = case globalIdDetails id of
				 RecordSelId lbl -> lbl
sof's avatar
sof committed
228

229
isRecordSelector id = case globalIdDetails id of
230 231
			RecordSelId lbl -> True
			other	  	-> False
sof's avatar
sof committed
232

233
isPrimOpId id = case globalIdDetails id of
234 235 236
		    PrimOpId op -> True
		    other	-> False

237
isPrimOpId_maybe id = case globalIdDetails id of
238 239 240
			    PrimOpId op -> Just op
			    other	-> Nothing

241
isDataConId id = case globalIdDetails id of
242 243
			DataConId _ -> True
			other	    -> False
sof's avatar
sof committed
244

245
isDataConId_maybe id = case globalIdDetails id of
246 247
			  DataConId con -> Just con
			  other	        -> Nothing
sof's avatar
sof committed
248

249
isDataConWrapId_maybe id = case globalIdDetails id of
250 251
				  DataConWrapId con -> Just con
				  other	            -> Nothing
252

253
isDataConWrapId id = case globalIdDetails id of
254 255
			DataConWrapId con -> True
			other	          -> False
256

257
	-- hasNoBinding returns True of an Id which may not have a
258 259
	-- binding, even though it is defined in this module.  Notably,
	-- the constructors of a dictionary are in this situation.
260 261 262 263
hasNoBinding id = case globalIdDetails id of
			DataConId _ -> True
			PrimOpId _  -> True
			other	    -> False
264

265
isImplicitId :: Id -> Bool
266 267 268
	-- isImplicitId tells whether an Id's info is implied by other
	-- declarations, so we don't need to put its signature in an interface
	-- file, even if it's mentioned in some other interface unfolding.
269
isImplicitId id
270
  = case globalIdDetails id of
271 272 273 274 275
	RecordSelId _   -> True	-- Includes dictionary selectors
        PrimOpId _      -> True
        DataConId _     -> True
	DataConWrapId _ -> True
		-- These are are implied by their type or class decl;
276 277 278
		-- remember that all type and class decls appear in the interface file.
		-- The dfun id must *not* be omitted, because it carries version info for
		-- the instance decl
279
	other		-> False
280 281 282 283
\end{code}

\begin{code}
isDeadBinder :: Id -> Bool
284
isDeadBinder bndr | isId bndr = isDeadOcc (idOccInfo bndr)
285
		  | otherwise = False	-- TyVars count as not dead
286 287 288
\end{code}


289 290
%************************************************************************
%*									*
291
\subsection{IdInfo stuff}
292 293 294
%*									*
%************************************************************************

295
\begin{code}
296 297
	---------------------------------
	-- ARITY
298 299 300 301 302
idArityInfo :: Id -> ArityInfo
idArityInfo id = arityInfo (idInfo id)

idArity :: Id -> Arity
idArity id = arityLowerBound (idArityInfo id)
303

304 305
setIdArityInfo :: Id -> ArityInfo -> Id
setIdArityInfo id arity = modifyIdInfo (`setArityInfo` arity) id
306

307 308
	---------------------------------
	-- STRICTNESS
309 310
idStrictness :: Id -> StrictnessInfo
idStrictness id = strictnessInfo (idInfo id)
311

312
setIdStrictness :: Id -> StrictnessInfo -> Id
313
setIdStrictness id strict_info = modifyIdInfo (`setStrictnessInfo` strict_info) id
314

315 316
-- isBottomingId returns true if an application to n args would diverge
isBottomingId :: Id -> Bool
317
isBottomingId id = isBottomingStrictness (idStrictness id)
318

319 320 321 322 323 324 325 326
	---------------------------------
	-- TYPE GENERALISATION
idTyGenInfo :: Id -> TyGenInfo
idTyGenInfo id = tyGenInfo (idInfo id)

setIdTyGenInfo :: Id -> TyGenInfo -> Id
setIdTyGenInfo id tygen_info = modifyIdInfo (`setTyGenInfo` tygen_info) id

327 328
	---------------------------------
	-- WORKER ID
329 330
idWorkerInfo :: Id -> WorkerInfo
idWorkerInfo id = workerInfo (idInfo id)
331 332

setIdWorkerInfo :: Id -> WorkerInfo -> Id
333
setIdWorkerInfo id work_info = modifyIdInfo (`setWorkerInfo` work_info) id
334

335 336
	---------------------------------
	-- UNFOLDING
337 338
idUnfolding :: Id -> Unfolding
idUnfolding id = unfoldingInfo (idInfo id)
339

340
setIdUnfolding :: Id -> Unfolding -> Id
341
setIdUnfolding id unfolding = modifyIdInfo (`setUnfoldingInfo` unfolding) id
sof's avatar
sof committed
342

343 344
	---------------------------------
	-- DEMAND
345 346
idDemandInfo :: Id -> Demand
idDemandInfo id = demandInfo (idInfo id)
347

348
setIdDemandInfo :: Id -> Demand -> Id
349
setIdDemandInfo id demand_info = modifyIdInfo (`setDemandInfo` demand_info) id
350

351 352
	---------------------------------
	-- SPECIALISATION
353 354
idSpecialisation :: Id -> CoreRules
idSpecialisation id = specInfo (idInfo id)
355

356 357
setIdSpecialisation :: Id -> CoreRules -> Id
setIdSpecialisation id spec_info = modifyIdInfo (`setSpecInfo` spec_info) id
358

359 360 361
	---------------------------------
	-- CG INFO
idCgInfo :: Id -> CgInfo
362 363 364 365 366
#ifdef DEBUG
idCgInfo id = case cgInfo (idInfo id) of
		  NoCgInfo -> pprPanic "idCgInfo" (ppr id)
		  info     -> info
#else
367
idCgInfo id = cgInfo (idInfo id)
368
#endif		
369 370 371 372

setIdCgInfo :: Id -> CgInfo -> Id
setIdCgInfo id cg_info = modifyIdInfo (`setCgInfo` cg_info) id

373 374
	---------------------------------
	-- CAF INFO
375
idCafInfo :: Id -> CafInfo
376 377 378 379
idCafInfo id = cgCafInfo (idCgInfo id)

	---------------------------------
	-- CG ARITY
380

381 382
idCgArity :: Id -> Arity
idCgArity id = cgArity (idCgInfo id)
383 384 385

	---------------------------------
	-- CPR INFO
386 387
idCprInfo :: Id -> CprInfo
idCprInfo id = cprInfo (idInfo id)
388 389

setIdCprInfo :: Id -> CprInfo -> Id
390
setIdCprInfo id cpr_info = modifyIdInfo (`setCprInfo` cpr_info) id
391 392 393

	---------------------------------
	-- Occcurrence INFO
394 395
idOccInfo :: Id -> OccInfo
idOccInfo id = occInfo (idInfo id)
396 397 398

setIdOccInfo :: Id -> OccInfo -> Id
setIdOccInfo id occ_info = modifyIdInfo (`setOccInfo` occ_info) id
399 400
\end{code}

sof's avatar
sof committed
401

402 403 404 405
	---------------------------------
	-- INLINING
The inline pragma tells us to be very keen to inline this Id, but it's still
OK not to if optimisation is switched off.
406 407

\begin{code}
408 409
idInlinePragma :: Id -> InlinePragInfo
idInlinePragma id = inlinePragInfo (idInfo id)
410

411
setInlinePragma :: Id -> InlinePragInfo -> Id
412
setInlinePragma id prag = modifyIdInfo (`setInlinePragInfo` prag) id
413

414
modifyInlinePragma :: Id -> (InlinePragInfo -> InlinePragInfo) -> Id
415
modifyInlinePragma id fn = modifyIdInfo (\info -> info `setInlinePragInfo` (fn (inlinePragInfo info))) id
416
\end{code}
417 418 419 420 421


	---------------------------------
	-- ONE-SHOT LAMBDAS
\begin{code}
422 423 424
idLBVarInfo :: Id -> LBVarInfo
idLBVarInfo id = lbvarInfo (idInfo id)

425
isOneShotLambda :: Id -> Bool
426 427 428 429 430 431 432 433
isOneShotLambda id = analysis || hack
  where analysis = case idLBVarInfo id of
                     LBVarInfo u    | u == usOnce             -> True
                     other                                    -> False
        hack     = case splitTyConApp_maybe (idType id) of
                     Just (tycon,_) | tycon == statePrimTyCon -> True
                     other                                    -> False

434 435 436 437 438 439 440 441 442 443 444
	-- The last clause is a gross hack.  It claims that 
	-- every function over realWorldStatePrimTy is a one-shot
	-- function.  This is pretty true in practice, and makes a big
	-- difference.  For example, consider
	--	a `thenST` \ r -> ...E...
	-- The early full laziness pass, if it doesn't know that r is one-shot
	-- will pull out E (let's say it doesn't mention r) to give
	--	let lvl = E in a `thenST` \ r -> ...lvl...
	-- When `thenST` gets inlined, we end up with
	--	let lvl = E in \s -> case a s of (r, s') -> ...lvl...
	-- and we don't re-inline E.
445
	--
446 447
	-- It would be better to spot that r was one-shot to start with, but
	-- I don't want to rely on that.
448 449 450
	--
	-- Another good example is in fill_in in PrelPack.lhs.  We should be able to
	-- spot that fill_in has arity 2 (and when Keith is done, we will) but we can't yet.
451 452

setOneShotLambda :: Id -> Id
453
setOneShotLambda id = modifyIdInfo (`setLBVarInfo` LBVarInfo usOnce) id
454 455 456 457 458 459 460 461 462

clearOneShotLambda :: Id -> Id
clearOneShotLambda id 
  | isOneShotLambda id = modifyIdInfo (`setLBVarInfo` NoLBVarInfo) id
  | otherwise	       = id			

-- But watch out: this may change the type of something else
--	f = \x -> e
-- If we change the one-shot-ness of x, f's type changes
463
\end{code}
464 465 466 467 468

\begin{code}
zapLamIdInfo :: Id -> Id
zapLamIdInfo id = maybeModifyIdInfo zapLamInfo id

469 470
zapDemandIdInfo id = maybeModifyIdInfo zapDemandInfo id
\end{code}