StgCmmClosure.hs 31.2 KB
 dias@eecs.harvard.edu committed Aug 14, 2008 1 2 3 4 5 6 7 8 9 10 11 ----------------------------------------------------------------------------- -- -- Stg to C-- code generation: -- -- The types LambdaFormInfo -- ClosureInfo -- -- Nothing monadic in here! -- -----------------------------------------------------------------------------  Simon Marlow committed Aug 25, 2011 12 {-# LANGUAGE RecordWildCards #-}  dias@eecs.harvard.edu committed Aug 14, 2008 13 module StgCmmClosure (  Simon Marlow committed Aug 25, 2011 14  DynTag, tagForCon, isSmallFamily,  dias@eecs.harvard.edu committed Aug 14, 2008 15 16  ConTagZ, dataConTagZ,  Simon Marlow committed Aug 25, 2011 17  isVoidRep, isGcPtrRep, addIdReps, addArgReps,  dias@eecs.harvard.edu committed Aug 14, 2008 18 19  argPrimRep,  Simon Marlow committed Aug 25, 2011 20 21  -- * LambdaFormInfo LambdaFormInfo, -- Abstract  dias@eecs.harvard.edu committed Aug 14, 2008 22 23 24  StandardFormInfo, -- ...ditto... mkLFThunk, mkLFReEntrant, mkConLFInfo, mkSelectorLFInfo, mkApLFInfo, mkLFImported, mkLFArgument, mkLFLetNoEscape,  Simon Marlow committed Aug 25, 2011 25 26 27  mkLFBlackHole, lfDynTag, maybeIsLFCon, isLFThunk, isLFReEntrant, lfUpdatable,  dias@eecs.harvard.edu committed Aug 14, 2008 28   Simon Marlow committed Aug 25, 2011 29 30 31 32 33 34  nodeMustPointToIt, CallMethod(..), getCallMethod, isKnownFun, funTag, tagForArity, -- * ClosureInfo  dias@eecs.harvard.edu committed Aug 14, 2008 35  ClosureInfo,  Simon Marlow committed Aug 25, 2011 36  mkClosureInfo,  Simon Marlow committed Aug 25, 2011 37  mkCmmInfo,  dias@eecs.harvard.edu committed Aug 14, 2008 38   Simon Marlow committed Aug 25, 2011 39 40  -- ** Inspection closureLFInfo, closureName,  Simon Marlow committed Aug 25, 2011 41   Simon Marlow committed Aug 25, 2011 42 43 44  -- ** Labels -- These just need the info table label closureInfoLabel, staticClosureLabel,  Simon Marlow committed Aug 25, 2011 45  closureRednCountsLabel, closureSlowEntryLabel, closureLocalEntryLabel,  dias@eecs.harvard.edu committed Aug 14, 2008 46   Simon Marlow committed Aug 25, 2011 47 48  -- ** Predicates -- These are really just functions on LambdaFormInfo  Simon Marlow committed Aug 25, 2011 49  closureUpdReqd, closureSingleEntry,  Simon Marlow committed Aug 25, 2011 50 51  closureReEntrant, closureFunInfo, isToplevClosure,  dias@eecs.harvard.edu committed Aug 14, 2008 52   Simon Marlow committed Aug 25, 2011 53 54  blackHoleOnEntry, -- Needs LambdaFormInfo and SMRep isStaticClosure, -- Needs SMPre  Simon Marlow committed Aug 25, 2011 55   Simon Marlow committed Aug 25, 2011 56  -- * InfoTables  Simon Marlow committed Aug 25, 2011 57  mkDataConInfoTable,  Simon Marlow committed Aug 25, 2011 58 59  cafBlackHoleInfoTable, staticClosureNeedsLink,  dias@eecs.harvard.edu committed Aug 14, 2008 60 61 62 63 64 65 66 67 68  ) where #include "../includes/MachDeps.h" #define FAST_STRING_NOT_NEEDED #include "HsVersions.h" import StgSyn import SMRep  Simon Marlow committed Aug 25, 2011 69 import Cmm  dias@eecs.harvard.edu committed Aug 14, 2008 70 71 72 73 74 75 76 77 78 79 80 81 82 83  import CLabel import StaticFlags import Id import IdInfo import DataCon import Name import Type import TypeRep import TcType import TyCon import BasicTypes import Outputable import Constants  Ian Lynagh committed Dec 18, 2008 84 import DynFlags  dias@eecs.harvard.edu committed Aug 14, 2008 85 86 87 88 89  ----------------------------------------------------------------------------- -- Representations -----------------------------------------------------------------------------  Simon Marlow committed Aug 25, 2011 90 91 -- Why are these here?  dias@eecs.harvard.edu committed Aug 14, 2008 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 addIdReps :: [Id] -> [(PrimRep, Id)] addIdReps ids = [(idPrimRep id, id) | id <- ids] addArgReps :: [StgArg] -> [(PrimRep, StgArg)] addArgReps args = [(argPrimRep arg, arg) | arg <- args] argPrimRep :: StgArg -> PrimRep argPrimRep arg = typePrimRep (stgArgType arg) isVoidRep :: PrimRep -> Bool isVoidRep VoidRep = True isVoidRep _other = False isGcPtrRep :: PrimRep -> Bool isGcPtrRep PtrRep = True isGcPtrRep _ = False ----------------------------------------------------------------------------- -- LambdaFormInfo ----------------------------------------------------------------------------- -- Information about an identifier, from the code generator's point of -- view. Every identifier is bound to a LambdaFormInfo in the -- environment, which gives the code generator enough info to be able to -- tail call or return that identifier. data LambdaFormInfo = LFReEntrant -- Reentrant closure (a function) TopLevelFlag -- True if top level !Int -- Arity. Invariant: always > 0 !Bool -- True <=> no fvs ArgDescr -- Argument descriptor (should really be in ClosureInfo) | LFThunk -- Thunk (zero arity) TopLevelFlag !Bool -- True <=> no free vars !Bool -- True <=> updatable (i.e., *not* single-entry) StandardFormInfo !Bool -- True <=> *might* be a function type | LFCon -- A saturated constructor application DataCon -- The constructor | LFUnknown -- Used for function arguments and imported things. -- We know nothing about this closure. -- Treat like updatable "LFThunk"... -- Imported things which we *do* know something about use -- one of the other LF constructors (eg LFReEntrant for -- known functions) !Bool -- True <=> *might* be a function type -- The False case is good when we want to enter it, -- because then we know the entry code will do -- For a function, the entry code is the fast entry point | LFUnLifted -- A value of unboxed type; -- always a value, neeeds evaluation | LFLetNoEscape -- See LetNoEscape module for precise description | LFBlackHole -- Used for the closures allocated to hold the result -- of a CAF. We want the target of the update frame to -- be in the heap, so we make a black hole to hold it.  Simon Marlow committed Aug 25, 2011 156 157 158  -- XXX we can very nearly get rid of this, but -- allocDynClosure needs a LambdaFormInfo  dias@eecs.harvard.edu committed Aug 14, 2008 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203  ------------------------- -- StandardFormInfo tells whether this thunk has one of -- a small number of standard forms data StandardFormInfo = NonStandardThunk -- Not of of the standard forms | SelectorThunk -- A SelectorThunk is of form -- case x of -- con a1,..,an -> ak -- and the constructor is from a single-constr type. WordOff -- 0-origin offset of ak within the "goods" of -- constructor (Recall that the a1,...,an may be laid -- out in the heap in a non-obvious order.) | ApThunk -- An ApThunk is of form -- x1 ... xn -- The code for the thunk just pushes x2..xn on the stack and enters x1. -- There are a few of these (for 1 <= n <= MAX_SPEC_AP_SIZE) pre-compiled -- in the RTS to save space. Int -- Arity, n ------------------------------------------------------ -- Building LambdaFormInfo ------------------------------------------------------ mkLFArgument :: Id -> LambdaFormInfo mkLFArgument id | isUnLiftedType ty = LFUnLifted | might_be_a_function ty = LFUnknown True | otherwise = LFUnknown False where ty = idType id ------------- mkLFLetNoEscape :: LambdaFormInfo mkLFLetNoEscape = LFLetNoEscape ------------- mkLFReEntrant :: TopLevelFlag -- True of top level  dias@eecs.harvard.edu committed Oct 13, 2008 204  -> [Id] -- Free vars  dias@eecs.harvard.edu committed Aug 14, 2008 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225  -> [Id] -- Args -> ArgDescr -- Argument descriptor -> LambdaFormInfo mkLFReEntrant top fvs args arg_descr = LFReEntrant top (length args) (null fvs) arg_descr ------------- mkLFThunk :: Type -> TopLevelFlag -> [Id] -> UpdateFlag -> LambdaFormInfo mkLFThunk thunk_ty top fvs upd_flag = ASSERT( not (isUpdatable upd_flag) || not (isUnLiftedType thunk_ty) ) LFThunk top (null fvs) (isUpdatable upd_flag) NonStandardThunk (might_be_a_function thunk_ty) -------------- might_be_a_function :: Type -> Bool -- Return False only if we are *sure* it's a data type -- Look through newtypes etc as much as poss might_be_a_function ty  Simon Peyton Jones committed Aug 03, 2011 226 227 228  = case tyConAppTyCon_maybe (repType ty) of Just tc -> not (isDataTyCon tc) Nothing -> True  dias@eecs.harvard.edu committed Aug 14, 2008 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262  ------------- mkConLFInfo :: DataCon -> LambdaFormInfo mkConLFInfo con = LFCon con ------------- mkSelectorLFInfo :: Id -> Int -> Bool -> LambdaFormInfo mkSelectorLFInfo id offset updatable = LFThunk NotTopLevel False updatable (SelectorThunk offset) (might_be_a_function (idType id)) ------------- mkApLFInfo :: Id -> UpdateFlag -> Arity -> LambdaFormInfo mkApLFInfo id upd_flag arity = LFThunk NotTopLevel (arity == 0) (isUpdatable upd_flag) (ApThunk arity) (might_be_a_function (idType id)) ------------- mkLFImported :: Id -> LambdaFormInfo mkLFImported id | Just con <- isDataConWorkId_maybe id , isNullaryRepDataCon con = LFCon con -- An imported nullary constructor -- We assume that the constructor is evaluated so that -- the id really does point directly to the constructor | arity > 0 = LFReEntrant TopLevel arity True (panic "arg_descr") | otherwise = mkLFArgument id -- Not sure of exact arity where arity = idArity id  Simon Marlow committed Aug 25, 2011 263 264 265 266 ------------ mkLFBlackHole :: LambdaFormInfo mkLFBlackHole = LFBlackHole  dias@eecs.harvard.edu committed Aug 14, 2008 267 268 269 270 271 272 273 274 275 276 277 ----------------------------------------------------- -- Dynamic pointer tagging ----------------------------------------------------- type ConTagZ = Int -- A *zero-indexed* contructor tag type DynTag = Int -- The tag on a *pointer* -- (from the dynamic-tagging paper) {- Note [Data constructor dynamic tags] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  Edward Z. Yang committed Apr 04, 2011 278 279 The family size of a data type (the number of constructors or the arity of a function) can be either:  dias@eecs.harvard.edu committed Aug 14, 2008 280 281 282 283  * small, if the family size < 2**tag_bits * big, otherwise. Small families can have the constructor tag in the tag bits.  Edward Z. Yang committed Apr 04, 2011 284 285 286 Big families only use the tag value 1 to represent evaluatedness. We don't have very many tag bits: for example, we have 2 bits on x86-32 and 3 bits on x86-64. -}  dias@eecs.harvard.edu committed Aug 14, 2008 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308  isSmallFamily :: Int -> Bool isSmallFamily fam_size = fam_size <= mAX_PTR_TAG -- We keep the *zero-indexed* tag in the srt_len field of the info -- table of a data constructor. dataConTagZ :: DataCon -> ConTagZ dataConTagZ con = dataConTag con - fIRST_TAG tagForCon :: DataCon -> DynTag tagForCon con | isSmallFamily fam_size = con_tag + 1 | otherwise = 1 where con_tag = dataConTagZ con fam_size = tyConFamilySize (dataConTyCon con) tagForArity :: Int -> DynTag tagForArity arity | isSmallFamily arity = arity | otherwise = 0 lfDynTag :: LambdaFormInfo -> DynTag  dias@eecs.harvard.edu committed Oct 13, 2008 309 310 -- Return the tag in the low order bits of a variable bound -- to this LambdaForm  dias@eecs.harvard.edu committed Nov 26, 2008 311 312 lfDynTag (LFCon con) = tagForCon con lfDynTag (LFReEntrant _ arity _ _) = tagForArity arity  dias@eecs.harvard.edu committed Aug 14, 2008 313 314 315 316 317 318 319 320 321 322 323 324 325 326 lfDynTag _other = 0 ----------------------------------------------------------------------------- -- Observing LambdaFormInfo ----------------------------------------------------------------------------- ------------- maybeIsLFCon :: LambdaFormInfo -> Maybe DataCon maybeIsLFCon (LFCon con) = Just con maybeIsLFCon _ = Nothing ------------ isLFThunk :: LambdaFormInfo -> Bool  Simon Marlow committed Aug 25, 2011 327 328 isLFThunk (LFThunk {}) = True isLFThunk LFBlackHole = True  dias@eecs.harvard.edu committed Aug 14, 2008 329 330 331 332 333  -- return True for a blackhole: this function is used to determine -- whether to use the thunk header in SMP mode, and a blackhole -- must have one. isLFThunk _ = False  Simon Marlow committed Aug 25, 2011 334 335 336 isLFReEntrant :: LambdaFormInfo -> Bool isLFReEntrant (LFReEntrant {}) = True isLFReEntrant _ = False  dias@eecs.harvard.edu committed Aug 14, 2008 337 338 339 340 341  ----------------------------------------------------------------------------- -- Choosing SM reps -----------------------------------------------------------------------------  Simon Marlow committed Aug 25, 2011 342 343 lfClosureType :: LambdaFormInfo -> ClosureTypeInfo lfClosureType (LFReEntrant _ arity _ argd) = Fun (fromIntegral arity) argd  Simon Marlow committed Aug 25, 2011 344 345 lfClosureType (LFCon con) = Constr (fromIntegral (dataConTagZ con)) (dataConIdentity con)  Simon Marlow committed Aug 25, 2011 346 347 348 349 350 351 lfClosureType (LFThunk _ _ _ is_sel _) = thunkClosureType is_sel lfClosureType _ = panic "lfClosureType" thunkClosureType :: StandardFormInfo -> ClosureTypeInfo thunkClosureType (SelectorThunk off) = ThunkSelector (fromIntegral off) thunkClosureType _ = Thunk  dias@eecs.harvard.edu committed Aug 14, 2008 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403  -- We *do* get non-updatable top-level thunks sometimes. eg. f = g -- gets compiled to a jump to g (if g has non-zero arity), instead of -- messing around with update frames and PAPs. We set the closure type -- to FUN_STATIC in this case. ----------------------------------------------------------------------------- -- nodeMustPointToIt ----------------------------------------------------------------------------- -- Be sure to see the stg-details notes about these... nodeMustPointToIt :: LambdaFormInfo -> Bool nodeMustPointToIt (LFReEntrant top _ no_fvs _) = not no_fvs || -- Certainly if it has fvs we need to point to it isNotTopLevel top -- If it is not top level we will point to it -- We can have a \r closure with no_fvs which -- is not top level as special case cgRhsClosure -- has been dissabled in favour of let floating -- For lex_profiling we also access the cost centre for a -- non-inherited function i.e. not top level -- the not top case above ensures this is ok. nodeMustPointToIt (LFCon _) = True -- Strictly speaking, the above two don't need Node to point -- to it if the arity = 0. But this is a *really* unlikely -- situation. If we know it's nil (say) and we are entering -- it. Eg: let x = [] in x then we will certainly have inlined -- x, since nil is a simple atom. So we gain little by not -- having Node point to known zero-arity things. On the other -- hand, we do lose something; Patrick's code for figuring out -- when something has been updated but not entered relies on -- having Node point to the result of an update. SLPJ -- 27/11/92. nodeMustPointToIt (LFThunk _ no_fvs updatable NonStandardThunk _) = updatable || not no_fvs || opt_SccProfilingOn -- For the non-updatable (single-entry case): -- -- True if has fvs (in which case we need access to them, and we -- should black-hole it) -- or profiling (in which case we need to recover the cost centre -- from inside it) nodeMustPointToIt (LFThunk {}) -- Node must point to a standard-form thunk = True nodeMustPointToIt (LFUnknown _) = True nodeMustPointToIt LFUnLifted = False  batterseapower committed Jul 28, 2011 404 nodeMustPointToIt LFBlackHole = True -- BH entry may require Node to point  dias@eecs.harvard.edu committed Aug 14, 2008 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 nodeMustPointToIt LFLetNoEscape = False ----------------------------------------------------------------------------- -- getCallMethod ----------------------------------------------------------------------------- {- The entry conventions depend on the type of closure being entered, whether or not it has free variables, and whether we're running sequentially or in parallel. Closure Node Argument Enter Characteristics Par Req'd Passing Via ------------------------------------------------------------------------------- Unknown & no & yes & stack & node Known fun (>1 arg), no fvs & no & no & registers & fast entry (enough args) & slow entry (otherwise) Known fun (>1 arg), fvs & no & yes & registers & fast entry (enough args) 0 arg, no fvs \r,\s & no & no & n/a & direct entry 0 arg, no fvs \u & no & yes & n/a & node 0 arg, fvs \r,\s & no & yes & n/a & direct entry 0 arg, fvs \u & no & yes & n/a & node Unknown & yes & yes & stack & node Known fun (>1 arg), no fvs & yes & no & registers & fast entry (enough args) & slow entry (otherwise) Known fun (>1 arg), fvs & yes & yes & registers & node 0 arg, no fvs \r,\s & yes & no & n/a & direct entry 0 arg, no fvs \u & yes & yes & n/a & node 0 arg, fvs \r,\s & yes & yes & n/a & node 0 arg, fvs \u & yes & yes & n/a & node \end{tabular} When black-holing, single-entry closures could also be entered via node (rather than directly) to catch double-entry. -} data CallMethod = EnterIt -- No args, not a function | JumpToIt -- A join point | ReturnIt -- It's a value (function, unboxed value, -- or constructor), so just return it. | SlowCall -- Unknown fun, or known fun with -- too few args. | DirectEntry -- Jump directly, with args in regs CLabel -- The code label Int -- Its arity  Ian Lynagh committed Dec 18, 2008 455 456 getCallMethod :: DynFlags -> Name -- Function being applied  dias@eecs.harvard.edu committed Aug 14, 2008 457 458 459 460 461  -> CafInfo -- Can it refer to CAF's? -> LambdaFormInfo -- Its info -> Int -- Number of available arguments -> CallMethod  Ian Lynagh committed Dec 18, 2008 462 getCallMethod _ _name _ lf_info _n_args  dias@eecs.harvard.edu committed Aug 14, 2008 463 464 465 466 467 468  | nodeMustPointToIt lf_info && opt_Parallel = -- If we're parallel, then we must always enter via node. -- The reason is that the closure may have been -- fetched since we allocated it. EnterIt  Ian Lynagh committed Dec 18, 2008 469 getCallMethod _ name caf (LFReEntrant _ arity _ _) n_args  dias@eecs.harvard.edu committed Aug 14, 2008 470 471 472  | n_args == 0 = ASSERT( arity /= 0 ) ReturnIt -- No args at all | n_args < arity = SlowCall -- Not enough args  dias@eecs.harvard.edu committed Nov 26, 2008 473  | otherwise = DirectEntry (enterIdLabel name caf) arity  dias@eecs.harvard.edu committed Aug 14, 2008 474   Ian Lynagh committed Dec 18, 2008 475 getCallMethod _ _name _ LFUnLifted n_args  dias@eecs.harvard.edu committed Aug 14, 2008 476 477  = ASSERT( n_args == 0 ) ReturnIt  Ian Lynagh committed Dec 18, 2008 478 getCallMethod _ _name _ (LFCon _) n_args  dias@eecs.harvard.edu committed Aug 14, 2008 479 480  = ASSERT( n_args == 0 ) ReturnIt  Ian Lynagh committed Dec 18, 2008 481 getCallMethod dflags name caf (LFThunk _ _ updatable std_form_info is_fun) n_args  dias@eecs.harvard.edu committed Aug 14, 2008 482 483 484 485 486  | is_fun -- it *might* be a function, so we must "call" it (which is always safe) = SlowCall -- We cannot just enter it [in eval/apply, the entry code -- is the fast-entry code] -- Since is_fun is False, we are *definitely* looking at a data value  Ian Lynagh committed Dec 18, 2008 487  | updatable || doingTickyProfiling dflags -- to catch double entry  dias@eecs.harvard.edu committed Aug 14, 2008 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504  {- OLD: || opt_SMP I decided to remove this, because in SMP mode it doesn't matter if we enter the same thunk multiple times, so the optimisation of jumping directly to the entry code is still valid. --SDM -} = EnterIt -- We used to have ASSERT( n_args == 0 ), but actually it is -- possible for the optimiser to generate -- let bot :: Int = error Int "urk" -- in (bot cast unsafeCoerce Int (Int -> Int)) 3 -- This happens as a result of the case-of-error transformation -- So the right thing to do is just to enter the thing | otherwise -- Jump direct to code for single-entry thunks = ASSERT( n_args == 0 ) DirectEntry (thunkEntryLabel name caf std_form_info updatable) 0  Ian Lynagh committed Dec 18, 2008 505 getCallMethod _ _name _ (LFUnknown True) _n_args  dias@eecs.harvard.edu committed Aug 14, 2008 506 507  = SlowCall -- might be a function  Ian Lynagh committed Dec 18, 2008 508 getCallMethod _ name _ (LFUnknown False) n_args  dias@eecs.harvard.edu committed Aug 14, 2008 509 510 511  = ASSERT2 ( n_args == 0, ppr name <+> ppr n_args ) EnterIt -- Not a function  batterseapower committed Jul 28, 2011 512 getCallMethod _ _name _ LFBlackHole _n_args  dias@eecs.harvard.edu committed Aug 14, 2008 513 514 515 516  = SlowCall -- Presumably the black hole has by now -- been updated, but we don't know with -- what, so we slow call it  Ian Lynagh committed Dec 18, 2008 517 getCallMethod _ _name _ LFLetNoEscape _n_args  dias@eecs.harvard.edu committed Aug 14, 2008 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611  = JumpToIt isKnownFun :: LambdaFormInfo -> Bool isKnownFun (LFReEntrant _ _ _ _) = True isKnownFun LFLetNoEscape = True isKnownFun _ = False ----------------------------------------------------------------------------- -- staticClosureRequired ----------------------------------------------------------------------------- {- staticClosureRequired is never called (hence commented out) SimonMar writes (Sept 07) It's an optimisation we used to apply at one time, I believe, but it got lost probably in the rewrite of the RTS/code generator. I left that code there to remind me to look into whether it was worth doing sometime {- Avoiding generating entries and info tables ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ At present, for every function we generate all of the following, just in case. But they aren't always all needed, as noted below: [NB1: all of this applies only to *functions*. Thunks always have closure, info table, and entry code.] [NB2: All are needed if the function is *exported*, just to play safe.] * Fast-entry code ALWAYS NEEDED * Slow-entry code Needed iff (a) we have any un-saturated calls to the function OR (b) the function is passed as an arg OR (c) we're in the parallel world and the function has free vars [Reason: in parallel world, we always enter functions with free vars via the closure.] * The function closure Needed iff (a) we have any un-saturated calls to the function OR (b) the function is passed as an arg OR (c) if the function has free vars (ie not top level) Why case (a) here? Because if the arg-satis check fails, UpdatePAP stuffs a pointer to the function closure in the PAP. [Could be changed; UpdatePAP could stuff in a code ptr instead, but doesn't seem worth it.] [NB: these conditions imply that we might need the closure without the slow-entry code. Here's how. f x y = let g w = ...x..y..w... in ...(g t)... Here we need a closure for g which contains x and y, but since the calls are all saturated we just jump to the fast entry point for g, with R1 pointing to the closure for g.] * Standard info table Needed iff (a) we have any un-saturated calls to the function OR (b) the function is passed as an arg OR (c) the function has free vars (ie not top level) NB. In the sequential world, (c) is only required so that the function closure has an info table to point to, to keep the storage manager happy. If (c) alone is true we could fake up an info table by choosing one of a standard family of info tables, whose entry code just bombs out. [NB In the parallel world (c) is needed regardless because we enter functions with free vars via the closure.] If (c) is retained, then we'll sometimes generate an info table (for storage mgr purposes) without slow-entry code. Then we need to use an error label in the info table to substitute for the absent slow entry code. -} staticClosureRequired :: Name -> StgBinderInfo -> LambdaFormInfo -> Bool staticClosureRequired binder bndr_info (LFReEntrant top_level _ _ _) -- It's a function = ASSERT( isTopLevel top_level ) -- Assumption: it's a top-level, no-free-var binding not (satCallsOnly bndr_info) staticClosureRequired binder other_binder_info other_lf_info = True -} -----------------------------------------------------------------------------  Simon Marlow committed Aug 25, 2011 612 -- Data types for closure information  dias@eecs.harvard.edu committed Aug 14, 2008 613 614 615 -----------------------------------------------------------------------------  Simon Marlow committed Aug 25, 2011 616 {- ClosureInfo: information about a binding  dias@eecs.harvard.edu committed Aug 14, 2008 617   Simon Marlow committed Aug 25, 2011 618 619 620  We make a ClosureInfo for each let binding (both top level and not), but not bindings for data constructors: for those we build a CmmInfoTable directly (see mkDataConInfoTable).  dias@eecs.harvard.edu committed Aug 14, 2008 621   Simon Marlow committed Aug 25, 2011 622 623  To a first approximation: ClosureInfo = (LambdaFormInfo, CmmInfoTable)  Simon Marlow committed Aug 25, 2011 624   Simon Marlow committed Aug 25, 2011 625 626 627 628 629  A ClosureInfo has enough information a) to construct the info table itself, and build other things related to the binding (e.g. slow entry points for a function) b) to allocate a closure containing that info pointer (i.e. it knows the info table label)  dias@eecs.harvard.edu committed Aug 14, 2008 630 631 632 633 -} data ClosureInfo = ClosureInfo {  Simon Marlow committed Aug 25, 2011 634 635 636 637 638 639 640 641 642 643 644 645 646  closureName :: !Name, -- The thing bound to this closure -- we don't really need this field: it's only used in generating -- code for ticky and profiling, and we could pass the information -- around separately, but it doesn't do much harm to keep it here. closureLFInfo :: !LambdaFormInfo, -- NOTE: not an LFCon -- this tells us about what the closure contains: it's right-hand-side. -- the rest is just an unpacked CmmInfoTable. closureInfoLabel :: !CLabel, closureSMRep :: !SMRep, -- representation used by storage mgr closureSRT :: !C_SRT, -- What SRT applies to this closure closureProf :: !ProfilingInfo  dias@eecs.harvard.edu committed Aug 14, 2008 647 648  }  Simon Marlow committed Aug 25, 2011 649 650 -- | Convert from 'ClosureInfo' to 'CmmInfoTable'. mkCmmInfo :: ClosureInfo -> CmmInfoTable  Simon Marlow committed Aug 25, 2011 651 652 653 654 655 mkCmmInfo ClosureInfo {..} = CmmInfoTable { cit_lbl = closureInfoLabel , cit_rep = closureSMRep , cit_prof = closureProf , cit_srt = closureSRT }  Simon Marlow committed Aug 25, 2011 656   dias@eecs.harvard.edu committed Aug 14, 2008 657 658 659 660 661 662 663 664 665 666 667 668  -------------------------------------- -- Building ClosureInfos -------------------------------------- mkClosureInfo :: Bool -- Is static -> Id -> LambdaFormInfo -> Int -> Int -- Total and pointer words -> C_SRT -> String -- String descriptor -> ClosureInfo  Simon Marlow committed Aug 25, 2011 669 mkClosureInfo is_static id lf_info tot_wds ptr_wds srt_info val_descr  Simon Marlow committed Aug 25, 2011 670 671 672 673 674 675  = ClosureInfo { closureName = name, closureLFInfo = lf_info, closureInfoLabel = info_lbl, closureSMRep = sm_rep, -- These four fields are a closureSRT = srt_info, -- CmmInfoTable closureProf = prof } -- ---  dias@eecs.harvard.edu committed Aug 14, 2008 676  where  Simon Marlow committed Aug 25, 2011 677 678 679  name = idName id sm_rep = mkHeapRep is_static ptr_wds nonptr_wds (lfClosureType lf_info) prof = mkProfilingInfo id val_descr  Simon Marlow committed Aug 25, 2011 680  nonptr_wds = tot_wds - ptr_wds  dias@eecs.harvard.edu committed Aug 14, 2008 681   Simon Marlow committed Aug 25, 2011 682  info_lbl = mkClosureInfoTableLabel id lf_info  dias@eecs.harvard.edu committed Aug 14, 2008 683 684  --------------------------------------  Simon Marlow committed Aug 25, 2011 685 -- Other functions over ClosureInfo  dias@eecs.harvard.edu committed Aug 14, 2008 686 687 --------------------------------------  Simon Marlow committed Aug 25, 2011 688 689 690 -- Eager blackholing is normally disabled, but can be turned on with -- -feager-blackholing. When it is on, we replace the info pointer of -- the thunk with stg_EAGER_BLACKHOLE_info on entry.  dias@eecs.harvard.edu committed Aug 14, 2008 691   Simon Marlow committed Aug 25, 2011 692 693 694 695 696 697 698 699 700 701 702 -- If we wanted to do eager blackholing with slop filling, -- we'd need to do it at the *end* of a basic block, otherwise -- we overwrite the free variables in the thunk that we still -- need. We have a patch for this from Andy Cheadle, but not -- incorporated yet. --SDM [6/2004] -- -- -- Previously, eager blackholing was enabled when ticky-ticky -- was on. But it didn't work, and it wasn't strictly necessary -- to bring back minimal ticky-ticky, so now EAGER_BLACKHOLING -- is unconditionally disabled. -- krc 1/2007  dias@eecs.harvard.edu committed Aug 14, 2008 703 704 705  -- Static closures are never themselves black-holed.  Simon Marlow committed Sep 06, 2011 706 707 blackHoleOnEntry :: ClosureInfo -> Bool blackHoleOnEntry cl_info  Simon Marlow committed Aug 25, 2011 708  | isStaticRep (closureSMRep cl_info)  dias@eecs.harvard.edu committed Aug 14, 2008 709 710 711  = False -- Never black-hole a static closure | otherwise  Simon Marlow committed Aug 25, 2011 712  = case closureLFInfo cl_info of  dias@eecs.harvard.edu committed Aug 14, 2008 713 714  LFReEntrant _ _ _ _ -> False LFLetNoEscape -> False  Simon Marlow committed Sep 06, 2011 715  LFThunk _ no_fvs _updatable _ _ -> not no_fvs -- to plug space-leaks.  Simon Marlow committed Aug 25, 2011 716  _other -> panic "blackHoleOnEntry" -- Should never happen  dias@eecs.harvard.edu committed Aug 14, 2008 717 718 719 720 721 722 723 724 725  isStaticClosure :: ClosureInfo -> Bool isStaticClosure cl_info = isStaticRep (closureSMRep cl_info) closureUpdReqd :: ClosureInfo -> Bool closureUpdReqd ClosureInfo{ closureLFInfo = lf_info } = lfUpdatable lf_info lfUpdatable :: LambdaFormInfo -> Bool lfUpdatable (LFThunk _ _ upd _ _) = upd  batterseapower committed Jul 28, 2011 726 lfUpdatable LFBlackHole = True  dias@eecs.harvard.edu committed Aug 14, 2008 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759  -- Black-hole closures are allocated to receive the results of an -- alg case with a named default... so they need to be updated. lfUpdatable _ = False closureSingleEntry :: ClosureInfo -> Bool closureSingleEntry (ClosureInfo { closureLFInfo = LFThunk _ _ upd _ _}) = not upd closureSingleEntry _ = False closureReEntrant :: ClosureInfo -> Bool closureReEntrant (ClosureInfo { closureLFInfo = LFReEntrant _ _ _ _ }) = True closureReEntrant _ = False closureFunInfo :: ClosureInfo -> Maybe (Int, ArgDescr) closureFunInfo (ClosureInfo { closureLFInfo = lf_info }) = lfFunInfo lf_info lfFunInfo :: LambdaFormInfo -> Maybe (Int, ArgDescr) lfFunInfo (LFReEntrant _ arity _ arg_desc) = Just (arity, arg_desc) lfFunInfo _ = Nothing funTag :: ClosureInfo -> DynTag funTag (ClosureInfo { closureLFInfo = lf_info }) = lfDynTag lf_info isToplevClosure :: ClosureInfo -> Bool isToplevClosure (ClosureInfo { closureLFInfo = lf_info }) = case lf_info of LFReEntrant TopLevel _ _ _ -> True LFThunk TopLevel _ _ _ _ -> True _other -> False -------------------------------------- -- Label generation --------------------------------------  Simon Marlow committed Aug 25, 2011 760 staticClosureLabel :: ClosureInfo -> CLabel  Simon Marlow committed Aug 25, 2011 761 staticClosureLabel = toClosureLbl . closureInfoLabel  Simon Marlow committed Aug 25, 2011 762 763  closureRednCountsLabel :: ClosureInfo -> CLabel  Simon Marlow committed Aug 25, 2011 764 closureRednCountsLabel = toRednCountsLbl . closureInfoLabel  Simon Marlow committed Aug 25, 2011 765 766  closureSlowEntryLabel :: ClosureInfo -> CLabel  Simon Marlow committed Aug 25, 2011 767 closureSlowEntryLabel = toSlowEntryLbl . closureInfoLabel  Simon Marlow committed Aug 25, 2011 768 769  closureLocalEntryLabel :: ClosureInfo -> CLabel  Simon Marlow committed Aug 25, 2011 770 771 772 closureLocalEntryLabel | tablesNextToCode = toInfoLbl . closureInfoLabel | otherwise = toEntryLbl . closureInfoLabel  batterseapower committed Jul 28, 2011 773   Simon Marlow committed Aug 25, 2011 774 775 mkClosureInfoTableLabel :: Id -> LambdaFormInfo -> CLabel mkClosureInfoTableLabel id lf_info  batterseapower committed Jul 28, 2011 776  = case lf_info of  Simon Marlow committed Aug 25, 2011 777  LFBlackHole -> mkCAFBlackHoleInfoTableLabel  dias@eecs.harvard.edu committed Aug 14, 2008 778   Simon Marlow committed Aug 25, 2011 779  LFThunk _ _ upd_flag (SelectorThunk offset) _  Simon Marlow committed Aug 25, 2011 780  -> mkSelectorInfoLabel upd_flag offset  dias@eecs.harvard.edu committed Aug 14, 2008 781   Simon Marlow committed Aug 25, 2011 782  LFThunk _ _ upd_flag (ApThunk arity) _  Simon Marlow committed Aug 25, 2011 783  -> mkApInfoTableLabel upd_flag arity  dias@eecs.harvard.edu committed Aug 14, 2008 784   Simon Marlow committed Aug 25, 2011 785 786  LFThunk{} -> std_mk_lbl name cafs LFReEntrant{} -> std_mk_lbl name cafs  Simon Marlow committed Aug 25, 2011 787  _other -> panic "closureInfoTableLabel"  dias@eecs.harvard.edu committed Aug 14, 2008 788   Simon Marlow committed Aug 25, 2011 789  where  Simon Marlow committed Aug 25, 2011 790 791  name = idName id  Simon Marlow committed Aug 25, 2011 792  std_mk_lbl | is_local = mkLocalInfoTableLabel  Simon Marlow committed Aug 25, 2011 793 794  | otherwise = mkInfoTableLabel  Simon Marlow committed Aug 25, 2011 795 796 797 798 799 800 801  cafs = idCafInfo id is_local = isDataConWorkId id -- Make the _info pointer for the implicit datacon worker -- binding local. The reason we can do this is that importing -- code always either uses the _closure or _con_info. By the -- invariants in CorePrep anything else gets eta expanded.  dias@eecs.harvard.edu committed Aug 14, 2008 802 803  thunkEntryLabel :: Name -> CafInfo -> StandardFormInfo -> Bool -> CLabel  Simon Marlow committed Aug 25, 2011 804 805 -- thunkEntryLabel is a local help function, not exported. It's used from -- getCallMethod.  dias@eecs.harvard.edu committed Aug 14, 2008 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 thunkEntryLabel _thunk_id _ (ApThunk arity) upd_flag = enterApLabel upd_flag arity thunkEntryLabel _thunk_id _ (SelectorThunk offset) upd_flag = enterSelectorLabel upd_flag offset thunkEntryLabel thunk_id c _ _ = enterIdLabel thunk_id c enterApLabel :: Bool -> Arity -> CLabel enterApLabel is_updatable arity | tablesNextToCode = mkApInfoTableLabel is_updatable arity | otherwise = mkApEntryLabel is_updatable arity enterSelectorLabel :: Bool -> WordOff -> CLabel enterSelectorLabel upd_flag offset | tablesNextToCode = mkSelectorInfoLabel upd_flag offset | otherwise = mkSelectorEntryLabel upd_flag offset enterIdLabel :: Name -> CafInfo -> CLabel enterIdLabel id c | tablesNextToCode = mkInfoTableLabel id c | otherwise = mkEntryLabel id c -------------------------------------- -- Profiling -------------------------------------- -- Profiling requires two pieces of information to be determined for -- each closure's info table --- description and type. -- The description is stored directly in the @CClosureInfoTable@ when the -- info table is built. -- The type is determined from the type information stored with the @Id@ -- in the closure info using @closureTypeDescr@.  Simon Marlow committed Aug 25, 2011 842 843 844 845 846 847 848 mkProfilingInfo :: Id -> String -> ProfilingInfo mkProfilingInfo id val_descr | not opt_SccProfilingOn = NoProfilingInfo | otherwise = ProfilingInfo ty_descr_w8 val_descr_w8 where ty_descr_w8 = stringToWord8s (getTyDescription (idType id)) val_descr_w8 = stringToWord8s val_descr  dias@eecs.harvard.edu committed Aug 14, 2008 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863  getTyDescription :: Type -> String getTyDescription ty = case (tcSplitSigmaTy ty) of { (_, _, tau_ty) -> case tau_ty of TyVarTy _ -> "*" AppTy fun _ -> getTyDescription fun FunTy _ res -> '-' : '>' : fun_result res TyConApp tycon _ -> getOccString tycon ForAllTy _ ty -> getTyDescription ty } where fun_result (FunTy _ res) = '>' : fun_result res fun_result other = getTyDescription other  Simon Marlow committed Aug 25, 2011 864 --------------------------------------  Simon Marlow committed Aug 25, 2011 865 -- CmmInfoTable-related things  Simon Marlow committed Aug 25, 2011 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 -------------------------------------- mkDataConInfoTable :: DataCon -> Bool -> Int -> Int -> CmmInfoTable mkDataConInfoTable data_con is_static ptr_wds nonptr_wds = CmmInfoTable { cit_lbl = info_lbl , cit_rep = sm_rep , cit_prof = prof , cit_srt = NoC_SRT } where name = dataConName data_con info_lbl | is_static = mkStaticInfoTableLabel name NoCafRefs | otherwise = mkConInfoTableLabel name NoCafRefs sm_rep = mkHeapRep is_static ptr_wds nonptr_wds cl_type cl_type = Constr (fromIntegral (dataConTagZ data_con)) (dataConIdentity data_con) prof | not opt_SccProfilingOn = NoProfilingInfo | otherwise = ProfilingInfo ty_descr val_descr ty_descr = stringToWord8s $occNameString$ getOccName $dataConTyCon data_con val_descr = stringToWord8s$ occNameString \$ getOccName data_con  Simon Marlow committed Aug 25, 2011 890   Simon Marlow committed Aug 25, 2011 891 892 893 894 895 896 897 898 899 -- We need a black-hole closure info to pass to @allocDynClosure@ when we -- want to allocate the black hole on entry to a CAF. cafBlackHoleInfoTable :: CmmInfoTable cafBlackHoleInfoTable = CmmInfoTable { cit_lbl = mkCAFBlackHoleInfoTableLabel , cit_rep = blackHoleRep , cit_prof = NoProfilingInfo , cit_srt = NoC_SRT }  Simon Marlow committed Aug 25, 2011 900 901 902 903 904 905 906 907 908 909 910 911  staticClosureNeedsLink :: CmmInfoTable -> Bool -- A static closure needs a link field to aid the GC when traversing -- the static closure graph. But it only needs such a field if either -- a) it has an SRT -- b) it's a constructor with one or more pointer fields -- In case (b), the constructor's fields themselves play the role -- of the SRT. staticClosureNeedsLink info_tbl@CmmInfoTable{ cit_rep = smrep } | isConRep smrep = not (isStaticNoCafCon smrep) | otherwise = needsSRT (cit_srt info_tbl) staticClosureNeedsLink _ = False  Simon Marlow committed Aug 25, 2011 912