2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
8 -- | CoreSyn holds all the main data types for use by for the Glasgow Haskell Compiler midsection
11 Expr(..), Alt, Bind(..), AltCon(..), Arg, Note(..),
12 CoreExpr, CoreAlt, CoreBind, CoreArg, CoreBndr,
13 TaggedExpr, TaggedAlt, TaggedBind, TaggedArg, TaggedBndr(..),
15 -- ** 'Expr' construction
17 mkApps, mkTyApps, mkVarApps,
19 mkIntLit, mkIntLitInt,
20 mkWordLit, mkWordLitWord,
21 mkCharLit, mkStringLit,
22 mkFloatLit, mkFloatLitFloat,
23 mkDoubleLit, mkDoubleLitDouble,
26 varToCoreExpr, varsToCoreExprs,
28 isTyVar, isId, cmpAltCon, cmpAlt, ltAlt,
30 -- ** Simple 'Expr' access functions and predicates
31 bindersOf, bindersOfBinds, rhssOfBind, rhssOfAlts,
32 collectBinders, collectTyBinders, collectValBinders, collectTyAndValBinders,
33 collectArgs, coreExprCc, flattenBinds,
35 isValArg, isTypeArg, valArgCount, valBndrCount, isRuntimeArg, isRuntimeVar,
37 -- * Unfolding data types
38 Unfolding(..), UnfoldingGuidance(..), InlineRuleInfo(..),
39 -- Abstract everywhere but in CoreUnfold.lhs
41 -- ** Constructing 'Unfolding's
42 noUnfolding, evaldUnfolding, mkOtherCon,
44 -- ** Predicates and deconstruction on 'Unfolding'
45 unfoldingTemplate, setUnfoldingTemplate,
46 maybeUnfoldingTemplate, otherCons, unfoldingArity,
47 isValueUnfolding, isEvaldUnfolding, isCheapUnfolding,
48 isExpandableUnfolding,
49 isInlineRule, isInlineRule_maybe, isClosedUnfolding, hasSomeUnfolding,
50 isStableUnfolding, canUnfold, neverUnfoldGuidance,
53 seqExpr, seqExprs, seqUnfolding,
55 -- * Annotated expression data types
56 AnnExpr, AnnExpr'(..), AnnBind(..), AnnAlt,
58 -- ** Operations on annotations
59 deAnnotate, deAnnotate', deAnnAlt, collectAnnBndrs,
61 -- * Core rule data types
62 CoreRule(..), -- CoreSubst, CoreTidy, CoreFVs, PprCore only
65 -- ** Operations on 'CoreRule's
66 seqRules, ruleArity, ruleName, ruleIdName, ruleActivation_maybe,
68 isBuiltinRule, isLocalRule
71 #include "HsVersions.h"
87 infixl 4 `mkApps`, `mkTyApps`, `mkVarApps`
88 -- Left associative, so that we can say (f `mkTyApps` xs `mkVarApps` ys)
91 %************************************************************************
93 \subsection{The main data types}
95 %************************************************************************
97 These data types are the heart of the compiler
100 infixl 8 `App` -- App brackets to the left
102 -- | This is the data type that represents GHCs core intermediate language. Currently
103 -- GHC uses System FC <http://research.microsoft.com/~simonpj/papers/ext-f/> for this purpose,
104 -- which is closely related to the simpler and better known System F <http://en.wikipedia.org/wiki/System_F>.
106 -- We get from Haskell source to this Core language in a number of stages:
108 -- 1. The source code is parsed into an abstract syntax tree, which is represented
109 -- by the data type 'HsExpr.HsExpr' with the names being 'RdrName.RdrNames'
111 -- 2. This syntax tree is /renamed/, which attaches a 'Unique.Unique' to every 'RdrName.RdrName'
112 -- (yielding a 'Name.Name') to disambiguate identifiers which are lexically identical.
113 -- For example, this program:
116 -- f x = let f x = x + 1
120 -- Would be renamed by having 'Unique's attached so it looked something like this:
123 -- f_1 x_2 = let f_3 x_4 = x_4 + 1
127 -- 3. The resulting syntax tree undergoes type checking (which also deals with instantiating
128 -- type class arguments) to yield a 'HsExpr.HsExpr' type that has 'Id.Id' as it's names.
130 -- 4. Finally the syntax tree is /desugared/ from the expressive 'HsExpr.HsExpr' type into
131 -- this 'Expr' type, which has far fewer constructors and hence is easier to perform
132 -- optimization, analysis and code generation on.
134 -- The type parameter @b@ is for the type of binders in the expression tree.
136 = Var Id -- ^ Variables
137 | Lit Literal -- ^ Primitive literals
138 | App (Expr b) (Arg b) -- ^ Applications: note that the argument may be a 'Type'.
140 -- See "CoreSyn#let_app_invariant" for another invariant
141 | Lam b (Expr b) -- ^ Lambda abstraction
142 | Let (Bind b) (Expr b) -- ^ Recursive and non recursive @let@s. Operationally
143 -- this corresponds to allocating a thunk for the things
144 -- bound and then executing the sub-expression.
146 -- #top_level_invariant#
147 -- #letrec_invariant#
149 -- The right hand sides of all top-level and recursive @let@s
150 -- /must/ be of lifted type (see "Type#type_classification" for
151 -- the meaning of /lifted/ vs. /unlifted/).
153 -- #let_app_invariant#
154 -- The right hand side of of a non-recursive 'Let' _and_ the argument of an 'App',
155 -- /may/ be of unlifted type, but only if the expression
156 -- is ok-for-speculation. This means that the let can be floated around
157 -- without difficulty. For example, this is OK:
159 -- > y::Int# = x +# 1#
161 -- But this is not, as it may affect termination if the expression is floated out:
163 -- > y::Int# = fac 4#
165 -- In this situation you should use @case@ rather than a @let@. The function
166 -- 'CoreUtils.needsCaseBinding' can help you determine which to generate, or
167 -- alternatively use 'MkCore.mkCoreLet' rather than this constructor directly,
168 -- which will generate a @case@ if necessary
171 -- We allow a /non-recursive/ let to bind a type variable, thus:
173 -- > Let (NonRec tv (Type ty)) body
175 -- This can be very convenient for postponing type substitutions until
176 -- the next run of the simplifier.
178 -- At the moment, the rest of the compiler only deals with type-let
179 -- in a Let expression, rather than at top level. We may want to revist
181 | Case (Expr b) b Type [Alt b] -- ^ Case split. Operationally this corresponds to evaluating
182 -- the scrutinee (expression examined) to weak head normal form
183 -- and then examining at most one level of resulting constructor (i.e. you
184 -- cannot do nested pattern matching directly with this).
186 -- The binder gets bound to the value of the scrutinee,
187 -- and the 'Type' must be that of all the case alternatives
190 -- This is one of the more complicated elements of the Core language, and comes
191 -- with a number of restrictions:
193 -- The 'DEFAULT' case alternative must be first in the list, if it occurs at all.
195 -- The remaining cases are in order of increasing
196 -- tag (for 'DataAlts') or
197 -- lit (for 'LitAlts').
198 -- This makes finding the relevant constructor easy, and makes comparison easier too.
200 -- The list of alternatives must be exhaustive. An /exhaustive/ case
201 -- does not necessarily mention all constructors:
204 -- data Foo = Red | Green | Blue
207 -- other -> f (case x of
212 -- The inner case does not need a @Red@ alternative, because @x@ can't be @Red@ at
213 -- that program point.
214 | Cast (Expr b) Coercion -- ^ Cast an expression to a particular type. This is used to implement @newtype@s
215 -- (a @newtype@ constructor or destructor just becomes a 'Cast' in Core) and GADTs.
216 | Note Note (Expr b) -- ^ Notes. These allow general information to be
217 -- added to expressions in the syntax tree
218 | Type Type -- ^ A type: this should only show up at the top
221 -- | Type synonym for expressions that occur in function argument positions.
222 -- Only 'Arg' should contain a 'Type' at top level, general 'Expr' should not
225 -- | A case split alternative. Consists of the constructor leading to the alternative,
226 -- the variables bound from the constructor, and the expression to be executed given that binding.
227 -- The default alternative is @(DEFAULT, [], rhs)@
228 type Alt b = (AltCon, [b], Expr b)
230 -- | A case alternative constructor (i.e. pattern match)
231 data AltCon = DataAlt DataCon -- ^ A plain data constructor: @case e of { Foo x -> ... }@.
232 -- Invariant: the 'DataCon' is always from a @data@ type, and never from a @newtype@
233 | LitAlt Literal -- ^ A literal: @case e of { 1 -> ... }@
234 | DEFAULT -- ^ Trivial alternative: @case e of { _ -> ... }@
237 -- | Binding, used for top level bindings in a module and local bindings in a @let@.
238 data Bind b = NonRec b (Expr b)
239 | Rec [(b, (Expr b))]
242 -------------------------- CoreSyn INVARIANTS ---------------------------
244 Note [CoreSyn top-level invariant]
245 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
246 See #toplevel_invariant#
248 Note [CoreSyn letrec invariant]
249 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
250 See #letrec_invariant#
252 Note [CoreSyn let/app invariant]
253 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
254 See #let_app_invariant#
256 This is intially enforced by DsUtils.mkCoreLet and mkCoreApp
258 Note [CoreSyn case invariants]
259 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
260 See #case_invariants#
262 Note [CoreSyn let goal]
263 ~~~~~~~~~~~~~~~~~~~~~~~
264 * The simplifier tries to ensure that if the RHS of a let is a constructor
265 application, its arguments are trivial, so that the constructor can be
275 -- | Allows attaching extra information to points in expressions rather than e.g. identifiers.
277 = SCC CostCentre -- ^ A cost centre annotation for profiling
278 | CoreNote String -- ^ A generic core annotation, propagated but not used by GHC
282 %************************************************************************
284 \subsection{Transformation rules}
286 %************************************************************************
288 The CoreRule type and its friends are dealt with mainly in CoreRules,
289 but CoreFVs, Subst, PprCore, CoreTidy also inspect the representation.
292 -- | A 'CoreRule' is:
294 -- * \"Local\" if the function it is a rule for is defined in the
295 -- same module as the rule itself.
297 -- * \"Orphan\" if nothing on the LHS is defined in the same module
298 -- as the rule itself
301 ru_name :: RuleName, -- ^ Name of the rule, for communication with the user
302 ru_act :: Activation, -- ^ When the rule is active
304 -- Rough-matching stuff
305 -- see comments with InstEnv.Instance( is_cls, is_rough )
306 ru_fn :: Name, -- ^ Name of the 'Id.Id' at the head of this rule
307 ru_rough :: [Maybe Name], -- ^ Name at the head of each argument to the left hand side
309 -- Proper-matching stuff
310 -- see comments with InstEnv.Instance( is_tvs, is_tys )
311 ru_bndrs :: [CoreBndr], -- ^ Variables quantified over
312 ru_args :: [CoreExpr], -- ^ Left hand side arguments
314 -- And the right-hand side
315 ru_rhs :: CoreExpr, -- ^ Right hand side of the rule
316 -- Occurrence info is guaranteed correct
317 -- See Note [OccInfo in unfoldings and rules]
320 ru_local :: Bool -- ^ @True@ iff the fn at the head of the rule is
321 -- defined in the same module as the rule
322 -- and is not an implicit 'Id' (like a record selector,
323 -- class operation, or data constructor)
325 -- NB: ru_local is *not* used to decide orphan-hood
326 -- c.g. MkIface.coreRuleToIfaceRule
329 -- | Built-in rules are used for constant folding
330 -- and suchlike. They have no free variables.
332 ru_name :: RuleName, -- ^ As above
333 ru_fn :: Name, -- ^ As above
334 ru_nargs :: Int, -- ^ Number of arguments that 'ru_try' consumes,
335 -- if it fires, including type arguments
336 ru_try :: [CoreExpr] -> Maybe CoreExpr
337 -- ^ This function does the rewrite. It given too many
338 -- arguments, it simply discards them; the returned 'CoreExpr'
339 -- is just the rewrite of 'ru_fn' applied to the first 'ru_nargs' args
341 -- See Note [Extra args in rule matching] in Rules.lhs
343 isBuiltinRule :: CoreRule -> Bool
344 isBuiltinRule (BuiltinRule {}) = True
345 isBuiltinRule _ = False
347 -- | The number of arguments the 'ru_fn' must be applied
348 -- to before the rule can match on it
349 ruleArity :: CoreRule -> Int
350 ruleArity (BuiltinRule {ru_nargs = n}) = n
351 ruleArity (Rule {ru_args = args}) = length args
353 ruleName :: CoreRule -> RuleName
356 ruleActivation_maybe :: CoreRule -> Maybe Activation
357 ruleActivation_maybe (BuiltinRule { }) = Nothing
358 ruleActivation_maybe (Rule { ru_act = act }) = Just act
360 -- | The 'Name' of the 'Id.Id' at the head of the rule left hand side
361 ruleIdName :: CoreRule -> Name
364 isLocalRule :: CoreRule -> Bool
365 isLocalRule = ru_local
367 -- | Set the 'Name' of the 'Id.Id' at the head of the rule left hand side
368 setRuleIdName :: Name -> CoreRule -> CoreRule
369 setRuleIdName nm ru = ru { ru_fn = nm }
373 %************************************************************************
377 %************************************************************************
379 The @Unfolding@ type is declared here to avoid numerous loops
382 -- | Records the /unfolding/ of an identifier, which is approximately the form the
383 -- identifier would have if we substituted its definition in for the identifier.
384 -- This type should be treated as abstract everywhere except in "CoreUnfold"
386 = NoUnfolding -- ^ We have no information about the unfolding
388 | OtherCon [AltCon] -- ^ It ain't one of these constructors.
389 -- @OtherCon xs@ also indicates that something has been evaluated
390 -- and hence there's no point in re-evaluating it.
391 -- @OtherCon []@ is used even for non-data-type values
392 -- to indicated evaluated-ness. Notably:
394 -- > data C = C !(Int -> Int)
395 -- > case x of { C f -> ... }
397 -- Here, @f@ gets an @OtherCon []@ unfolding.
399 | DFunUnfolding DataCon [CoreExpr]
400 -- The Unfolding of a DFunId
401 -- df = /\a1..am. \d1..dn. MkD (op1 a1..am d1..dn)
402 -- (op2 a1..am d1..dn)
403 -- where Arity = n, the number of dict args to the dfun
404 -- The [CoreExpr] are the superclasses and methods [op1,op2],
405 -- in positional order.
406 -- They are usually variables, but can be trivial expressions
407 -- instead (e.g. a type application).
409 | CoreUnfolding { -- An unfolding for an Id with no pragma, or perhaps a NOINLINE pragma
410 -- (For NOINLINE, the phase, if any, is in the InlinePragInfo for this Id.)
411 uf_tmpl :: CoreExpr, -- Template; occurrence info is correct
412 uf_arity :: Arity, -- Number of value arguments expected
413 uf_is_top :: Bool, -- True <=> top level binding
414 uf_is_value :: Bool, -- exprIsHNF template (cached); it is ok to discard a `seq` on
416 uf_is_cheap :: Bool, -- True <=> doesn't waste (much) work to expand inside an inlining
417 -- Cached version of exprIsCheap
418 uf_expandable :: Bool, -- True <=> can expand in RULE matching
419 -- Cached version of exprIsExpandable
420 uf_guidance :: UnfoldingGuidance -- Tells about the *size* of the template.
422 -- ^ An unfolding with redundant cached information. Parameters:
424 -- uf_tmpl: Template used to perform unfolding;
425 -- NB: Occurrence info is guaranteed correct:
426 -- see Note [OccInfo in unfoldings and rules]
428 -- uf_is_top: Is this a top level binding?
430 -- uf_is_value: 'exprIsHNF' template (cached); it is ok to discard a 'seq' on
433 -- uf_is_cheap: Does this waste only a little work if we expand it inside an inlining?
434 -- Basically this is a cached version of 'exprIsCheap'
436 -- uf_guidance: Tells us about the /size/ of the unfolding template
438 ------------------------------------------------
439 -- | 'UnfoldingGuidance' says when unfolding should take place
440 data UnfoldingGuidance
441 = UnfoldAlways -- There is /no original definition/, so you'd better unfold.
442 -- The unfolding is guaranteed to have no free variables
443 -- so no need to think about it during dependency analysis
445 | InlineRule { -- See Note [InlineRules]
446 -- Be very keen to inline this
447 -- The uf_tmpl is the *original* RHS; do *not* replace it on
448 -- each simlifier run. Hence, the *actual* RHS of the function
449 -- may be different by now, because it may have been optimised.
450 ug_ir_info :: InlineRuleInfo, -- Supplementary info about the InlineRule
451 ug_small :: Bool -- True <=> the RHS is so small (eg no bigger than a call)
452 -- that you should always inline a saturated call,
453 } -- regardless of how boring the context is
454 -- See Note [INLINE for small functions] in CoreUnfold]
456 | UnfoldIfGoodArgs { -- Arose from a normal Id; the info here is the
457 -- result of a simple analysis of the RHS
459 ug_args :: [Int], -- Discount if the argument is evaluated.
460 -- (i.e., a simplification will definitely
461 -- be possible). One elt of the list per *value* arg.
463 ug_size :: Int, -- The "size" of the unfolding.
465 ug_res :: Int -- Scrutinee discount: the discount to substract if the thing is in
466 } -- a context (case (thing args) of ...),
467 -- (where there are the right number of arguments.)
472 = InlSat -- A user-specifed or compiler injected INLINE pragma
473 -- ONLY inline when it's applied to 'arity' arguments
475 | InlUnSat -- The compiler decided to "capture" the RHS into an
476 -- InlineRule, but do not require that it appears saturated
478 | InlWrapper Id -- This unfolding is a the wrapper in a
479 -- worker/wrapper split from the strictness analyser
480 -- Used to abbreviate the uf_tmpl in interface files
481 -- which don't need to contain the RHS;
482 -- it can be derived from the strictness info
484 ------------------------------------------------
485 noUnfolding :: Unfolding
486 -- ^ There is no known 'Unfolding'
487 evaldUnfolding :: Unfolding
488 -- ^ This unfolding marks the associated thing as being evaluated
490 noUnfolding = NoUnfolding
491 evaldUnfolding = OtherCon []
493 mkOtherCon :: [AltCon] -> Unfolding
494 mkOtherCon = OtherCon
496 seqUnfolding :: Unfolding -> ()
497 seqUnfolding (CoreUnfolding { uf_tmpl = e, uf_is_top = top,
498 uf_is_value = b1, uf_is_cheap = b2,
499 uf_expandable = b3, uf_arity = a, uf_guidance = g})
500 = seqExpr e `seq` top `seq` b1 `seq` a `seq` b2 `seq` b3 `seq` seqGuidance g
504 seqGuidance :: UnfoldingGuidance -> ()
505 seqGuidance (UnfoldIfGoodArgs ns n b) = n `seq` sum ns `seq` b `seq` ()
510 -- | Retrieves the template of an unfolding: panics if none is known
511 unfoldingTemplate :: Unfolding -> CoreExpr
512 unfoldingTemplate = uf_tmpl
514 setUnfoldingTemplate :: Unfolding -> CoreExpr -> Unfolding
515 setUnfoldingTemplate unf rhs = unf { uf_tmpl = rhs }
517 -- | Retrieves the template of an unfolding if possible
518 maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
519 maybeUnfoldingTemplate (CoreUnfolding { uf_tmpl = expr }) = Just expr
520 maybeUnfoldingTemplate _ = Nothing
522 -- | The constructors that the unfolding could never be:
523 -- returns @[]@ if no information is available
524 otherCons :: Unfolding -> [AltCon]
525 otherCons (OtherCon cons) = cons
528 -- | Determines if it is certainly the case that the unfolding will
529 -- yield a value (something in HNF): returns @False@ if unsure
530 isValueUnfolding :: Unfolding -> Bool
531 -- Returns False for OtherCon
532 isValueUnfolding (CoreUnfolding { uf_is_value = is_evald }) = is_evald
533 isValueUnfolding _ = False
535 -- | Determines if it possibly the case that the unfolding will
536 -- yield a value. Unlike 'isValueUnfolding' it returns @True@
538 isEvaldUnfolding :: Unfolding -> Bool
539 -- Returns True for OtherCon
540 isEvaldUnfolding (OtherCon _) = True
541 isEvaldUnfolding (CoreUnfolding { uf_is_value = is_evald }) = is_evald
542 isEvaldUnfolding _ = False
544 -- | Is the thing we will unfold into certainly cheap?
545 isCheapUnfolding :: Unfolding -> Bool
546 isCheapUnfolding (CoreUnfolding { uf_is_cheap = is_cheap }) = is_cheap
547 isCheapUnfolding _ = False
549 isExpandableUnfolding :: Unfolding -> Bool
550 isExpandableUnfolding (CoreUnfolding { uf_expandable = is_expable }) = is_expable
551 isExpandableUnfolding _ = False
553 isInlineRule :: Unfolding -> Bool
554 isInlineRule (CoreUnfolding { uf_guidance = InlineRule {}}) = True
555 isInlineRule _ = False
557 isInlineRule_maybe :: Unfolding -> Maybe InlineRuleInfo
558 isInlineRule_maybe (CoreUnfolding {
559 uf_guidance = InlineRule { ug_ir_info = inl } }) = Just inl
560 isInlineRule_maybe _ = Nothing
562 isStableUnfolding :: Unfolding -> Bool
563 -- True of unfoldings that should not be overwritten
564 -- by a CoreUnfolding for the RHS of a let-binding
565 isStableUnfolding (CoreUnfolding { uf_guidance = InlineRule {} }) = True
566 isStableUnfolding (DFunUnfolding {}) = True
567 isStableUnfolding _ = False
569 unfoldingArity :: Unfolding -> Arity
570 unfoldingArity (CoreUnfolding { uf_arity = arity }) = arity
571 unfoldingArity _ = panic "unfoldingArity"
573 isClosedUnfolding :: Unfolding -> Bool -- No free variables
574 isClosedUnfolding (CoreUnfolding {}) = False
575 isClosedUnfolding _ = True
577 -- | Only returns False if there is no unfolding information available at all
578 hasSomeUnfolding :: Unfolding -> Bool
579 hasSomeUnfolding NoUnfolding = False
580 hasSomeUnfolding _ = True
582 neverUnfoldGuidance :: UnfoldingGuidance -> Bool
583 neverUnfoldGuidance UnfoldNever = True
584 neverUnfoldGuidance _ = False
586 canUnfold :: Unfolding -> Bool
587 canUnfold (CoreUnfolding { uf_guidance = g }) = not (neverUnfoldGuidance g)
596 you intend that calls (f e) are replaced by <rhs>[e/x] So we
597 should capture (\x.<rhs>) in the Unfolding of 'f', and never meddle
598 with it. Meanwhile, we can optimise <rhs> to our heart's content,
599 leaving the original unfolding intact in Unfolding of 'f'.
601 So the representation of an Unfolding has changed quite a bit
602 (see CoreSyn). An INLINE pragma gives rise to an InlineRule
605 Moreover, it's only used when 'f' is applied to the
606 specified number of arguments; that is, the number of argument on
607 the LHS of the '=' sign in the original source definition.
608 For example, (.) is now defined in the libraries like this
610 (.) f g = \x -> f (g x)
611 so that it'll inline when applied to two arguments. If 'x' appeared
614 it'd only inline when applied to three arguments. This slightly-experimental
615 change was requested by Roman, but it seems to make sense.
617 See also Note [Inlining an InlineRule] in CoreUnfold.
620 Note [OccInfo in unfoldings and rules]
621 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
622 In unfoldings and rules, we guarantee that the template is occ-analysed,
623 so that the occurence info on the binders is correct. This is important,
624 because the Simplifier does not re-analyse the template when using it. If
625 the occurrence info is wrong
626 - We may get more simpifier iterations than necessary, because
627 once-occ info isn't there
628 - More seriously, we may get an infinite loop if there's a Rec
629 without a loop breaker marked
632 %************************************************************************
634 \subsection{The main data type}
636 %************************************************************************
639 -- The Ord is needed for the FiniteMap used in the lookForConstructor
640 -- in SimplEnv. If you declared that lookForConstructor *ignores*
641 -- constructor-applications with LitArg args, then you could get
644 instance Outputable AltCon where
645 ppr (DataAlt dc) = ppr dc
646 ppr (LitAlt lit) = ppr lit
647 ppr DEFAULT = ptext (sLit "__DEFAULT")
649 instance Show AltCon where
650 showsPrec p con = showsPrecSDoc p (ppr con)
652 cmpAlt :: Alt b -> Alt b -> Ordering
653 cmpAlt (con1, _, _) (con2, _, _) = con1 `cmpAltCon` con2
655 ltAlt :: Alt b -> Alt b -> Bool
656 ltAlt a1 a2 = (a1 `cmpAlt` a2) == LT
658 cmpAltCon :: AltCon -> AltCon -> Ordering
659 -- ^ Compares 'AltCon's within a single list of alternatives
660 cmpAltCon DEFAULT DEFAULT = EQ
661 cmpAltCon DEFAULT _ = LT
663 cmpAltCon (DataAlt d1) (DataAlt d2) = dataConTag d1 `compare` dataConTag d2
664 cmpAltCon (DataAlt _) DEFAULT = GT
665 cmpAltCon (LitAlt l1) (LitAlt l2) = l1 `compare` l2
666 cmpAltCon (LitAlt _) DEFAULT = GT
668 cmpAltCon con1 con2 = WARN( True, text "Comparing incomparable AltCons" <+>
669 ppr con1 <+> ppr con2 )
673 %************************************************************************
675 \subsection{Useful synonyms}
677 %************************************************************************
680 -- | The common case for the type of binders and variables when
681 -- we are manipulating the Core language within GHC
683 -- | Expressions where binders are 'CoreBndr's
684 type CoreExpr = Expr CoreBndr
685 -- | Argument expressions where binders are 'CoreBndr's
686 type CoreArg = Arg CoreBndr
687 -- | Binding groups where binders are 'CoreBndr's
688 type CoreBind = Bind CoreBndr
689 -- | Case alternatives where binders are 'CoreBndr's
690 type CoreAlt = Alt CoreBndr
693 %************************************************************************
697 %************************************************************************
700 -- | Binders are /tagged/ with a t
701 data TaggedBndr t = TB CoreBndr t -- TB for "tagged binder"
703 type TaggedBind t = Bind (TaggedBndr t)
704 type TaggedExpr t = Expr (TaggedBndr t)
705 type TaggedArg t = Arg (TaggedBndr t)
706 type TaggedAlt t = Alt (TaggedBndr t)
708 instance Outputable b => Outputable (TaggedBndr b) where
709 ppr (TB b l) = char '<' <> ppr b <> comma <> ppr l <> char '>'
711 instance Outputable b => OutputableBndr (TaggedBndr b) where
712 pprBndr _ b = ppr b -- Simple
716 %************************************************************************
718 \subsection{Core-constructing functions with checking}
720 %************************************************************************
723 -- | Apply a list of argument expressions to a function expression in a nested fashion. Prefer to
724 -- use 'CoreUtils.mkCoreApps' if possible
725 mkApps :: Expr b -> [Arg b] -> Expr b
726 -- | Apply a list of type argument expressions to a function expression in a nested fashion
727 mkTyApps :: Expr b -> [Type] -> Expr b
728 -- | Apply a list of type or value variables to a function expression in a nested fashion
729 mkVarApps :: Expr b -> [Var] -> Expr b
730 -- | Apply a list of argument expressions to a data constructor in a nested fashion. Prefer to
731 -- use 'MkCore.mkCoreConApps' if possible
732 mkConApp :: DataCon -> [Arg b] -> Expr b
734 mkApps f args = foldl App f args
735 mkTyApps f args = foldl (\ e a -> App e (Type a)) f args
736 mkVarApps f vars = foldl (\ e a -> App e (varToCoreExpr a)) f vars
737 mkConApp con args = mkApps (Var (dataConWorkId con)) args
740 -- | Create a machine integer literal expression of type @Int#@ from an @Integer@.
741 -- If you want an expression of type @Int@ use 'MkCore.mkIntExpr'
742 mkIntLit :: Integer -> Expr b
743 -- | Create a machine integer literal expression of type @Int#@ from an @Int@.
744 -- If you want an expression of type @Int@ use 'MkCore.mkIntExpr'
745 mkIntLitInt :: Int -> Expr b
747 mkIntLit n = Lit (mkMachInt n)
748 mkIntLitInt n = Lit (mkMachInt (toInteger n))
750 -- | Create a machine word literal expression of type @Word#@ from an @Integer@.
751 -- If you want an expression of type @Word@ use 'MkCore.mkWordExpr'
752 mkWordLit :: Integer -> Expr b
753 -- | Create a machine word literal expression of type @Word#@ from a @Word@.
754 -- If you want an expression of type @Word@ use 'MkCore.mkWordExpr'
755 mkWordLitWord :: Word -> Expr b
757 mkWordLit w = Lit (mkMachWord w)
758 mkWordLitWord w = Lit (mkMachWord (toInteger w))
760 -- | Create a machine character literal expression of type @Char#@.
761 -- If you want an expression of type @Char@ use 'MkCore.mkCharExpr'
762 mkCharLit :: Char -> Expr b
763 -- | Create a machine string literal expression of type @Addr#@.
764 -- If you want an expression of type @String@ use 'MkCore.mkStringExpr'
765 mkStringLit :: String -> Expr b
767 mkCharLit c = Lit (mkMachChar c)
768 mkStringLit s = Lit (mkMachString s)
770 -- | Create a machine single precision literal expression of type @Float#@ from a @Rational@.
771 -- If you want an expression of type @Float@ use 'MkCore.mkFloatExpr'
772 mkFloatLit :: Rational -> Expr b
773 -- | Create a machine single precision literal expression of type @Float#@ from a @Float@.
774 -- If you want an expression of type @Float@ use 'MkCore.mkFloatExpr'
775 mkFloatLitFloat :: Float -> Expr b
777 mkFloatLit f = Lit (mkMachFloat f)
778 mkFloatLitFloat f = Lit (mkMachFloat (toRational f))
780 -- | Create a machine double precision literal expression of type @Double#@ from a @Rational@.
781 -- If you want an expression of type @Double@ use 'MkCore.mkDoubleExpr'
782 mkDoubleLit :: Rational -> Expr b
783 -- | Create a machine double precision literal expression of type @Double#@ from a @Double@.
784 -- If you want an expression of type @Double@ use 'MkCore.mkDoubleExpr'
785 mkDoubleLitDouble :: Double -> Expr b
787 mkDoubleLit d = Lit (mkMachDouble d)
788 mkDoubleLitDouble d = Lit (mkMachDouble (toRational d))
790 -- | Bind all supplied binding groups over an expression in a nested let expression. Prefer to
791 -- use 'CoreUtils.mkCoreLets' if possible
792 mkLets :: [Bind b] -> Expr b -> Expr b
793 -- | Bind all supplied binders over an expression in a nested lambda expression. Prefer to
794 -- use 'CoreUtils.mkCoreLams' if possible
795 mkLams :: [b] -> Expr b -> Expr b
797 mkLams binders body = foldr Lam body binders
798 mkLets binds body = foldr Let body binds
801 -- | Create a binding group where a type variable is bound to a type. Per "CoreSyn#type_let",
802 -- this can only be used to bind something in a non-recursive @let@ expression
803 mkTyBind :: TyVar -> Type -> CoreBind
804 mkTyBind tv ty = NonRec tv (Type ty)
806 -- | Convert a binder into either a 'Var' or 'Type' 'Expr' appropriately
807 varToCoreExpr :: CoreBndr -> Expr b
808 varToCoreExpr v | isId v = Var v
809 | otherwise = Type (mkTyVarTy v)
811 varsToCoreExprs :: [CoreBndr] -> [Expr b]
812 varsToCoreExprs vs = map varToCoreExpr vs
816 %************************************************************************
818 \subsection{Simple access functions}
820 %************************************************************************
823 -- | Extract every variable by this group
824 bindersOf :: Bind b -> [b]
825 bindersOf (NonRec binder _) = [binder]
826 bindersOf (Rec pairs) = [binder | (binder, _) <- pairs]
828 -- | 'bindersOf' applied to a list of binding groups
829 bindersOfBinds :: [Bind b] -> [b]
830 bindersOfBinds binds = foldr ((++) . bindersOf) [] binds
832 rhssOfBind :: Bind b -> [Expr b]
833 rhssOfBind (NonRec _ rhs) = [rhs]
834 rhssOfBind (Rec pairs) = [rhs | (_,rhs) <- pairs]
836 rhssOfAlts :: [Alt b] -> [Expr b]
837 rhssOfAlts alts = [e | (_,_,e) <- alts]
839 -- | Collapse all the bindings in the supplied groups into a single
840 -- list of lhs\/rhs pairs suitable for binding in a 'Rec' binding group
841 flattenBinds :: [Bind b] -> [(b, Expr b)]
842 flattenBinds (NonRec b r : binds) = (b,r) : flattenBinds binds
843 flattenBinds (Rec prs1 : binds) = prs1 ++ flattenBinds binds
848 -- | We often want to strip off leading lambdas before getting down to
849 -- business. This function is your friend.
850 collectBinders :: Expr b -> ([b], Expr b)
851 -- | Collect as many type bindings as possible from the front of a nested lambda
852 collectTyBinders :: CoreExpr -> ([TyVar], CoreExpr)
853 -- | Collect as many value bindings as possible from the front of a nested lambda
854 collectValBinders :: CoreExpr -> ([Id], CoreExpr)
855 -- | Collect type binders from the front of the lambda first,
856 -- then follow up by collecting as many value bindings as possible
857 -- from the resulting stripped expression
858 collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)
863 go bs (Lam b e) = go (b:bs) e
864 go bs e = (reverse bs, e)
866 collectTyAndValBinders expr
869 (tvs, body1) = collectTyBinders expr
870 (ids, body) = collectValBinders body1
872 collectTyBinders expr
875 go tvs (Lam b e) | isTyVar b = go (b:tvs) e
876 go tvs e = (reverse tvs, e)
878 collectValBinders expr
881 go ids (Lam b e) | isId b = go (b:ids) e
882 go ids body = (reverse ids, body)
886 -- | Takes a nested application expression and returns the the function
887 -- being applied and the arguments to which it is applied
888 collectArgs :: Expr b -> (Expr b, [Arg b])
892 go (App f a) as = go f (a:as)
897 -- | Gets the cost centre enclosing an expression, if any.
898 -- It looks inside lambdas because @(scc \"foo\" \\x.e) = \\x. scc \"foo\" e@
899 coreExprCc :: Expr b -> CostCentre
900 coreExprCc (Note (SCC cc) _) = cc
901 coreExprCc (Note _ e) = coreExprCc e
902 coreExprCc (Lam _ e) = coreExprCc e
903 coreExprCc _ = noCostCentre
906 %************************************************************************
908 \subsection{Predicates}
910 %************************************************************************
912 At one time we optionally carried type arguments through to runtime.
913 @isRuntimeVar v@ returns if (Lam v _) really becomes a lambda at runtime,
914 i.e. if type applications are actual lambdas because types are kept around
915 at runtime. Similarly isRuntimeArg.
918 -- | Will this variable exist at runtime?
919 isRuntimeVar :: Var -> Bool
922 -- | Will this argument expression exist at runtime?
923 isRuntimeArg :: CoreExpr -> Bool
924 isRuntimeArg = isValArg
926 -- | Returns @False@ iff the expression is a 'Type' expression at its top level
927 isValArg :: Expr b -> Bool
928 isValArg (Type _) = False
931 -- | Returns @True@ iff the expression is a 'Type' expression at its top level
932 isTypeArg :: Expr b -> Bool
933 isTypeArg (Type _) = True
936 -- | The number of binders that bind values rather than types
937 valBndrCount :: [CoreBndr] -> Int
938 valBndrCount = count isId
940 -- | The number of argument expressions that are values rather than types at their top level
941 valArgCount :: [Arg b] -> Int
942 valArgCount = count isValArg
946 %************************************************************************
948 \subsection{Seq stuff}
950 %************************************************************************
953 seqExpr :: CoreExpr -> ()
954 seqExpr (Var v) = v `seq` ()
955 seqExpr (Lit lit) = lit `seq` ()
956 seqExpr (App f a) = seqExpr f `seq` seqExpr a
957 seqExpr (Lam b e) = seqBndr b `seq` seqExpr e
958 seqExpr (Let b e) = seqBind b `seq` seqExpr e
959 seqExpr (Case e b t as) = seqExpr e `seq` seqBndr b `seq` seqType t `seq` seqAlts as
960 seqExpr (Cast e co) = seqExpr e `seq` seqType co
961 seqExpr (Note n e) = seqNote n `seq` seqExpr e
962 seqExpr (Type t) = seqType t
964 seqExprs :: [CoreExpr] -> ()
966 seqExprs (e:es) = seqExpr e `seq` seqExprs es
968 seqNote :: Note -> ()
969 seqNote (CoreNote s) = s `seq` ()
972 seqBndr :: CoreBndr -> ()
973 seqBndr b = b `seq` ()
975 seqBndrs :: [CoreBndr] -> ()
977 seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs
979 seqBind :: Bind CoreBndr -> ()
980 seqBind (NonRec b e) = seqBndr b `seq` seqExpr e
981 seqBind (Rec prs) = seqPairs prs
983 seqPairs :: [(CoreBndr, CoreExpr)] -> ()
985 seqPairs ((b,e):prs) = seqBndr b `seq` seqExpr e `seq` seqPairs prs
987 seqAlts :: [CoreAlt] -> ()
989 seqAlts ((c,bs,e):alts) = c `seq` seqBndrs bs `seq` seqExpr e `seq` seqAlts alts
991 seqRules :: [CoreRule] -> ()
993 seqRules (Rule { ru_bndrs = bndrs, ru_args = args, ru_rhs = rhs } : rules)
994 = seqBndrs bndrs `seq` seqExprs (rhs:args) `seq` seqRules rules
995 seqRules (BuiltinRule {} : rules) = seqRules rules
998 %************************************************************************
1000 \subsection{Annotated core}
1002 %************************************************************************
1005 -- | Annotated core: allows annotation at every node in the tree
1006 type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)
1008 -- | A clone of the 'Expr' type but allowing annotation at every tree node
1009 data AnnExpr' bndr annot
1012 | AnnLam bndr (AnnExpr bndr annot)
1013 | AnnApp (AnnExpr bndr annot) (AnnExpr bndr annot)
1014 | AnnCase (AnnExpr bndr annot) bndr Type [AnnAlt bndr annot]
1015 | AnnLet (AnnBind bndr annot) (AnnExpr bndr annot)
1016 | AnnCast (AnnExpr bndr annot) Coercion
1017 | AnnNote Note (AnnExpr bndr annot)
1020 -- | A clone of the 'Alt' type but allowing annotation at every tree node
1021 type AnnAlt bndr annot = (AltCon, [bndr], AnnExpr bndr annot)
1023 -- | A clone of the 'Bind' type but allowing annotation at every tree node
1024 data AnnBind bndr annot
1025 = AnnNonRec bndr (AnnExpr bndr annot)
1026 | AnnRec [(bndr, AnnExpr bndr annot)]
1030 deAnnotate :: AnnExpr bndr annot -> Expr bndr
1031 deAnnotate (_, e) = deAnnotate' e
1033 deAnnotate' :: AnnExpr' bndr annot -> Expr bndr
1034 deAnnotate' (AnnType t) = Type t
1035 deAnnotate' (AnnVar v) = Var v
1036 deAnnotate' (AnnLit lit) = Lit lit
1037 deAnnotate' (AnnLam binder body) = Lam binder (deAnnotate body)
1038 deAnnotate' (AnnApp fun arg) = App (deAnnotate fun) (deAnnotate arg)
1039 deAnnotate' (AnnCast e co) = Cast (deAnnotate e) co
1040 deAnnotate' (AnnNote note body) = Note note (deAnnotate body)
1042 deAnnotate' (AnnLet bind body)
1043 = Let (deAnnBind bind) (deAnnotate body)
1045 deAnnBind (AnnNonRec var rhs) = NonRec var (deAnnotate rhs)
1046 deAnnBind (AnnRec pairs) = Rec [(v,deAnnotate rhs) | (v,rhs) <- pairs]
1048 deAnnotate' (AnnCase scrut v t alts)
1049 = Case (deAnnotate scrut) v t (map deAnnAlt alts)
1051 deAnnAlt :: AnnAlt bndr annot -> Alt bndr
1052 deAnnAlt (con,args,rhs) = (con,args,deAnnotate rhs)
1056 -- | As 'collectBinders' but for 'AnnExpr' rather than 'Expr'
1057 collectAnnBndrs :: AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
1061 collect bs (_, AnnLam b body) = collect (b:bs) body
1062 collect bs body = (reverse bs, body)