1 {-# LANGUAGE PackageImports #-}
3 -- Functions to bring a Core expression in normal form. This module provides a
4 -- top level function "normalize", and defines the actual transformation passes that
7 module CLasH.Normalize (getNormalized, normalizeExpr, splitNormalized) where
11 import qualified Maybe
13 import qualified "transformers" Control.Monad.Trans as Trans
14 import qualified Control.Monad as Monad
15 import qualified Control.Monad.Trans.Writer as Writer
16 import qualified Data.Map as Map
17 import qualified Data.Monoid as Monoid
22 import qualified UniqSupply
23 import qualified CoreUtils
25 import qualified TcType
28 import qualified VarSet
29 import qualified NameSet
30 import qualified CoreFVs
31 import qualified CoreUtils
32 import qualified MkCore
33 import qualified HscTypes
34 import Outputable ( showSDoc, ppr, nest )
37 import CLasH.Normalize.NormalizeTypes
38 import CLasH.Translator.TranslatorTypes
39 import CLasH.Normalize.NormalizeTools
40 import CLasH.VHDL.VHDLTypes
41 import qualified CLasH.Utils as Utils
42 import CLasH.Utils.Core.CoreTools
43 import CLasH.Utils.Core.BinderTools
44 import CLasH.Utils.Pretty
46 --------------------------------
47 -- Start of transformations
48 --------------------------------
50 --------------------------------
52 --------------------------------
53 eta, etatop :: Transform
54 eta expr | is_fun expr && not (is_lam expr) = do
55 let arg_ty = (fst . Type.splitFunTy . CoreUtils.exprType) expr
56 id <- Trans.lift $ mkInternalVar "param" arg_ty
57 change (Lam id (App expr (Var id)))
58 -- Leave all other expressions unchanged
60 etatop = notappargs ("eta", eta)
62 --------------------------------
64 --------------------------------
65 beta, betatop :: Transform
66 -- Substitute arg for x in expr
67 beta (App (Lam x expr) arg) = change $ substitute [(x, arg)] expr
68 -- Propagate the application into the let
69 beta (App (Let binds expr) arg) = change $ Let binds (App expr arg)
70 -- Propagate the application into each of the alternatives
71 beta (App (Case scrut b ty alts) arg) = change $ Case scrut b ty' alts'
73 alts' = map (\(con, bndrs, expr) -> (con, bndrs, (App expr arg))) alts
74 ty' = CoreUtils.applyTypeToArg ty arg
75 -- Leave all other expressions unchanged
76 beta expr = return expr
77 -- Perform this transform everywhere
78 betatop = everywhere ("beta", beta)
80 --------------------------------
82 --------------------------------
83 -- Try to move casts as much downward as possible.
84 castprop, castproptop :: Transform
85 castprop (Cast (Let binds expr) ty) = change $ Let binds (Cast expr ty)
86 castprop expr@(Cast (Case scrut b _ alts) ty) = change (Case scrut b ty alts')
88 alts' = map (\(con, bndrs, expr) -> (con, bndrs, (Cast expr ty))) alts
89 -- Leave all other expressions unchanged
90 castprop expr = return expr
91 -- Perform this transform everywhere
92 castproptop = everywhere ("castprop", castprop)
94 --------------------------------
95 -- Cast simplification. Mostly useful for state packing and unpacking, but
96 -- perhaps for others as well.
97 --------------------------------
98 castsimpl, castsimpltop :: Transform
99 castsimpl expr@(Cast val ty) = do
100 -- Don't extract values that are already simpl
101 local_var <- Trans.lift $ is_local_var val
102 -- Don't extract values that are not representable, to prevent loops with
105 if (not local_var) && repr
107 -- Generate a binder for the expression
108 id <- Trans.lift $ mkBinderFor val "castval"
109 -- Extract the expression
110 change $ Let (NonRec id val) (Cast (Var id) ty)
113 -- Leave all other expressions unchanged
114 castsimpl expr = return expr
115 -- Perform this transform everywhere
116 castsimpltop = everywhere ("castsimpl", castsimpl)
118 --------------------------------
119 -- let derecursification
120 --------------------------------
121 letderec, letderectop :: Transform
122 letderec expr@(Let (Rec binds) res) = case liftable of
123 -- Nothing is liftable, just return
125 -- Something can be lifted, generate a new let expression
126 _ -> change $ MkCore.mkCoreLets newbinds res
128 -- Make a list of all the binders bound in this recursive let
129 bndrs = map fst binds
130 -- See which bindings are liftable
131 (liftable, nonliftable) = List.partition canlift binds
132 -- Create nonrec bindings for each liftable binding and a single recursive
133 -- binding for all others
134 newbinds = (map (uncurry NonRec) liftable) ++ [Rec nonliftable]
135 -- Any expression that does not use any of the binders in this recursive let
136 -- can be lifted into a nonrec let. It can't use its own binder either,
137 -- since that would mean the binding is self-recursive and should be in a
138 -- single bind recursive let.
139 canlift (bndr, e) = not $ expr_uses_binders bndrs e
140 -- Leave all other expressions unchanged
141 letderec expr = return expr
142 -- Perform this transform everywhere
143 letderectop = everywhere ("letderec", letderec)
145 --------------------------------
146 -- let simplification
147 --------------------------------
148 letsimpl, letsimpltop :: Transform
149 -- Put the "in ..." value of a let in its own binding, but not when the
150 -- expression is already a local variable, or not representable (to prevent loops with inlinenonrep).
151 letsimpl expr@(Let (Rec binds) res) = do
153 local_var <- Trans.lift $ is_local_var res
154 if not local_var && repr
156 -- If the result is not a local var already (to prevent loops with
157 -- ourselves), extract it.
158 id <- Trans.lift $ mkBinderFor res "foo"
160 change $ Let (Rec (bind:binds)) (Var id)
162 -- If the result is already a local var, don't extract it.
165 -- Leave all other expressions unchanged
166 letsimpl expr = return expr
167 -- Perform this transform everywhere
168 letsimpltop = everywhere ("letsimpl", letsimpl)
170 --------------------------------
172 --------------------------------
173 letflat, letflattop :: Transform
174 letflat (Let (Rec binds) expr) = do
175 -- Turn each binding into a list of bindings (possibly containing just one
176 -- element, of course)
177 bindss <- Monad.mapM flatbind binds
178 -- Concat all the bindings
179 let binds' = concat bindss
180 -- Return the new let. We don't use change here, since possibly nothing has
181 -- changed. If anything has changed, flatbind has already flagged that
183 return $ Let (Rec binds') expr
185 -- Turns a binding of a let into a multiple bindings, or any other binding
186 -- into a list with just that binding
187 flatbind :: (CoreBndr, CoreExpr) -> TransformMonad [(CoreBndr, CoreExpr)]
188 flatbind (b, Let (Rec binds) expr) = change ((b, expr):binds)
189 flatbind (b, expr) = return [(b, expr)]
190 -- Leave all other expressions unchanged
191 letflat expr = return expr
192 -- Perform this transform everywhere
193 letflattop = everywhere ("letflat", letflat)
195 --------------------------------
196 -- Simple let binding removal
197 --------------------------------
198 -- Remove a = b bindings from let expressions everywhere
199 letremovetop :: Transform
200 letremovetop = everywhere ("letremove", inlinebind (\(b, e) -> Trans.lift $ is_local_var e))
202 --------------------------------
203 -- Unused let binding removal
204 --------------------------------
205 letremoveunused, letremoveunusedtop :: Transform
206 letremoveunused expr@(Let (Rec binds) res) = do
207 -- Filter out all unused binds.
208 let binds' = filter dobind binds
209 -- Only set the changed flag if binds got removed
210 changeif (length binds' /= length binds) (Let (Rec binds') res)
212 bound_exprs = map snd binds
213 -- For each bind check if the bind is used by res or any of the bound
215 dobind (bndr, _) = any (expr_uses_binders [bndr]) (res:bound_exprs)
216 -- Leave all other expressions unchanged
217 letremoveunused expr = return expr
218 letremoveunusedtop = everywhere ("letremoveunused", letremoveunused)
220 --------------------------------
221 -- Identical let binding merging
222 --------------------------------
223 -- Merge two bindings in a let if they are identical
224 -- TODO: We would very much like to use GHC's CSE module for this, but that
225 -- doesn't track if something changed or not, so we can't use it properly.
226 letmerge, letmergetop :: Transform
227 letmerge expr@(Let (Rec binds) res) = do
228 binds' <- domerge binds
229 return (Let (Rec binds') res)
231 domerge :: [(CoreBndr, CoreExpr)] -> TransformMonad [(CoreBndr, CoreExpr)]
232 domerge [] = return []
234 es' <- mapM (mergebinds e) es
238 -- Uses the second bind to simplify the second bind, if applicable.
239 mergebinds :: (CoreBndr, CoreExpr) -> (CoreBndr, CoreExpr) -> TransformMonad (CoreBndr, CoreExpr)
240 mergebinds (b1, e1) (b2, e2)
241 -- Identical expressions? Replace the second binding with a reference to
243 | CoreUtils.cheapEqExpr e1 e2 = change $ (b2, Var b1)
244 -- Different expressions? Don't change
245 | otherwise = return (b2, e2)
246 -- Leave all other expressions unchanged
247 letmerge expr = return expr
248 letmergetop = everywhere ("letmerge", letmerge)
250 --------------------------------
252 --------------------------------
253 -- Remove a = B bindings, with B :: a -> b, or B :: forall x . T, from let
254 -- expressions everywhere. This means that any value that still needs to be
255 -- applied to something else (polymorphic values need to be applied to a
256 -- Type) will be inlined, and will eventually be applied to all their
259 -- This is a tricky function, which is prone to create loops in the
260 -- transformations. To fix this, we make sure that no transformation will
261 -- create a new let binding with a function type. These other transformations
262 -- will just not work on those function-typed values at first, but the other
263 -- transformations (in particular β-reduction) should make sure that the type
264 -- of those values eventually becomes primitive.
265 inlinenonreptop :: Transform
266 inlinenonreptop = everywhere ("inlinenonrep", inlinebind ((Monad.liftM not) . isRepr . snd))
268 --------------------------------
269 -- Scrutinee simplification
270 --------------------------------
271 scrutsimpl,scrutsimpltop :: Transform
272 -- Don't touch scrutinees that are already simple
273 scrutsimpl expr@(Case (Var _) _ _ _) = return expr
274 -- Replace all other cases with a let that binds the scrutinee and a new
275 -- simple scrutinee, but only when the scrutinee is representable (to prevent
276 -- loops with inlinenonrep, though I don't think a non-representable scrutinee
277 -- will be supported anyway...)
278 scrutsimpl expr@(Case scrut b ty alts) = do
282 id <- Trans.lift $ mkBinderFor scrut "scrut"
283 change $ Let (NonRec id scrut) (Case (Var id) b ty alts)
286 -- Leave all other expressions unchanged
287 scrutsimpl expr = return expr
288 -- Perform this transform everywhere
289 scrutsimpltop = everywhere ("scrutsimpl", scrutsimpl)
291 --------------------------------
292 -- Case binder wildening
293 --------------------------------
294 casesimpl, casesimpltop :: Transform
295 -- This is already a selector case (or, if x does not appear in bndrs, a very
296 -- simple case statement that will be removed by caseremove below). Just leave
298 casesimpl expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr
299 -- Make sure that all case alternatives have only wild binders and simple
301 -- This is done by creating a new let binding for each non-wild binder, which
302 -- is bound to a new simple selector case statement and for each complex
303 -- expression. We do this only for representable types, to prevent loops with
305 casesimpl expr@(Case scrut b ty alts) = do
306 (bindingss, alts') <- (Monad.liftM unzip) $ mapM doalt alts
307 let bindings = concat bindingss
308 -- Replace the case with a let with bindings and a case
309 let newlet = (Let (Rec bindings) (Case scrut b ty alts'))
310 -- If there are no non-wild binders, or this case is already a simple
311 -- selector (i.e., a single alt with exactly one binding), already a simple
312 -- selector altan no bindings (i.e., no wild binders in the original case),
313 -- don't change anything, otherwise, replace the case.
314 if null bindings then return expr else change newlet
316 -- Generate a single wild binder, since they are all the same
317 wild = MkCore.mkWildBinder
318 -- Wilden the binders of one alt, producing a list of bindings as a
320 doalt :: CoreAlt -> TransformMonad ([(CoreBndr, CoreExpr)], CoreAlt)
321 doalt (con, bndrs, expr) = do
322 -- Make each binder wild, if possible
323 bndrs_res <- Monad.zipWithM dobndr bndrs [0..]
324 let (newbndrs, bindings_maybe) = unzip bndrs_res
325 -- Extract a complex expression, if possible. For this we check if any of
326 -- the new list of bndrs are used by expr. We can't use free_vars here,
327 -- since that looks at the old bndrs.
328 let uses_bndrs = not $ VarSet.isEmptyVarSet $ CoreFVs.exprSomeFreeVars (`elem` newbndrs) $ expr
329 (exprbinding_maybe, expr') <- doexpr expr uses_bndrs
330 -- Create a new alternative
331 let newalt = (con, newbndrs, expr')
332 let bindings = Maybe.catMaybes (exprbinding_maybe : bindings_maybe)
333 return (bindings, newalt)
335 -- Make wild alternatives for each binder
336 wildbndrs = map (\bndr -> MkCore.mkWildBinder (Id.idType bndr)) bndrs
337 -- A set of all the binders that are used by the expression
338 free_vars = CoreFVs.exprSomeFreeVars (`elem` bndrs) expr
339 -- Look at the ith binder in the case alternative. Return a new binder
340 -- for it (either the same one, or a wild one) and optionally a let
341 -- binding containing a case expression.
342 dobndr :: CoreBndr -> Int -> TransformMonad (CoreBndr, Maybe (CoreBndr, CoreExpr))
344 repr <- isRepr (Var b)
345 -- Is b wild (e.g., not a free var of expr. Since b is only in scope
346 -- in expr, this means that b is unused if expr does not use it.)
347 let wild = not (VarSet.elemVarSet b free_vars)
348 -- Create a new binding for any representable binder that is not
349 -- already wild and is representable (to prevent loops with
351 if (not wild) && repr
353 -- Create on new binder that will actually capture a value in this
354 -- case statement, and return it.
355 let bty = (Id.idType b)
356 id <- Trans.lift $ mkInternalVar "sel" bty
357 let binders = take i wildbndrs ++ [id] ++ drop (i+1) wildbndrs
358 let caseexpr = Case scrut b bty [(con, binders, Var id)]
359 return (wildbndrs!!i, Just (b, caseexpr))
361 -- Just leave the original binder in place, and don't generate an
362 -- extra selector case.
364 -- Process the expression of a case alternative. Accepts an expression
365 -- and whether this expression uses any of the binders in the
366 -- alternative. Returns an optional new binding and a new expression.
367 doexpr :: CoreExpr -> Bool -> TransformMonad (Maybe (CoreBndr, CoreExpr), CoreExpr)
368 doexpr expr uses_bndrs = do
369 local_var <- Trans.lift $ is_local_var expr
371 -- Extract any expressions that do not use any binders from this
372 -- alternative, is not a local var already and is representable (to
373 -- prevent loops with inlinenonrep).
374 if (not uses_bndrs) && (not local_var) && repr
376 id <- Trans.lift $ mkBinderFor expr "caseval"
377 -- We don't flag a change here, since casevalsimpl will do that above
378 -- based on Just we return here.
379 return $ (Just (id, expr), Var id)
381 -- Don't simplify anything else
382 return (Nothing, expr)
383 -- Leave all other expressions unchanged
384 casesimpl expr = return expr
385 -- Perform this transform everywhere
386 casesimpltop = everywhere ("casesimpl", casesimpl)
388 --------------------------------
390 --------------------------------
391 -- Remove case statements that have only a single alternative and only wild
393 caseremove, caseremovetop :: Transform
394 -- Replace a useless case by the value of its single alternative
395 caseremove (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr
396 -- Find if any of the binders are used by expr
397 where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
398 -- Leave all other expressions unchanged
399 caseremove expr = return expr
400 -- Perform this transform everywhere
401 caseremovetop = everywhere ("caseremove", caseremove)
403 --------------------------------
404 -- Argument extraction
405 --------------------------------
406 -- Make sure that all arguments of a representable type are simple variables.
407 appsimpl, appsimpltop :: Transform
408 -- Simplify all representable arguments. Do this by introducing a new Let
409 -- that binds the argument and passing the new binder in the application.
410 appsimpl expr@(App f arg) = do
411 -- Check runtime representability
413 local_var <- Trans.lift $ is_local_var arg
414 if repr && not local_var
415 then do -- Extract representable arguments
416 id <- Trans.lift $ mkBinderFor arg "arg"
417 change $ Let (NonRec id arg) (App f (Var id))
418 else -- Leave non-representable arguments unchanged
420 -- Leave all other expressions unchanged
421 appsimpl expr = return expr
422 -- Perform this transform everywhere
423 appsimpltop = everywhere ("appsimpl", appsimpl)
425 --------------------------------
426 -- Function-typed argument propagation
427 --------------------------------
428 -- Remove all applications to function-typed arguments, by duplication the
429 -- function called with the function-typed parameter replaced by the free
430 -- variables of the argument passed in.
431 argprop, argproptop :: Transform
432 -- Transform any application of a named function (i.e., skip applications of
433 -- lambda's). Also skip applications that have arguments with free type
434 -- variables, since we can't inline those.
435 argprop expr@(App _ _) | is_var fexpr = do
436 -- Find the body of the function called
437 body_maybe <- Trans.lift $ getGlobalBind f
440 -- Process each of the arguments in turn
441 (args', changed) <- Writer.listen $ mapM doarg args
442 -- See if any of the arguments changed
443 case Monoid.getAny changed of
445 let (newargs', newparams', oldargs) = unzip3 args'
446 let newargs = concat newargs'
447 let newparams = concat newparams'
448 -- Create a new body that consists of a lambda for all new arguments and
449 -- the old body applied to some arguments.
450 let newbody = MkCore.mkCoreLams newparams (MkCore.mkCoreApps body oldargs)
451 -- Create a new function with the same name but a new body
452 newf <- Trans.lift $ mkFunction f newbody
453 -- Replace the original application with one of the new function to the
455 change $ MkCore.mkCoreApps (Var newf) newargs
457 -- Don't change the expression if none of the arguments changed
460 -- If we don't have a body for the function called, leave it unchanged (it
461 -- should be a primitive function then).
462 Nothing -> return expr
464 -- Find the function called and the arguments
465 (fexpr, args) = collectArgs expr
468 -- Process a single argument and return (args, bndrs, arg), where args are
469 -- the arguments to replace the given argument in the original
470 -- application, bndrs are the binders to include in the top-level lambda
471 -- in the new function body, and arg is the argument to apply to the old
473 doarg :: CoreExpr -> TransformMonad ([CoreExpr], [CoreBndr], CoreExpr)
476 bndrs <- Trans.lift getGlobalBinders
477 let interesting var = Var.isLocalVar var && (not $ var `elem` bndrs)
478 if not repr && not (is_var arg && interesting (exprToVar arg)) && not (has_free_tyvars arg)
480 -- Propagate all complex arguments that are not representable, but not
481 -- arguments with free type variables (since those would require types
482 -- not known yet, which will always be known eventually).
483 -- Find interesting free variables, each of which should be passed to
484 -- the new function instead of the original function argument.
486 -- Interesting vars are those that are local, but not available from the
487 -- top level scope (functions from this module are defined as local, but
488 -- they're not local to this function, so we can freely move references
489 -- to them into another function).
490 let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting arg
491 -- Mark the current expression as changed
493 return (map Var free_vars, free_vars, arg)
495 -- Representable types will not be propagated, and arguments with free
496 -- type variables will be propagated later.
497 -- TODO: preserve original naming?
498 id <- Trans.lift $ mkBinderFor arg "param"
499 -- Just pass the original argument to the new function, which binds it
500 -- to a new id and just pass that new id to the old function body.
501 return ([arg], [id], mkReferenceTo id)
502 -- Leave all other expressions unchanged
503 argprop expr = return expr
504 -- Perform this transform everywhere
505 argproptop = everywhere ("argprop", argprop)
507 --------------------------------
508 -- Function-typed argument extraction
509 --------------------------------
510 -- This transform takes any function-typed argument that cannot be propagated
511 -- (because the function that is applied to it is a builtin function), and
512 -- puts it in a brand new top level binder. This allows us to for example
513 -- apply map to a lambda expression This will not conflict with inlinenonrep,
514 -- since that only inlines local let bindings, not top level bindings.
515 funextract, funextracttop :: Transform
516 funextract expr@(App _ _) | is_var fexpr = do
517 body_maybe <- Trans.lift $ getGlobalBind f
519 -- We don't have a function body for f, so we can perform this transform.
521 -- Find the new arguments
522 args' <- mapM doarg args
523 -- And update the arguments. We use return instead of changed, so the
524 -- changed flag doesn't get set if none of the args got changed.
525 return $ MkCore.mkCoreApps fexpr args'
526 -- We have a function body for f, leave this application to funprop
527 Just _ -> return expr
529 -- Find the function called and the arguments
530 (fexpr, args) = collectArgs expr
532 -- Change any arguments that have a function type, but are not simple yet
533 -- (ie, a variable or application). This means to create a new function
534 -- for map (\f -> ...) b, but not for map (foo a) b.
536 -- We could use is_applicable here instead of is_fun, but I think
537 -- arguments to functions could only have forall typing when existential
538 -- typing is enabled. Not sure, though.
539 doarg arg | not (is_simple arg) && is_fun arg = do
540 -- Create a new top level binding that binds the argument. Its body will
541 -- be extended with lambda expressions, to take any free variables used
542 -- by the argument expression.
543 let free_vars = VarSet.varSetElems $ CoreFVs.exprFreeVars arg
544 let body = MkCore.mkCoreLams free_vars arg
545 id <- Trans.lift $ mkBinderFor body "fun"
546 Trans.lift $ addGlobalBind id body
547 -- Replace the argument with a reference to the new function, applied to
549 change $ MkCore.mkCoreApps (Var id) (map Var free_vars)
550 -- Leave all other arguments untouched
551 doarg arg = return arg
553 -- Leave all other expressions unchanged
554 funextract expr = return expr
555 -- Perform this transform everywhere
556 funextracttop = everywhere ("funextract", funextract)
558 --------------------------------
559 -- End of transformations
560 --------------------------------
565 -- What transforms to run?
566 transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letderectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letmergetop, letremoveunusedtop, castsimpltop]
568 -- | Returns the normalized version of the given function.
570 CoreBndr -- ^ The function to get
571 -> TranslatorSession CoreExpr -- The normalized function body
573 getNormalized bndr = Utils.makeCached bndr tsNormalized $ do
574 if is_poly (Var bndr)
576 -- This should really only happen at the top level... TODO: Give
577 -- a different error if this happens down in the recursion.
578 error $ "\nNormalize.normalizeBind: Function " ++ show bndr ++ " is polymorphic, can't normalize"
580 expr <- getBinding bndr
581 normalizeExpr (show bndr) expr
583 -- | Normalize an expression
585 String -- ^ What are we normalizing? For debug output only.
586 -> CoreSyn.CoreExpr -- ^ The expression to normalize
587 -> TranslatorSession CoreSyn.CoreExpr -- ^ The normalized expression
589 normalizeExpr what expr = do
590 -- Normalize this expression
591 trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr ) ++ "\n") $ return ()
592 expr' <- dotransforms transforms expr
593 trace ("\n" ++ what ++ " after normalization:\n\n" ++ showSDoc ( ppr expr')) $ return ()
596 -- | Get the value that is bound to the given binder at top level. Fails when
597 -- there is no such binding.
599 CoreBndr -- ^ The binder to get the expression for
600 -> TranslatorSession CoreExpr -- ^ The value bound to the binder
602 getBinding bndr = Utils.makeCached bndr tsBindings $ do
603 -- If the binding isn't in the "cache" (bindings map), then we can't create
604 -- it out of thin air, so return an error.
605 error $ "Normalize.getBinding: Unknown function requested: " ++ show bndr
607 -- | Split a normalized expression into the argument binders, top level
608 -- bindings and the result binder.
610 CoreExpr -- ^ The normalized expression
611 -> ([CoreBndr], [Binding], CoreBndr)
612 splitNormalized expr = (args, binds, res)
614 (args, letexpr) = CoreSyn.collectBinders expr
615 (binds, resexpr) = flattenLets letexpr
616 res = case resexpr of
618 _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n"
620 -- | Flattens nested lets into a single list of bindings. The expression
621 -- passed does not have to be a let expression, if it isn't an empty list of
622 -- bindings is returned.
624 CoreExpr -- ^ The expression to flatten.
625 -> ([Binding], CoreExpr) -- ^ The bindings and resulting expression.
626 flattenLets (Let binds expr) =
627 (bindings ++ bindings', expr')
629 -- Recursively flatten the contained expression
630 (bindings', expr') =flattenLets expr
631 -- Flatten our own bindings to remove the Rec / NonRec constructors
632 bindings = CoreSyn.flattenBinds [binds]
633 flattenLets expr = ([], expr)