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 -- Don't simplify a let that evaluates to another let, since this is already
150 -- normal form (and would cause infinite loops with letflat below).
151 letsimpl expr@(Let _ (Let _ _)) = return expr
152 -- Put the "in ..." value of a let in its own binding, but not when the
153 -- expression is already a local variable, or not representable (to prevent loops with inlinenonrep).
154 letsimpl expr@(Let binds res) = do
156 local_var <- Trans.lift $ is_local_var res
157 if not local_var && repr
159 -- If the result is not a local var already (to prevent loops with
160 -- ourselves), extract it.
161 id <- Trans.lift $ mkBinderFor res "foo"
162 change $ Let binds (Let (NonRec id res) (Var id))
164 -- If the result is already a local var, don't extract it.
167 -- Leave all other expressions unchanged
168 letsimpl expr = return expr
169 -- Perform this transform everywhere
170 letsimpltop = everywhere ("letsimpl", letsimpl)
172 --------------------------------
174 --------------------------------
175 -- Takes a let that binds another let, and turns that into two nested lets.
177 -- let b = (let b' = expr' in res') in res
179 -- let b' = expr' in (let b = res' in res)
180 letflat, letflattop :: Transform
181 letflat (Let (NonRec b (Let (NonRec b' expr') res')) res) =
182 change $ Let (NonRec b' expr') (Let (NonRec b res') res)
183 -- Leave all other expressions unchanged
184 letflat expr = return expr
185 -- Perform this transform everywhere
186 letflattop = everywhere ("letflat", letflat)
188 --------------------------------
190 --------------------------------
191 -- Remove empty (recursive) lets
192 letremove, letremovetop :: Transform
193 letremove (Let (Rec []) res) = change $ res
194 -- Leave all other expressions unchanged
195 letremove expr = return expr
196 -- Perform this transform everywhere
197 letremovetop = everywhere ("letremove", letremove)
199 --------------------------------
200 -- Simple let binding removal
201 --------------------------------
202 -- Remove a = b bindings from let expressions everywhere
203 letremovesimpletop :: Transform
204 letremovesimpletop = everywhere ("letremovesimple", inlinebind (\(b, e) -> Trans.lift $ is_local_var e))
206 --------------------------------
207 -- Unused let binding removal
208 --------------------------------
209 letremoveunused, letremoveunusedtop :: Transform
210 letremoveunused expr@(Let (Rec binds) res) = do
211 -- Filter out all unused binds.
212 let binds' = filter dobind binds
213 -- Only set the changed flag if binds got removed
214 changeif (length binds' /= length binds) (Let (Rec binds') res)
216 bound_exprs = map snd binds
217 -- For each bind check if the bind is used by res or any of the bound
219 dobind (bndr, _) = any (expr_uses_binders [bndr]) (res:bound_exprs)
220 -- Leave all other expressions unchanged
221 letremoveunused expr = return expr
222 letremoveunusedtop = everywhere ("letremoveunused", letremoveunused)
224 --------------------------------
225 -- Identical let binding merging
226 --------------------------------
227 -- Merge two bindings in a let if they are identical
228 -- TODO: We would very much like to use GHC's CSE module for this, but that
229 -- doesn't track if something changed or not, so we can't use it properly.
230 letmerge, letmergetop :: Transform
231 letmerge expr@(Let _ _) = do
232 let (binds, res) = flattenLets expr
233 binds' <- domerge binds
234 return $ MkCore.mkCoreLets (map (uncurry NonRec) binds') res
236 domerge :: [(CoreBndr, CoreExpr)] -> TransformMonad [(CoreBndr, CoreExpr)]
237 domerge [] = return []
239 es' <- mapM (mergebinds e) es
243 -- Uses the second bind to simplify the second bind, if applicable.
244 mergebinds :: (CoreBndr, CoreExpr) -> (CoreBndr, CoreExpr) -> TransformMonad (CoreBndr, CoreExpr)
245 mergebinds (b1, e1) (b2, e2)
246 -- Identical expressions? Replace the second binding with a reference to
248 | CoreUtils.cheapEqExpr e1 e2 = change $ (b2, Var b1)
249 -- Different expressions? Don't change
250 | otherwise = return (b2, e2)
251 -- Leave all other expressions unchanged
252 letmerge expr = return expr
253 letmergetop = everywhere ("letmerge", letmerge)
255 --------------------------------
257 --------------------------------
258 -- Remove a = B bindings, with B :: a -> b, or B :: forall x . T, from let
259 -- expressions everywhere. This means that any value that still needs to be
260 -- applied to something else (polymorphic values need to be applied to a
261 -- Type) will be inlined, and will eventually be applied to all their
264 -- This is a tricky function, which is prone to create loops in the
265 -- transformations. To fix this, we make sure that no transformation will
266 -- create a new let binding with a function type. These other transformations
267 -- will just not work on those function-typed values at first, but the other
268 -- transformations (in particular β-reduction) should make sure that the type
269 -- of those values eventually becomes primitive.
270 inlinenonreptop :: Transform
271 inlinenonreptop = everywhere ("inlinenonrep", inlinebind ((Monad.liftM not) . isRepr . snd))
273 --------------------------------
274 -- Scrutinee simplification
275 --------------------------------
276 scrutsimpl,scrutsimpltop :: Transform
277 -- Don't touch scrutinees that are already simple
278 scrutsimpl expr@(Case (Var _) _ _ _) = return expr
279 -- Replace all other cases with a let that binds the scrutinee and a new
280 -- simple scrutinee, but only when the scrutinee is representable (to prevent
281 -- loops with inlinenonrep, though I don't think a non-representable scrutinee
282 -- will be supported anyway...)
283 scrutsimpl expr@(Case scrut b ty alts) = do
287 id <- Trans.lift $ mkBinderFor scrut "scrut"
288 change $ Let (NonRec id scrut) (Case (Var id) b ty alts)
291 -- Leave all other expressions unchanged
292 scrutsimpl expr = return expr
293 -- Perform this transform everywhere
294 scrutsimpltop = everywhere ("scrutsimpl", scrutsimpl)
296 --------------------------------
297 -- Case binder wildening
298 --------------------------------
299 casesimpl, casesimpltop :: Transform
300 -- This is already a selector case (or, if x does not appear in bndrs, a very
301 -- simple case statement that will be removed by caseremove below). Just leave
303 casesimpl expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr
304 -- Make sure that all case alternatives have only wild binders and simple
306 -- This is done by creating a new let binding for each non-wild binder, which
307 -- is bound to a new simple selector case statement and for each complex
308 -- expression. We do this only for representable types, to prevent loops with
310 casesimpl expr@(Case scrut b ty alts) = do
311 (bindingss, alts') <- (Monad.liftM unzip) $ mapM doalt alts
312 let bindings = concat bindingss
313 -- Replace the case with a let with bindings and a case
314 let newlet = (Let (Rec bindings) (Case scrut b ty alts'))
315 -- If there are no non-wild binders, or this case is already a simple
316 -- selector (i.e., a single alt with exactly one binding), already a simple
317 -- selector altan no bindings (i.e., no wild binders in the original case),
318 -- don't change anything, otherwise, replace the case.
319 if null bindings then return expr else change newlet
321 -- Generate a single wild binder, since they are all the same
322 wild = MkCore.mkWildBinder
323 -- Wilden the binders of one alt, producing a list of bindings as a
325 doalt :: CoreAlt -> TransformMonad ([(CoreBndr, CoreExpr)], CoreAlt)
326 doalt (con, bndrs, expr) = do
327 -- Make each binder wild, if possible
328 bndrs_res <- Monad.zipWithM dobndr bndrs [0..]
329 let (newbndrs, bindings_maybe) = unzip bndrs_res
330 -- Extract a complex expression, if possible. For this we check if any of
331 -- the new list of bndrs are used by expr. We can't use free_vars here,
332 -- since that looks at the old bndrs.
333 let uses_bndrs = not $ VarSet.isEmptyVarSet $ CoreFVs.exprSomeFreeVars (`elem` newbndrs) $ expr
334 (exprbinding_maybe, expr') <- doexpr expr uses_bndrs
335 -- Create a new alternative
336 let newalt = (con, newbndrs, expr')
337 let bindings = Maybe.catMaybes (exprbinding_maybe : bindings_maybe)
338 return (bindings, newalt)
340 -- Make wild alternatives for each binder
341 wildbndrs = map (\bndr -> MkCore.mkWildBinder (Id.idType bndr)) bndrs
342 -- A set of all the binders that are used by the expression
343 free_vars = CoreFVs.exprSomeFreeVars (`elem` bndrs) expr
344 -- Look at the ith binder in the case alternative. Return a new binder
345 -- for it (either the same one, or a wild one) and optionally a let
346 -- binding containing a case expression.
347 dobndr :: CoreBndr -> Int -> TransformMonad (CoreBndr, Maybe (CoreBndr, CoreExpr))
349 repr <- isRepr (Var b)
350 -- Is b wild (e.g., not a free var of expr. Since b is only in scope
351 -- in expr, this means that b is unused if expr does not use it.)
352 let wild = not (VarSet.elemVarSet b free_vars)
353 -- Create a new binding for any representable binder that is not
354 -- already wild and is representable (to prevent loops with
356 if (not wild) && repr
358 -- Create on new binder that will actually capture a value in this
359 -- case statement, and return it.
360 let bty = (Id.idType b)
361 id <- Trans.lift $ mkInternalVar "sel" bty
362 let binders = take i wildbndrs ++ [id] ++ drop (i+1) wildbndrs
363 let caseexpr = Case scrut b bty [(con, binders, Var id)]
364 return (wildbndrs!!i, Just (b, caseexpr))
366 -- Just leave the original binder in place, and don't generate an
367 -- extra selector case.
369 -- Process the expression of a case alternative. Accepts an expression
370 -- and whether this expression uses any of the binders in the
371 -- alternative. Returns an optional new binding and a new expression.
372 doexpr :: CoreExpr -> Bool -> TransformMonad (Maybe (CoreBndr, CoreExpr), CoreExpr)
373 doexpr expr uses_bndrs = do
374 local_var <- Trans.lift $ is_local_var expr
376 -- Extract any expressions that do not use any binders from this
377 -- alternative, is not a local var already and is representable (to
378 -- prevent loops with inlinenonrep).
379 if (not uses_bndrs) && (not local_var) && repr
381 id <- Trans.lift $ mkBinderFor expr "caseval"
382 -- We don't flag a change here, since casevalsimpl will do that above
383 -- based on Just we return here.
384 return $ (Just (id, expr), Var id)
386 -- Don't simplify anything else
387 return (Nothing, expr)
388 -- Leave all other expressions unchanged
389 casesimpl expr = return expr
390 -- Perform this transform everywhere
391 casesimpltop = everywhere ("casesimpl", casesimpl)
393 --------------------------------
395 --------------------------------
396 -- Remove case statements that have only a single alternative and only wild
398 caseremove, caseremovetop :: Transform
399 -- Replace a useless case by the value of its single alternative
400 caseremove (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr
401 -- Find if any of the binders are used by expr
402 where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
403 -- Leave all other expressions unchanged
404 caseremove expr = return expr
405 -- Perform this transform everywhere
406 caseremovetop = everywhere ("caseremove", caseremove)
408 --------------------------------
409 -- Argument extraction
410 --------------------------------
411 -- Make sure that all arguments of a representable type are simple variables.
412 appsimpl, appsimpltop :: Transform
413 -- Simplify all representable arguments. Do this by introducing a new Let
414 -- that binds the argument and passing the new binder in the application.
415 appsimpl expr@(App f arg) = do
416 -- Check runtime representability
418 local_var <- Trans.lift $ is_local_var arg
419 if repr && not local_var
420 then do -- Extract representable arguments
421 id <- Trans.lift $ mkBinderFor arg "arg"
422 change $ Let (NonRec id arg) (App f (Var id))
423 else -- Leave non-representable arguments unchanged
425 -- Leave all other expressions unchanged
426 appsimpl expr = return expr
427 -- Perform this transform everywhere
428 appsimpltop = everywhere ("appsimpl", appsimpl)
430 --------------------------------
431 -- Function-typed argument propagation
432 --------------------------------
433 -- Remove all applications to function-typed arguments, by duplication the
434 -- function called with the function-typed parameter replaced by the free
435 -- variables of the argument passed in.
436 argprop, argproptop :: Transform
437 -- Transform any application of a named function (i.e., skip applications of
438 -- lambda's). Also skip applications that have arguments with free type
439 -- variables, since we can't inline those.
440 argprop expr@(App _ _) | is_var fexpr = do
441 -- Find the body of the function called
442 body_maybe <- Trans.lift $ getGlobalBind f
445 -- Process each of the arguments in turn
446 (args', changed) <- Writer.listen $ mapM doarg args
447 -- See if any of the arguments changed
448 case Monoid.getAny changed of
450 let (newargs', newparams', oldargs) = unzip3 args'
451 let newargs = concat newargs'
452 let newparams = concat newparams'
453 -- Create a new body that consists of a lambda for all new arguments and
454 -- the old body applied to some arguments.
455 let newbody = MkCore.mkCoreLams newparams (MkCore.mkCoreApps body oldargs)
456 -- Create a new function with the same name but a new body
457 newf <- Trans.lift $ mkFunction f newbody
458 -- Replace the original application with one of the new function to the
460 change $ MkCore.mkCoreApps (Var newf) newargs
462 -- Don't change the expression if none of the arguments changed
465 -- If we don't have a body for the function called, leave it unchanged (it
466 -- should be a primitive function then).
467 Nothing -> return expr
469 -- Find the function called and the arguments
470 (fexpr, args) = collectArgs expr
473 -- Process a single argument and return (args, bndrs, arg), where args are
474 -- the arguments to replace the given argument in the original
475 -- application, bndrs are the binders to include in the top-level lambda
476 -- in the new function body, and arg is the argument to apply to the old
478 doarg :: CoreExpr -> TransformMonad ([CoreExpr], [CoreBndr], CoreExpr)
481 bndrs <- Trans.lift getGlobalBinders
482 let interesting var = Var.isLocalVar var && (not $ var `elem` bndrs)
483 if not repr && not (is_var arg && interesting (exprToVar arg)) && not (has_free_tyvars arg)
485 -- Propagate all complex arguments that are not representable, but not
486 -- arguments with free type variables (since those would require types
487 -- not known yet, which will always be known eventually).
488 -- Find interesting free variables, each of which should be passed to
489 -- the new function instead of the original function argument.
491 -- Interesting vars are those that are local, but not available from the
492 -- top level scope (functions from this module are defined as local, but
493 -- they're not local to this function, so we can freely move references
494 -- to them into another function).
495 let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting arg
496 -- Mark the current expression as changed
498 return (map Var free_vars, free_vars, arg)
500 -- Representable types will not be propagated, and arguments with free
501 -- type variables will be propagated later.
502 -- TODO: preserve original naming?
503 id <- Trans.lift $ mkBinderFor arg "param"
504 -- Just pass the original argument to the new function, which binds it
505 -- to a new id and just pass that new id to the old function body.
506 return ([arg], [id], mkReferenceTo id)
507 -- Leave all other expressions unchanged
508 argprop expr = return expr
509 -- Perform this transform everywhere
510 argproptop = everywhere ("argprop", argprop)
512 --------------------------------
513 -- Function-typed argument extraction
514 --------------------------------
515 -- This transform takes any function-typed argument that cannot be propagated
516 -- (because the function that is applied to it is a builtin function), and
517 -- puts it in a brand new top level binder. This allows us to for example
518 -- apply map to a lambda expression This will not conflict with inlinenonrep,
519 -- since that only inlines local let bindings, not top level bindings.
520 funextract, funextracttop :: Transform
521 funextract expr@(App _ _) | is_var fexpr = do
522 body_maybe <- Trans.lift $ getGlobalBind f
524 -- We don't have a function body for f, so we can perform this transform.
526 -- Find the new arguments
527 args' <- mapM doarg args
528 -- And update the arguments. We use return instead of changed, so the
529 -- changed flag doesn't get set if none of the args got changed.
530 return $ MkCore.mkCoreApps fexpr args'
531 -- We have a function body for f, leave this application to funprop
532 Just _ -> return expr
534 -- Find the function called and the arguments
535 (fexpr, args) = collectArgs expr
537 -- Change any arguments that have a function type, but are not simple yet
538 -- (ie, a variable or application). This means to create a new function
539 -- for map (\f -> ...) b, but not for map (foo a) b.
541 -- We could use is_applicable here instead of is_fun, but I think
542 -- arguments to functions could only have forall typing when existential
543 -- typing is enabled. Not sure, though.
544 doarg arg | not (is_simple arg) && is_fun arg = do
545 -- Create a new top level binding that binds the argument. Its body will
546 -- be extended with lambda expressions, to take any free variables used
547 -- by the argument expression.
548 let free_vars = VarSet.varSetElems $ CoreFVs.exprFreeVars arg
549 let body = MkCore.mkCoreLams free_vars arg
550 id <- Trans.lift $ mkBinderFor body "fun"
551 Trans.lift $ addGlobalBind id body
552 -- Replace the argument with a reference to the new function, applied to
554 change $ MkCore.mkCoreApps (Var id) (map Var free_vars)
555 -- Leave all other arguments untouched
556 doarg arg = return arg
558 -- Leave all other expressions unchanged
559 funextract expr = return expr
560 -- Perform this transform everywhere
561 funextracttop = everywhere ("funextract", funextract)
563 --------------------------------
564 -- End of transformations
565 --------------------------------
570 -- What transforms to run?
571 transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letderectop, letremovetop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letmergetop, letremoveunusedtop, castsimpltop]
573 -- | Returns the normalized version of the given function.
575 CoreBndr -- ^ The function to get
576 -> TranslatorSession CoreExpr -- The normalized function body
578 getNormalized bndr = Utils.makeCached bndr tsNormalized $ do
579 if is_poly (Var bndr)
581 -- This should really only happen at the top level... TODO: Give
582 -- a different error if this happens down in the recursion.
583 error $ "\nNormalize.normalizeBind: Function " ++ show bndr ++ " is polymorphic, can't normalize"
585 expr <- getBinding bndr
586 normalizeExpr (show bndr) expr
588 -- | Normalize an expression
590 String -- ^ What are we normalizing? For debug output only.
591 -> CoreSyn.CoreExpr -- ^ The expression to normalize
592 -> TranslatorSession CoreSyn.CoreExpr -- ^ The normalized expression
594 normalizeExpr what expr = do
595 -- Normalize this expression
596 trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr ) ++ "\n") $ return ()
597 expr' <- dotransforms transforms expr
598 trace ("\n" ++ what ++ " after normalization:\n\n" ++ showSDoc ( ppr expr')) $ return ()
601 -- | Get the value that is bound to the given binder at top level. Fails when
602 -- there is no such binding.
604 CoreBndr -- ^ The binder to get the expression for
605 -> TranslatorSession CoreExpr -- ^ The value bound to the binder
607 getBinding bndr = Utils.makeCached bndr tsBindings $ do
608 -- If the binding isn't in the "cache" (bindings map), then we can't create
609 -- it out of thin air, so return an error.
610 error $ "Normalize.getBinding: Unknown function requested: " ++ show bndr
612 -- | Split a normalized expression into the argument binders, top level
613 -- bindings and the result binder.
615 CoreExpr -- ^ The normalized expression
616 -> ([CoreBndr], [Binding], CoreBndr)
617 splitNormalized expr = (args, binds, res)
619 (args, letexpr) = CoreSyn.collectBinders expr
620 (binds, resexpr) = flattenLets letexpr
621 res = case resexpr of
623 _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n"