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
29 import qualified VarSet
30 import qualified NameSet
31 import qualified CoreFVs
32 import qualified CoreUtils
33 import qualified MkCore
34 import qualified HscTypes
35 import Outputable ( showSDoc, ppr, nest )
38 import CLasH.Normalize.NormalizeTypes
39 import CLasH.Translator.TranslatorTypes
40 import CLasH.Normalize.NormalizeTools
41 import CLasH.VHDL.VHDLTypes
42 import qualified CLasH.Utils as Utils
43 import CLasH.Utils.Core.CoreTools
44 import CLasH.Utils.Core.BinderTools
45 import CLasH.Utils.Pretty
47 --------------------------------
48 -- Start of transformations
49 --------------------------------
51 --------------------------------
53 --------------------------------
54 eta, etatop :: Transform
55 eta expr | is_fun expr && not (is_lam expr) = do
56 let arg_ty = (fst . Type.splitFunTy . CoreUtils.exprType) expr
57 id <- Trans.lift $ mkInternalVar "param" arg_ty
58 change (Lam id (App expr (Var id)))
59 -- Leave all other expressions unchanged
61 etatop = notappargs ("eta", eta)
63 --------------------------------
65 --------------------------------
66 beta, betatop :: Transform
67 -- Substitute arg for x in expr
68 beta (App (Lam x expr) arg) = change $ substitute [(x, arg)] expr
69 -- Propagate the application into the let
70 beta (App (Let binds expr) arg) = change $ Let binds (App expr arg)
71 -- Propagate the application into each of the alternatives
72 beta (App (Case scrut b ty alts) arg) = change $ Case scrut b ty' alts'
74 alts' = map (\(con, bndrs, expr) -> (con, bndrs, (App expr arg))) alts
75 ty' = CoreUtils.applyTypeToArg ty arg
76 -- Leave all other expressions unchanged
77 beta expr = return expr
78 -- Perform this transform everywhere
79 betatop = everywhere ("beta", beta)
81 --------------------------------
83 --------------------------------
84 -- Try to move casts as much downward as possible.
85 castprop, castproptop :: Transform
86 castprop (Cast (Let binds expr) ty) = change $ Let binds (Cast expr ty)
87 castprop expr@(Cast (Case scrut b _ alts) ty) = change (Case scrut b ty alts')
89 alts' = map (\(con, bndrs, expr) -> (con, bndrs, (Cast expr ty))) alts
90 -- Leave all other expressions unchanged
91 castprop expr = return expr
92 -- Perform this transform everywhere
93 castproptop = everywhere ("castprop", castprop)
95 --------------------------------
96 -- Cast simplification. Mostly useful for state packing and unpacking, but
97 -- perhaps for others as well.
98 --------------------------------
99 castsimpl, castsimpltop :: Transform
100 castsimpl expr@(Cast val ty) = do
101 -- Don't extract values that are already simpl
102 local_var <- Trans.lift $ is_local_var val
103 -- Don't extract values that are not representable, to prevent loops with
106 if (not local_var) && repr
108 -- Generate a binder for the expression
109 id <- Trans.lift $ mkBinderFor val "castval"
110 -- Extract the expression
111 change $ Let (NonRec id val) (Cast (Var id) ty)
114 -- Leave all other expressions unchanged
115 castsimpl expr = return expr
116 -- Perform this transform everywhere
117 castsimpltop = everywhere ("castsimpl", castsimpl)
120 --------------------------------
121 -- Lambda simplication
122 --------------------------------
123 -- Ensure that a lambda always evaluates to a let expressions or a simple
124 -- variable reference.
125 lambdasimpl, lambdasimpltop :: Transform
126 -- Don't simplify a lambda that evaluates to let, since this is already
127 -- normal form (and would cause infinite loops).
128 lambdasimpl expr@(Lam _ (Let _ _)) = return expr
129 -- Put the of a lambda in its own binding, but not when the expression is
130 -- already a local variable, or not representable (to prevent loops with
132 lambdasimpl expr@(Lam bndr res) = do
134 local_var <- Trans.lift $ is_local_var res
135 if not local_var && repr
137 id <- Trans.lift $ mkBinderFor res "res"
138 change $ Lam bndr (Let (NonRec id res) (Var id))
140 -- If the result is already a local var or not representable, don't
144 -- Leave all other expressions unchanged
145 lambdasimpl expr = return expr
146 -- Perform this transform everywhere
147 lambdasimpltop = everywhere ("lambdasimpl", lambdasimpl)
149 --------------------------------
150 -- let derecursification
151 --------------------------------
152 letderec, letderectop :: Transform
153 letderec expr@(Let (Rec binds) res) = case liftable of
154 -- Nothing is liftable, just return
156 -- Something can be lifted, generate a new let expression
157 _ -> change $ mkNonRecLets liftable (Let (Rec nonliftable) res)
159 -- Make a list of all the binders bound in this recursive let
160 bndrs = map fst binds
161 -- See which bindings are liftable
162 (liftable, nonliftable) = List.partition canlift binds
163 -- Any expression that does not use any of the binders in this recursive let
164 -- can be lifted into a nonrec let. It can't use its own binder either,
165 -- since that would mean the binding is self-recursive and should be in a
166 -- single bind recursive let.
167 canlift (bndr, e) = not $ expr_uses_binders bndrs e
168 -- Leave all other expressions unchanged
169 letderec expr = return expr
170 -- Perform this transform everywhere
171 letderectop = everywhere ("letderec", letderec)
173 --------------------------------
174 -- let simplification
175 --------------------------------
176 letsimpl, letsimpltop :: Transform
177 -- Don't simplify a let that evaluates to another let, since this is already
178 -- normal form (and would cause infinite loops with letflat below).
179 letsimpl expr@(Let _ (Let _ _)) = return expr
180 -- Put the "in ..." value of a let in its own binding, but not when the
181 -- expression is already a local variable, or not representable (to prevent loops with inlinenonrep).
182 letsimpl expr@(Let binds res) = do
184 local_var <- Trans.lift $ is_local_var res
185 if not local_var && repr
187 -- If the result is not a local var already (to prevent loops with
188 -- ourselves), extract it.
189 id <- Trans.lift $ mkBinderFor res "foo"
190 change $ Let binds (Let (NonRec id res) (Var id))
192 -- If the result is already a local var, don't extract it.
195 -- Leave all other expressions unchanged
196 letsimpl expr = return expr
197 -- Perform this transform everywhere
198 letsimpltop = everywhere ("letsimpl", letsimpl)
200 --------------------------------
202 --------------------------------
203 -- Takes a let that binds another let, and turns that into two nested lets.
205 -- let b = (let b' = expr' in res') in res
207 -- let b' = expr' in (let b = res' in res)
208 letflat, letflattop :: Transform
209 -- Turn a nonrec let that binds a let into two nested lets.
210 letflat (Let (NonRec b (Let binds res')) res) =
211 change $ Let binds (Let (NonRec b res') res)
212 letflat (Let (Rec binds) expr) = do
213 -- Flatten each binding.
214 binds' <- Utils.concatM $ Monad.mapM flatbind binds
215 -- Return the new let. We don't use change here, since possibly nothing has
216 -- changed. If anything has changed, flatbind has already flagged that
218 return $ Let (Rec binds') expr
220 -- Turns a binding of a let into a multiple bindings, or any other binding
221 -- into a list with just that binding
222 flatbind :: (CoreBndr, CoreExpr) -> TransformMonad [(CoreBndr, CoreExpr)]
223 flatbind (b, Let (Rec binds) expr) = change ((b, expr):binds)
224 flatbind (b, Let (NonRec b' expr') expr) = change [(b, expr), (b', expr')]
225 flatbind (b, expr) = return [(b, expr)]
226 -- Leave all other expressions unchanged
227 letflat expr = return expr
228 -- Perform this transform everywhere
229 letflattop = everywhere ("letflat", letflat)
231 --------------------------------
233 --------------------------------
234 -- Remove empty (recursive) lets
235 letremove, letremovetop :: Transform
236 letremove (Let (Rec []) res) = change $ res
237 -- Leave all other expressions unchanged
238 letremove expr = return expr
239 -- Perform this transform everywhere
240 letremovetop = everywhere ("letremove", letremove)
242 --------------------------------
243 -- Simple let binding removal
244 --------------------------------
245 -- Remove a = b bindings from let expressions everywhere
246 letremovesimpletop :: Transform
247 letremovesimpletop = everywhere ("letremovesimple", inlinebind (\(b, e) -> Trans.lift $ is_local_var e))
249 --------------------------------
250 -- Unused let binding removal
251 --------------------------------
252 letremoveunused, letremoveunusedtop :: Transform
253 letremoveunused expr@(Let (NonRec b bound) res) = do
254 let used = expr_uses_binders [b] res
258 letremoveunused expr@(Let (Rec binds) res) = do
259 -- Filter out all unused binds.
260 let binds' = filter dobind binds
261 -- Only set the changed flag if binds got removed
262 changeif (length binds' /= length binds) (Let (Rec binds') res)
264 bound_exprs = map snd binds
265 -- For each bind check if the bind is used by res or any of the bound
267 dobind (bndr, _) = any (expr_uses_binders [bndr]) (res:bound_exprs)
268 -- Leave all other expressions unchanged
269 letremoveunused expr = return expr
270 letremoveunusedtop = everywhere ("letremoveunused", letremoveunused)
273 --------------------------------
274 -- Identical let binding merging
275 --------------------------------
276 -- Merge two bindings in a let if they are identical
277 -- TODO: We would very much like to use GHC's CSE module for this, but that
278 -- doesn't track if something changed or not, so we can't use it properly.
279 letmerge, letmergetop :: Transform
280 letmerge expr@(Let _ _) = do
281 let (binds, res) = flattenLets expr
282 binds' <- domerge binds
283 return $ mkNonRecLets binds' res
285 domerge :: [(CoreBndr, CoreExpr)] -> TransformMonad [(CoreBndr, CoreExpr)]
286 domerge [] = return []
288 es' <- mapM (mergebinds e) es
292 -- Uses the second bind to simplify the second bind, if applicable.
293 mergebinds :: (CoreBndr, CoreExpr) -> (CoreBndr, CoreExpr) -> TransformMonad (CoreBndr, CoreExpr)
294 mergebinds (b1, e1) (b2, e2)
295 -- Identical expressions? Replace the second binding with a reference to
297 | CoreUtils.cheapEqExpr e1 e2 = change $ (b2, Var b1)
298 -- Different expressions? Don't change
299 | otherwise = return (b2, e2)
300 -- Leave all other expressions unchanged
301 letmerge expr = return expr
302 letmergetop = everywhere ("letmerge", letmerge)
305 --------------------------------
307 --------------------------------
308 -- Remove a = B bindings, with B :: a -> b, or B :: forall x . T, from let
309 -- expressions everywhere. This means that any value that still needs to be
310 -- applied to something else (polymorphic values need to be applied to a
311 -- Type) will be inlined, and will eventually be applied to all their
314 -- This is a tricky function, which is prone to create loops in the
315 -- transformations. To fix this, we make sure that no transformation will
316 -- create a new let binding with a function type. These other transformations
317 -- will just not work on those function-typed values at first, but the other
318 -- transformations (in particular β-reduction) should make sure that the type
319 -- of those values eventually becomes primitive.
320 inlinenonreptop :: Transform
321 inlinenonreptop = everywhere ("inlinenonrep", inlinebind ((Monad.liftM not) . isRepr . snd))
323 inlinetoplevel, inlinetopleveltop :: Transform
324 -- Any system name is candidate for inlining. Never inline user-defined
325 -- functions, to preserver structure.
326 inlinetoplevel expr@(Var f) | not $ isUserDefined f = do
327 -- See if this is a top level binding for which we have a body
328 body_maybe <- Trans.lift $ getGlobalBind f
331 -- Get the normalized version
332 norm <- Trans.lift $ getNormalized f
338 -- No body, this is probably a local variable or builtin or external
340 Nothing -> return expr
341 -- Leave all other expressions unchanged
342 inlinetoplevel expr = return expr
343 inlinetopleveltop = everywhere ("inlinetoplevel", inlinetoplevel)
345 needsInline :: CoreExpr -> Bool
346 needsInline expr = case splitNormalized expr of
347 -- Inline any function that only has a single definition, it is probably
348 -- simple enough. This might inline some stuff that it shouldn't though it
349 -- will never inline user-defined functions (inlinetoplevel only tries
350 -- system names) and inlining should never break things.
351 (args, [bind], res) -> True
354 --------------------------------
355 -- Scrutinee simplification
356 --------------------------------
357 scrutsimpl,scrutsimpltop :: Transform
358 -- Don't touch scrutinees that are already simple
359 scrutsimpl expr@(Case (Var _) _ _ _) = return expr
360 -- Replace all other cases with a let that binds the scrutinee and a new
361 -- simple scrutinee, but only when the scrutinee is representable (to prevent
362 -- loops with inlinenonrep, though I don't think a non-representable scrutinee
363 -- will be supported anyway...)
364 scrutsimpl expr@(Case scrut b ty alts) = do
368 id <- Trans.lift $ mkBinderFor scrut "scrut"
369 change $ Let (NonRec id scrut) (Case (Var id) b ty alts)
372 -- Leave all other expressions unchanged
373 scrutsimpl expr = return expr
374 -- Perform this transform everywhere
375 scrutsimpltop = everywhere ("scrutsimpl", scrutsimpl)
377 --------------------------------
378 -- Case binder wildening
379 --------------------------------
380 casesimpl, casesimpltop :: Transform
381 -- This is already a selector case (or, if x does not appear in bndrs, a very
382 -- simple case statement that will be removed by caseremove below). Just leave
384 casesimpl expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr
385 -- Make sure that all case alternatives have only wild binders and simple
387 -- This is done by creating a new let binding for each non-wild binder, which
388 -- is bound to a new simple selector case statement and for each complex
389 -- expression. We do this only for representable types, to prevent loops with
391 casesimpl expr@(Case scrut b ty alts) = do
392 (bindingss, alts') <- (Monad.liftM unzip) $ mapM doalt alts
393 let bindings = concat bindingss
394 -- Replace the case with a let with bindings and a case
395 let newlet = mkNonRecLets bindings (Case scrut b ty alts')
396 -- If there are no non-wild binders, or this case is already a simple
397 -- selector (i.e., a single alt with exactly one binding), already a simple
398 -- selector altan no bindings (i.e., no wild binders in the original case),
399 -- don't change anything, otherwise, replace the case.
400 if null bindings then return expr else change newlet
402 -- Generate a single wild binder, since they are all the same
403 wild = MkCore.mkWildBinder
404 -- Wilden the binders of one alt, producing a list of bindings as a
406 doalt :: CoreAlt -> TransformMonad ([(CoreBndr, CoreExpr)], CoreAlt)
407 doalt (con, bndrs, expr) = do
408 -- Make each binder wild, if possible
409 bndrs_res <- Monad.zipWithM dobndr bndrs [0..]
410 let (newbndrs, bindings_maybe) = unzip bndrs_res
411 -- Extract a complex expression, if possible. For this we check if any of
412 -- the new list of bndrs are used by expr. We can't use free_vars here,
413 -- since that looks at the old bndrs.
414 let uses_bndrs = not $ VarSet.isEmptyVarSet $ CoreFVs.exprSomeFreeVars (`elem` newbndrs) $ expr
415 (exprbinding_maybe, expr') <- doexpr expr uses_bndrs
416 -- Create a new alternative
417 let newalt = (con, newbndrs, expr')
418 let bindings = Maybe.catMaybes (bindings_maybe ++ [exprbinding_maybe])
419 return (bindings, newalt)
421 -- Make wild alternatives for each binder
422 wildbndrs = map (\bndr -> MkCore.mkWildBinder (Id.idType bndr)) bndrs
423 -- A set of all the binders that are used by the expression
424 free_vars = CoreFVs.exprSomeFreeVars (`elem` bndrs) expr
425 -- Look at the ith binder in the case alternative. Return a new binder
426 -- for it (either the same one, or a wild one) and optionally a let
427 -- binding containing a case expression.
428 dobndr :: CoreBndr -> Int -> TransformMonad (CoreBndr, Maybe (CoreBndr, CoreExpr))
431 -- Is b wild (e.g., not a free var of expr. Since b is only in scope
432 -- in expr, this means that b is unused if expr does not use it.)
433 let wild = not (VarSet.elemVarSet b free_vars)
434 -- Create a new binding for any representable binder that is not
435 -- already wild and is representable (to prevent loops with
437 if (not wild) && repr
439 -- Create on new binder that will actually capture a value in this
440 -- case statement, and return it.
441 let bty = (Id.idType b)
442 id <- Trans.lift $ mkInternalVar "sel" bty
443 let binders = take i wildbndrs ++ [id] ++ drop (i+1) wildbndrs
444 let caseexpr = Case scrut b bty [(con, binders, Var id)]
445 return (wildbndrs!!i, Just (b, caseexpr))
447 -- Just leave the original binder in place, and don't generate an
448 -- extra selector case.
450 -- Process the expression of a case alternative. Accepts an expression
451 -- and whether this expression uses any of the binders in the
452 -- alternative. Returns an optional new binding and a new expression.
453 doexpr :: CoreExpr -> Bool -> TransformMonad (Maybe (CoreBndr, CoreExpr), CoreExpr)
454 doexpr expr uses_bndrs = do
455 local_var <- Trans.lift $ is_local_var expr
457 -- Extract any expressions that do not use any binders from this
458 -- alternative, is not a local var already and is representable (to
459 -- prevent loops with inlinenonrep).
460 if (not uses_bndrs) && (not local_var) && repr
462 id <- Trans.lift $ mkBinderFor expr "caseval"
463 -- We don't flag a change here, since casevalsimpl will do that above
464 -- based on Just we return here.
465 return $ (Just (id, expr), Var id)
467 -- Don't simplify anything else
468 return (Nothing, expr)
469 -- Leave all other expressions unchanged
470 casesimpl expr = return expr
471 -- Perform this transform everywhere
472 casesimpltop = everywhere ("casesimpl", casesimpl)
474 --------------------------------
476 --------------------------------
477 -- Remove case statements that have only a single alternative and only wild
479 caseremove, caseremovetop :: Transform
480 -- Replace a useless case by the value of its single alternative
481 caseremove (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr
482 -- Find if any of the binders are used by expr
483 where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
484 -- Leave all other expressions unchanged
485 caseremove expr = return expr
486 -- Perform this transform everywhere
487 caseremovetop = everywhere ("caseremove", caseremove)
489 --------------------------------
490 -- Argument extraction
491 --------------------------------
492 -- Make sure that all arguments of a representable type are simple variables.
493 appsimpl, appsimpltop :: Transform
494 -- Simplify all representable arguments. Do this by introducing a new Let
495 -- that binds the argument and passing the new binder in the application.
496 appsimpl expr@(App f arg) = do
497 -- Check runtime representability
499 local_var <- Trans.lift $ is_local_var arg
500 if repr && not local_var
501 then do -- Extract representable arguments
502 id <- Trans.lift $ mkBinderFor arg "arg"
503 change $ Let (NonRec id arg) (App f (Var id))
504 else -- Leave non-representable arguments unchanged
506 -- Leave all other expressions unchanged
507 appsimpl expr = return expr
508 -- Perform this transform everywhere
509 appsimpltop = everywhere ("appsimpl", appsimpl)
511 --------------------------------
512 -- Function-typed argument propagation
513 --------------------------------
514 -- Remove all applications to function-typed arguments, by duplication the
515 -- function called with the function-typed parameter replaced by the free
516 -- variables of the argument passed in.
517 argprop, argproptop :: Transform
518 -- Transform any application of a named function (i.e., skip applications of
519 -- lambda's). Also skip applications that have arguments with free type
520 -- variables, since we can't inline those.
521 argprop expr@(App _ _) | is_var fexpr = do
522 -- Find the body of the function called
523 body_maybe <- Trans.lift $ getGlobalBind f
526 -- Process each of the arguments in turn
527 (args', changed) <- Writer.listen $ mapM doarg args
528 -- See if any of the arguments changed
529 case Monoid.getAny changed of
531 let (newargs', newparams', oldargs) = unzip3 args'
532 let newargs = concat newargs'
533 let newparams = concat newparams'
534 -- Create a new body that consists of a lambda for all new arguments and
535 -- the old body applied to some arguments.
536 let newbody = MkCore.mkCoreLams newparams (MkCore.mkCoreApps body oldargs)
537 -- Create a new function with the same name but a new body
538 newf <- Trans.lift $ mkFunction f newbody
539 -- Replace the original application with one of the new function to the
541 change $ MkCore.mkCoreApps (Var newf) newargs
543 -- Don't change the expression if none of the arguments changed
546 -- If we don't have a body for the function called, leave it unchanged (it
547 -- should be a primitive function then).
548 Nothing -> return expr
550 -- Find the function called and the arguments
551 (fexpr, args) = collectArgs expr
554 -- Process a single argument and return (args, bndrs, arg), where args are
555 -- the arguments to replace the given argument in the original
556 -- application, bndrs are the binders to include in the top-level lambda
557 -- in the new function body, and arg is the argument to apply to the old
559 doarg :: CoreExpr -> TransformMonad ([CoreExpr], [CoreBndr], CoreExpr)
562 bndrs <- Trans.lift getGlobalBinders
563 let interesting var = Var.isLocalVar var && (not $ var `elem` bndrs)
564 if not repr && not (is_var arg && interesting (exprToVar arg)) && not (has_free_tyvars arg)
566 -- Propagate all complex arguments that are not representable, but not
567 -- arguments with free type variables (since those would require types
568 -- not known yet, which will always be known eventually).
569 -- Find interesting free variables, each of which should be passed to
570 -- the new function instead of the original function argument.
572 -- Interesting vars are those that are local, but not available from the
573 -- top level scope (functions from this module are defined as local, but
574 -- they're not local to this function, so we can freely move references
575 -- to them into another function).
576 let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting arg
577 -- Mark the current expression as changed
579 return (map Var free_vars, free_vars, arg)
581 -- Representable types will not be propagated, and arguments with free
582 -- type variables will be propagated later.
583 -- TODO: preserve original naming?
584 id <- Trans.lift $ mkBinderFor arg "param"
585 -- Just pass the original argument to the new function, which binds it
586 -- to a new id and just pass that new id to the old function body.
587 return ([arg], [id], mkReferenceTo id)
588 -- Leave all other expressions unchanged
589 argprop expr = return expr
590 -- Perform this transform everywhere
591 argproptop = everywhere ("argprop", argprop)
593 --------------------------------
594 -- Function-typed argument extraction
595 --------------------------------
596 -- This transform takes any function-typed argument that cannot be propagated
597 -- (because the function that is applied to it is a builtin function), and
598 -- puts it in a brand new top level binder. This allows us to for example
599 -- apply map to a lambda expression This will not conflict with inlinenonrep,
600 -- since that only inlines local let bindings, not top level bindings.
601 funextract, funextracttop :: Transform
602 funextract expr@(App _ _) | is_var fexpr = do
603 body_maybe <- Trans.lift $ getGlobalBind f
605 -- We don't have a function body for f, so we can perform this transform.
607 -- Find the new arguments
608 args' <- mapM doarg args
609 -- And update the arguments. We use return instead of changed, so the
610 -- changed flag doesn't get set if none of the args got changed.
611 return $ MkCore.mkCoreApps fexpr args'
612 -- We have a function body for f, leave this application to funprop
613 Just _ -> return expr
615 -- Find the function called and the arguments
616 (fexpr, args) = collectArgs expr
618 -- Change any arguments that have a function type, but are not simple yet
619 -- (ie, a variable or application). This means to create a new function
620 -- for map (\f -> ...) b, but not for map (foo a) b.
622 -- We could use is_applicable here instead of is_fun, but I think
623 -- arguments to functions could only have forall typing when existential
624 -- typing is enabled. Not sure, though.
625 doarg arg | not (is_simple arg) && is_fun arg = do
626 -- Create a new top level binding that binds the argument. Its body will
627 -- be extended with lambda expressions, to take any free variables used
628 -- by the argument expression.
629 let free_vars = VarSet.varSetElems $ CoreFVs.exprFreeVars arg
630 let body = MkCore.mkCoreLams free_vars arg
631 id <- Trans.lift $ mkBinderFor body "fun"
632 Trans.lift $ addGlobalBind id body
633 -- Replace the argument with a reference to the new function, applied to
635 change $ MkCore.mkCoreApps (Var id) (map Var free_vars)
636 -- Leave all other arguments untouched
637 doarg arg = return arg
639 -- Leave all other expressions unchanged
640 funextract expr = return expr
641 -- Perform this transform everywhere
642 funextracttop = everywhere ("funextract", funextract)
644 --------------------------------
645 -- Ensure that a function that just returns another function (or rather,
646 -- another top-level binder) is still properly normalized. This is a temporary
647 -- solution, we should probably integrate this pass with lambdasimpl and
649 --------------------------------
650 simplrestop expr@(Lam _ _) = return expr
651 simplrestop expr@(Let _ _) = return expr
652 simplrestop expr = do
653 local_var <- Trans.lift $ is_local_var expr
654 -- Don't extract values that are not representable, to prevent loops with
657 if local_var || not repr
661 id <- Trans.lift $ mkBinderFor expr "res"
662 change $ Let (NonRec id expr) (Var id)
663 --------------------------------
664 -- End of transformations
665 --------------------------------
670 -- What transforms to run?
671 transforms = [inlinetopleveltop, argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letderectop, letremovetop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letremoveunusedtop, castsimpltop, lambdasimpltop, simplrestop]
673 -- | Returns the normalized version of the given function.
675 CoreBndr -- ^ The function to get
676 -> TranslatorSession CoreExpr -- The normalized function body
678 getNormalized bndr = Utils.makeCached bndr tsNormalized $ do
679 if is_poly (Var bndr)
681 -- This should really only happen at the top level... TODO: Give
682 -- a different error if this happens down in the recursion.
683 error $ "\nNormalize.normalizeBind: Function " ++ show bndr ++ " is polymorphic, can't normalize"
685 expr <- getBinding bndr
686 normalizeExpr (show bndr) expr
688 -- | Normalize an expression
690 String -- ^ What are we normalizing? For debug output only.
691 -> CoreSyn.CoreExpr -- ^ The expression to normalize
692 -> TranslatorSession CoreSyn.CoreExpr -- ^ The normalized expression
694 normalizeExpr what expr = do
695 -- Normalize this expression
696 trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr ) ++ "\n") $ return ()
697 expr' <- dotransforms transforms expr
698 trace ("\n" ++ what ++ " after normalization:\n\n" ++ showSDoc ( ppr expr')) $ return ()
701 -- | Get the value that is bound to the given binder at top level. Fails when
702 -- there is no such binding.
704 CoreBndr -- ^ The binder to get the expression for
705 -> TranslatorSession CoreExpr -- ^ The value bound to the binder
707 getBinding bndr = Utils.makeCached bndr tsBindings $ do
708 -- If the binding isn't in the "cache" (bindings map), then we can't create
709 -- it out of thin air, so return an error.
710 error $ "Normalize.getBinding: Unknown function requested: " ++ show bndr
712 -- | Split a normalized expression into the argument binders, top level
713 -- bindings and the result binder.
715 CoreExpr -- ^ The normalized expression
716 -> ([CoreBndr], [Binding], CoreBndr)
717 splitNormalized expr = (args, binds, res)
719 (args, letexpr) = CoreSyn.collectBinders expr
720 (binds, resexpr) = flattenLets letexpr
721 res = case resexpr of
723 _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n"