-- Standard modules
import Debug.Trace
import qualified Maybe
+import qualified List
import qualified "transformers" Control.Monad.Trans as Trans
import qualified Control.Monad as Monad
import qualified Control.Monad.Trans.Writer as Writer
-import qualified Data.Map as Map
+import qualified Data.Accessor.Monad.Trans.State as MonadState
import qualified Data.Monoid as Monoid
-import Data.Accessor
+import qualified Data.Map as Map
-- GHC API
import CoreSyn
-import qualified UniqSupply
import qualified CoreUtils
+import qualified BasicTypes
import qualified Type
-import qualified TcType
+import qualified TysWiredIn
import qualified Id
import qualified Var
+import qualified Name
+import qualified DataCon
import qualified VarSet
-import qualified NameSet
import qualified CoreFVs
-import qualified CoreUtils
+import qualified Class
import qualified MkCore
-import qualified HscTypes
import Outputable ( showSDoc, ppr, nest )
-- Local imports
import CLasH.Normalize.NormalizeTypes
import CLasH.Translator.TranslatorTypes
import CLasH.Normalize.NormalizeTools
-import CLasH.VHDL.VHDLTypes
+import CLasH.VHDL.Constants (builtinIds)
import qualified CLasH.Utils as Utils
import CLasH.Utils.Core.CoreTools
import CLasH.Utils.Core.BinderTools
--------------------------------
--------------------------------
--- η abstraction
+-- η expansion
--------------------------------
-eta, etatop :: Transform
-eta expr | is_fun expr && not (is_lam expr) = do
+-- Make sure all parameters to the normalized functions are named by top
+-- level lambda expressions. For this we apply η expansion to the
+-- function body (possibly enclosed in some lambda abstractions) while
+-- it has a function type. Eventually this will result in a function
+-- body consisting of a bunch of nested lambdas containing a
+-- non-function value (e.g., a complete application).
+eta :: Transform
+eta c expr | is_fun expr && not (is_lam expr) && all (== LambdaBody) c = do
let arg_ty = (fst . Type.splitFunTy . CoreUtils.exprType) expr
id <- Trans.lift $ mkInternalVar "param" arg_ty
change (Lam id (App expr (Var id)))
-- Leave all other expressions unchanged
-eta e = return e
-etatop = notappargs ("eta", eta)
+eta c e = return e
--------------------------------
-- β-reduction
--------------------------------
-beta, betatop :: Transform
--- Substitute arg for x in expr
-beta (App (Lam x expr) arg) = change $ substitute [(x, arg)] expr
+beta :: Transform
+-- Substitute arg for x in expr. For value lambda's, also clone before
+-- substitution.
+beta c (App (Lam x expr) arg) | CoreSyn.isTyVar x = setChanged >> substitute x arg c expr
+ | otherwise = setChanged >> substitute_clone x arg c expr
-- Propagate the application into the let
-beta (App (Let binds expr) arg) = change $ Let binds (App expr arg)
+beta c (App (Let binds expr) arg) = change $ Let binds (App expr arg)
-- Propagate the application into each of the alternatives
-beta (App (Case scrut b ty alts) arg) = change $ Case scrut b ty' alts'
+beta c (App (Case scrut b ty alts) arg) = change $ Case scrut b ty' alts'
where
alts' = map (\(con, bndrs, expr) -> (con, bndrs, (App expr arg))) alts
ty' = CoreUtils.applyTypeToArg ty arg
-- Leave all other expressions unchanged
-beta expr = return expr
--- Perform this transform everywhere
-betatop = everywhere ("beta", beta)
+beta c expr = return expr
+
+--------------------------------
+-- Case of known constructor simplification
+--------------------------------
+-- If a case expressions scrutinizes a datacon application, we can
+-- determine which alternative to use and remove the case alltogether.
+-- We replace it with a let expression the binds every binder in the
+-- alternative bound to the corresponding argument of the datacon. We do
+-- this instead of substituting the binders, to prevent duplication of
+-- work and preserve sharing wherever appropriate.
+knowncase :: Transform
+knowncase context expr@(Case scrut@(App _ _) bndr ty alts) | not bndr_used = do
+ case collectArgs scrut of
+ (Var f, args) -> case Id.isDataConId_maybe f of
+ -- Not a dataconstructor? Don't change anything (probably a
+ -- function, then)
+ Nothing -> return expr
+ Just dc -> do
+ let (altcon, bndrs, res) = case List.find (\(altcon, bndrs, res) -> altcon == (DataAlt dc)) alts of
+ Just alt -> alt -- Return the alternative found
+ Nothing -> head alts -- If the datacon is not present, the first must be the default alternative
+ -- Double check if we have either the correct alternative, or
+ -- the default.
+ if altcon /= (DataAlt dc) && altcon /= DEFAULT then error ("Normalize.knowncase: Invalid core, datacon not found in alternatives and DEFAULT alternative is not first? " ++ pprString expr) else return ()
+ -- Find out how many arguments to drop (type variables and
+ -- predicates like dictionaries).
+ let (tvs, preds, _, _) = DataCon.dataConSig dc
+ let count = length tvs + length preds
+ -- Create a let expression that binds each of the binders in
+ -- this alternative to the corresponding argument of the data
+ -- constructor.
+ let binds = zip bndrs (drop count args)
+ change $ Let (Rec binds) res
+ _ -> return expr -- Scrutinee is not an application of a var
+ where
+ is_used (_, _, expr) = expr_uses_binders [bndr] expr
+ bndr_used = or $ map is_used alts
+
+-- Leave all other expressions unchanged
+knowncase c expr = return expr
--------------------------------
-- Cast propagation
--------------------------------
-- Try to move casts as much downward as possible.
-castprop, castproptop :: Transform
-castprop (Cast (Let binds expr) ty) = change $ Let binds (Cast expr ty)
-castprop expr@(Cast (Case scrut b _ alts) ty) = change (Case scrut b ty alts')
+castprop :: Transform
+castprop c (Cast (Let binds expr) ty) = change $ Let binds (Cast expr ty)
+castprop c expr@(Cast (Case scrut b _ alts) ty) = change (Case scrut b ty alts')
where
alts' = map (\(con, bndrs, expr) -> (con, bndrs, (Cast expr ty))) alts
-- Leave all other expressions unchanged
-castprop expr = return expr
--- Perform this transform everywhere
-castproptop = everywhere ("castprop", castprop)
+castprop c expr = return expr
--------------------------------
-- Cast simplification. Mostly useful for state packing and unpacking, but
-- perhaps for others as well.
--------------------------------
-castsimpl, castsimpltop :: Transform
-castsimpl expr@(Cast val ty) = do
+castsimpl :: Transform
+castsimpl c expr@(Cast val ty) = do
-- Don't extract values that are already simpl
local_var <- Trans.lift $ is_local_var val
-- Don't extract values that are not representable, to prevent loops with
-- Generate a binder for the expression
id <- Trans.lift $ mkBinderFor val "castval"
-- Extract the expression
- change $ Let (Rec [(id, val)]) (Cast (Var id) ty)
+ change $ Let (NonRec id val) (Cast (Var id) ty)
else
return expr
-- Leave all other expressions unchanged
-castsimpl expr = return expr
--- Perform this transform everywhere
-castsimpltop = everywhere ("castsimpl", castsimpl)
+castsimpl c expr = return expr
--------------------------------
--- let recursification
+-- Return value simplification
--------------------------------
-letrec, letrectop :: Transform
-letrec (Let (NonRec b expr) res) = change $ Let (Rec [(b, expr)]) res
--- Leave all other expressions unchanged
-letrec expr = return expr
--- Perform this transform everywhere
-letrectop = everywhere ("letrec", letrec)
+-- Ensure the return value of a function follows proper normal form. eta
+-- expansion ensures the body starts with lambda abstractions, this
+-- transformation ensures that the lambda abstractions always contain a
+-- recursive let and that, when the return value is representable, the
+-- let contains a local variable reference in its body.
+retvalsimpl c expr | all (== LambdaBody) c && not (is_lam expr) && not (is_let expr) = do
+ local_var <- Trans.lift $ is_local_var expr
+ repr <- isRepr expr
+ if not local_var && repr
+ then do
+ id <- Trans.lift $ mkBinderFor expr "res"
+ change $ Let (Rec [(id, expr)]) (Var id)
+ else
+ return expr
---------------------------------
--- let simplification
---------------------------------
-letsimpl, letsimpltop :: Transform
--- Put the "in ..." value of a let in its own binding, but not when the
--- expression is already a local variable, or not representable (to prevent loops with inlinenonrep).
-letsimpl expr@(Let (Rec binds) res) = do
- repr <- isRepr res
- local_var <- Trans.lift $ is_local_var res
+retvalsimpl c expr@(Let (Rec binds) body) | all (== LambdaBody) c = do
+ -- Don't extract values that are already a local variable, to prevent
+ -- loops with ourselves.
+ local_var <- Trans.lift $ is_local_var body
+ -- Don't extract values that are not representable, to prevent loops with
+ -- inlinenonrep
+ repr <- isRepr body
if not local_var && repr
then do
- -- If the result is not a local var already (to prevent loops with
- -- ourselves), extract it.
- id <- Trans.lift $ mkBinderFor res "foo"
- let bind = (id, res)
- change $ Let (Rec (bind:binds)) (Var id)
+ id <- Trans.lift $ mkBinderFor body "res"
+ change $ Let (Rec ((id, body):binds)) (Var id)
else
- -- If the result is already a local var, don't extract it.
return expr
+
+-- Leave all other expressions unchanged
+retvalsimpl c expr = return expr
+
+--------------------------------
+-- let derecursification
+--------------------------------
+letrec :: Transform
+letrec c expr@(Let (NonRec bndr val) res) =
+ change $ Let (Rec [(bndr, val)]) res
+
-- Leave all other expressions unchanged
-letsimpl expr = return expr
--- Perform this transform everywhere
-letsimpltop = everywhere ("letsimpl", letsimpl)
+letrec c expr = return expr
--------------------------------
-- let flattening
--------------------------------
-letflat, letflattop :: Transform
-letflat (Let (Rec binds) expr) = do
- -- Turn each binding into a list of bindings (possibly containing just one
- -- element, of course)
- bindss <- Monad.mapM flatbind binds
- -- Concat all the bindings
- let binds' = concat bindss
+-- Takes a let that binds another let, and turns that into two nested lets.
+-- e.g., from:
+-- let b = (let b' = expr' in res') in res
+-- to:
+-- let b' = expr' in (let b = res' in res)
+letflat :: Transform
+-- Turn a nonrec let that binds a let into two nested lets.
+letflat c (Let (NonRec b (Let binds res')) res) =
+ change $ Let binds (Let (NonRec b res') res)
+letflat c (Let (Rec binds) expr) = do
+ -- Flatten each binding.
+ binds' <- Utils.concatM $ Monad.mapM flatbind binds
-- Return the new let. We don't use change here, since possibly nothing has
-- changed. If anything has changed, flatbind has already flagged that
-- change.
-- into a list with just that binding
flatbind :: (CoreBndr, CoreExpr) -> TransformMonad [(CoreBndr, CoreExpr)]
flatbind (b, Let (Rec binds) expr) = change ((b, expr):binds)
+ flatbind (b, Let (NonRec b' expr') expr) = change [(b, expr), (b', expr')]
flatbind (b, expr) = return [(b, expr)]
-- Leave all other expressions unchanged
-letflat expr = return expr
--- Perform this transform everywhere
-letflattop = everywhere ("letflat", letflat)
+letflat c expr = return expr
+
+--------------------------------
+-- empty let removal
+--------------------------------
+-- Remove empty (recursive) lets
+letremove :: Transform
+letremove c (Let (Rec []) res) = change res
+-- Leave all other expressions unchanged
+letremove c expr = return expr
--------------------------------
-- Simple let binding removal
--------------------------------
-- Remove a = b bindings from let expressions everywhere
-letremovetop :: Transform
-letremovetop = everywhere ("letremove", inlinebind (\(b, e) -> Trans.lift $ is_local_var e))
+letremovesimple :: Transform
+letremovesimple = inlinebind (\(b, e) -> Trans.lift $ is_local_var e)
--------------------------------
-- Unused let binding removal
--------------------------------
-letremoveunused, letremoveunusedtop :: Transform
-letremoveunused expr@(Let (Rec binds) res) = do
+letremoveunused :: Transform
+letremoveunused c expr@(Let (NonRec b bound) res) = do
+ let used = expr_uses_binders [b] res
+ if used
+ then return expr
+ else change res
+letremoveunused c expr@(Let (Rec binds) res) = do
-- Filter out all unused binds.
let binds' = filter dobind binds
-- Only set the changed flag if binds got removed
-- expressions
dobind (bndr, _) = any (expr_uses_binders [bndr]) (res:bound_exprs)
-- Leave all other expressions unchanged
-letremoveunused expr = return expr
-letremoveunusedtop = everywhere ("letremoveunused", letremoveunused)
+letremoveunused c expr = return expr
+{-
--------------------------------
-- Identical let binding merging
--------------------------------
-- Merge two bindings in a let if they are identical
-- TODO: We would very much like to use GHC's CSE module for this, but that
-- doesn't track if something changed or not, so we can't use it properly.
-letmerge, letmergetop :: Transform
-letmerge expr@(Let (Rec binds) res) = do
+letmerge :: Transform
+letmerge c expr@(Let _ _) = do
+ let (binds, res) = flattenLets expr
binds' <- domerge binds
- return (Let (Rec binds') res)
+ return $ mkNonRecLets binds' res
where
domerge :: [(CoreBndr, CoreExpr)] -> TransformMonad [(CoreBndr, CoreExpr)]
domerge [] = return []
-- Different expressions? Don't change
| otherwise = return (b2, e2)
-- Leave all other expressions unchanged
-letmerge expr = return expr
-letmergetop = everywhere ("letmerge", letmerge)
-
+letmerge c expr = return expr
+-}
+
--------------------------------
--- Function inlining
+-- Non-representable binding inlining
--------------------------------
--- Remove a = B bindings, with B :: a -> b, or B :: forall x . T, from let
--- expressions everywhere. This means that any value that still needs to be
--- applied to something else (polymorphic values need to be applied to a
--- Type) will be inlined, and will eventually be applied to all their
--- arguments.
+-- Remove a = B bindings, with B of a non-representable type, from let
+-- expressions everywhere. This means that any value that we can't generate a
+-- signal for, will be inlined and hopefully turned into something we can
+-- represent.
--
-- This is a tricky function, which is prone to create loops in the
-- transformations. To fix this, we make sure that no transformation will
--- create a new let binding with a function type. These other transformations
--- will just not work on those function-typed values at first, but the other
--- transformations (in particular β-reduction) should make sure that the type
--- of those values eventually becomes primitive.
-inlinenonreptop :: Transform
-inlinenonreptop = everywhere ("inlinenonrep", inlinebind ((Monad.liftM not) . isRepr . snd))
+-- create a new let binding with a non-representable type. These other
+-- transformations will just not work on those function-typed values at first,
+-- but the other transformations (in particular β-reduction) should make sure
+-- that the type of those values eventually becomes representable.
+inlinenonrep :: Transform
+inlinenonrep = inlinebind ((Monad.liftM not) . isRepr . snd)
+
+--------------------------------
+-- Top level function inlining
+--------------------------------
+-- This transformation inlines simple top level bindings. Simple
+-- currently means that the body is only a single application (though
+-- the complexity of the arguments is not currently checked) or that the
+-- normalized form only contains a single binding. This should catch most of the
+-- cases where a top level function is created that simply calls a type class
+-- method with a type and dictionary argument, e.g.
+-- fromInteger = GHC.Num.fromInteger (SizedWord D8) $dNum
+-- which is later called using simply
+-- fromInteger (smallInteger 10)
+--
+-- These useless wrappers are created by GHC automatically. If we don't
+-- inline them, we get loads of useless components cluttering the
+-- generated VHDL.
+--
+-- Note that the inlining could also inline simple functions defined by
+-- the user, not just GHC generated functions. It turns out to be near
+-- impossible to reliably determine what functions are generated and
+-- what functions are user-defined. Instead of guessing (which will
+-- inline less than we want) we will just inline all simple functions.
+--
+-- Only functions that are actually completely applied and bound by a
+-- variable in a let expression are inlined. These are the expressions
+-- that will eventually generate instantiations of trivial components.
+-- By not inlining any other reference, we also prevent looping problems
+-- with funextract and inlinedict.
+inlinetoplevel :: Transform
+inlinetoplevel (LetBinding:_) expr | not (is_fun expr) =
+ case collectArgs expr of
+ (Var f, args) -> do
+ body_maybe <- needsInline f
+ case body_maybe of
+ Just body -> do
+ -- Regenerate all uniques in the to-be-inlined expression
+ body_uniqued <- Trans.lift $ genUniques body
+ -- And replace the variable reference with the unique'd body.
+ change (mkApps body_uniqued args)
+ -- No need to inline
+ Nothing -> return expr
+ -- This is not an application of a binder, leave it unchanged.
+ _ -> return expr
+
+-- Leave all other expressions unchanged
+inlinetoplevel c expr = return expr
+
+-- | Does the given binder need to be inlined? If so, return the body to
+-- be used for inlining.
+needsInline :: CoreBndr -> TransformMonad (Maybe CoreExpr)
+needsInline f = do
+ body_maybe <- Trans.lift $ getGlobalBind f
+ case body_maybe of
+ -- No body available?
+ Nothing -> return Nothing
+ Just body -> case CoreSyn.collectArgs body of
+ -- The body is some (top level) binder applied to 0 or more
+ -- arguments. That should be simple enough to inline.
+ (Var f, args) -> return $ Just body
+ -- Body is more complicated, try normalizing it
+ _ -> do
+ norm_maybe <- Trans.lift $ getNormalized_maybe False f
+ case norm_maybe of
+ -- Noth normalizeable
+ Nothing -> return Nothing
+ Just norm -> case splitNormalizedNonRep norm of
+ -- The function has just a single binding, so that's simple
+ -- enough to inline.
+ (args, [bind], Var res) -> return $ Just norm
+ -- More complicated function, don't inline
+ _ -> return Nothing
+
+--------------------------------
+-- Dictionary inlining
+--------------------------------
+-- Inline all top level dictionaries, that are in a position where
+-- classopresolution can actually resolve them. This makes this
+-- transformation look similar to classoperesolution below, but we'll
+-- keep them separated for clarity. By not inlining other dictionaries,
+-- we prevent expression sizes exploding when huge type level integer
+-- dictionaries are inlined which can never be expanded (in casts, for
+-- example).
+inlinedict c expr@(App (App (Var sel) ty) (Var dict)) | not is_builtin && is_classop = do
+ body_maybe <- Trans.lift $ getGlobalBind dict
+ case body_maybe of
+ -- No body available (no source available, or a local variable /
+ -- argument)
+ Nothing -> return expr
+ Just body -> change (App (App (Var sel) ty) body)
+ where
+ -- Is this a builtin function / method?
+ is_builtin = elem (Name.getOccString sel) builtinIds
+ -- Are we dealing with a class operation selector?
+ is_classop = Maybe.isJust (Id.isClassOpId_maybe sel)
+
+-- Leave all other expressions unchanged
+inlinedict c expr = return expr
+
+--------------------------------
+-- ClassOp resolution
+--------------------------------
+-- Resolves any class operation to the actual operation whenever
+-- possible. Class methods (as well as parent dictionary selectors) are
+-- special "functions" that take a type and a dictionary and evaluate to
+-- the corresponding method. A dictionary is nothing more than a
+-- special dataconstructor applied to the type the dictionary is for,
+-- each of the superclasses and all of the class method definitions for
+-- that particular type. Since dictionaries all always inlined (top
+-- levels dictionaries are inlined by inlinedict, local dictionaries are
+-- inlined by inlinenonrep), we will eventually have something like:
+--
+-- baz
+-- @ CLasH.HardwareTypes.Bit
+-- (D:Baz @ CLasH.HardwareTypes.Bit bitbaz)
+--
+-- Here, baz is the method selector for the baz method, while
+-- D:Baz is the dictionary constructor for the Baz and bitbaz is the baz
+-- method defined in the Baz Bit instance declaration.
+--
+-- To resolve this, we can look at the ClassOp IdInfo from the baz Id,
+-- which contains the Class it is defined for. From the Class, we can
+-- get a list of all selectors (both parent class selectors as well as
+-- method selectors). Since the arguments to D:Baz (after the type
+-- argument) correspond exactly to this list, we then look up baz in
+-- that list and replace the entire expression by the corresponding
+-- argument to D:Baz.
+--
+-- We don't resolve methods that have a builtin translation (such as
+-- ==), since the actual implementation is not always (easily)
+-- translateable. For example, when deriving ==, GHC generates code
+-- using $con2tag functions to translate a datacon to an int and compare
+-- that with GHC.Prim.==# . Better to avoid that for now.
+classopresolution :: Transform
+classopresolution c expr@(App (App (Var sel) ty) dict) | not is_builtin =
+ case Id.isClassOpId_maybe sel of
+ -- Not a class op selector
+ Nothing -> return expr
+ Just cls -> case collectArgs dict of
+ (_, []) -> return expr -- Dict is not an application (e.g., not inlined yet)
+ (Var dictdc, (ty':selectors)) | not (Maybe.isJust (Id.isDataConId_maybe dictdc)) -> return expr -- Dictionary is not a datacon yet (but e.g., a top level binder)
+ | tyargs_neq ty ty' -> error $ "Normalize.classopresolution: Applying class selector to dictionary without matching type?\n" ++ pprString expr
+ | otherwise ->
+ let selector_ids = Class.classSelIds cls in
+ -- Find the selector used in the class' list of selectors
+ case List.elemIndex sel selector_ids of
+ Nothing -> error $ "Normalize.classopresolution: Selector not found in class' selector list? This should not happen!\nExpression: " ++ pprString expr ++ "\nClass: " ++ show cls ++ "\nSelectors: " ++ show selector_ids
+ -- Get the corresponding argument from the dictionary
+ Just n -> change (selectors!!n)
+ (_, _) -> return expr -- Not applying a variable? Don't touch
+ where
+ -- Compare two type arguments, returning True if they are _not_
+ -- equal
+ tyargs_neq (Type ty1) (Type ty2) = not $ Type.coreEqType ty1 ty2
+ tyargs_neq _ _ = True
+ -- Is this a builtin function / method?
+ is_builtin = elem (Name.getOccString sel) builtinIds
+
+-- Leave all other expressions unchanged
+classopresolution c expr = return expr
--------------------------------
-- Scrutinee simplification
--------------------------------
-scrutsimpl,scrutsimpltop :: Transform
+scrutsimpl :: Transform
-- Don't touch scrutinees that are already simple
-scrutsimpl expr@(Case (Var _) _ _ _) = return expr
+scrutsimpl c expr@(Case (Var _) _ _ _) = return expr
-- Replace all other cases with a let that binds the scrutinee and a new
-- simple scrutinee, but only when the scrutinee is representable (to prevent
-- loops with inlinenonrep, though I don't think a non-representable scrutinee
-- will be supported anyway...)
-scrutsimpl expr@(Case scrut b ty alts) = do
+scrutsimpl c expr@(Case scrut b ty alts) = do
repr <- isRepr scrut
if repr
then do
id <- Trans.lift $ mkBinderFor scrut "scrut"
- change $ Let (Rec [(id, scrut)]) (Case (Var id) b ty alts)
+ change $ Let (NonRec id scrut) (Case (Var id) b ty alts)
else
return expr
-- Leave all other expressions unchanged
-scrutsimpl expr = return expr
--- Perform this transform everywhere
-scrutsimpltop = everywhere ("scrutsimpl", scrutsimpl)
+scrutsimpl c expr = return expr
+
+--------------------------------
+-- Scrutinee binder removal
+--------------------------------
+-- A case expression can have an extra binder, to which the scrutinee is bound
+-- after bringing it to WHNF. This is used for forcing evaluation of strict
+-- arguments. Since strictness does not matter for us (rather, everything is
+-- sort of strict), this binder is ignored when generating VHDL, and must thus
+-- be wild in the normal form.
+scrutbndrremove :: Transform
+-- If the scrutinee is already simple, and the bndr is not wild yet, replace
+-- all occurences of the binder with the scrutinee variable.
+scrutbndrremove c (Case (Var scrut) bndr ty alts) | bndr_used = do
+ alts' <- mapM subs_bndr alts
+ change $ Case (Var scrut) wild ty alts'
+ where
+ is_used (_, _, expr) = expr_uses_binders [bndr] expr
+ bndr_used = or $ map is_used alts
+ subs_bndr (con, bndrs, expr) = do
+ expr' <- substitute bndr (Var scrut) c expr
+ return (con, bndrs, expr')
+ wild = MkCore.mkWildBinder (Id.idType bndr)
+-- Leave all other expressions unchanged
+scrutbndrremove c expr = return expr
--------------------------------
-- Case binder wildening
--------------------------------
-casesimpl, casesimpltop :: Transform
+casesimpl :: Transform
-- This is already a selector case (or, if x does not appear in bndrs, a very
-- simple case statement that will be removed by caseremove below). Just leave
-- it be.
-casesimpl expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr
+casesimpl c expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr
-- Make sure that all case alternatives have only wild binders and simple
-- expressions.
-- This is done by creating a new let binding for each non-wild binder, which
-- is bound to a new simple selector case statement and for each complex
-- expression. We do this only for representable types, to prevent loops with
-- inlinenonrep.
-casesimpl expr@(Case scrut b ty alts) = do
+casesimpl c expr@(Case scrut bndr ty alts) | not bndr_used = do
(bindingss, alts') <- (Monad.liftM unzip) $ mapM doalt alts
let bindings = concat bindingss
-- Replace the case with a let with bindings and a case
- let newlet = (Let (Rec bindings) (Case scrut b ty alts'))
+ let newlet = mkNonRecLets bindings (Case scrut bndr ty alts')
-- If there are no non-wild binders, or this case is already a simple
-- selector (i.e., a single alt with exactly one binding), already a simple
-- selector altan no bindings (i.e., no wild binders in the original case),
-- don't change anything, otherwise, replace the case.
if null bindings then return expr else change newlet
where
+ -- Check if the scrutinee binder is used
+ is_used (_, _, expr) = expr_uses_binders [bndr] expr
+ bndr_used = or $ map is_used alts
-- Generate a single wild binder, since they are all the same
wild = MkCore.mkWildBinder
-- Wilden the binders of one alt, producing a list of bindings as a
-- Extract a complex expression, if possible. For this we check if any of
-- the new list of bndrs are used by expr. We can't use free_vars here,
-- since that looks at the old bndrs.
- let uses_bndrs = not $ VarSet.isEmptyVarSet $ CoreFVs.exprSomeFreeVars (`elem` newbndrs) $ expr
+ let uses_bndrs = not $ VarSet.isEmptyVarSet $ CoreFVs.exprSomeFreeVars (`elem` newbndrs) expr
(exprbinding_maybe, expr') <- doexpr expr uses_bndrs
-- Create a new alternative
let newalt = (con, newbndrs, expr')
- let bindings = Maybe.catMaybes (exprbinding_maybe : bindings_maybe)
+ let bindings = Maybe.catMaybes (bindings_maybe ++ [exprbinding_maybe])
return (bindings, newalt)
where
-- Make wild alternatives for each binder
-- binding containing a case expression.
dobndr :: CoreBndr -> Int -> TransformMonad (CoreBndr, Maybe (CoreBndr, CoreExpr))
dobndr b i = do
- repr <- isRepr (Var b)
+ repr <- isRepr b
-- Is b wild (e.g., not a free var of expr. Since b is only in scope
-- in expr, this means that b is unused if expr does not use it.)
let wild = not (VarSet.elemVarSet b free_vars)
-- inlinenonrep).
if (not wild) && repr
then do
- -- Create on new binder that will actually capture a value in this
+ caseexpr <- Trans.lift $ mkSelCase scrut i
+ -- Create a new binder that will actually capture a value in this
-- case statement, and return it.
- let bty = (Id.idType b)
- id <- Trans.lift $ mkInternalVar "sel" bty
- let binders = take i wildbndrs ++ [id] ++ drop (i+1) wildbndrs
- let caseexpr = Case scrut b bty [(con, binders, Var id)]
return (wildbndrs!!i, Just (b, caseexpr))
else
-- Just leave the original binder in place, and don't generate an
id <- Trans.lift $ mkBinderFor expr "caseval"
-- We don't flag a change here, since casevalsimpl will do that above
-- based on Just we return here.
- return $ (Just (id, expr), Var id)
+ return (Just (id, expr), Var id)
else
-- Don't simplify anything else
return (Nothing, expr)
-- Leave all other expressions unchanged
-casesimpl expr = return expr
--- Perform this transform everywhere
-casesimpltop = everywhere ("casesimpl", casesimpl)
+casesimpl c expr = return expr
--------------------------------
-- Case removal
--------------------------------
-- Remove case statements that have only a single alternative and only wild
-- binders.
-caseremove, caseremovetop :: Transform
+caseremove :: Transform
-- Replace a useless case by the value of its single alternative
-caseremove (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr
+caseremove c (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr
-- Find if any of the binders are used by expr
- where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
+ where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` b:bndrs))) expr
-- Leave all other expressions unchanged
-caseremove expr = return expr
--- Perform this transform everywhere
-caseremovetop = everywhere ("caseremove", caseremove)
+caseremove c expr = return expr
--------------------------------
-- Argument extraction
--------------------------------
-- Make sure that all arguments of a representable type are simple variables.
-appsimpl, appsimpltop :: Transform
+appsimpl :: Transform
-- Simplify all representable arguments. Do this by introducing a new Let
-- that binds the argument and passing the new binder in the application.
-appsimpl expr@(App f arg) = do
+appsimpl c expr@(App f arg) = do
-- Check runtime representability
repr <- isRepr arg
local_var <- Trans.lift $ is_local_var arg
if repr && not local_var
then do -- Extract representable arguments
id <- Trans.lift $ mkBinderFor arg "arg"
- change $ Let (Rec [(id, arg)]) (App f (Var id))
+ change $ Let (NonRec id arg) (App f (Var id))
else -- Leave non-representable arguments unchanged
return expr
-- Leave all other expressions unchanged
-appsimpl expr = return expr
--- Perform this transform everywhere
-appsimpltop = everywhere ("appsimpl", appsimpl)
+appsimpl c expr = return expr
--------------------------------
-- Function-typed argument propagation
-- Remove all applications to function-typed arguments, by duplication the
-- function called with the function-typed parameter replaced by the free
-- variables of the argument passed in.
-argprop, argproptop :: Transform
+argprop :: Transform
-- Transform any application of a named function (i.e., skip applications of
-- lambda's). Also skip applications that have arguments with free type
-- variables, since we can't inline those.
-argprop expr@(App _ _) | is_var fexpr = do
+argprop c expr@(App _ _) | is_var fexpr = do
-- Find the body of the function called
body_maybe <- Trans.lift $ getGlobalBind f
case body_maybe of
let newbody = MkCore.mkCoreLams newparams (MkCore.mkCoreApps body oldargs)
-- Create a new function with the same name but a new body
newf <- Trans.lift $ mkFunction f newbody
+
+ Trans.lift $ MonadState.modify tsInitStates (\ismap ->
+ let init_state_maybe = Map.lookup f ismap in
+ case init_state_maybe of
+ Nothing -> ismap
+ Just init_state -> Map.insert newf init_state ismap)
-- Replace the original application with one of the new function to the
-- new arguments.
change $ MkCore.mkCoreApps (Var newf) newargs
doarg arg = do
repr <- isRepr arg
bndrs <- Trans.lift getGlobalBinders
- let interesting var = Var.isLocalVar var && (not $ var `elem` bndrs)
+ let interesting var = Var.isLocalVar var && (var `notElem` bndrs)
if not repr && not (is_var arg && interesting (exprToVar arg)) && not (has_free_tyvars arg)
then do
-- Propagate all complex arguments that are not representable, but not
let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting arg
-- Mark the current expression as changed
setChanged
+ -- TODO: Clone the free_vars (and update references in arg), since
+ -- this might cause conflicts if two arguments that are propagated
+ -- share a free variable. Also, we are now introducing new variables
+ -- into a function that are not fresh, which violates the binder
+ -- uniqueness invariant.
return (map Var free_vars, free_vars, arg)
else do
-- Representable types will not be propagated, and arguments with free
-- type variables will be propagated later.
+ -- Note that we implicitly remove any type variables in the type of
+ -- the original argument by using the type of the actual argument
+ -- for the new formal parameter.
-- TODO: preserve original naming?
id <- Trans.lift $ mkBinderFor arg "param"
-- Just pass the original argument to the new function, which binds it
-- to a new id and just pass that new id to the old function body.
return ([arg], [id], mkReferenceTo id)
-- Leave all other expressions unchanged
-argprop expr = return expr
--- Perform this transform everywhere
-argproptop = everywhere ("argprop", argprop)
+argprop c expr = return expr
+
+--------------------------------
+-- Non-representable result inlining
+--------------------------------
+-- This transformation takes a function (top level binding) that has a
+-- non-representable result (e.g., a tuple containing a function, or an
+-- Integer. The latter can occur in some cases as the result of the
+-- fromIntegerT function) and inlines enough of the function to make the
+-- result representable again.
+--
+-- This is done by first normalizing the function and then "inlining"
+-- the result. Since no unrepresentable let bindings are allowed in
+-- normal form, we can be sure that all free variables of the result
+-- expression will be representable (Note that we probably can't
+-- guarantee that all representable parts of the expression will be free
+-- variables, so we might inline more than strictly needed).
+--
+-- The new function result will be a tuple containing all free variables
+-- of the old result, so the old result can be rebuild at the caller.
+--
+-- We take care not to inline dictionary id's, which are top level
+-- bindings with a non-representable result type as well, since those
+-- will never become VHDL signals directly. There is a separate
+-- transformation (inlinedict) that specifically inlines dictionaries
+-- only when it is useful.
+inlinenonrepresult :: Transform
+
+-- Apply to any (application of) a reference to a top level function
+-- that is fully applied (i.e., dos not have a function type) but is not
+-- representable. We apply in any context, since non-representable
+-- expressions are generally left alone and can occur anywhere.
+inlinenonrepresult context expr | not (is_fun expr) =
+ case collectArgs expr of
+ (Var f, args) | not (Id.isDictId f) -> do
+ repr <- isRepr expr
+ if not repr
+ then do
+ body_maybe <- Trans.lift $ getNormalized_maybe True f
+ case body_maybe of
+ Just body -> do
+ let (bndrs, binds, res) = splitNormalizedNonRep body
+ if has_free_tyvars res
+ then
+ -- Don't touch anything with free type variables, since
+ -- we can't return those. We'll wait until argprop
+ -- removed those variables.
+ return expr
+ else do
+ -- Get the free local variables of res
+ global_bndrs <- Trans.lift getGlobalBinders
+ let interesting var = Var.isLocalVar var && (var `notElem` global_bndrs)
+ let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting res
+ let free_var_types = map Id.idType free_vars
+ let n_free_vars = length free_vars
+ -- Get a tuple datacon to wrap around the free variables
+ let fvs_datacon = TysWiredIn.tupleCon BasicTypes.Boxed n_free_vars
+ let fvs_datacon_id = DataCon.dataConWorkId fvs_datacon
+ -- Let the function now return a tuple with references to
+ -- all free variables of the old return value. First pass
+ -- all the types of the variables, since tuple
+ -- constructors are polymorphic.
+ let newres = mkApps (Var fvs_datacon_id) (map Type free_var_types ++ map Var free_vars)
+ -- Recreate the function body with the changed return value
+ let newbody = mkLams bndrs (Let (Rec binds) newres)
+ -- Create the new function
+ f' <- Trans.lift $ mkFunction f newbody
+
+ -- Call the new function
+ let newapp = mkApps (Var f') args
+ res_bndr <- Trans.lift $ mkBinderFor newapp "res"
+ -- Create extractor case expressions to extract each of the
+ -- free variables from the tuple.
+ sel_cases <- Trans.lift $ mapM (mkSelCase (Var res_bndr)) [0..n_free_vars-1]
+
+ -- Bind the res_bndr to the result of the new application
+ -- and each of the free variables to the corresponding
+ -- selector case. Replace the let body with the original
+ -- body of the called function (which can still access all
+ -- of its free variables, from the let).
+ let binds = (res_bndr, newapp):(zip free_vars sel_cases)
+ let letexpr = Let (Rec binds) res
+
+ -- Finally, regenarate all uniques in the new expression,
+ -- since the free variables could otherwise become
+ -- duplicated. It is not strictly necessary to regenerate
+ -- res, since we're moving that expression, but it won't
+ -- hurt.
+ letexpr_uniqued <- Trans.lift $ genUniques letexpr
+ change letexpr_uniqued
+ Nothing -> return expr
+ else
+ -- Don't touch representable expressions or (applications of)
+ -- dictionary ids.
+ return expr
+ -- Not a reference to or application of a top level function
+ _ -> return expr
+-- Leave all other expressions unchanged
+inlinenonrepresult c expr = return expr
+
--------------------------------
-- Function-typed argument extraction
-- puts it in a brand new top level binder. This allows us to for example
-- apply map to a lambda expression This will not conflict with inlinenonrep,
-- since that only inlines local let bindings, not top level bindings.
-funextract, funextracttop :: Transform
-funextract expr@(App _ _) | is_var fexpr = do
+funextract :: Transform
+funextract c expr@(App _ _) | is_var fexpr = do
body_maybe <- Trans.lift $ getGlobalBind f
case body_maybe of
-- We don't have a function body for f, so we can perform this transform.
doarg arg = return arg
-- Leave all other expressions unchanged
-funextract expr = return expr
--- Perform this transform everywhere
-funextracttop = everywhere ("funextract", funextract)
+funextract c expr = return expr
--------------------------------
-- End of transformations
-- What transforms to run?
-transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letrectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letmergetop, letremoveunusedtop, castsimpltop]
-
--- | Returns the normalized version of the given function.
+transforms = [ ("inlinedict", inlinedict)
+ , ("inlinetoplevel", inlinetoplevel)
+ , ("inlinenonrepresult", inlinenonrepresult)
+ , ("knowncase", knowncase)
+ , ("classopresolution", classopresolution)
+ , ("argprop", argprop)
+ , ("funextract", funextract)
+ , ("eta", eta)
+ , ("beta", beta)
+ , ("castprop", castprop)
+ , ("letremovesimple", letremovesimple)
+ , ("letrec", letrec)
+ , ("letremove", letremove)
+ , ("retvalsimpl", retvalsimpl)
+ , ("letflat", letflat)
+ , ("scrutsimpl", scrutsimpl)
+ , ("scrutbndrremove", scrutbndrremove)
+ , ("casesimpl", casesimpl)
+ , ("caseremove", caseremove)
+ , ("inlinenonrep", inlinenonrep)
+ , ("appsimpl", appsimpl)
+ , ("letremoveunused", letremoveunused)
+ , ("castsimpl", castsimpl)
+ ]
+
+-- | Returns the normalized version of the given function, or an error
+-- if it is not a known global binder.
getNormalized ::
- CoreBndr -- ^ The function to get
+ Bool -- ^ Allow the result to be unrepresentable?
+ -> CoreBndr -- ^ The function to get
-> TranslatorSession CoreExpr -- The normalized function body
-
-getNormalized bndr = Utils.makeCached bndr tsNormalized $ do
- if is_poly (Var bndr)
- then
- -- This should really only happen at the top level... TODO: Give
- -- a different error if this happens down in the recursion.
- error $ "\nNormalize.normalizeBind: Function " ++ show bndr ++ " is polymorphic, can't normalize"
- else do
- expr <- getBinding bndr
- normalizeExpr (show bndr) expr
+getNormalized result_nonrep bndr = do
+ norm <- getNormalized_maybe result_nonrep bndr
+ return $ Maybe.fromMaybe
+ (error $ "Normalize.getNormalized: Unknown or non-representable function requested: " ++ show bndr)
+ norm
+
+-- | Returns the normalized version of the given function, or Nothing
+-- when the binder is not a known global binder or is not normalizeable.
+getNormalized_maybe ::
+ Bool -- ^ Allow the result to be unrepresentable?
+ -> CoreBndr -- ^ The function to get
+ -> TranslatorSession (Maybe CoreExpr) -- The normalized function body
+
+getNormalized_maybe result_nonrep bndr = do
+ expr_maybe <- getGlobalBind bndr
+ normalizeable <- isNormalizeable result_nonrep bndr
+ if not normalizeable || Maybe.isNothing expr_maybe
+ then
+ -- Binder not normalizeable or not found
+ return Nothing
+ else do
+ -- Binder found and is monomorphic. Normalize the expression
+ -- and cache the result.
+ normalized <- Utils.makeCached bndr tsNormalized $
+ normalizeExpr (show bndr) (Maybe.fromJust expr_maybe)
+ return (Just normalized)
-- | Normalize an expression
normalizeExpr ::
-> TranslatorSession CoreSyn.CoreExpr -- ^ The normalized expression
normalizeExpr what expr = do
- -- Introduce an empty Let at the top level, so there will always be
- -- a let in the expression (none of the transformations will remove
- -- the last let).
- let expr' = Let (Rec []) expr
+ startcount <- MonadState.get tsTransformCounter
+ expr_uniqued <- genUniques expr
-- Normalize this expression
- trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr' ) ++ "\n") $ return ()
- expr'' <- dotransforms transforms expr'
- trace ("\n" ++ what ++ " after normalization:\n\n" ++ showSDoc ( ppr expr'')) $ return ()
- return expr''
-
--- | Get the value that is bound to the given binder at top level. Fails when
--- there is no such binding.
-getBinding ::
- CoreBndr -- ^ The binder to get the expression for
- -> TranslatorSession CoreExpr -- ^ The value bound to the binder
-
-getBinding bndr = Utils.makeCached bndr tsBindings $ do
- -- If the binding isn't in the "cache" (bindings map), then we can't create
- -- it out of thin air, so return an error.
- error $ "Normalize.getBinding: Unknown function requested: " ++ show bndr
+ trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr_uniqued ) ++ "\n") $ return ()
+ expr' <- dotransforms transforms expr_uniqued
+ endcount <- MonadState.get tsTransformCounter
+ trace ("\n" ++ what ++ " after normalization:\n\n" ++ showSDoc ( ppr expr')
+ ++ "\nNeeded " ++ show (endcount - startcount) ++ " transformations to normalize " ++ what) $
+ return expr'
-- | Split a normalized expression into the argument binders, top level
--- bindings and the result binder.
+-- bindings and the result binder. This function returns an error if
+-- the type of the expression is not representable.
splitNormalized ::
CoreExpr -- ^ The normalized expression
-> ([CoreBndr], [Binding], CoreBndr)
-splitNormalized expr = (args, binds, res)
+splitNormalized expr =
+ case splitNormalizedNonRep expr of
+ (args, binds, Var res) -> (args, binds, res)
+ _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n"
+
+-- Split a normalized expression, whose type can be unrepresentable.
+splitNormalizedNonRep::
+ CoreExpr -- ^ The normalized expression
+ -> ([CoreBndr], [Binding], CoreExpr)
+splitNormalizedNonRep expr = (args, binds, resexpr)
where
(args, letexpr) = CoreSyn.collectBinders expr
(binds, resexpr) = flattenLets letexpr
- res = case resexpr of
- (Var x) -> x
- _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n"
-
--- | Flattens nested lets into a single list of bindings. The expression
--- passed does not have to be a let expression, if it isn't an empty list of
--- bindings is returned.
-flattenLets ::
- CoreExpr -- ^ The expression to flatten.
- -> ([Binding], CoreExpr) -- ^ The bindings and resulting expression.
-flattenLets (Let binds expr) =
- (bindings ++ bindings', expr')
- where
- -- Recursively flatten the contained expression
- (bindings', expr') =flattenLets expr
- -- Flatten our own bindings to remove the Rec / NonRec constructors
- bindings = CoreSyn.flattenBinds [binds]
-flattenLets expr = ([], expr)
projects / matthijs / master-project / cλash.git / blobdiff