+{-# LANGUAGE PackageImports #-}
--
-- Functions to bring a Core expression in normal form. This module provides a
-- top level function "normalize", and defines the actual transformation passes that
-- are performed.
--
-module Normalize (normalize) where
+module Normalize (normalizeModule) where
-- Standard modules
import Debug.Trace
import qualified Maybe
+import qualified "transformers" Control.Monad.Trans as Trans
import qualified Control.Monad as Monad
+import qualified Data.Map as Map
+import Data.Accessor
-- GHC API
import CoreSyn
import qualified CoreUtils
import qualified Type
import qualified Id
-import qualified UniqSet
+import qualified Var
+import qualified VarSet
import qualified CoreFVs
import Outputable ( showSDoc, ppr, nest )
-- Don't simplifiy lets that are already simple
letsimpl expr@(Let _ (Var _)) = return expr
-- Put the "in ..." value of a let in its own binding, but not when the
--- expression has a function type (to prevent loops with inlinefun).
-letsimpl (Let (Rec binds) expr) | not $ is_fun expr = do
+-- expression is applicable (to prevent loops with inlinefun).
+letsimpl (Let (Rec binds) expr) | not $ is_applicable expr = do
id <- mkInternalVar "foo" (CoreUtils.exprType expr)
let bind = (id, expr)
change $ Let (Rec (bind:binds)) (Var id)
--------------------------------
-- Function inlining
--------------------------------
--- Remove a = B bindings, with B :: a -> b, from let expressions everywhere.
+-- 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.
+--
-- 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
-- transformations (in particular β-reduction) should make sure that the type
-- of those values eventually becomes primitive.
inlinefuntop :: Transform
-inlinefuntop = everywhere ("inlinefun", inlinebind (Type.isFunTy . CoreUtils.exprType . snd))
+inlinefuntop = everywhere ("inlinefun", inlinebind (is_applicable . snd))
--------------------------------
-- Scrutinee simplification
-- Don't touch scrutinees that are already simple
scrutsimpl expr@(Case (Var _) _ _ _) = return expr
-- Replace all other cases with a let that binds the scrutinee and a new
--- simple scrutinee, but not when the scrutinee is a function type (to prevent
--- loops with inlinefun, though I don't think a scrutinee can have a function
--- type...)
-scrutsimpl (Case scrut b ty alts) | not $ is_fun scrut = do
+-- simple scrutinee, but not when the scrutinee is applicable (to prevent
+-- loops with inlinefun, though I don't think a scrutinee can be
+-- applicable...)
+scrutsimpl (Case scrut b ty alts) | not $ is_applicable scrut = do
id <- mkInternalVar "scrut" (CoreUtils.exprType scrut)
change $ Let (Rec [(id, scrut)]) (Case (Var id) b ty alts)
-- Leave all other expressions unchanged
-- replacing the case value with that id. Only do this when the case value
-- does not use any of the binders bound by this alternative, for that would
-- cause those binders to become unbound when moving the value outside of
- -- the case statement. Also, don't create a binding for function-typed
+ -- the case statement. Also, don't create a binding for applicable
-- expressions, to prevent loops with inlinefun.
- doalt (con, bndrs, expr) | (not usesvars) && (not $ is_fun expr) = do
+ doalt (con, bndrs, expr) | (not usesvars) && (not $ is_applicable expr) = do
id <- mkInternalVar "caseval" (CoreUtils.exprType expr)
-- We don't flag a change here, since casevalsimpl will do that above
-- based on Just we return here.
return $ (Just (id, expr), (con, bndrs, Var id))
-- Find if any of the binders are used by expr
- where usesvars = (not . UniqSet.isEmptyUniqSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
+ where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
-- Don't simplify anything else
doalt alt = return (Nothing, alt)
-- Leave all other expressions unchanged
-- Replace a useless case by the value of its single alternative
caseremove (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr
-- Find if any of the binders are used by expr
- where usesvars = (not . UniqSet.isEmptyUniqSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
+ where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr
-- Leave all other expressions unchanged
caseremove expr = return expr
-- Perform this transform everywhere
appsimpl, appsimpltop :: Transform
-- Don't simplify arguments that are already simple
appsimpl expr@(App f (Var _)) = return expr
--- Simplify all arguments that do not have a function type (to prevent loops
--- with inlinefun) and is not a type argument. Do this by introducing a new
--- Let that binds the argument and passing the new binder in the application.
-appsimpl (App f expr) | (not $ is_fun expr) && (not $ CoreSyn.isTypeArg expr) = do
+-- Simplify all non-applicable (to prevent loops with inlinefun) arguments,
+-- except for type arguments (since a let can't bind type vars, only a lambda
+-- can). Do this by introducing a new Let that binds the argument and passing
+-- the new binder in the application.
+appsimpl (App f expr) | (not $ is_applicable expr) && (not $ CoreSyn.isTypeArg expr) = do
id <- mkInternalVar "arg" (CoreUtils.exprType expr)
change $ Let (Rec [(id, expr)]) (App f (Var id))
-- Leave all other expressions unchanged
-- Perform this transform everywhere
appsimpltop = everywhere ("appsimpl", appsimpl)
+
+--------------------------------
+-- Type argument propagation
+--------------------------------
+-- Remove all applications to type arguments, by duplicating the function
+-- called with the type application in its new definition. We leave
+-- dictionaries that might be associated with the type untouched, the funprop
+-- transform should propagate these later on.
+typeprop, typeproptop :: Transform
+-- Transform any function that is applied to a type argument. Since type
+-- arguments are always the first ones to apply and we'll remove all type
+-- arguments, we can simply do them one by one. We only propagate type
+-- arguments without any free tyvars, since tyvars those wouldn't be in scope
+-- in the new function.
+typeprop expr@(App (Var f) arg@(Type ty)) | not $ has_free_tyvars arg = do
+ id <- cloneVar f
+ let newty = Type.applyTy (Id.idType f) ty
+ let newf = Var.setVarType id newty
+ body_maybe <- Trans.lift $ getGlobalBind f
+ case body_maybe of
+ Just body -> do
+ let newbody = App body (Type ty)
+ Trans.lift $ addGlobalBind newf newbody
+ change (Var newf)
+ -- If we don't have a body for the function called, leave it unchanged (it
+ -- should be a primitive function then).
+ Nothing -> return expr
+-- Leave all other expressions unchanged
+typeprop expr = return expr
+-- Perform this transform everywhere
+typeproptop = everywhere ("typeprop", typeprop)
+
-- TODO: introduce top level let if needed?
--------------------------------
-- What transforms to run?
-transforms = [etatop, betatop, letremovetop, letrectop, letsimpltop, letflattop, casewildtop, scrutsimpltop, casevalsimpltop, caseremovetop, inlinefuntop, appsimpltop]
+transforms = [typeproptop, etatop, betatop, letremovetop, letrectop, letsimpltop, letflattop, casewildtop, scrutsimpltop, casevalsimpltop, caseremovetop, inlinefuntop, appsimpltop]
+
+-- Turns the given bind into VHDL
+normalizeModule ::
+ UniqSupply.UniqSupply -- ^ A UniqSupply we can use
+ -> [(CoreBndr, CoreExpr)] -- ^ All bindings we know (i.e., in the current module)
+ -> [CoreBndr] -- ^ The bindings to generate VHDL for (i.e., the top level bindings)
+ -> [Bool] -- ^ For each of the bindings to generate VHDL for, if it is stateful
+ -> [(CoreBndr, CoreExpr)] -- ^ The resulting VHDL
--- Normalize a core expression by running transforms until none applies
--- anymore. Uses a UniqSupply to generate new identifiers.
-normalize :: UniqSupply.UniqSupply -> CoreExpr -> CoreExpr
-normalize = dotransforms transforms
+normalizeModule uniqsupply bindings generate_for statefuls = runTransformSession uniqsupply $ do
+ -- Put all the bindings in this module in the tsBindings map
+ putA tsBindings (Map.fromList bindings)
+ -- (Recursively) normalize each of the requested bindings
+ mapM normalizeBind generate_for
+ -- Get all initial bindings and the ones we produced
+ bindings_map <- getA tsBindings
+ let bindings = Map.assocs bindings_map
+ normalized_bindings <- getA tsNormalized
+ -- But return only the normalized bindings
+ return $ filter ((flip VarSet.elemVarSet normalized_bindings) . fst) bindings
+normalizeBind :: CoreBndr -> TransformSession ()
+normalizeBind bndr = do
+ normalized_funcs <- getA tsNormalized
+ -- See if this function was normalized already
+ if VarSet.elemVarSet bndr normalized_funcs
+ then
+ -- Yup, don't do it again
+ return ()
+ else do
+ -- Nope, note that it has been and do it.
+ modA tsNormalized (flip VarSet.extendVarSet bndr)
+ expr_maybe <- getGlobalBind bndr
+ case expr_maybe of
+ Just expr -> do
+ -- Normalize this expression
+ expr' <- dotransforms transforms expr
+ let expr'' = trace ("Before:\n\n" ++ showSDoc ( ppr expr ) ++ "\n\nAfter:\n\n" ++ showSDoc ( ppr expr')) expr'
+ -- And store the normalized version in the session
+ modA tsBindings (Map.insert bndr expr'')
+ -- Find all vars used with a function type. All of these should be global
+ -- binders (i.e., functions used), since any local binders with a function
+ -- type should have been inlined already.
+ let used_funcs_set = CoreFVs.exprSomeFreeVars (\v -> (Type.isFunTy . snd . Type.splitForAllTys . Id.idType) v) expr''
+ let used_funcs = VarSet.varSetElems used_funcs_set
+ -- Process each of the used functions recursively
+ mapM normalizeBind used_funcs
+ return ()
+ -- We don't have a value for this binder, let's assume this is a builtin
+ -- function. This might need some extra checking and a nice error
+ -- message).
+ Nothing -> return ()
projects / matthijs / master-project / cλash.git / blobdiff