409 lines
19 KiB
Haskell
409 lines
19 KiB
Haskell
{-
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Tock: a compiler for parallel languages
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Copyright (C) 2007, 2008 University of Kent
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 2 of the License, or (at your
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option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program. If not, see <http://www.gnu.org/licenses/>.
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-}
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-- | Passes associated with the backends
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module BackendPasses (addSizesActualParameters, addSizesFormalParameters, declareSizesArray, simplifySlices, squashArrays, transformWaitFor) where
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import Control.Monad.State
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import Data.Generics
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import qualified Data.Map as Map
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import qualified AST as A
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import CompState
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import Errors
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import EvalConstants
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import Metadata
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import Pass
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import PrettyShow
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import qualified Properties as Prop
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import ShowCode
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import Traversal
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import Types
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import Utils
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squashArrays :: [Pass]
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squashArrays =
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[ removeDirections
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, removeUnneededDirections
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, simplifySlices
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, declareSizesArray
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, addSizesFormalParameters
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, addSizesActualParameters
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, fixMinInt
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]
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prereq :: [Property]
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prereq = Prop.agg_namesDone ++ Prop.agg_typesDone ++ Prop.agg_functionsGone ++ [Prop.subscriptsPulledUp, Prop.arrayLiteralsExpanded]
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-- | Remove all variable directions.
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-- They're unimportant in occam code once the directions have been checked,
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-- and this somewhat simplifies the work of the later passes.
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removeDirections :: Pass
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removeDirections
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= occamAndCOnlyPass "Remove variable directions"
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prereq
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[Prop.directionsRemoved]
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(applyDepthM (return . doVariable))
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where
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doVariable :: A.Variable -> A.Variable
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doVariable (A.DirectedVariable _ _ v) = v
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doVariable v = v
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-- | Remove variable directions that are superfluous. This prevents confusing
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-- later passes, where the user has written something like:
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-- []CHAN INT da! IS ...:
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-- foo(da!)
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--
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-- The second direction specifier is unneeded, and will confuse passes such as
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-- those adding sizes parameters (which looks for plain variables, since directed
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-- arrays should already have been pulled up).
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removeUnneededDirections :: Pass
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removeUnneededDirections
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= occamOnlyPass "Remove unneeded variable directions"
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prereq
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[]
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(applyDepthM doVariable)
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where
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doVariable :: Transform (A.Variable)
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doVariable whole@(A.DirectedVariable m dir v)
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= do t <- astTypeOf v
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case t of
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A.Chan {} -> return whole
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A.Array _ (A.Chan {}) -> return whole
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A.ChanEnd chanDir _ _ | dir == chanDir -> return v
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A.Array _ (A.ChanEnd chanDir _ _) | dir == chanDir -> return v
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_ -> diePC m $ formatCode "Direction applied to non-channel type: %" t
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doVariable v = return v
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-- | Turns any literals equivalent to a MOSTNEG back into a MOSTNEG
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-- The reason for doing this is that C (and presumably C++) don't technically (according
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-- to the standard) allow you to write INT_MIN directly as a constant. GCC certainly
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-- warns about it. So this pass takes any MOSTNEG-equivalent values (that will have been
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-- converted to constants in the constant folding earlier) and turns them back
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-- into MOSTNEG, for which the C backend uses INT_MIN and similar, which avoid
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-- this problem.
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fixMinInt :: Pass
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fixMinInt
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= cOrCppOnlyPass "Turn any literals that are equal to MOSTNEG INT back into MOSTNEG INT"
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prereq
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[]
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(applyDepthM doExpression)
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where
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doExpression :: Transform (A.Expression)
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doExpression l@(A.Literal m t (A.IntLiteral m' s))
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= do folded <- constantFold (A.MostNeg m t)
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case folded of
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(A.Literal _ _ (A.IntLiteral _ s'), _, _)
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-> if (s == s')
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then return $ A.MostNeg m t
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else return l
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_ -> return l -- This can happen as some literals retain the Infer
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-- type which fails the constant folding
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doExpression e = return e
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transformWaitFor :: Pass
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transformWaitFor = cOnlyPass "Transform wait for guards into wait until guards"
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[]
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[Prop.waitForRemoved]
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(applyDepthM doAlt)
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where
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doAlt :: A.Process -> PassM A.Process
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doAlt a@(A.Alt m pri s)
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= do (s',(specs,code)) <- runStateT (transformOnly doWaitFor s) ([],[])
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if (null specs && null code)
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then return a
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else return $ A.Seq m $ foldr addSpec (A.Several m (code ++ [A.Only m $ A.Alt m pri s'])) specs
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doAlt p = return p
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addSpec :: Data a => (A.Structured a -> A.Structured a) -> A.Structured a -> A.Structured a
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addSpec spec inner = spec inner
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doWaitFor :: Meta -> A.Alternative -> StateT ([A.Structured A.Process -> A.Structured A.Process], [A.Structured A.Process]) PassM (A.Structured A.Alternative)
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doWaitFor m'' a@(A.Alternative m cond tim (A.InputTimerFor m' e) p)
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= do (specs, init) <- get
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id <- lift $ makeNonce "waitFor"
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let n = A.Name m id
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let var = A.Variable m n
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put (specs ++ [A.Spec m (A.Specification m n (A.Declaration m A.Time))],
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init ++ [A.Only m $ A.Input m tim
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(A.InputTimerRead m (A.InVariable m var)),
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A.Only m $ A.Assign m [var] $ A.ExpressionList m [A.Dyadic m A.Plus (A.ExprVariable m var) e]])
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return $ A.Only m'' $ A.Alternative m cond tim (A.InputTimerAfter m' (A.ExprVariable m' var)) p
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doWaitFor m a = return $ A.Only m a
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append_sizes :: A.Name -> A.Name
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append_sizes n = n {A.nameName = A.nameName n ++ "_sizes"}
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-- | Declares a _sizes array for every array, statically sized or dynamically sized.
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-- For each record type it declares a _sizes array too.
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declareSizesArray :: Pass
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declareSizesArray = occamOnlyPass "Declare array-size arrays"
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(prereq ++ [Prop.slicesSimplified, Prop.arrayConstructorsRemoved])
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[Prop.arraySizesDeclared]
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(applyDepthSM doStructured)
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where
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defineSizesName :: Meta -> A.Name -> A.SpecType -> PassM ()
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defineSizesName m n spec
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= defineName n $ A.NameDef { A.ndMeta = m
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, A.ndName = A.nameName n
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, A.ndOrigName = A.nameName n
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, A.ndSpecType = spec
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, A.ndAbbrevMode = A.ValAbbrev
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, A.ndNameSource = A.NameNonce
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, A.ndPlacement = A.Unplaced
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}
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-- Strips all the array subscripts from a variable:
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findInnerVar :: A.Variable -> (Maybe A.Expression, A.Variable)
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findInnerVar wv@(A.SubscriptedVariable m sub v) = case sub of
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A.SubscriptField {} -> (Nothing, wv)
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A.SubscriptFromFor _ _ _ for -> (Just for, snd $ findInnerVar v) -- Keep the outer most
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A.Subscript {} -> findInnerVar v
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findInnerVar (A.DirectedVariable _ _ v) = findInnerVar v
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findInnerVar v = (Nothing, v)
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-- | Generate the @_sizes@ array for a 'Retypes' expression.
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retypesSizes :: Meta -> A.Name -> [A.Dimension] -> A.Type -> A.Variable -> PassM A.Specification
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retypesSizes m n_sizes ds elemT v@(A.Variable _ nSrc)
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= do biDest <- bytesInType (A.Array ds elemT)
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tSrc <- astTypeOf v
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biSrc <- bytesInType tSrc
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-- Figure out the size of the source.
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srcSize <-
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case (biSrc, tSrc) of
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-- Fixed-size source -- easy.
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(BIJust size, _) -> return size
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-- Variable-size source -- it must be an array, so multiply
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-- together the dimensions.
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(_, A.Array ds t) ->
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do BIJust elementSize <- bytesInType t
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return $ foldl mulExprs elementSize dSizes
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where
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srcSizes = A.Variable m $ append_sizes nSrc
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dSizes = [case d of
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-- Fixed dimension.
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A.Dimension e -> e
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-- Variable dimension -- use the corresponding
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-- element of its _sizes array.
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A.UnknownDimension ->
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A.ExprVariable m $ A.SubscriptedVariable m (A.Subscript m A.NoCheck $ makeConstant m i) srcSizes
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| (d, i) <- zip ds [0..]]
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_ -> dieP m "Cannot compute size of source type"
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-- Build the _sizes array for the destination.
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sizeSpecType <-
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case biDest of
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-- Destination size is fixed -- so we must know the dimensions.
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BIJust _ ->
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return $ makeStaticSizeSpec m n_sizes ds
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-- Destination has one free dimension, so we need to compute
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-- it.
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BIOneFree destSize n ->
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let newDim = A.Dimension $ divExprs srcSize destSize
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ds' = replaceAt n newDim ds in
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return $ makeStaticSizeSpec m n_sizes ds'
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defineSizesName m n_sizes sizeSpecType
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return $ A.Specification m n_sizes sizeSpecType
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abbrevVarSizes :: Meta -> A.Name -> [A.Dimension] -> A.Variable -> PassM A.Specification
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abbrevVarSizes m n_sizes ds outerV
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= do -- Find the inner most variable (i.e. strip all the array subscripts)
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let (sliceSize, innerV) = findInnerVar outerV
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-- Figure out the _sizes variable to abbreviate; either the _sizes variable corresponding
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-- to the abbreviation source (for everything but record fields)
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-- or the globally declared record field _sizes constant
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varSrcSizes <- case innerV of
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A.Variable _ srcN -> return (A.Variable m $ append_sizes srcN)
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A.SubscriptedVariable _ (A.SubscriptField _ fieldName) recordV ->
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do A.Record recordName <- astTypeOf recordV
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return (A.Variable m $ A.Name m $ A.nameName recordName ++ A.nameName fieldName ++ "_sizes")
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A.DirectedVariable _ _ (A.Variable _ srcN) -> return (A.Variable m
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$ append_sizes srcN)
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_ -> diePC m $ formatCode "Cannot handle variable % in abbrevVarSizes" innerV
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-- Get the dimensions of the source variable:
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innerVT <- astTypeOf innerV
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srcDs <- case innerVT of
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(A.Array srcDs _) -> return srcDs
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_ -> diePC m $ formatCode ("Unexpected type in abbrev var"
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++ " (%) in declareSizesArray: %") innerV innerVT
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-- Calculate the correct subscript into the source _sizes variable to get to the dimensions for the destination:
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let sizeDiff = length srcDs - length ds
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subSrcSizeVar = A.SubscriptedVariable m (A.SubscriptFromFor m A.NoCheck (makeConstant m sizeDiff) (makeConstant m $ length ds)) varSrcSizes
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sizeType = A.Array [makeDimension m $ length ds] A.Int
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sizeExpr = case sliceSize of
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Just exp -> let subDims = [A.SubscriptedVariable m (A.Subscript m A.NoCheck $ makeConstant m n) varSrcSizes | n <- [1 .. (length srcDs - 1)]] in
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A.Literal m sizeType $ A.ArrayListLiteral m $ A.Several m $
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A.Only m exp : map (A.Only m . A.ExprVariable m) subDims
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Nothing -> A.ExprVariable m subSrcSizeVar
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sizeSpecType = A.IsExpr m A.ValAbbrev sizeType sizeExpr
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defineSizesName m n_sizes sizeSpecType
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return $ A.Specification m n_sizes sizeSpecType
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doStructured :: Data a => A.Structured a -> PassM (A.Structured a)
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doStructured str@(A.Spec m sp@(A.Specification m' n spec) s)
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= do t <- typeOfSpec spec
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case (spec, t) of
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(_, Just (A.Array ds elemT)) ->
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do let n_sizes = append_sizes n
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let defineStaticSizes ds
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= do let st = makeStaticSizeSpec m' n_sizes ds
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defineSizesName m' n_sizes st
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return $ A.Specification m' n_sizes st
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sizeSpec <-
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if elem A.UnknownDimension ds
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-- At least one unknown dimension:
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then case spec of
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-- TODO I think retyping a channel array ends up
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-- here, and probably isn't handled right
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A.Retypes _ _ _ v ->
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retypesSizes m' n_sizes ds elemT v
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A.Is _ _ _ v ->
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abbrevVarSizes m n_sizes ds v
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A.IsChannelArray _ _ vs ->
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defineStaticSizes [makeDimension m' (length vs)]
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A.IsExpr _ _ _ (A.ExprVariable _ v) ->
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abbrevVarSizes m n_sizes ds v
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-- The dimensions in a literal should all be
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-- static:
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A.IsExpr _ _ _ (A.Literal _ (A.Array ds' _) _) ->
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defineStaticSizes ds'
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_ ->
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dieP m $ "Could not handle unknown array spec: "
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++ pshow spec
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-- Everything is statically sized:
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else defineStaticSizes ds
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return (A.Spec m sizeSpec $ A.Spec m sp $ s)
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(A.RecordType m _ fs, _) ->
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do fieldDeclarations <-
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foldM (declareFieldSizes (A.nameName n) m) s fs
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return $ A.Spec m sp fieldDeclarations
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_ -> return str
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doStructured s = return s
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makeStaticSizeSpec :: Meta -> A.Name -> [A.Dimension] -> A.SpecType
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makeStaticSizeSpec m n ds = makeDynamicSizeSpec m n es
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where
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es = [case d of A.Dimension e -> e | d <- ds]
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makeDynamicSizeSpec :: Meta -> A.Name -> [A.Expression] -> A.SpecType
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makeDynamicSizeSpec m n es = sizeSpecType
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where
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sizeType = A.Array [makeDimension m $ length es] A.Int
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sizeLit = A.Literal m sizeType $ A.ArrayListLiteral m $ A.Several m $ map (A.Only m) es
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sizeSpecType = A.IsExpr m A.ValAbbrev sizeType sizeLit
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declareFieldSizes :: Data a => String -> Meta -> A.Structured a -> (A.Name, A.Type) -> PassM (A.Structured a)
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declareFieldSizes prep m inner (n, A.Array ds _)
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= do let n_sizes = n {A.nameName = prep ++ A.nameName n}
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sizeSpecType = makeStaticSizeSpec m n_sizes ds
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defineSizesName m n_sizes sizeSpecType
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return $ A.Spec m (A.Specification m n_sizes sizeSpecType) inner
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declareFieldSizes _ _ s _ = return s
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-- | A pass for adding _sizes parameters to PROC arguments
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-- TODO in future, only add _sizes for variable-sized parameters
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addSizesFormalParameters :: Pass
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addSizesFormalParameters = occamOnlyPass "Add array-size arrays to PROC headers"
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(prereq ++ [Prop.arraySizesDeclared])
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[]
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(applyDepthM doSpecification)
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where
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doSpecification :: A.Specification -> PassM A.Specification
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doSpecification (A.Specification m n (A.Proc m' sm args body))
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= do (args', newargs) <- transformFormals m args
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let newspec = A.Proc m' sm args' body
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modify (\cs -> cs {csNames = Map.adjust (\nd -> nd { A.ndSpecType = newspec }) (A.nameName n) (csNames cs)})
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mapM_ (recordArg m') newargs
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return $ A.Specification m n newspec
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doSpecification st = return st
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recordArg :: Meta -> A.Formal -> PassM ()
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recordArg m (A.Formal am t n)
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= defineName n $ A.NameDef {
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A.ndMeta = m
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,A.ndName = A.nameName n
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,A.ndOrigName = A.nameName n
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,A.ndSpecType = A.Declaration m t
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,A.ndAbbrevMode = A.ValAbbrev
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,A.ndNameSource = A.NameNonce
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,A.ndPlacement = A.Unplaced}
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transformFormals :: Meta -> [A.Formal] -> PassM ([A.Formal], [A.Formal])
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transformFormals _ [] = return ([],[])
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transformFormals m ((f@(A.Formal am t n)):fs)
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= case t of
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A.Array ds _ -> do let sizeType = A.Array [makeDimension m $ length ds] A.Int
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let newf = A.Formal A.ValAbbrev sizeType (append_sizes n)
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(rest, moreNew) <- transformFormals m fs
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return (f : newf : rest, newf : moreNew)
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_ -> do (rest, new) <- transformFormals m fs
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return (f : rest, new)
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-- | A pass for adding _sizes parameters to actuals in PROC calls
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addSizesActualParameters :: Pass
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addSizesActualParameters = occamOnlyPass "Add array-size arrays to PROC calls"
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(prereq ++ [Prop.arraySizesDeclared])
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[]
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(applyDepthM doProcess)
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where
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doProcess :: A.Process -> PassM A.Process
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doProcess (A.ProcCall m n params)
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= concatMapM transformActual params >>* A.ProcCall m n
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doProcess p = return p
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transformActual :: A.Actual -> PassM [A.Actual]
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transformActual a@(A.ActualVariable v)
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= transformActualVariable a v
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transformActual a@(A.ActualExpression (A.ExprVariable _ v))
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= transformActualVariable a v
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transformActual a = return [a]
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transformActualVariable :: A.Actual -> A.Variable -> PassM [A.Actual]
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transformActualVariable a v@(A.Variable m n)
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= do t <- astTypeOf v
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case t of
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A.Array ds _ ->
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return [a, A.ActualVariable a_sizes]
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_ -> return [a]
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where
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a_sizes = A.Variable m (append_sizes n)
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transformActualVariable a _ = return [a]
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-- | Transforms all slices into the FromFor form.
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simplifySlices :: Pass
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simplifySlices = occamOnlyPass "Simplify array slices"
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prereq
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[Prop.slicesSimplified]
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(applyDepthM doVariable)
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where
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doVariable :: A.Variable -> PassM A.Variable
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doVariable (A.SubscriptedVariable m (A.SubscriptFor m' check for) v)
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= return (A.SubscriptedVariable m (A.SubscriptFromFor m' check (makeConstant m' 0) for) v)
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doVariable (A.SubscriptedVariable m (A.SubscriptFrom m' check from) v)
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= do A.Array (d:_) _ <- astTypeOf v
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limit <- case d of
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A.Dimension n -> return n
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A.UnknownDimension -> return $ A.SizeVariable m' v
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return (A.SubscriptedVariable m (A.SubscriptFromFor m' check from (A.Dyadic m A.Subtr limit from)) v)
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doVariable v = return v
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