3005dfb506
The existing constant-folding code in the parser is still there, since it needs to know whether things are constant, and A.Dimension expects an Int. However, this pass is useful because it does a better job of constant folding than the parser would on its own: it can fold subexpressions of expressions that are as a whole not constant.
73 lines
2.5 KiB
Haskell
73 lines
2.5 KiB
Haskell
{-
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Tock: a compiler for parallel languages
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Copyright (C) 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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-- | The occam-specific frontend passes.
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module OccamPasses (occamPasses, foldConstants) where
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import Data.Generics
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import qualified AST as A
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import CompState
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import EvalConstants
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import Pass
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import qualified Properties as Prop
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-- | Occam-specific frontend passes.
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occamPasses :: [Pass]
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occamPasses = makePassesDep' ((== FrontendOccam) . csFrontend)
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[ ("Fold constants", foldConstants,
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[],
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[Prop.constantsFolded])
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, ("Dummy occam pass", dummyOccamPass,
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[],
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Prop.agg_namesDone ++ [Prop.expressionTypesChecked,
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Prop.inferredTypesRecorded, Prop.mainTagged,
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Prop.processTypesChecked])
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]
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-- | Fold constant expressions.
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foldConstants :: Data t => t -> PassM t
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foldConstants = doGeneric `extM` doSpecification `extM` doExpression
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where
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doGeneric :: Data t => t -> PassM t
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doGeneric = makeGeneric foldConstants
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-- When an expression is abbreviated, try to fold it, and update its
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-- definition so that it can be used when folding later expressions.
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doSpecification :: A.Specification -> PassM A.Specification
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doSpecification s@(A.Specification m n (A.IsExpr m' am t e))
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= do e' <- doExpression e
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let st' = A.IsExpr m' am t e'
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modifyName n (\nd -> nd { A.ndType = st' })
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return $ A.Specification m n st'
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doSpecification s = doGeneric s
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-- For all other expressions, just try to fold them.
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-- We recurse into the expression first so that we fold subexpressions of
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-- non-constant expressions too.
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doExpression :: A.Expression -> PassM A.Expression
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doExpression e
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= do e' <- doGeneric e
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(e'', _, _) <- constantFold e'
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return e''
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-- | A dummy pass for things that haven't been separated out into passes yet.
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dummyOccamPass :: Data t => t -> PassM t
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dummyOccamPass = return
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