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Added support for multiplication to the usage checking

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Neil Brown 2007-12-17 11:56:51 +00:00
parent 337d339641
commit d23baf719b
1 changed files with 22 additions and 4 deletions
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26
transformations/ArrayUsageCheck.hs
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@ -110,13 +110,31 @@ makeEquations es high = makeEquations' >>* (\(s,v,lh) -> (s,squareEquations (pai
flatten (A.Literal _ _ (A.IntLiteral _ n)) = return (1,[Const (read n)])
flatten (A.Dyadic m op lhs rhs) | op == A.Add = combine' (flatten lhs) (flatten rhs)
| op == A.Subtr = combine' (flatten lhs) (liftM (transformPair id (scale (-1))) $ flatten rhs)
-- TODO Mul and Div
| op == A.Mul = multiplyOut' (flatten lhs) (flatten rhs)
-- TODO Div (either constant on bottom, or common (variable) factor(s) with top)
| otherwise = throwError ("Unhandleable operator found in expression: " ++ show op)
flatten (A.ExprVariable _ v) = return (1,[Scale 1 v])
flatten other = throwError ("Unhandleable item found in expression: " ++ show other)
--TODO we need to handle lots more different expression types in future.
multiplyOut' :: Either String (Integer,[FlattenedExp]) -> Either String (Integer,[FlattenedExp]) -> Either String (Integer,[FlattenedExp])
multiplyOut' x y = do {x' <- x; y' <- y; multiplyOut x' y'}
multiplyOut :: (Integer,[FlattenedExp]) -> (Integer,[FlattenedExp]) -> Either String (Integer,[FlattenedExp])
multiplyOut (lx,lhs) (rx,rhs) = do exps <- mapM (uncurry mult) pairs
return (lx * rx, exps)
where
pairs = product2 (lhs,rhs)
mult :: FlattenedExp -> FlattenedExp -> Either String FlattenedExp
mult (Const x) (Const y) = return $ Const (x*y)
mult (Scale n v) (Const x) = return $ Scale (n*x) v
mult (Const x) (Scale n v) = return $ Scale (n*x) v
mult (Scale _ v) (Scale _ v')
= throwError $ "Cannot deal with non-linear equations; during flattening found: "
++ show v ++ " * " ++ show v'
-- | Scales a flattened expression by the given integer scaling.
scale :: Integer -> [FlattenedExp] -> [FlattenedExp]
scale sc = map scale'
@ -126,13 +144,13 @@ makeEquations es high = makeEquations' >>* (\(s,v,lh) -> (s,squareEquations (pai
-- | An easy way of applying combine to two monadic returns
combine' :: Either String (Integer,[FlattenedExp]) -> Either String (Integer,[FlattenedExp]) -> Either String (Integer,[FlattenedExp])
combine' x y = do {x' <- x; y' <- y; combine x' y'}
combine' = liftM2 combine
-- | Combines (adds) two flattened expressions with a divisor.
-- Given (nx,ex) and (ny,ey), representing ex/nx and ey/ny, this becomes
-- ((ny*ex)+(nx*ey)/nx*ny (i.e. standard mathematics!).
combine :: (Integer,[FlattenedExp]) -> (Integer,[FlattenedExp]) -> Either String (Integer,[FlattenedExp])
combine (nx, ex) (ny, ey) = return $ (nx * ny, scale ny ex ++ scale nx ey)
combine :: (Integer,[FlattenedExp]) -> (Integer,[FlattenedExp]) -> (Integer,[FlattenedExp])
combine (nx, ex) (ny, ey) = (nx * ny, scale ny ex ++ scale nx ey)
-- | Finds the index associated with a particular variable; either by finding an existing index