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Fixed a bug in the constant folding, where anything divided by -1 was being evaluated to zero

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Neil Brown 2009-01-23 15:48:39 +00:00
parent 15a4a59bcf
commit 2a8ee9a420
1 changed files with 5 additions and 5 deletions
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10
common/EvalConstants.hs
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@ -203,7 +203,7 @@ evalMonadic A.MonadicBitNot a = evalMonadicOp complement a
evalMonadic A.MonadicNot (OccBool b) = return $ OccBool (not b)
evalMonadic op _ = throwError (Nothing, "bad monadic op: " ++ show op)
evalDyadicOp :: (forall t. (Num t, Integral t, Bits t) => t -> t -> t) -> OccValue -> OccValue -> EvalM OccValue
evalDyadicOp :: (forall t. (Num t, Integral t, Bounded t, Bits t) => t -> t -> t) -> OccValue -> OccValue -> EvalM OccValue
evalDyadicOp f (OccByte a) (OccByte b) = return $ OccByte (f a b)
evalDyadicOp f (OccUInt16 a) (OccUInt16 b) = return $ OccUInt16 (f a b)
evalDyadicOp f (OccUInt32 a) (OccUInt32 b) = return $ OccUInt32 (f a b)
@ -235,14 +235,14 @@ logicalShiftR val n = rotateR (foldl clearBit val [0 .. (n - 1)]) n
-- | Equivalent to 'div', but handles @minBound `div` (-1)@ correctly.
-- (GHC's doesn't, at least as of 6.8.1.)
safeDiv :: Integral a => a -> a -> a
safeDiv a (-1) = 0
safeDiv :: (Integral a, Bounded a) => a -> a -> a
safeDiv a (-1) | a == minBound = 0 -- Should be an overflow
safeDiv a b = div a b
-- | Equivalent to 'rem', but handles @minBound `rem` (-1)@ correctly.
-- (GHC's doesn't, at least as of 6.8.1.)
safeRem :: Integral a => a -> a -> a
safeRem a (-1) = 0
safeRem :: (Integral a, Bounded a) => a -> a -> a
safeRem a (-1) | a == minBound = 0 -- The correct answer
safeRem a b = rem a b
evalDyadic :: A.DyadicOp -> OccValue -> OccValue -> EvalM OccValue