#6156: Optimiser bug on linux-powerpc
-----------------------------------------+----------------------------------
Reporter: erikd | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.4.1 | Keywords:
Os: Linux | Architecture: powerpc
Failure: Incorrect result at runtime | Testcase:
Blockedby: | Blocking:
Related: |
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Found a small chunk of code in the cryptocipher package that when compiled
and run, produces a difference result when optimised compared to compiling
un-optimised.
Note this is only a problem with PowerPC. On x86-64 there is no difference
in the output between the optimised version and the un-optimised version.
I have two simple files (Camellia.hs):
{{{
module Camellia where
import Data.Bits
import Data.Word
import Debug.Trace
fl :: Word64 -> Word64 -> Word64
fl fin sk =
let (x1, x2) = w64tow32 fin in
let (k1, k2) = w64tow32 sk in
let y2 = x2 `xor` ((x1 .&. k1) `rotateL` 1) in
let y1 = x1 `xor` (y2 .|. k2) in
trace (show fin ++ " " ++ show sk ++ " -> " ++ show (w32tow64 (y1,
y2))) $ w32tow64 (y1, y2)
w64tow32 :: Word64 -> (Word32, Word32)
w64tow32 w = (fromIntegral (w `shiftR` 32), fromIntegral (w .&.
0xffffffff))
w32tow64 :: (Word32, Word32) -> Word64
w32tow64 (x1, x2) = ((fromIntegral x1) `shiftL` 32) .|. (fromIntegral x2)
}}}
and a main program (camellia-test.hs):
{{{
import Data.Word
import qualified Camellia as Camellia
a, b :: Word64
a = 1238988323332265734
b = 11185553392205053542
main :: IO ()
main =
putStrLn $ "Camellia.fl " ++ show a ++ " " ++ show b ++ " -> " ++ show
(Camellia.fl a b)
}}}
I'm also using this Makefile:
{{{
TARGETS = camilla-test-std camilla-test-opt
check : $(TARGETS)
./camilla-test-std
./camilla-test-opt
clean :
make clean-temp-files
rm -f $(TARGETS)
clean-temp-files :
rm -f camilla-test.o camilla-test.hi Camellia.o Camellia.hi
camilla-test-opt : camilla-test.hs Camellia.hs
ghc -Wall -O2 --make -i:Tests $< -o $@
make clean-temp-files
camilla-test-std : camilla-test.hs Camellia.hs
ghc -Wall --make -i:Tests $< -o $@
make clean-temp-files
}}}
When I run the two programs I get:
{{{
./camilla-test-std
1238988323332265734 11185553392205053542 -> 18360184157246690566
Camellia.fl 1238988323332265734 11185553392205053542 ->
18360184157246690566
./camilla-test-opt
1238988323332265734 11185553392205053542 -> 3698434091925017862
Camellia.fl 38662 15974 -> 3698434091925017862
}}}
So there are two problems here:
a) Showing Word64 values is not working correctly in the optimised
version.
b) The function Camelia.fl produces the wrong result in the optimised
version.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6156>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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