buildCFG xs = buildCFG' M.empty xs' xs'
where
xs' :: [OffIns]
- xs' = evalState (calculateInstructionOffset xs >>= markBackwardTargets) []
-
--- get already calculated jmp-targets and mark the predecessor of the
--- target-instruction as "FallThrough". we just care about backwards
--- jumps here (forward jumps are handled in buildCFG')
-markBackwardTargets :: [OffIns] -> AnalyseState
-markBackwardTargets [] = return []
-markBackwardTargets (x:[]) = return [x]
-markBackwardTargets (x@(x_off,x_bbend,x_ins):y@(y_off,_,_):xs) = do
- rest <- markBackwardTargets (y:xs)
- targets <- get
- let isTarget = y_off `elem` targets
- x_new = case x_bbend of
- Just _ -> x -- already marked, don't change
- Nothing -> if isTarget then checkX y_off else x
- checkX w16 = case x_bbend of
- Nothing -> (x_off, Just $ FallThrough w16, x_ins) -- mark previous insn
- _ -> error "basicblock: something is wrong"
- return $ x_new:rest
-
+ xs' = evalState (calculateInstructionOffset xs) []
buildCFG' :: MapBB -> [OffIns] -> [OffIns] -> MapBB
IRETURN -> notarget
ARETURN -> notarget
RETURN -> notarget
- _ -> ((off, Nothing, x):) <$> next
+ _ -> normalins
where
+ normalins = do
+ tailinsns <- next -- eval remaining instructions
+ isNextInsATarget <- (elem newoffset) <$> get
+ let bbtyp = if isNextInsATarget
+ then Just $ FallThrough newoffset
+ else Nothing
+ return $ (off, bbtyp, x):tailinsns
notarget = ((off, Just Return, x):) <$> next
onetarget w16 = do
let jump = off `addW16Signed` w16
let jump = off `addW16Signed` w16
modify (jump:)
((off, Just $ TwoTarget nojump jump, x):) <$> next
- next = cio' newoffset xs
- newoffset = (off + insnLength x, Nothing, NOP)
+ next = cio' nextins xs
+ nextins = (newoffset, Nothing, NOP)
+ newoffset = off + insnLength x
-- TODO(bernhard): does GHC memomize results? i.e. does it calculate the size
-- of `NOP' only once?