-- Also, don't forget to stop at the old end of the stack (oldByte),
-- which may differ depending on whether there is an update frame.
+
+type RegSlotInfo
+ = ( Int -- Offset from oldest byte of Old area
+ , LocalReg -- The register
+ , Int) -- Width of the register
+
live_ptrs :: ByteOff -> BlockEnv SubAreaSet -> AreaMap -> BlockId -> [Maybe LocalReg]
live_ptrs oldByte slotEnv areaMap bid =
-- pprTrace "live_ptrs for" (ppr bid <+> text (show oldByte ++ "-" ++ show youngByte) <+>
-- pprTrace ("stack layout for " ++ show bid ++ ": ") (ppr res) $ res
res
where res = reverse $ slotsToList youngByte liveSlots []
+
+ slotsToList :: Int -> [RegSlotInfo] -> [Maybe LocalReg] -> [Maybe LocalReg]
+ -- n starts at youngByte and is decremented down to oldByte
+ -- Returns a list, one element per word, with
+ -- (Just r) meaning 'pointer register r is saved here',
+ -- Nothing meaning 'non-pointer or empty'
+
slotsToList n [] results | n == oldByte = results -- at old end of stack frame
+
slotsToList n (s : _) _ | n == oldByte =
pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
ppr n <+> ppr liveSlots <+> ppr youngByte)
+
slotsToList n _ _ | n < oldByte =
panic "stack slots not allocated on word boundaries?"
+
slotsToList n l@((n', r, w) : rst) results =
if n == (n' + w) then -- slot's young byte is at n
ASSERT (not (isPtr r) ||
(Nothing : results)
where next = n - wORD_SIZE
stack_rep = if isPtr r then Just r else Nothing
+
slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
+
non_ptr_younger_than next (n', r, w) =
n' + w > next &&
ASSERT (not (isPtr r))
True
isPtr = isGcPtrType . localRegType
+
+ liveSlots :: [RegSlotInfo]
liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
(foldFM (\_ -> flip $ foldl add_slot) [] slots)
+ add_slot :: [RegSlotInfo] -> SubArea -> [RegSlotInfo]
add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
if off == w && widthInBytes (typeWidth ty) == w then
(expectJust "add_slot" (lookupFM areaMap a), r, w) : rst
-- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
-- SO IT'S ALL GOING IN THE SAME DIRECTION.
-- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
+
+ slots :: SubAreaSet -- The SubAreaSet for 'bid'
slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
youngByte = expectJust "live_ptrs bid_pos" $ lookupFM areaMap (CallArea (Young bid))