Commit dbcd7b75 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com

Comments and type signatures only

parent 011680bd
......@@ -77,6 +77,12 @@ import ZipDataflow
-- 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) <+>
......@@ -84,12 +90,22 @@ live_ptrs oldByte slotEnv areaMap bid =
-- 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) ||
......@@ -100,15 +116,20 @@ live_ptrs oldByte slotEnv areaMap bid =
(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
......@@ -125,6 +146,8 @@ live_ptrs oldByte slotEnv areaMap bid =
-- 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))
......
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