-module CmmCPS (cmmCPS) where
+module CmmCPS (
+ -- | Converts C-- with full proceedures and parameters
+ -- to a CPS transformed C-- with the stack made manifest.
+ cmmCPS
+) where
#include "HsVersions.h"
import CmmLint
import PprCmm
-import Dataflow (fixedpoint)
+import Dataflow
import CmmLive
+import CmmBrokenBlock
+import CmmProcPoint
+import CmmCallConv
import MachOp
import ForeignCall
import IO
import Data.List
+-----------------------------------------------------------------------------
+-- |Top level driver for the CPS pass
+-----------------------------------------------------------------------------
+cmmCPS :: DynFlags -- ^ Dynamic flags: -dcmm-lint -ddump-cps-cmm
+ -> [Cmm] -- ^ Input C-- with Proceedures
+ -> IO [Cmm] -- ^ Output CPS transformed C--
+cmmCPS dflags abstractC = do
+ when (dopt Opt_DoCmmLinting dflags) $
+ do showPass dflags "CmmLint"
+ case firstJust $ map cmmLint abstractC of
+ Just err -> do printDump err
+ ghcExit dflags 1
+ Nothing -> return ()
+ showPass dflags "CPS"
+
+ -- TODO: more lint checking
+ -- check for use of branches to non-existant blocks
+ -- check for use of Sp, SpLim, R1, R2, etc.
+
+ uniqSupply <- mkSplitUniqSupply 'p'
+ let supplies = listSplitUniqSupply uniqSupply
+ let doCpsProc s (Cmm c) =
+ Cmm $ concat $ zipWith cpsProc (listSplitUniqSupply s) c
+ let continuationC = zipWith doCpsProc supplies abstractC
+
+ dumpIfSet_dyn dflags Opt_D_dump_cps_cmm "CPS Cmm" (pprCmms continuationC)
+
+ -- TODO: add option to dump Cmm to file
+
+ return continuationC
+
+-----------------------------------------------------------------------------
+-- |CPS a single CmmTop (proceedure)
+-- Only 'CmmProc' are transformed 'CmmData' will be left alone.
+-----------------------------------------------------------------------------
+
+cpsProc :: UniqSupply
+ -> CmmTop -- ^Input proceedure
+ -> [CmmTop] -- ^Output proceedure and continuations
+cpsProc uniqSupply x@(CmmData _ _) = [x]
+cpsProc uniqSupply x@(CmmProc info_table ident params blocks) = cps_procs
+ where
+ uniqes :: [[Unique]]
+ uniqes = map uniqsFromSupply $ listSplitUniqSupply uniqSupply
+
+ -- Break the block at each function call.
+ -- The part after the function call will have to become a continuation.
+ broken_blocks :: [BrokenBlock]
+ broken_blocks =
+ concat $ zipWith3 breakBlock uniqes blocks
+ (FunctionEntry ident params:repeat ControlEntry)
+
+ -- Calculate live variables for each broken block.
+ --
+ -- Nothing can be live on entry to the first block
+ -- so we could take the tail, but for now we wont
+ -- to help future proof the code.
+ live :: BlockEntryLiveness
+ live = cmmLiveness $ map cmmBlockFromBrokenBlock broken_blocks
+
+ -- Calculate which blocks must be made into full fledged procedures.
+ proc_points :: UniqSet BlockId
+ proc_points = calculateProcPoints broken_blocks
+
+ -- Construct a map so we can lookup a broken block by its 'BlockId'.
+ block_env :: BlockEnv BrokenBlock
+ block_env = blocksToBlockEnv broken_blocks
+
+ -- Group the blocks into continuations based on the set of proc-points.
+ continuations :: [Continuation]
+ continuations = map (gatherBlocksIntoContinuation proc_points block_env)
+ (uniqSetToList proc_points)
+
+ -- Select the stack format on entry to each continuation.
+ --
+ -- This is an association list instead of a UniqFM because
+ -- CLabel's don't have a 'Uniqueable' instance.
+ formats :: [(CLabel, StackFormat)]
+ formats = selectStackFormat live continuations
+
+ -- Do the actual CPS transform.
+ cps_procs :: [CmmTop]
+ cps_procs = map (continuationToProc formats) continuations
+
--------------------------------------------------------------------------------
-- The format for the call to a continuation
-- and heap memory (not sure if that's usefull at all though, but it may
-- be worth exploring the design space).
-data BrokenBlock
- = BrokenBlock {
- brokenBlockId :: BlockId, -- Like a CmmBasicBlock
- brokenBlockEntry :: BlockEntryInfo,
- -- How this block can be entered
-
- brokenBlockStmts :: [CmmStmt],
- -- Like a CmmBasicBlock
- -- (but without the last statement)
-
- brokenBlockTargets :: [BlockId],
- -- Blocks that this block could
- -- branch to one either by conditional
- -- branches or via the last statement
-
- brokenBlockExit :: FinalStmt
- -- How the block can be left
- }
-
continuationLabel (Continuation _ _ l _ _) = l
data Continuation =
Continuation
-- to a label. To jump to the first block in a Proc,
-- use the appropriate CLabel.
-data BlockEntryInfo
- = FunctionEntry -- Beginning of a function
- CLabel -- The function name
- CmmFormals -- Aguments to function
-
- | ContinuationEntry -- Return point of a call
- CmmFormals -- return values (argument to continuation)
- -- TODO:
- -- | ProcPointEntry -- no return values, but some live might end up as params or possibly in the frame
-
- | ControlEntry -- A label in the input
-
--- Final statement in a BlokenBlock
--- Constructors and arguments match those in Cmm,
--- but are restricted to branches, returns, jumps, calls and switches
-data FinalStmt
- = FinalBranch
- BlockId -- next block (must be a ControlEntry)
-
- | FinalReturn
- CmmActuals -- return values
-
- | FinalJump
- CmmExpr -- the function to call
- CmmActuals -- arguments to call
-
- | FinalCall
- BlockId -- next block after call (must be a ContinuationEntry)
- CmmCallTarget -- the function to call
- CmmFormals -- results from call (redundant with ContinuationEntry)
- CmmActuals -- arguments to call
- (Maybe [GlobalReg]) -- registers that must be saved (TODO)
-
- | FinalSwitch
- CmmExpr [Maybe BlockId] -- Table branch
-
- -- TODO: | ProcPointExit (needed?)
-
-- Describes the layout of a stack frame for a continuation
data StackFormat
= StackFormat
-- A block can be a continuation of another block (w/ or w/o joins)
-- A block can be an entry to a function
-blocksToBlockEnv :: [BrokenBlock] -> BlockEnv BrokenBlock
-blocksToBlockEnv blocks = listToUFM $ map (\b -> (brokenBlockId b, b)) blocks
-
-----------------------------------------------------------------------------
-calculateOwnership :: UniqSet BlockId -> [BrokenBlock] -> BlockEnv (UniqSet BlockId)
-calculateOwnership proc_points blocks =
- fixedpoint dependants update (map brokenBlockId blocks) emptyUFM
- where
- blocks_ufm :: BlockEnv BrokenBlock
- blocks_ufm = blocksToBlockEnv blocks
-
- dependants :: BlockId -> [BlockId]
- dependants ident =
- brokenBlockTargets $ lookupWithDefaultUFM
- blocks_ufm unknown_block ident
-
- update :: BlockId -> Maybe BlockId
- -> BlockEnv (UniqSet BlockId) -> Maybe (BlockEnv (UniqSet BlockId))
- update ident cause owners =
- case (cause, ident `elementOfUniqSet` proc_points) of
- (Nothing, True) -> Just $ addToUFM owners ident (unitUniqSet ident)
- (Nothing, False) -> Nothing
- (Just cause', True) -> Nothing
- (Just cause', False) ->
- if (sizeUniqSet old) == (sizeUniqSet new)
- then Nothing
- else Just $ addToUFM owners ident new
- where
- old = lookupWithDefaultUFM owners emptyUniqSet ident
- new = old `unionUniqSets` lookupWithDefaultUFM owners emptyUniqSet cause'
-
- unknown_block = panic "unknown BlockId in selectStackFormat"
-
-calculateProcPoints :: [BrokenBlock] -> UniqSet BlockId
-calculateProcPoints blocks = calculateProcPoints' init_proc_points blocks
- where
- init_proc_points = mkUniqSet $
- map brokenBlockId $
- filter always_proc_point blocks
- always_proc_point BrokenBlock {
- brokenBlockEntry = FunctionEntry _ _ } = True
- always_proc_point BrokenBlock {
- brokenBlockEntry = ContinuationEntry _ } = True
- always_proc_point _ = False
-
-calculateProcPoints' :: UniqSet BlockId -> [BrokenBlock] -> UniqSet BlockId
-calculateProcPoints' old_proc_points blocks =
- if sizeUniqSet old_proc_points == sizeUniqSet new_proc_points
- then old_proc_points
- else calculateProcPoints' new_proc_points blocks
- where
- owners = calculateOwnership old_proc_points blocks
- new_proc_points = unionManyUniqSets (old_proc_points:(map (calculateProcPoints'' owners) blocks))
-
-calculateProcPoints'' :: BlockEnv (UniqSet BlockId) -> BrokenBlock -> UniqSet BlockId
-calculateProcPoints'' owners block =
- unionManyUniqSets (map (f parent_id) child_ids)
- where
- parent_id = brokenBlockId block
- child_ids = brokenBlockTargets block
- -- TODO: name for f
- f parent_id child_id =
- if needs_proc_point
- then unitUniqSet child_id
- else emptyUniqSet
- where
- parent_owners = lookupWithDefaultUFM owners emptyUniqSet parent_id
- child_owners = lookupWithDefaultUFM owners emptyUniqSet child_id
- needs_proc_point = not $ isEmptyUniqSet $ child_owners `minusUniqSet` parent_owners
collectNonProcPointTargets ::
UniqSet BlockId -> BlockEnv BrokenBlock
-- TODO: remove redundant uniqSetToList
new_targets = current_targets `unionUniqSets` (mkUniqSet targets)
-buildContinuation ::
+-- TODO: insert proc point code here
+-- * Branches and switches to proc points may cause new blocks to be created
+-- (or proc points could leave behind phantom blocks that just jump to them)
+-- * Proc points might get some live variables passed as arguments
+
+gatherBlocksIntoContinuation ::
UniqSet BlockId -> BlockEnv BrokenBlock
-> BlockId -> Continuation
-buildContinuation proc_points blocks start =
+gatherBlocksIntoContinuation proc_points blocks start =
Continuation is_entry info_table clabel params body
where
children = (collectNonProcPointTargets proc_points blocks (unitUniqSet start) start) `delOneFromUniqSet` start
--------------------------------------------------------------------------------
-- For now just select the continuation orders in the order they are in the set with no gaps
-selectStackFormat2 :: BlockEnv CmmLive -> [Continuation] -> [(CLabel, StackFormat)]
-selectStackFormat2 live continuations =
+selectStackFormat :: BlockEnv CmmLive -> [Continuation] -> [(CLabel, StackFormat)]
+selectStackFormat live continuations =
map (\c -> (continuationLabel c, selectStackFormat' c)) continuations
where
selectStackFormat' (Continuation True info_table label formals blocks) =
- --let ident = brokenBlockId $ head blocks -- TODO: CLabel isn't a uniquable, but we need a better way than this
- --in
StackFormat (Just label) 0 []
selectStackFormat' (Continuation False info_table label formals blocks) =
-- TODO: assumes the first block is the entry block
extend_format (StackFormat label size offsets) reg =
StackFormat label (slot_size reg + size) ((CmmLocal reg, size) : offsets)
- unknown_block = panic "unknown BlockId in selectStackFormat"
-
-slot_size reg = ((machRepByteWidth (localRegRep reg) - 1) `div` wORD_SIZE) + 1
+ slot_size :: LocalReg -> Int
+ slot_size reg = ((machRepByteWidth (localRegRep reg) - 1) `div` wORD_SIZE) + 1
-constructContinuation :: [(CLabel, StackFormat)] -> Continuation -> CmmTop
-constructContinuation formats (Continuation is_entry info label formals blocks) =
- CmmProc info label formals (map (constructContinuation2' label formats) blocks)
+ unknown_block = panic "unknown BlockId in selectStackFormat"
-constructContinuation2' :: CLabel -> [(CLabel, StackFormat)] -> BrokenBlock
- -> CmmBasicBlock
-constructContinuation2' curr_ident formats (BrokenBlock ident entry stmts _ exit) =
- BasicBlock ident (prefix++stmts++postfix)
+continuationToProc :: [(CLabel, StackFormat)] -> Continuation -> CmmTop
+continuationToProc formats (Continuation is_entry info label formals blocks) =
+ CmmProc info label formals (map (continuationToProc' label formats) blocks)
where
- curr_format = maybe unknown_block id $ lookup curr_ident formats
- unknown_block = panic "unknown BlockId in constructContinuation"
- prefix = case entry of
- ControlEntry -> []
- FunctionEntry _ _ -> []
- ContinuationEntry formals ->
- unpack_continuation curr_format
- postfix = case exit of
- FinalBranch next -> [CmmBranch next]
- FinalSwitch expr targets -> [CmmSwitch expr targets]
- FinalReturn arguments ->
- exit_function curr_format
- (CmmLoad (CmmReg spReg) wordRep)
- arguments
- FinalJump target arguments ->
- exit_function curr_format target arguments
- -- TODO: do something about global saves
- FinalCall next (CmmForeignCall target CmmCallConv)
- results arguments saves ->
+ continuationToProc' :: CLabel -> [(CLabel, StackFormat)] -> BrokenBlock
+ -> CmmBasicBlock
+ continuationToProc' curr_ident formats (BrokenBlock ident entry stmts _ exit) =
+ BasicBlock ident (prefix++stmts++postfix)
+ where
+ curr_format = maybe unknown_block id $ lookup curr_ident formats
+ unknown_block = panic "unknown BlockId in continuationToProc"
+ prefix = case entry of
+ ControlEntry -> []
+ FunctionEntry _ _ -> []
+ ContinuationEntry formals ->
+ unpack_continuation curr_format
+ postfix = case exit of
+ FinalBranch next -> [CmmBranch next]
+ FinalSwitch expr targets -> [CmmSwitch expr targets]
+ FinalReturn arguments ->
+ exit_function curr_format
+ (CmmLoad (CmmReg spReg) wordRep)
+ arguments
+ FinalJump target arguments ->
+ exit_function curr_format target arguments
+ FinalCall next (CmmForeignCall target CmmCallConv)
+ results arguments ->
pack_continuation curr_format cont_format ++
[CmmJump target arguments]
where
cont_format = maybe unknown_block id $
lookup (mkReturnPtLabel $ getUnique next) formats
- FinalCall next _ results arguments saves -> panic "unimplemented CmmCall"
+ FinalCall next _ results arguments -> panic "unimplemented CmmCall"
--------------------------------------------------------------------------------
-- Functions that generate CmmStmt sequences
(CmmMachOp (MO_U_Lt $ cmmRegRep spReg)
[CmmRegOff spReg max_frame_size, CmmReg spLimReg])
gc_block]
- gc_block = undefined -- TODO: get stack and heap checks to go to same
+ gc_block = panic "gc_check not implemented" -- TODO: get stack and heap checks to go to same
-- TODO: fix branches to proc point (we have to insert a new block to marshel the continuation)
pack_continuation :: StackFormat -> StackFormat -> [CmmStmt]
(CmmLoad (CmmRegOff spReg (wORD_SIZE*offset)) (cmmRegRep reg))
| (reg, offset) <- curr_offsets]
------------------------------------------------------------------------------
--- Breaking basic blocks on function calls
------------------------------------------------------------------------------
-
------------------------------------------------------------------------------
--- Takes a basic block and breaks it up into a list of broken blocks
---
--- Takes a basic block and returns a list of basic blocks that
--- each have at most 1 CmmCall in them which must occur at the end.
--- Also returns with each basic block, the variables that will
--- be arguments to the continuation of the block once the call (if any)
--- returns.
-
-breakBlock :: [Unique] -> CmmBasicBlock -> BlockEntryInfo -> [BrokenBlock]
-breakBlock uniques (BasicBlock ident stmts) entry =
- breakBlock' uniques ident entry [] [] stmts where
- breakBlock' uniques current_id entry exits accum_stmts stmts =
- case stmts of
- [] -> panic "block doesn't end in jump, goto or return"
- [CmmJump target arguments] ->
- [BrokenBlock current_id entry accum_stmts
- exits
- (FinalJump target arguments)]
- [CmmReturn arguments] ->
- [BrokenBlock current_id entry accum_stmts
- exits
- (FinalReturn arguments)]
- [CmmBranch target] ->
- [BrokenBlock current_id entry accum_stmts
- (target:exits)
- (FinalBranch target)]
- [CmmSwitch expr targets] ->
- [BrokenBlock current_id entry accum_stmts
- (mapMaybe id targets ++ exits)
- (FinalSwitch expr targets)]
- (CmmJump _ _:_) ->
- panic "jump in middle of block"
- (CmmReturn _:_) ->
- panic "return in middle of block"
- (CmmBranch _:_) ->
- panic "branch in middle of block"
- (CmmSwitch _ _:_) ->
- panic ("switch in middle of block" ++ (showSDoc $ ppr stmts))
- (CmmCall target results arguments saves:stmts) -> block : rest
- where
- new_id = BlockId $ head uniques
- block = BrokenBlock current_id entry accum_stmts
- (new_id:exits)
- (FinalCall new_id target results arguments saves)
- rest = breakBlock' (tail uniques) new_id
- (ContinuationEntry results) [] [] stmts
- (s@(CmmCondBranch test target):stmts) ->
- breakBlock' uniques current_id entry
- (target:exits) (accum_stmts++[s]) stmts
- (s:stmts) ->
- breakBlock' uniques current_id entry
- exits (accum_stmts++[s]) stmts
-
---------------------------------
--- Convert from a BrokenBlock
--- to a CmmBasicBlock so the
--- liveness analysis can run
--- on it.
---------------------------------
-cmmBlockFromBrokenBlock :: BrokenBlock -> CmmBasicBlock
-cmmBlockFromBrokenBlock (BrokenBlock ident _ stmts _ exit) =
- BasicBlock ident (stmts++exit_stmt)
- where
- exit_stmt =
- case exit of
- FinalBranch target -> [CmmBranch target]
- FinalReturn arguments -> [CmmReturn arguments]
- FinalJump target arguments -> [CmmJump target arguments]
- FinalSwitch expr targets -> [CmmSwitch expr targets]
- FinalCall branch_target call_target results arguments saves ->
- [CmmCall call_target results arguments saves,
- CmmBranch branch_target]
-
------------------------------------------------------------------------------
--- CPS a single CmmTop (proceedure)
------------------------------------------------------------------------------
-
-cpsProc :: UniqSupply -> CmmTop -> [CmmTop]
-cpsProc uniqSupply x@(CmmData _ _) = [x]
-cpsProc uniqSupply x@(CmmProc info_table ident params blocks) =
- --[CmmProc info_table ident params cps_blocks]
- cps_continuations
- where
- uniqes :: [[Unique]]
- uniqes = map uniqsFromSupply $ listSplitUniqSupply uniqSupply
-
- -- Break the block at each function call
- broken_blocks :: [BrokenBlock]
- broken_blocks = concat $ zipWith3 breakBlock uniqes blocks
- (FunctionEntry ident params:repeat ControlEntry)
-
- -- Calculate live variables for each broken block
- live :: BlockEntryLiveness
- live = cmmLiveness $ map cmmBlockFromBrokenBlock broken_blocks
- -- nothing can be live on entry to the first block so we could take the tail
-
- proc_points :: UniqSet BlockId
- proc_points = calculateProcPoints broken_blocks
-
- continuations :: [Continuation]
- continuations = map (buildContinuation proc_points (blocksToBlockEnv broken_blocks)) (uniqSetToList proc_points)
-
- -- TODO: insert proc point code here
- -- * Branches and switches to proc points may cause new blocks to be created
- -- (or proc points could leave behind phantom blocks that just jump to them)
- -- * Proc points might get some live variables passed as arguments
-
- -- TODO: let blocks_with_live = map (cmmLivenessComment live . snd) broken_blocks
-
- --procs = groupBlocksIntoContinuations live broken_blocks
-
- -- Select the stack format on entry to each block
- formats2 :: [(CLabel, StackFormat)]
- formats2 = selectStackFormat2 live continuations
-
- -- Do the actual CPS transform
- cps_continuations :: [CmmTop]
- cps_continuations = map (constructContinuation formats2) continuations
-
---------------------------------------------------------------------------------
-cmmCPS :: DynFlags
- -> [Cmm] -- C-- with Proceedures
- -> IO [Cmm] -- Output: CPS transformed C--
-
-cmmCPS dflags abstractC = do
- when (dopt Opt_DoCmmLinting dflags) $
- do showPass dflags "CmmLint"
- case firstJust $ map cmmLint abstractC of
- Just err -> do printDump err
- ghcExit dflags 1
- Nothing -> return ()
- showPass dflags "CPS"
- -- TODO: check for use of branches to non-existant blocks
- -- TODO: check for use of Sp, SpLim, R1, R2, etc.
- -- TODO: find out if it is valid to create a new unique source like this
- uniqSupply <- mkSplitUniqSupply 'p'
- let supplies = listSplitUniqSupply uniqSupply
- let continuationC = zipWith (\s (Cmm c) -> Cmm $ concat $ zipWith (cpsProc) (listSplitUniqSupply s) c) supplies abstractC
-
- dumpIfSet_dyn dflags Opt_D_dump_cps_cmm "CPS Cmm" (pprCmms continuationC)
- -- TODO: add option to dump Cmm to file
- return continuationC
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