2 -- | Converts C-- with full proceedures and parameters
3 -- to a CPS transformed C-- with the stack made manifest.
7 #include "HsVersions.h"
41 -----------------------------------------------------------------------------
42 -- |Top level driver for the CPS pass
43 -----------------------------------------------------------------------------
44 cmmCPS :: DynFlags -- ^ Dynamic flags: -dcmm-lint -ddump-cps-cmm
45 -> [GenCmm CmmStatic CmmInfo CmmStmt] -- ^ Input C-- with Proceedures
46 -> IO [GenCmm CmmStatic [CmmStatic] CmmStmt] -- ^ Output CPS transformed C--
47 cmmCPS dflags abstractC = do
48 when (dopt Opt_DoCmmLinting dflags) $
49 do showPass dflags "CmmLint"
50 case firstJust $ map cmmLint abstractC of
51 Just err -> do printDump err
56 -- TODO: more lint checking
57 -- check for use of branches to non-existant blocks
58 -- check for use of Sp, SpLim, R1, R2, etc.
60 uniqSupply <- mkSplitUniqSupply 'p'
61 let supplies = listSplitUniqSupply uniqSupply
62 let doCpsProc s (Cmm c) =
63 Cmm $ concat $ zipWith cpsProc (listSplitUniqSupply s) c
64 let continuationC = zipWith doCpsProc supplies abstractC
66 dumpIfSet_dyn dflags Opt_D_dump_cps_cmm "CPS Cmm" (pprCmms continuationC)
68 -- TODO: add option to dump Cmm to file
72 stg_gc_gen = mkRtsApFastLabel SLIT("gen_cg_TODO") --panic "Need the label for gc"
73 make_gc_block block_id fun_label formals safety = BasicBlock block_id stmts
75 stmts = [CmmCall stg_gc_gen_target [] [] safety,
76 CmmJump fun_expr actuals]
78 CmmForeignCall (CmmLit (CmmLabel stg_gc_gen)) CmmCallConv
79 actuals = map (\x -> (CmmReg (CmmLocal x), NoHint)) formals
80 fun_expr = CmmLit (CmmLabel fun_label)
82 make_gc_check stack_use gc_block =
84 (CmmMachOp (MO_U_Lt $ cmmRegRep spReg)
85 [CmmReg stack_use, CmmReg spLimReg])
88 force_gc_block old_info stack_use block_id fun_label formals =
90 CmmNonInfo (Just existing) -> (old_info, [], make_gc_check stack_use existing)
91 CmmInfo _ (Just existing) _ _ -> (old_info, [], make_gc_check stack_use existing)
93 -> (CmmNonInfo (Just block_id),
94 [make_gc_block block_id fun_label formals (CmmSafe NoC_SRT)],
95 make_gc_check stack_use block_id)
96 CmmInfo prof Nothing type_tag type_info
97 -> (CmmInfo prof (Just block_id) type_tag type_info,
98 [make_gc_block block_id fun_label formals (CmmSafe srt)],
99 make_gc_check stack_use block_id)
101 srt = case type_info of
102 ConstrInfo _ _ _ -> NoC_SRT
103 FunInfo _ srt' _ _ _ _ -> srt'
104 ThunkInfo _ srt' -> srt'
105 ThunkSelectorInfo _ srt' -> srt'
106 ContInfo _ srt' -> srt'
108 -----------------------------------------------------------------------------
109 -- |CPS a single CmmTop (proceedure)
110 -- Only 'CmmProc' are transformed 'CmmData' will be left alone.
111 -----------------------------------------------------------------------------
113 cpsProc :: UniqSupply
114 -> GenCmmTop CmmStatic CmmInfo CmmStmt -- ^Input proceedure
115 -> [GenCmmTop CmmStatic [CmmStatic] CmmStmt] -- ^Output proceedure and continuations
116 cpsProc uniqSupply (CmmData sec dat) = [CmmData sec dat]
117 cpsProc uniqSupply (CmmProc info ident params blocks) = info_procs
119 (uniqSupply1, uniqSupply2) = splitUniqSupply uniqSupply
120 uniques :: [[Unique]]
121 uniques = map uniqsFromSupply $ listSplitUniqSupply uniqSupply1
122 (gc_unique:stack_use_unique:info_uniques):adaptor_uniques:block_uniques = uniques
123 proc_uniques = map (map uniqsFromSupply . listSplitUniqSupply) $ listSplitUniqSupply uniqSupply2
125 stack_use = CmmLocal (LocalReg stack_use_unique (cmmRegRep spReg) KindPtr)
128 forced_gc :: (CmmInfo, [CmmBasicBlock], [CmmStmt])
129 forced_gc = force_gc_block info stack_use (BlockId gc_unique) ident params
130 (forced_info, gc_blocks, check_stmts) = forced_gc
134 (BasicBlock id stmts) : bs ->
135 (BasicBlock id (check_stmts ++ stmts)) : (bs ++ gc_blocks)
136 [] -> [] -- If there is no code then we don't need a stack check
138 forced_gc_id = case forced_info of
139 CmmNonInfo (Just x) -> x
140 CmmInfo _ (Just x) _ _ -> x
142 -- Break the block at each function call.
143 -- The part after the function call will have to become a continuation.
144 broken_blocks :: ([(BlockId, ContFormat)], [BrokenBlock])
146 (\x -> (concatMap fst x, concatMap snd x)) $
147 zipWith3 (breakBlock [forced_gc_id])
150 (FunctionEntry forced_info ident params :
153 f' = selectContinuations (fst broken_blocks)
154 broken_blocks' = map (makeContinuationEntries f') $
156 zipWith (adaptBlockToFormat f')
160 -- Calculate live variables for each broken block.
162 -- Nothing can be live on entry to the first block
163 -- so we could take the tail, but for now we wont
164 -- to help future proof the code.
165 live :: BlockEntryLiveness
166 live = cmmLiveness $ map cmmBlockFromBrokenBlock broken_blocks'
168 -- Calculate which blocks must be made into full fledged procedures.
169 proc_points :: UniqSet BlockId
170 proc_points = calculateProcPoints broken_blocks'
172 -- Construct a map so we can lookup a broken block by its 'BlockId'.
173 block_env :: BlockEnv BrokenBlock
174 block_env = blocksToBlockEnv broken_blocks'
176 -- Group the blocks into continuations based on the set of proc-points.
177 continuations :: [Continuation (Either C_SRT CmmInfo)]
178 continuations = map (gatherBlocksIntoContinuation live proc_points block_env)
179 (uniqSetToList proc_points)
181 -- Select the stack format on entry to each continuation.
182 -- Return the max stack offset and an association list
184 -- This is an association list instead of a UniqFM because
185 -- CLabel's don't have a 'Uniqueable' instance.
186 formats :: [(CLabel, -- key
187 (CmmFormals, -- arguments
188 Maybe CLabel, -- label in top slot
189 [Maybe LocalReg]))] -- slots
190 formats = selectContinuationFormat live continuations
192 -- Do a little meta-processing on the stack formats such as
193 -- getting the individual frame sizes and the maximum frame size
194 formats' :: (WordOff, [(CLabel, ContinuationFormat)])
195 formats' = processFormats formats continuations
197 -- Update the info table data on the continuations with
198 -- the selected stack formats.
199 continuations' :: [Continuation CmmInfo]
200 continuations' = map (applyContinuationFormat (snd formats')) continuations
202 -- Do the actual CPS transform.
203 cps_procs :: [CmmTop]
204 cps_procs = zipWith (continuationToProc formats' stack_use) proc_uniques continuations'
206 -- Convert the info tables from CmmInfo to [CmmStatic]
207 -- We might want to put this in another pass eventually
208 info_procs :: [RawCmmTop]
209 info_procs = concat (zipWith mkInfoTable info_uniques cps_procs)
211 -----------------------------------------------------------------------------
213 collectNonProcPointTargets ::
214 UniqSet BlockId -> BlockEnv BrokenBlock
215 -> UniqSet BlockId -> [BlockId] -> UniqSet BlockId
216 collectNonProcPointTargets proc_points blocks current_targets new_blocks =
217 if sizeUniqSet current_targets == sizeUniqSet new_targets
220 (collectNonProcPointTargets proc_points blocks)
224 blocks' = map (lookupWithDefaultUFM blocks (panic "TODO")) new_blocks
226 -- Note the subtlety that since the extra branch after a call
227 -- will always be to a block that is a proc-point,
228 -- this subtraction will always remove that case
229 uniqSetToList $ (unionManyUniqSets $ map (mkUniqSet . brokenBlockTargets) blocks')
230 `minusUniqSet` proc_points
231 -- TODO: remove redundant uniqSetToList
232 new_targets = current_targets `unionUniqSets` (mkUniqSet targets)
234 -- TODO: insert proc point code here
235 -- * Branches and switches to proc points may cause new blocks to be created
236 -- (or proc points could leave behind phantom blocks that just jump to them)
237 -- * Proc points might get some live variables passed as arguments
239 gatherBlocksIntoContinuation ::
240 BlockEntryLiveness -> UniqSet BlockId -> BlockEnv BrokenBlock
241 -> BlockId -> Continuation (Either C_SRT CmmInfo)
242 gatherBlocksIntoContinuation live proc_points blocks start =
243 Continuation info_table clabel params is_gc_cont body
245 children = (collectNonProcPointTargets proc_points blocks (unitUniqSet start) [start]) `minusUniqSet` (unitUniqSet start)
246 start_block = lookupWithDefaultUFM blocks (panic "TODO") start
247 unknown_block = panic "unknown block in gatherBlocksIntoContinuation"
248 children_blocks = map (lookupWithDefaultUFM blocks (panic "TODO")) (uniqSetToList children)
249 body = start_block : children_blocks
251 -- We can't properly annotate the continuation's stack parameters
252 -- at this point because this is before stack selection
253 -- but we want to keep the C_SRT around so we use 'Either'.
254 info_table = case start_block_entry of
255 FunctionEntry info _ _ -> Right info
256 ContinuationEntry _ srt _ -> Left srt
257 ControlEntry -> Right (CmmNonInfo Nothing)
259 is_gc_cont = case start_block_entry of
260 FunctionEntry _ _ _ -> False
261 ContinuationEntry _ _ gc_cont -> gc_cont
262 ControlEntry -> False
264 start_block_entry = brokenBlockEntry start_block
265 clabel = case start_block_entry of
266 FunctionEntry _ label _ -> label
267 _ -> mkReturnPtLabel $ getUnique start
268 params = case start_block_entry of
269 FunctionEntry _ _ args -> args
270 ContinuationEntry args _ _ -> args
273 lookupWithDefaultUFM live unknown_block start
274 -- it's a proc-point, pass lives in parameter registers
276 --------------------------------------------------------------------------------
277 -- For now just select the continuation orders in the order they are in the set with no gaps
279 selectContinuationFormat :: BlockEnv CmmLive
280 -> [Continuation (Either C_SRT CmmInfo)]
281 -> [(CLabel, (CmmFormals, Maybe CLabel, [Maybe LocalReg]))]
282 selectContinuationFormat live continuations =
283 map (\c -> (continuationLabel c, selectContinuationFormat' c)) continuations
285 -- User written continuations
286 selectContinuationFormat' (Continuation
287 (Right (CmmInfo _ _ _ (ContInfo format srt)))
289 (formals, Just label, format)
290 -- Either user written non-continuation code
291 -- or CPS generated proc-points
292 selectContinuationFormat' (Continuation (Right _) _ formals _ _) =
293 (formals, Nothing, [])
294 -- CPS generated continuations
295 selectContinuationFormat' (Continuation (Left srt) label formals _ blocks) =
296 -- TODO: assumes the first block is the entry block
297 let ident = brokenBlockId $ head blocks -- TODO: CLabel isn't a uniquable, but we need a better way than this
300 map Just $ uniqSetToList $
301 lookupWithDefaultUFM live unknown_block ident)
303 unknown_block = panic "unknown BlockId in selectContinuationFormat"
305 processFormats :: [(CLabel, (CmmFormals, Maybe CLabel, [Maybe LocalReg]))]
306 -> [Continuation (Either C_SRT CmmInfo)]
307 -> (WordOff, [(CLabel, ContinuationFormat)])
308 processFormats formats continuations = (max_size, formats')
311 0 : map (continuationMaxStack formats') continuations
312 formats' = map make_format formats
313 make_format (label, (formals, top, stack)) =
316 continuation_formals = formals,
317 continuation_label = top,
318 continuation_frame_size = stack_size stack +
322 continuation_stack = stack })
324 -- TODO: get rid of "+ 1" etc.
325 label_size = 1 :: WordOff
328 stack_size (Nothing:formats) = 1 + stack_size formats -- one dead word
329 stack_size (Just reg:formats) = width + stack_size formats
331 width = machRepByteWidth (localRegRep reg) `quot` wORD_SIZE
332 -- TODO: it would be better if we had a machRepWordWidth
334 continuationMaxStack :: [(CLabel, ContinuationFormat)]
337 continuationMaxStack _ (Continuation _ _ _ True _) = 0
338 continuationMaxStack formats (Continuation _ label _ False blocks) =
339 max_arg_size + continuation_frame_size stack_format
341 stack_format = maybe unknown_format id $ lookup label formats
342 unknown_format = panic "Unknown format in continuationMaxStack"
344 max_arg_size = maximum $ 0 : map block_max_arg_size blocks
346 block_max_arg_size block =
347 maximum (final_arg_size (brokenBlockExit block) :
348 map stmt_arg_size (brokenBlockStmts block))
350 final_arg_size (FinalReturn args) =
351 argumentsSize (cmmExprRep . fst) args
352 final_arg_size (FinalJump _ args) =
353 argumentsSize (cmmExprRep . fst) args
354 final_arg_size (FinalCall next _ _ args _ True) = 0
355 final_arg_size (FinalCall next _ _ args _ False) =
356 -- We have to account for the stack used when we build a frame
357 -- for the *next* continuation from *this* continuation
358 argumentsSize (cmmExprRep . fst) args +
359 continuation_frame_size next_format
361 next_format = maybe unknown_format id $ lookup next' formats
362 next' = mkReturnPtLabel $ getUnique next
366 stmt_arg_size (CmmJump _ args) =
367 argumentsSize (cmmExprRep . fst) args
368 stmt_arg_size (CmmCall _ _ _ (CmmSafe _)) =
369 panic "Safe call in processFormats"
370 stmt_arg_size (CmmReturn _) =
371 panic "CmmReturn in processFormats"
374 -----------------------------------------------------------------------------
375 applyContinuationFormat :: [(CLabel, ContinuationFormat)]
376 -> Continuation (Either C_SRT CmmInfo)
377 -> Continuation CmmInfo
379 -- User written continuations
380 applyContinuationFormat formats (Continuation
381 (Right (CmmInfo prof gc tag (ContInfo _ srt)))
382 label formals is_gc blocks) =
383 Continuation (CmmInfo prof gc tag (ContInfo format srt))
384 label formals is_gc blocks
386 format = continuation_stack $ maybe unknown_block id $ lookup label formats
387 unknown_block = panic "unknown BlockId in applyContinuationFormat"
389 -- Either user written non-continuation code or CPS generated proc-point
390 applyContinuationFormat formats (Continuation
391 (Right info) label formals is_gc blocks) =
392 Continuation info label formals is_gc blocks
394 -- CPS generated continuations
395 applyContinuationFormat formats (Continuation
396 (Left srt) label formals is_gc blocks) =
397 Continuation (CmmInfo prof gc tag (ContInfo (continuation_stack $ format) srt))
398 label formals is_gc blocks
400 gc = Nothing -- Generated continuations never need a stack check
401 -- TODO prof: this is the same as the current implementation
402 -- but I think it could be improved
403 prof = ProfilingInfo zeroCLit zeroCLit
404 tag = rET_SMALL -- cmmToRawCmm may convert it to rET_BIG
405 format = maybe unknown_block id $ lookup label formats
406 unknown_block = panic "unknown BlockId in applyContinuationFormat"