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 CmmInfo 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 CmmInfo (Just existing) _ _
91 -> (old_info, [], make_gc_check stack_use existing)
92 CmmInfo Nothing update_frame info_table
93 -> (CmmInfo (Just block_id) update_frame info_table,
94 [make_gc_block block_id fun_label formals (CmmSafe $ cmmInfoTableSRT info_table)],
95 make_gc_check stack_use block_id)
97 cmmInfoTableSRT CmmNonInfoTable = NoC_SRT
98 cmmInfoTableSRT (CmmInfoTable _ _ (ConstrInfo _ _ _)) = NoC_SRT
99 cmmInfoTableSRT (CmmInfoTable _ _ (FunInfo _ srt _ _ _ _)) = srt
100 cmmInfoTableSRT (CmmInfoTable _ _ (ThunkInfo _ srt)) = srt
101 cmmInfoTableSRT (CmmInfoTable _ _ (ThunkSelectorInfo _ srt)) = srt
102 cmmInfoTableSRT (CmmInfoTable _ _ (ContInfo _ srt)) = srt
104 -----------------------------------------------------------------------------
105 -- |CPS a single CmmTop (proceedure)
106 -- Only 'CmmProc' are transformed 'CmmData' will be left alone.
107 -----------------------------------------------------------------------------
109 cpsProc :: UniqSupply
110 -> GenCmmTop CmmStatic CmmInfo CmmStmt -- ^Input proceedure
111 -> [GenCmmTop CmmStatic CmmInfo CmmStmt] -- ^Output proceedure and continuations
113 -- Data blocks don't need to be CPS transformed
114 cpsProc uniqSupply proc@(CmmData _ _) = [proc]
116 -- Empty functions just don't work with the CPS algorithm, but
117 -- they don't need the transformation anyway so just output them directly
118 cpsProc uniqSupply proc@(CmmProc _ _ _ []) = [proc]
120 -- CPS transform for those procs that actually need it
121 cpsProc uniqSupply (CmmProc info ident params blocks) = cps_procs
123 (uniqSupply1, uniqSupply2) = splitUniqSupply uniqSupply
124 uniques :: [[Unique]]
125 uniques = map uniqsFromSupply $ listSplitUniqSupply uniqSupply1
126 (gc_unique:gc_block_unique:stack_use_unique:info_uniques):adaptor_uniques:block_uniques = uniques
127 proc_uniques = map (map uniqsFromSupply . listSplitUniqSupply) $ listSplitUniqSupply uniqSupply2
129 stack_use = CmmLocal (LocalReg stack_use_unique (cmmRegRep spReg) KindPtr)
132 forced_gc :: (CmmInfo, [CmmBasicBlock], [CmmStmt])
133 forced_gc = force_gc_block info stack_use (BlockId gc_unique) ident params
134 (forced_info, gc_blocks, check_stmts) = forced_gc
135 gc_block_id = BlockId gc_block_unique
138 BasicBlock gc_block_id
139 (check_stmts++[CmmBranch $ blockId $ head blocks]) :
142 forced_gc_id = case forced_info of
143 CmmInfo (Just x) _ _ -> x
145 update_frame = case info of CmmInfo _ u _ -> u
147 -- Break the block at each function call.
148 -- The part after the function call will have to become a continuation.
149 broken_blocks :: ([(BlockId, ContFormat)], [BrokenBlock])
151 (\x -> (concatMap fst x, concatMap snd x)) $
152 zipWith3 (breakBlock [forced_gc_id])
155 (FunctionEntry forced_info ident params :
158 f' = selectContinuations (fst broken_blocks)
159 broken_blocks' = map (makeContinuationEntries f') $
161 zipWith (adaptBlockToFormat f')
165 -- Calculate live variables for each broken block.
167 -- Nothing can be live on entry to the first block
168 -- so we could take the tail, but for now we wont
169 -- to help future proof the code.
170 live :: BlockEntryLiveness
171 live = cmmLiveness $ map cmmBlockFromBrokenBlock broken_blocks'
173 -- Calculate which blocks must be made into full fledged procedures.
174 proc_points :: UniqSet BlockId
175 proc_points = calculateProcPoints broken_blocks'
177 -- Construct a map so we can lookup a broken block by its 'BlockId'.
178 block_env :: BlockEnv BrokenBlock
179 block_env = blocksToBlockEnv broken_blocks'
181 -- Group the blocks into continuations based on the set of proc-points.
182 continuations :: [Continuation (Either C_SRT CmmInfo)]
183 continuations = map (gatherBlocksIntoContinuation live proc_points block_env)
184 (uniqSetToList proc_points)
186 -- Select the stack format on entry to each continuation.
187 -- Return the max stack offset and an association list
189 -- This is an association list instead of a UniqFM because
190 -- CLabel's don't have a 'Uniqueable' instance.
191 formats :: [(CLabel, -- key
192 (CmmFormals, -- arguments
193 Maybe CLabel, -- label in top slot
194 [Maybe LocalReg]))] -- slots
195 formats = selectContinuationFormat live continuations
197 -- Do a little meta-processing on the stack formats such as
198 -- getting the individual frame sizes and the maximum frame size
199 formats' :: (WordOff, WordOff, [(CLabel, ContinuationFormat)])
200 formats'@(_, _, format_list) = processFormats formats update_frame continuations
202 -- Update the info table data on the continuations with
203 -- the selected stack formats.
204 continuations' :: [Continuation CmmInfo]
205 continuations' = map (applyContinuationFormat format_list) continuations
207 -- Do the actual CPS transform.
208 cps_procs :: [CmmTop]
209 cps_procs = zipWith (continuationToProc formats' stack_use) proc_uniques continuations'
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 (CmmInfo Nothing Nothing CmmNonInfoTable)
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 _ _ (CmmInfoTable _ _ (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]))]
307 -> [Continuation (Either C_SRT CmmInfo)]
308 -> (WordOff, WordOff, [(CLabel, ContinuationFormat)])
309 processFormats formats update_frame continuations =
310 (max_size + update_frame_size, update_frame_size, formats')
313 0 : map (continuationMaxStack formats') continuations
314 formats' = map make_format formats
315 make_format (label, (formals, top, stack)) =
318 continuation_formals = formals,
319 continuation_label = top,
320 continuation_frame_size = stack_size stack +
324 continuation_stack = stack })
326 update_frame_size = case update_frame of
328 (Just (UpdateFrame _ args))
329 -> label_size + update_size args
332 update_size (expr:exprs) = width + update_size exprs
334 width = machRepByteWidth (cmmExprRep expr) `quot` wORD_SIZE
335 -- TODO: it would be better if we had a machRepWordWidth
337 -- TODO: get rid of "+ 1" etc.
338 label_size = 1 :: WordOff
341 stack_size (Nothing:formats) = 1 + stack_size formats -- one dead word
342 stack_size (Just reg:formats) = width + stack_size formats
344 width = machRepByteWidth (localRegRep reg) `quot` wORD_SIZE
345 -- TODO: it would be better if we had a machRepWordWidth
347 continuationMaxStack :: [(CLabel, ContinuationFormat)]
350 continuationMaxStack _ (Continuation _ _ _ True _) = 0
351 continuationMaxStack formats (Continuation _ label _ False blocks) =
352 max_arg_size + continuation_frame_size stack_format
354 stack_format = maybe unknown_format id $ lookup label formats
355 unknown_format = panic "Unknown format in continuationMaxStack"
357 max_arg_size = maximum $ 0 : map block_max_arg_size blocks
359 block_max_arg_size block =
360 maximum (final_arg_size (brokenBlockExit block) :
361 map stmt_arg_size (brokenBlockStmts block))
363 final_arg_size (FinalReturn args) =
364 argumentsSize (cmmExprRep . fst) args
365 final_arg_size (FinalJump _ args) =
366 argumentsSize (cmmExprRep . fst) args
367 final_arg_size (FinalCall next _ _ args _ True) = 0
368 final_arg_size (FinalCall next _ _ args _ False) =
369 -- We have to account for the stack used when we build a frame
370 -- for the *next* continuation from *this* continuation
371 argumentsSize (cmmExprRep . fst) args +
372 continuation_frame_size next_format
374 next_format = maybe unknown_format id $ lookup next' formats
375 next' = mkReturnPtLabel $ getUnique next
379 stmt_arg_size (CmmJump _ args) =
380 argumentsSize (cmmExprRep . fst) args
381 stmt_arg_size (CmmCall _ _ _ (CmmSafe _)) =
382 panic "Safe call in processFormats"
383 stmt_arg_size (CmmReturn _) =
384 panic "CmmReturn in processFormats"
387 -----------------------------------------------------------------------------
388 applyContinuationFormat :: [(CLabel, ContinuationFormat)]
389 -> Continuation (Either C_SRT CmmInfo)
390 -> Continuation CmmInfo
392 -- User written continuations
393 applyContinuationFormat formats (Continuation
394 (Right (CmmInfo gc update_frame (CmmInfoTable prof tag (ContInfo _ srt))))
395 label formals is_gc blocks) =
396 Continuation (CmmInfo gc update_frame (CmmInfoTable prof tag (ContInfo format srt)))
397 label formals is_gc blocks
399 format = continuation_stack $ maybe unknown_block id $ lookup label formats
400 unknown_block = panic "unknown BlockId in applyContinuationFormat"
402 -- Either user written non-continuation code or CPS generated proc-point
403 applyContinuationFormat formats (Continuation
404 (Right info) label formals is_gc blocks) =
405 Continuation info label formals is_gc blocks
407 -- CPS generated continuations
408 applyContinuationFormat formats (Continuation
409 (Left srt) label formals is_gc blocks) =
410 Continuation (CmmInfo gc Nothing (CmmInfoTable prof tag (ContInfo (continuation_stack $ format) srt)))
411 label formals is_gc blocks
413 gc = Nothing -- Generated continuations never need a stack check
414 -- TODO prof: this is the same as the current implementation
415 -- but I think it could be improved
416 prof = ProfilingInfo zeroCLit zeroCLit
417 tag = rET_SMALL -- cmmToRawCmm may convert it to rET_BIG
418 format = maybe unknown_block id $ lookup label formats
419 unknown_block = panic "unknown BlockId in applyContinuationFormat"