2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[SCCfinal]{Modify and collect code generation for final STG program}
6 This is now a sort-of-normal STG-to-STG pass (WDP 94/06), run by stg2stg.
8 * Traverses the STG program collecting the cost centres. These are
9 required to declare the cost centres at the start of code
12 Note: because of cross-module unfolding, some of these cost centres
13 may be from other modules. But will still have to give them
14 "extern" declarations.
16 * Puts on CAF cost-centres if the user has asked for individual CAF
19 * Ditto for individual DICT cost-centres.
21 * Boxes top-level inherited functions passed as arguments.
23 * "Distributes" given cost-centres to all as-yet-unmarked RHSs.
27 -- The above warning supression flag is a temporary kludge.
28 -- While working on this module you are encouraged to remove it and fix
29 -- any warnings in the module. See
30 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
33 module SCCfinal ( stgMassageForProfiling ) where
35 #include "HsVersions.h"
39 import StaticFlags ( opt_AutoSccsOnIndividualCafs )
40 import CostCentre -- lots of things
44 import UniqSupply ( splitUniqSupply, UniqSupply )
46 import UniqSupply ( uniqFromSupply )
49 import ListSetOps ( removeDups )
54 stgMassageForProfiling
56 -> Module -- module name
57 -> UniqSupply -- unique supply
58 -> [StgBinding] -- input
59 -> (CollectedCCs, [StgBinding])
61 stgMassageForProfiling this_pkg mod_name us stg_binds
63 ((local_ccs, extern_ccs, cc_stacks),
65 = initMM mod_name us (do_top_bindings stg_binds)
67 (fixed_ccs, fixed_cc_stacks)
68 = if opt_AutoSccsOnIndividualCafs
69 then ([],[]) -- don't need "all CAFs" CC
70 -- (for Prelude, we use PreludeCC)
71 else ([all_cafs_cc], [all_cafs_ccs])
73 local_ccs_no_dups = fst (removeDups cmpCostCentre local_ccs)
74 extern_ccs_no_dups = fst (removeDups cmpCostCentre extern_ccs)
76 ((fixed_ccs ++ local_ccs_no_dups,
78 fixed_cc_stacks ++ cc_stacks), stg_binds2)
81 all_cafs_cc = mkAllCafsCC mod_name
82 all_cafs_ccs = mkSingletonCCS all_cafs_cc
85 do_top_bindings :: [StgBinding] -> MassageM [StgBinding]
87 do_top_bindings [] = return []
89 do_top_bindings (StgNonRec b rhs : bs) = do
90 rhs' <- do_top_rhs b rhs
91 addTopLevelIshId b $ do
92 bs' <- do_top_bindings bs
93 return (StgNonRec b rhs' : bs')
95 do_top_bindings (StgRec pairs : bs)
96 = addTopLevelIshIds binders $ do
97 pairs2 <- mapM do_pair pairs
98 bs' <- do_top_bindings bs
99 return (StgRec pairs2 : bs')
101 binders = map fst pairs
102 do_pair (b, rhs) = do
103 rhs2 <- do_top_rhs b rhs
107 do_top_rhs :: Id -> StgRhs -> MassageM StgRhs
109 do_top_rhs binder (StgRhsClosure _ bi fv u srt [] (StgSCC cc (StgConApp con args)))
110 | not (isSccCountCostCentre cc) && not (isDllConApp this_pkg con args)
111 -- Trivial _scc_ around nothing but static data
112 -- Eliminate _scc_ ... and turn into StgRhsCon
114 -- isDllConApp checks for LitLit args too
115 = return (StgRhsCon dontCareCCS con args)
117 {- Can't do this one with cost-centre stacks: --SDM
118 do_top_rhs binder (StgRhsClosure no_cc bi fv u [] (StgSCC ty cc expr))
119 | (noCCSAttached no_cc || currentOrSubsumedCCS no_cc)
120 && not (isSccCountCostCentre cc)
121 -- Top level CAF without a cost centre attached
122 -- Attach and collect cc of trivial _scc_ in body
124 expr' <- set_prevailing_cc cc (do_expr expr)
125 return (StgRhsClosure cc bi fv u [] expr')
128 do_top_rhs binder (StgRhsClosure no_cc bi fv u srt [] body)
129 | noCCSAttached no_cc || currentOrSubsumedCCS no_cc = do
130 -- Top level CAF without a cost centre attached
131 -- Attach CAF cc (collect if individual CAF ccs)
132 caf_ccs <- if opt_AutoSccsOnIndividualCafs
133 then let cc = mkAutoCC binder modl CafCC
134 ccs = mkSingletonCCS cc
135 -- careful: the binder might be :Main.main,
136 -- which doesn't belong to module mod_name.
137 -- bug #249, tests prof001, prof002
138 modl | Just m <- nameModule_maybe (idName binder) = m
139 | otherwise = mod_name
146 body' <- set_prevailing_cc caf_ccs (do_expr body)
147 return (StgRhsClosure caf_ccs bi fv u srt [] body')
149 do_top_rhs binder (StgRhsClosure cc bi fv u srt [] body)
150 -- Top level CAF with cost centre attached
151 -- Should this be a CAF cc ??? Does this ever occur ???
152 = pprPanic "SCCfinal: CAF with cc:" (ppr cc)
154 do_top_rhs binder (StgRhsClosure no_ccs bi fv u srt args body)
155 -- Top level function, probably subsumed
156 | noCCSAttached no_ccs
157 = do body' <- set_lambda_cc (do_expr body)
158 return (StgRhsClosure subsumedCCS bi fv u srt args body')
161 = pprPanic "SCCfinal: CAF with cc:" (ppr no_ccs)
163 do_top_rhs binder (StgRhsCon ccs con args)
164 -- Top-level (static) data is not counted in heap
165 -- profiles; nor do we set CCCS from it; so we
166 -- just slam in dontCareCostCentre
167 = return (StgRhsCon dontCareCCS con args)
170 do_expr :: StgExpr -> MassageM StgExpr
172 do_expr (StgLit l) = return (StgLit l)
174 do_expr (StgApp fn args)
175 = boxHigherOrderArgs (StgApp fn) args
177 do_expr (StgConApp con args)
178 = boxHigherOrderArgs (\args -> StgConApp con args) args
180 do_expr (StgOpApp con args res_ty)
181 = boxHigherOrderArgs (\args -> StgOpApp con args res_ty) args
183 do_expr (StgSCC cc expr) = do -- Ha, we found a cost centre!
185 expr' <- do_expr expr
186 return (StgSCC cc expr')
188 do_expr (StgCase expr fv1 fv2 bndr srt alt_type alts) = do
189 expr' <- do_expr expr
190 alts' <- mapM do_alt alts
191 return (StgCase expr' fv1 fv2 bndr srt alt_type alts')
193 do_alt (id, bs, use_mask, e) = do
195 return (id, bs, use_mask, e')
197 do_expr (StgLet b e) = do
201 do_expr (StgLetNoEscape lvs1 lvs2 b e) = do
203 return (StgLetNoEscape lvs1 lvs2 b e)
205 do_expr (StgTick m n expr) = do
206 expr' <- do_expr expr
207 return (StgTick m n expr')
210 do_expr other = pprPanic "SCCfinal.do_expr" (ppr other)
213 ----------------------------------
215 do_let (StgNonRec b rhs) e = do
217 addTopLevelIshId b $ do
219 return (StgNonRec b rhs',e')
221 do_let (StgRec pairs) e
222 = addTopLevelIshIds binders $ do
223 pairs' <- mapM do_pair pairs
225 return (StgRec pairs', e')
227 binders = map fst pairs
228 do_pair (b, rhs) = do
232 ----------------------------------
233 do_rhs :: StgRhs -> MassageM StgRhs
234 -- We play much the same game as we did in do_top_rhs above;
235 -- but we don't have to worry about cafs etc.
238 do_rhs (StgRhsClosure closure_cc bi fv u [] (StgSCC ty cc (StgCon (DataCon con) args _)))
239 | not (isSccCountCostCentre cc)
241 return (StgRhsCon cc con args)
244 do_rhs (StgRhsClosure _ bi fv u srt args expr) = do
245 (expr', ccs) <- slurpSCCs currentCCS expr
246 expr'' <- do_expr expr'
247 return (StgRhsClosure ccs bi fv u srt args expr'')
249 slurpSCCs ccs (StgSCC cc e)
251 slurpSCCs (cc `pushCCOnCCS` ccs) e
255 do_rhs (StgRhsCon cc con args)
256 = return (StgRhsCon currentCCS con args)
259 %************************************************************************
261 \subsection{Boxing higher-order args}
263 %************************************************************************
265 Boxing is *turned off* at the moment, until we can figure out how to
266 do it properly in general.
270 :: ([StgArg] -> StgExpr)
271 -- An application lacking its arguments
272 -> [StgArg] -- arguments which we might box
275 #ifndef PROF_DO_BOXING
276 boxHigherOrderArgs almost_expr args
277 = return (almost_expr args)
279 boxHigherOrderArgs almost_expr args = do
280 ids <- getTopLevelIshIds
281 (let_bindings, new_args) <- mapAccumLM (do_arg ids) [] args
282 return (foldr (mk_stg_let currentCCS) (almost_expr new_args) let_bindings)
286 do_arg ids bindings arg@(StgVarArg old_var)
287 | (not (isLocalVar old_var) || elemVarSet old_var ids)
288 && isFunTy (dropForAlls var_type)
289 = do -- make a trivial let-binding for the top-level function
292 new_var = mkSysLocal FSLIT("sf") uniq var_type
293 return ( (new_var, old_var) : bindings, StgVarArg new_var )
295 var_type = idType old_var
297 do_arg ids bindings arg = return (bindings, arg)
300 mk_stg_let :: CostCentreStack -> (Id, Id) -> StgExpr -> StgExpr
302 mk_stg_let cc (new_var, old_var) body
304 rhs_body = StgApp old_var [{-args-}]
305 rhs_closure = StgRhsClosure cc stgArgOcc [{-fvs-}] ReEntrant NoSRT{-eeek!!!-} [{-args-}] rhs_body
307 StgLet (StgNonRec new_var rhs_closure) body
309 bOGUS_LVs = emptyUniqSet -- easier to print than: panic "mk_stg_let: LVs"
313 %************************************************************************
315 \subsection{Boring monad stuff for this}
317 %************************************************************************
320 newtype MassageM result
322 unMassageM :: Module -- module name
323 -> CostCentreStack -- prevailing CostCentre
324 -- if none, subsumedCosts at top-level
325 -- currentCostCentre at nested levels
327 -> VarSet -- toplevel-ish Ids for boxing
329 -> (CollectedCCs, result)
332 instance Monad MassageM where
333 return x = MassageM (\_ _ _ _ ccs -> (ccs, x))
337 -- the initMM function also returns the final CollectedCCs
339 initMM :: Module -- module name, which we may consult
344 initMM mod_name init_us (MassageM m) = m mod_name noCCS init_us emptyVarSet ([],[],[])
346 thenMM :: MassageM a -> (a -> MassageM b) -> MassageM b
347 thenMM_ :: MassageM a -> (MassageM b) -> MassageM b
349 thenMM expr cont = MassageM $ \mod scope_cc us ids ccs ->
350 case splitUniqSupply us of { (s1, s2) ->
351 case unMassageM expr mod scope_cc s1 ids ccs of { (ccs2, result) ->
352 unMassageM (cont result) mod scope_cc s2 ids ccs2 }}
354 thenMM_ expr cont = MassageM $ \mod scope_cc us ids ccs ->
355 case splitUniqSupply us of { (s1, s2) ->
356 case unMassageM expr mod scope_cc s1 ids ccs of { (ccs2, _) ->
357 unMassageM cont mod scope_cc s2 ids ccs2 }}
359 #ifdef PROF_DO_BOXING
360 getUniqueMM :: MassageM Unique
361 getUniqueMM = MassageM \mod scope_cc us ids ccs -> (ccs, uniqFromSupply us)
364 addTopLevelIshId :: Id -> MassageM a -> MassageM a
365 addTopLevelIshId id scope
366 = MassageM $ \mod scope_cc us ids ccs ->
367 if isCurrentCCS scope_cc then unMassageM scope mod scope_cc us ids ccs
368 else unMassageM scope mod scope_cc us (extendVarSet ids id) ccs
370 addTopLevelIshIds :: [Id] -> MassageM a -> MassageM a
371 addTopLevelIshIds [] cont = cont
372 addTopLevelIshIds (id:ids) cont
373 = addTopLevelIshId id (addTopLevelIshIds ids cont)
375 getTopLevelIshIds :: MassageM VarSet
376 getTopLevelIshIds = MassageM $ \mod scope_cc us ids ccs -> (ccs, ids)
379 The prevailing CCS is used to tell whether we're in a top-levelish
380 position, where top-levelish is defined as "not inside a lambda".
381 Prevailing CCs used to be used for something much more complicated,
385 set_lambda_cc :: MassageM a -> MassageM a
387 = MassageM $ \mod scope_cc us ids ccs
388 -> unMassageM action mod currentCCS us ids ccs
390 set_prevailing_cc :: CostCentreStack -> MassageM a -> MassageM a
391 set_prevailing_cc cc_to_set_to action
392 = MassageM $ \mod scope_cc us ids ccs
393 -> unMassageM action mod cc_to_set_to us ids ccs
395 get_prevailing_cc :: MassageM CostCentreStack
396 get_prevailing_cc = MassageM $ \mod scope_cc us ids ccs -> (ccs, scope_cc)
400 collectCC :: CostCentre -> MassageM ()
401 collectCC cc = MassageM $ \mod_name scope_cc us ids (local_ccs, extern_ccs, ccss)
402 -> ASSERT(not (noCCAttached cc))
403 if (cc `ccFromThisModule` mod_name) then
404 ((cc : local_ccs, extern_ccs, ccss), ())
405 else -- must declare it "extern"
406 ((local_ccs, cc : extern_ccs, ccss), ())
408 -- Version of collectCC used when we definitely want to declare this
409 -- CC as local, even if its module name is not the same as the current
410 -- module name (eg. the special :Main module) see bug #249, #1472,
411 -- test prof001,prof002.
412 collectNewCC :: CostCentre -> MassageM ()
413 collectNewCC cc = MassageM $ \mod_name scope_cc us ids (local_ccs, extern_ccs, ccss)
414 -> ((cc : local_ccs, extern_ccs, ccss), ())
416 collectCCS :: CostCentreStack -> MassageM ()
418 collectCCS ccs = MassageM $ \mod_name scope_cc us ids (local_ccs, extern_ccs, ccss)
419 -> ASSERT(not (noCCSAttached ccs))
420 ((local_ccs, extern_ccs, ccs : ccss), ())