2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
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.
26 module SCCfinal ( stgMassageForProfiling ) where
28 #include "HsVersions.h"
32 import CmdLineOpts ( opt_AutoSccsOnIndividualCafs )
33 import CostCentre -- lots of things
34 import MkId ( mkSysLocal )
35 import Id ( idType, emptyIdSet, Id )
36 import SrcLoc ( noSrcLoc )
37 import Type ( splitSigmaTy, splitFunTy_maybe )
38 import UniqSupply ( getUnique, splitUniqSupply, UniqSupply )
39 import Unique ( Unique )
40 import Util ( removeDups, assertPanic, trace )
43 infixr 9 `thenMM`, `thenMM_`
47 type CollectedCCs = ([CostCentre], -- locally defined ones
48 [CostCentre]) -- ones needing "extern" decls
50 stgMassageForProfiling
51 :: FAST_STRING -> FAST_STRING -- module name, group name
52 -> UniqSupply -- unique supply
53 -> [StgBinding] -- input
54 -> (CollectedCCs, [StgBinding])
56 stgMassageForProfiling mod_name grp_name us stg_binds
58 ((local_ccs, extern_ccs),
60 = initMM mod_name us (mapMM do_top_binding stg_binds)
63 = if do_auto_sccs_on_cafs
64 then [] -- don't need "all CAFs" CC (for Prelude, we use PreludeCC)
67 local_ccs_no_dups = fst (removeDups cmpCostCentre local_ccs)
68 extern_ccs_no_dups = fst (removeDups cmpCostCentre extern_ccs)
70 ((fixed_ccs ++ local_ccs_no_dups, extern_ccs_no_dups), stg_binds2)
72 do_auto_sccs_on_cafs = opt_AutoSccsOnIndividualCafs -- only use!
74 all_cafs_cc = mkAllCafsCC mod_name grp_name
77 do_top_binding :: StgBinding -> MassageM StgBinding
79 do_top_binding (StgNonRec b rhs)
80 = do_top_rhs b rhs `thenMM` \ rhs' ->
81 returnMM (StgNonRec b rhs')
83 do_top_binding (StgRec pairs)
84 = mapMM do_pair pairs `thenMM` \ pairs2 ->
85 returnMM (StgRec pairs2)
88 = do_top_rhs b rhs `thenMM` \ rhs2 ->
92 do_top_rhs :: Id -> StgRhs -> MassageM StgRhs
94 do_top_rhs binder (StgRhsClosure _ bi fv u [] (StgSCC ty cc (StgCon con args lvs)))
95 | not (isSccCountCostCentre cc)
96 -- Trivial _scc_ around nothing but static data
97 -- Eliminate _scc_ ... and turn into StgRhsCon
98 = returnMM (StgRhsCon dontCareCostCentre con args)
100 do_top_rhs binder (StgRhsClosure no_cc bi fv u [] (StgSCC ty cc expr))
101 | (noCostCentreAttached no_cc || currentOrSubsumedCosts no_cc)
102 && not (isSccCountCostCentre cc)
103 -- Top level CAF without a cost centre attached
104 -- Attach and collect cc of trivial _scc_ in body
105 = collectCC cc `thenMM_`
106 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
107 returnMM (StgRhsClosure cc bi fv u [] expr')
109 do_top_rhs binder (StgRhsClosure no_cc bi fv u [] body)
110 | noCostCentreAttached no_cc || currentOrSubsumedCosts no_cc
111 -- Top level CAF without a cost centre attached
112 -- Attach CAF cc (collect if individual CAF ccs)
115 = if do_auto_sccs_on_cafs then
116 (True, mkAutoCC binder mod_name grp_name IsCafCC)
120 (if collect then collectCC caf_cc else nopMM) `thenMM_`
121 set_prevailing_cc caf_cc (do_expr body) `thenMM` \ body' ->
122 returnMM (StgRhsClosure caf_cc bi fv u [] body')
124 do_top_rhs binder (StgRhsClosure cc bi fv u [] body)
125 -- Top level CAF with cost centre attached
126 -- Should this be a CAF cc ??? Does this ever occur ???
127 = trace ("SCCfinal: CAF with cc: " ++ showCostCentre False cc) $
128 collectCC cc `thenMM_`
129 set_prevailing_cc cc (do_expr body) `thenMM` \ body' ->
130 returnMM (StgRhsClosure cc bi fv u [] body')
132 do_top_rhs binder (StgRhsClosure _ bi fv u args (StgSCC ty cc expr))
133 | not (isSccCountCostCentre cc)
134 -- Top level function with trivial _scc_ in body
135 -- Attach and collect cc of trivial _scc_
136 = collectCC cc `thenMM_`
137 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
138 returnMM (StgRhsClosure cc bi fv u args expr')
140 do_top_rhs binder (StgRhsClosure cc bi fv u args body)
141 -- Top level function, probably subsumed
143 (cc_closure, cc_body)
144 = if noCostCentreAttached cc
145 then (subsumedCosts, useCurrentCostCentre)
148 set_prevailing_cc cc_body (do_expr body) `thenMM` \ body' ->
149 returnMM (StgRhsClosure cc_closure bi fv u args body')
151 do_top_rhs binder (StgRhsCon cc con args)
152 -- Top-level (static) data is not counted in heap
153 -- profiles; nor do we set CCC from it; so we
154 -- just slam in dontCareCostCentre
155 = returnMM (StgRhsCon dontCareCostCentre con args)
158 do_expr :: StgExpr -> MassageM StgExpr
160 do_expr (StgApp fn args lvs)
161 = boxHigherOrderArgs (StgApp fn) args lvs
163 do_expr (StgCon con args lvs)
164 = boxHigherOrderArgs (StgCon con) args lvs
166 do_expr (StgPrim op args lvs)
167 = boxHigherOrderArgs (StgPrim op) args lvs
169 do_expr (StgSCC ty cc expr) -- Ha, we found a cost centre!
170 = collectCC cc `thenMM_`
171 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
172 returnMM (StgSCC ty cc expr')
174 do_expr (StgCase expr fv1 fv2 uniq alts)
175 = do_expr expr `thenMM` \ expr' ->
176 do_alts alts `thenMM` \ alts' ->
177 returnMM (StgCase expr' fv1 fv2 uniq alts')
179 do_alts (StgAlgAlts ty alts def)
180 = mapMM do_alt alts `thenMM` \ alts' ->
181 do_deflt def `thenMM` \ def' ->
182 returnMM (StgAlgAlts ty alts' def')
184 do_alt (id, bs, use_mask, e)
185 = do_expr e `thenMM` \ e' ->
186 returnMM (id, bs, use_mask, e')
188 do_alts (StgPrimAlts ty alts def)
189 = mapMM do_alt alts `thenMM` \ alts' ->
190 do_deflt def `thenMM` \ def' ->
191 returnMM (StgPrimAlts ty alts' def')
194 = do_expr e `thenMM` \ e' ->
197 do_deflt StgNoDefault = returnMM StgNoDefault
198 do_deflt (StgBindDefault b is_used e)
199 = do_expr e `thenMM` \ e' ->
200 returnMM (StgBindDefault b is_used e')
203 = do_binding b `thenMM` \ b' ->
204 do_expr e `thenMM` \ e' ->
205 returnMM (StgLet b' e')
207 do_expr (StgLetNoEscape lvs1 lvs2 rhs body)
208 = do_binding rhs `thenMM` \ rhs' ->
209 do_expr body `thenMM` \ body' ->
210 returnMM (StgLetNoEscape lvs1 lvs2 rhs' body')
213 do_binding :: StgBinding -> MassageM StgBinding
215 do_binding (StgNonRec b rhs)
216 = do_rhs rhs `thenMM` \ rhs' ->
217 returnMM (StgNonRec b rhs')
219 do_binding (StgRec pairs)
220 = mapMM do_pair pairs `thenMM` \ new_pairs ->
221 returnMM (StgRec new_pairs)
224 = do_rhs rhs `thenMM` \ rhs' ->
227 do_rhs :: StgRhs -> MassageM StgRhs
228 -- We play much the same game as we did in do_top_rhs above;
229 -- but we don't have to worry about cafs etc.
231 do_rhs (StgRhsClosure _ bi fv u [] (StgSCC ty cc (StgCon con args lvs)))
232 | not (isSccCountCostCentre cc)
233 = collectCC cc `thenMM_`
234 returnMM (StgRhsCon cc con args)
236 do_rhs (StgRhsClosure _ bi fv u args (StgSCC ty cc expr))
237 | not (isSccCountCostCentre cc)
238 = collectCC cc `thenMM_`
239 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
240 returnMM (StgRhsClosure cc bi fv u args expr')
242 do_rhs (StgRhsClosure cc bi fv u args body)
243 = set_prevailing_cc_maybe cc $ \ cc' ->
244 set_lambda_cc (do_expr body) `thenMM` \ body' ->
245 returnMM (StgRhsClosure cc' bi fv u args body')
247 do_rhs (StgRhsCon cc con args)
248 = set_prevailing_cc_maybe cc $ \ cc' ->
249 returnMM (StgRhsCon cc' con args)
251 -- ToDo: Box args and sort out any let bindings ???
252 -- Nope: maybe later? WDP 94/06
255 %************************************************************************
257 \subsection{Boxing higher-order args}
259 %************************************************************************
263 :: ([StgArg] -> StgLiveVars -> StgExpr)
264 -- An application lacking its arguments and live-var info
265 -> [StgArg] -- arguments which we might box
266 -> StgLiveVars -- live var info, which we do *not* try
267 -- to maintain/update (setStgVarInfo will
271 boxHigherOrderArgs almost_expr args live_vars
272 = returnMM (almost_expr args live_vars)
274 {- No boxing for now ... should be moved to desugarer and preserved ...
276 boxHigherOrderArgs almost_expr args live_vars
277 = get_prevailing_cc `thenMM` \ cc ->
278 if (isCafCC cc || isDictCC cc) then
279 -- no boxing required inside CAF/DICT cc
280 -- since CAF/DICT functions are subsumed anyway
281 returnMM (almost_expr args live_vars)
283 mapAccumMM do_arg [] args `thenMM` \ (let_bindings, new_args) ->
284 returnMM (foldr (mk_stg_let cc) (almost_expr new_args live_vars) let_bindings)
287 do_arg bindings atom@(StgLitAtom _) = returnMM (bindings, atom)
289 do_arg bindings atom@(StgVarAtom old_var)
291 var_type = getIdUniType old_var
293 if toplevelishId old_var && isFunType (getTauType var_type)
295 -- make a trivial let-binding for the top-level function
296 getUniqueMM `thenMM` \ uniq ->
298 new_var = mkSysLocal SLIT("ho") uniq var_type noSrcLoc
300 returnMM ( (new_var, old_var) : bindings, StgVarAtom new_var )
302 returnMM (bindings, atom)
305 mk_stg_let :: CostCentre -> (Id, Id) -> StgExpr -> StgExpr
307 mk_stg_let cc (new_var, old_var) body
309 rhs_body = StgApp (StgVarAtom old_var) [{-args-}] bOGUS_LVs
310 rhs_closure = StgRhsClosure cc stgArgOcc [{-fvs-}] ReEntrant [{-args-}] rhs_body
312 StgLet (StgNonRec new_var rhs_closure) body
314 bOGUS_LVs = emptyUniqSet -- easier to print than: panic "mk_stg_let: LVs"
318 %************************************************************************
320 \subsection{Boring monad stuff for this}
322 %************************************************************************
326 = FAST_STRING -- module name
327 -> CostCentre -- prevailing CostCentre
328 -- if none, subsumedCosts at top-level
329 -- useCurrentCostCentre at nested levels
332 -> (CollectedCCs, result)
334 -- the initUs function also returns the final UniqueSupply and CollectedCCs
336 initMM :: FAST_STRING -- module name, which we may consult
341 initMM mod_name init_us m = m mod_name noCostCentre init_us ([],[])
343 thenMM :: MassageM a -> (a -> MassageM b) -> MassageM b
344 thenMM_ :: MassageM a -> (MassageM b) -> MassageM b
346 thenMM expr cont mod scope_cc us ccs
347 = case splitUniqSupply us of { (s1, s2) ->
348 case (expr mod scope_cc s1 ccs) of { (ccs2, result) ->
349 cont result mod scope_cc s2 ccs2 }}
351 thenMM_ expr cont mod scope_cc us ccs
352 = case splitUniqSupply us of { (s1, s2) ->
353 case (expr mod scope_cc s1 ccs) of { (ccs2, _) ->
354 cont mod scope_cc s2 ccs2 }}
356 returnMM :: a -> MassageM a
357 returnMM result mod scope_cc us ccs = (ccs, result)
360 nopMM mod scope_cc us ccs = (ccs, ())
362 mapMM :: (a -> MassageM b) -> [a] -> MassageM [b]
364 mapMM f [] = returnMM []
366 = f m `thenMM` \ r ->
367 mapMM f ms `thenMM` \ rs ->
370 mapAccumMM :: (acc -> x -> MassageM (acc, y)) -> acc -> [x] -> MassageM (acc, [y])
372 mapAccumMM f b [] = returnMM (b, [])
373 mapAccumMM f b (m:ms)
374 = f b m `thenMM` \ (b2, r) ->
375 mapAccumMM f b2 ms `thenMM` \ (b3, rs) ->
378 getUniqueMM :: MassageM Unique
379 getUniqueMM mod scope_cc us ccs = (ccs, getUnique us)
383 set_prevailing_cc :: CostCentre -> MassageM a -> MassageM a
384 set_prevailing_cc cc_to_set_to action mod scope_cc us ccs
385 -- set unconditionally
386 = action mod cc_to_set_to us ccs
388 set_prevailing_cc_maybe :: CostCentre -> (CostCentre -> MassageM a) -> MassageM a
389 set_prevailing_cc_maybe cc_to_try action mod scope_cc us ccs
390 -- set only if a real cost centre
393 = if noCostCentreAttached cc_to_try || currentOrSubsumedCosts cc_to_try
394 then scope_cc -- carry on as before
395 else cc_to_try -- use new cost centre
397 action cc_to_use mod cc_to_use us ccs
399 set_lambda_cc :: MassageM a -> MassageM a
400 set_lambda_cc action mod scope_cc us ccs
401 -- used when moving inside a lambda;
402 -- if we were chugging along as "caf/dict" we change to "ccc"
405 = if isCafCC scope_cc || isDictCC scope_cc
406 then useCurrentCostCentre
409 action mod cc_to_use us ccs
412 get_prevailing_cc :: MassageM CostCentre
413 get_prevailing_cc mod scope_cc us ccs = (ccs, scope_cc)
418 collectCC :: CostCentre -> MassageM ()
420 collectCC cc mod_name scope_cc us (local_ccs, extern_ccs)
421 = ASSERT(not (noCostCentreAttached cc))
422 ASSERT(not (currentOrSubsumedCosts cc))
423 if (cc `ccFromThisModule` mod_name) then
424 ((cc : local_ccs, extern_ccs), ())
425 else -- must declare it "extern"
426 ((local_ccs, cc : extern_ccs), ())