2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
4 \section[SimplCore]{Driver for simplifying @Core@ programs}
7 #include "HsVersions.h"
9 module SimplCore ( core2core ) where
12 IMPORT_1_3(IO(hPutStr,stderr))
14 import AnalFBWW ( analFBWW )
15 import Bag ( isEmptyBag, foldBag )
16 import BinderInfo ( BinderInfo{-instance Outputable-} )
17 import CgCompInfo ( uNFOLDING_CREATION_THRESHOLD,
18 uNFOLDING_USE_THRESHOLD,
19 uNFOLDING_OVERRIDE_THRESHOLD,
20 uNFOLDING_CON_DISCOUNT_WEIGHT
22 import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), switchIsOn,
24 opt_D_simplifier_stats,
25 opt_D_verbose_core2core,
28 opt_ReportWhyUnfoldingsDisallowed,
30 opt_UnfoldingCreationThreshold,
31 opt_UnfoldingOverrideThreshold,
32 opt_UnfoldingUseThreshold
34 import CoreLint ( lintCoreBindings )
37 import CoreUtils ( substCoreBindings, manifestlyWHNF )
38 import ErrUtils ( ghcExit )
39 import FiniteMap ( FiniteMap )
40 import FloatIn ( floatInwards )
41 import FloatOut ( floatOutwards )
42 import FoldrBuildWW ( mkFoldrBuildWW )
43 import Id ( idType, toplevelishId, idWantsToBeINLINEd,
44 unfoldingUnfriendlyId,
45 nullIdEnv, addOneToIdEnv, delOneFromIdEnv,
46 lookupIdEnv, SYN_IE(IdEnv),
47 GenId{-instance Outputable-}
49 import IdInfo ( mkUnfolding )
50 import LiberateCase ( liberateCase )
51 import MagicUFs ( MagicUnfoldingFun )
52 import Maybes ( maybeToBool )
53 import Outputable ( Outputable(..){-instance * (,) -} )
55 import PprStyle ( PprStyle(..) )
56 import PprType ( GenType{-instance Outputable-}, GenTyVar{-ditto-} )
57 import Pretty ( ppShow, ppAboves, ppAbove, ppCat, ppStr )
58 import SAT ( doStaticArgs )
59 import SimplMonad ( zeroSimplCount, showSimplCount, SimplCount )
60 import SimplPgm ( simplifyPgm )
61 import SimplVar ( leastItCouldCost )
63 import SpecUtils ( pprSpecErrs )
64 import StrictAnal ( saWwTopBinds )
65 import TyVar ( nullTyVarEnv, GenTyVar{-instance Eq-} )
66 import Unique ( Unique{-instance Eq-} )
67 import UniqSupply ( splitUniqSupply )
68 import Util ( panic{-ToDo:rm-} )
71 import Deforest ( deforestProgram )
72 import DefUtils ( deforestable )
75 isWrapperFor = panic "SimplCore.isWrapperFor (ToDo)"
76 isWrapperId = panic "SimplCore.isWrapperId (ToDo)"
80 core2core :: [CoreToDo] -- spec of what core-to-core passes to do
81 -> FAST_STRING -- module name (profiling only)
82 -> PprStyle -- printing style (for debugging only)
83 -> UniqSupply -- a name supply
84 -> [TyCon] -- local data tycons and tycon specialisations
85 -> FiniteMap TyCon [(Bool, [Maybe Type])]
86 -> [CoreBinding] -- input...
88 ([CoreBinding], -- results: program, plus...
89 IdEnv UnfoldingDetails, -- unfoldings to be exported from here
90 SpecialiseData) -- specialisation data
92 core2core core_todos module_name ppr_style us local_tycons tycon_specs binds
93 = if null core_todos then -- very rare, I suspect...
94 -- well, we still must do some renumbering
96 (substCoreBindings nullIdEnv nullTyVarEnv binds us,
101 (if do_verbose_core2core then
102 hPutStr stderr "VERBOSE CORE-TO-CORE:\n"
105 -- better do the main business
106 foldl_mn do_core_pass
107 (binds, us, nullIdEnv, init_specdata, zeroSimplCount)
109 >>= \ (processed_binds, _, inline_env, spec_data, simpl_stats) ->
111 (if opt_D_simplifier_stats
112 then hPutStr stderr ("\nSimplifier Stats:\n")
114 hPutStr stderr (showSimplCount simpl_stats)
120 return (processed_binds, inline_env, spec_data)
122 init_specdata = initSpecData local_tycons tycon_specs
124 do_verbose_core2core = opt_D_verbose_core2core
126 lib_case_threshold -- ToDo: HACK HACK HACK : FIX ME FIX ME FIX ME
127 -- Use 4x a known threshold
128 = case opt_UnfoldingOverrideThreshold of
129 Nothing -> 4 * uNFOLDING_USE_THRESHOLD
133 core_linter = if opt_DoCoreLinting
134 then lintCoreBindings ppr_style
135 else ( \ whodunnit spec_done binds -> binds )
138 do_core_pass info@(binds, us, inline_env, spec_data, simpl_stats) to_do
140 (us1, us2) = splitUniqSupply us
143 CoreDoSimplify simpl_sw_chkr
144 -> _scc_ "CoreSimplify"
145 begin_pass ("Simplify" ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild
146 then " (foldr/build)" else "") >>
147 case (simplifyPgm binds simpl_sw_chkr simpl_stats us1) of
148 (p, it_cnt, simpl_stats2)
149 -> end_pass False us2 p inline_env spec_data simpl_stats2
150 ("Simplify (" ++ show it_cnt ++ ")"
151 ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild
152 then " foldr/build" else "")
154 CoreDoFoldrBuildWorkerWrapper
155 -> _scc_ "CoreDoFoldrBuildWorkerWrapper"
157 case (mkFoldrBuildWW us1 binds) of { binds2 ->
158 end_pass False us2 binds2 inline_env spec_data simpl_stats "FBWW" }
160 CoreDoFoldrBuildWWAnal
161 -> _scc_ "CoreDoFoldrBuildWWAnal"
162 begin_pass "AnalFBWW" >>
163 case (analFBWW binds) of { binds2 ->
164 end_pass False us2 binds2 inline_env spec_data simpl_stats "AnalFBWW" }
167 -> _scc_ "LiberateCase"
168 begin_pass "LiberateCase" >>
169 case (liberateCase lib_case_threshold binds) of { binds2 ->
170 end_pass False us2 binds2 inline_env spec_data simpl_stats "LiberateCase" }
172 CoreDoCalcInlinings1 -- avoid inlinings w/ cost-centres
173 -> _scc_ "CoreInlinings1"
174 begin_pass "CalcInlinings" >>
175 case (calcInlinings False inline_env binds) of { inline_env2 ->
176 end_pass False us2 binds inline_env2 spec_data simpl_stats "CalcInlinings" }
178 CoreDoCalcInlinings2 -- allow inlinings w/ cost-centres
179 -> _scc_ "CoreInlinings2"
180 begin_pass "CalcInlinings" >>
181 case (calcInlinings True inline_env binds) of { inline_env2 ->
182 end_pass False us2 binds inline_env2 spec_data simpl_stats "CalcInlinings" }
185 -> _scc_ "FloatInwards"
186 begin_pass "FloatIn" >>
187 case (floatInwards binds) of { binds2 ->
188 end_pass False us2 binds2 inline_env spec_data simpl_stats "FloatIn" }
191 -> _scc_ "CoreFloating"
192 begin_pass "FloatOut" >>
193 case (floatOutwards us1 binds) of { binds2 ->
194 end_pass False us2 binds2 inline_env spec_data simpl_stats "FloatOut" }
197 -> _scc_ "CoreStaticArgs"
198 begin_pass "StaticArgs" >>
199 case (doStaticArgs binds us1) of { binds2 ->
200 end_pass False us2 binds2 inline_env spec_data simpl_stats "StaticArgs" }
201 -- Binds really should be dependency-analysed for static-
202 -- arg transformation... Not to worry, they probably are.
203 -- (I don't think it *dies* if they aren't [WDP 94/04/15])
206 -> _scc_ "CoreStranal"
207 begin_pass "StrAnal" >>
208 case (saWwTopBinds us1 binds) of { binds2 ->
209 end_pass False us2 binds2 inline_env spec_data simpl_stats "StrAnal" }
212 -> _scc_ "Specialise"
213 begin_pass "Specialise" >>
214 case (specProgram us1 binds spec_data) of {
215 (p, spec_data2@(SpecData _ spec_noerrs _ _ _
216 spec_errs spec_warn spec_tyerrs)) ->
218 -- if we got errors, we die straight away
219 (if not spec_noerrs ||
220 (opt_ShowImportSpecs && not (isEmptyBag spec_warn)) then
221 hPutStr stderr (ppShow 1000 {-pprCols-}
222 (pprSpecErrs module_name spec_errs spec_warn spec_tyerrs))
223 >> hPutStr stderr "\n"
227 (if not spec_noerrs then -- Stop here if specialisation errors occured
232 end_pass False us2 p inline_env spec_data2 simpl_stats "Specialise"
237 -> error "ERROR: CoreDoDeforest: not built into compiler\n"
239 -> _scc_ "Deforestation"
240 begin_pass "Deforestation" >>
241 case (deforestProgram binds us1) of { binds2 ->
242 end_pass False us2 binds2 inline_env spec_data simpl_stats "Deforestation" }
245 CoreDoPrintCore -- print result of last pass
246 -> end_pass True us2 binds inline_env spec_data simpl_stats "Print"
248 -------------------------------------------------
251 = if opt_D_show_passes
252 then \ what -> hPutStr stderr ("*** Core2Core: "++what++"\n")
253 else \ what -> return ()
255 end_pass print us2 binds2 inline_env2
256 spec_data2@(SpecData spec_done _ _ _ _ _ _ _)
258 = -- report verbosely, if required
259 (if (do_verbose_core2core && not print) ||
260 (print && not do_verbose_core2core)
262 hPutStr stderr ("\n*** "++what++":\n")
264 hPutStr stderr (ppShow 1000
265 (ppAboves (map (pprCoreBinding ppr_style) binds2)))
271 linted_binds = core_linter what spec_done binds2
274 (linted_binds, -- processed binds, possibly run thru CoreLint
275 us2, -- UniqueSupply for the next guy
276 inline_env2, -- possibly-updated inline env
277 spec_data2, -- possibly-updated specialisation info
278 simpl_stats2 -- accumulated simplifier stats
281 -- here so it can be inlined...
282 foldl_mn f z [] = return z
283 foldl_mn f z (x:xs) = f z x >>= \ zz ->
287 --- ToDo: maybe move elsewhere ---
289 For top-level, exported binders that either (a)~have been INLINEd by
290 the programmer or (b)~are sufficiently ``simple'' that they should be
291 inlined, we want to record this info in a suitable IdEnv.
293 But: if something has a ``wrapper unfolding,'' we do NOT automatically
294 give it a regular unfolding (exception below). We usually assume its
295 worker will get a ``regular'' unfolding. We can then treat these two
296 levels of unfolding separately (we tend to be very friendly towards
297 wrapper unfoldings, for example), giving more fine-tuned control.
299 The exception is: If the ``regular unfolding'' mentions no other
300 global Ids (i.e., it's all PrimOps and cases and local Ids) then we
301 assume it must be really good and we take it anyway.
303 We also need to check that everything in the RHS (values and types)
304 will be visible on the other side of an interface, too.
307 calcInlinings :: Bool -- True => inlinings with _scc_s are OK
308 -> IdEnv UnfoldingDetails
310 -> IdEnv UnfoldingDetails
312 calcInlinings scc_s_OK inline_env_so_far top_binds
314 result = foldl calci inline_env_so_far top_binds
316 --pprTrace "inline env:\n" (ppAboves (map pp_item (getIdEnvMapping result)))
319 pp_item (binder, details)
320 = ppCat [ppr PprDebug binder, ppStr "=>", pp_det details]
322 pp_det NoUnfoldingDetails = ppStr "_N_"
323 --LATER: pp_det (IWantToBeINLINEd _) = ppStr "INLINE"
324 pp_det (GenForm _ expr guide)
325 = ppAbove (ppr PprDebug guide) (ppr PprDebug expr)
326 pp_det other = ppStr "???"
329 my_trace = if opt_ReportWhyUnfoldingsDisallowed
331 else \ msg stuff -> stuff
333 (unfolding_creation_threshold, explicit_creation_threshold)
334 = case opt_UnfoldingCreationThreshold of
335 Nothing -> (uNFOLDING_CREATION_THRESHOLD, False)
336 Just xx -> (xx, True)
339 = case opt_UnfoldingUseThreshold of
340 Nothing -> uNFOLDING_USE_THRESHOLD
343 unfold_override_threshold
344 = case opt_UnfoldingOverrideThreshold of
345 Nothing -> uNFOLDING_OVERRIDE_THRESHOLD
348 con_discount_weight = uNFOLDING_CON_DISCOUNT_WEIGHT
350 calci inline_env (Rec pairs)
351 = foldl (calc True{-recursive-}) inline_env pairs
353 calci inline_env bind@(NonRec binder rhs)
354 = calc False{-not recursive-} inline_env (binder, rhs)
356 ---------------------------------------
358 calc is_recursive inline_env (binder, rhs)
359 | not (toplevelishId binder)
360 = --pprTrace "giving up on not top-level:" (ppr PprDebug binder)
363 | rhs_mentions_an_unmentionable
364 || (not explicit_INLINE_requested
365 && (rhs_looks_like_a_caf || guidance_says_don't || guidance_size_too_big))
368 = if explicit_INLINE_requested
369 && not (isWrapperId binder) -- these always claim to be INLINEd
370 && not have_inlining_already
371 then trace -- we'd better have a look...
374 which = if scc_s_OK then " (late):" else " (early):"
376 my_my_trace ("unfolding disallowed for"++which++(ppShow 80 (ppr PprDebug binder))) (
380 | rhs `isWrapperFor` binder
381 -- Don't add an explicit "unfolding"; let the worker/wrapper
382 -- stuff do its thing. INLINE things don't get w/w'd, so
386 #if ! OMIT_DEFORESTER
387 -- For the deforester: bypass the barbed wire for recursive
388 -- functions that want to be inlined and are tagged deforestable
389 -- by the user, allowing these things to be communicated
390 -- across module boundaries.
393 explicit_INLINE_requested &&
394 deforestable binder &&
395 scc_s_OK -- hack, only get them in
397 = glorious_success UnfoldAlways
400 | is_recursive && not rhs_looks_like_a_data_val
401 -- The only recursive defns we are prepared to tolerate at the
402 -- moment is top-level very-obviously-a-data-value ones.
403 -- We *need* these for dictionaries to be exported!
404 = --pprTrace "giving up on rec:" (ppr PprDebug binder)
407 -- Not really interested unless it's exported, but doing it
408 -- this way (not worrying about export-ness) gets us all the
409 -- workers/specs, etc., too; which we will need for generating
410 -- interfaces. We are also not interested if this binder is
411 -- in the environment we already have (perhaps from a previous
412 -- run of calcInlinings -- "earlier" is presumed to mean
415 | explicit_INLINE_requested
416 = glorious_success UnfoldAlways
419 = glorious_success guidance
423 = calcUnfoldingGuidance scc_s_OK max_out_threshold rhs
425 max_out_threshold = if explicit_INLINE_requested
426 then 100000 -- you asked for it, you got it
427 else unfolding_creation_threshold
431 UnfoldAlways -> 0 -- *extremely* small
432 EssentialUnfolding -> 0 -- ditto
433 UnfoldIfGoodArgs _ _ _ size -> size
435 guidance_says_don't = case guidance of { UnfoldNever -> True; _ -> False }
437 guidance_size_too_big
438 -- Does the guidance suggest that this unfolding will
439 -- be of no use *no matter* the arguments given to it?
440 -- Could be more sophisticated...
442 UnfoldAlways -> False
443 EssentialUnfolding -> False
444 UnfoldIfGoodArgs _ no_val_args arg_info_vec size
446 -> if explicit_creation_threshold then
447 False -- user set threshold; don't second-guess...
449 else if no_val_args == 0 && rhs_looks_like_a_data_val then
450 False -- we'd like a top-level data constr to be
451 -- visible even if it is never unfolded
455 = leastItCouldCost con_discount_weight size no_val_args
456 arg_info_vec rhs_arg_tys
458 -- (if (unfold_use_threshold < cost) then (pprTrace "cost:" (ppInt cost)) else \x->x ) (
459 unfold_use_threshold < cost
463 rhs_looks_like_a_caf = not (manifestlyWHNF rhs)
465 rhs_looks_like_a_data_val
466 = case (collectBinders rhs) of
467 (_, _, [], Con _ _) -> True
471 = case (collectBinders rhs) of
472 (_, _, val_binders, _) -> map idType val_binders
474 (mentioned_ids, _, _, mentions_litlit)
475 = mentionedInUnfolding (\x -> x) rhs
477 rhs_mentions_an_unmentionable
478 = foldBag (||) unfoldingUnfriendlyId False mentioned_ids
480 -- ToDo: probably need to chk tycons/classes...
482 mentions_no_other_ids = isEmptyBag mentioned_ids
484 explicit_INLINE_requested
485 -- did it come from a user {-# INLINE ... #-}?
486 -- (Warning: must avoid including wrappers.)
487 = idWantsToBeINLINEd binder
488 && not (rhs `isWrapperFor` binder)
490 have_inlining_already = maybeToBool (lookupIdEnv inline_env binder)
492 ignominious_defeat = inline_env -- just give back what we got
495 "glorious_success" is ours if we've found a suitable unfolding.
497 But we check for a couple of fine points.
499 (1) If this Id already has an inlining in the inline_env,
500 we don't automatically take it -- the earlier one is
501 "likely" to be better.
503 But if the new one doesn't mention any other global
504 Ids, and it's pretty small (< UnfoldingOverrideThreshold),
505 then we take the chance that the new one *is* better.
507 (2) If we have an Id w/ a worker/wrapper split (with
508 an unfolding for the wrapper), we tend to want to keep
509 it -- and *nuke* any inlining that we conjured up
512 But, again, if this unfolding doesn't mention any
513 other global Ids (and small enough), then it is
514 probably better than the worker/wrappery, so we take
517 glorious_success guidance
519 new_env = addOneToIdEnv inline_env binder (mkUnfolding guidance rhs)
521 foldr_building = opt_FoldrBuildOn
523 if (not have_inlining_already) then
524 -- Not in env: we take it no matter what
525 -- NB: we could check for worker/wrapper-ness,
526 -- but the truth is we probably haven't run
527 -- the strictness analyser yet.
530 else if explicit_INLINE_requested then
531 -- If it was a user INLINE, then we know it's already
532 -- in the inline_env; we stick with what we already
534 --pprTrace "giving up on INLINE:" (ppr PprDebug binder)
537 else if isWrapperId binder then
538 -- It's in the env, but we have since worker-wrapperised;
539 -- we either take this new one (because it's so good),
540 -- or we *undo* the one in the inline_env, so the
541 -- wrapper-inlining will take over.
543 if mentions_no_other_ids {- *** && size <= unfold_override_threshold -} then
546 delOneFromIdEnv inline_env binder
549 -- It's in the env, nothing to do w/ worker wrapper;
550 -- we'll take it if it is better.
552 if not foldr_building -- ANDY hates us... (see below)
553 && mentions_no_other_ids
554 && guidance_size <= unfold_override_threshold then
557 --pprTrace "giving up on final hurdle:" (ppCat [ppr PprDebug binder, ppInt guidance_size, ppInt unfold_override_threshold])
558 ignominious_defeat -- and at the last hurdle, too!
561 ANDY, on the hatred of the check above; why obliterate it? Consider
563 head xs = foldr (\ x _ -> x) (_|_) xs
565 This then is exported via a pragma. However,
566 *if* you include the extra code above, you will
567 export the non-foldr/build version.