2 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
4 \section[AbsCUtils]{Help functions for Abstract~C datatype}
9 mkAbstractCs, mkAbsCStmts,
13 mixedTypeLocn, mixedPtrLocn,
17 -- printing/forcing stuff comes from PprAbsC
20 #include "HsVersions.h"
23 import Digraph ( stronglyConnComp, SCC(..) )
24 import DataCon ( fIRST_TAG, ConTag )
25 import Literal ( literalPrimRep, mkMachWord )
26 import PrimRep ( getPrimRepSize, PrimRep(..) )
27 import Unique ( Unique{-instance Eq-} )
28 import UniqSupply ( uniqFromSupply, uniqsFromSupply, splitUniqSupply,
30 import CmdLineOpts ( opt_OutputLanguage, opt_EmitCExternDecls )
31 import PrimOp ( PrimOp(..), CCall(..), isDynamicTarget )
32 import Panic ( panic )
34 import Maybe ( isJust )
39 Check if there is any real code in some Abstract~C. If so, return it
40 (@Just ...@); otherwise, return @Nothing@. Don't be too strict!
42 It returns the "reduced" code in the Just part so that the work of
43 discarding AbsCNops isn't lost, and so that if the caller uses
44 the reduced version there's less danger of a big tree of AbsCNops getting
45 materialised and causing a space leak.
48 nonemptyAbsC :: AbstractC -> Maybe AbstractC
49 nonemptyAbsC AbsCNop = Nothing
50 nonemptyAbsC (AbsCStmts s1 s2) = case (nonemptyAbsC s1) of
51 Nothing -> nonemptyAbsC s2
52 Just x -> Just (AbsCStmts x s2)
53 nonemptyAbsC s@(CSimultaneous c) = case (nonemptyAbsC c) of
56 nonemptyAbsC other = Just other
60 mkAbstractCs :: [AbstractC] -> AbstractC
61 mkAbstractCs [] = AbsCNop
62 mkAbstractCs cs = foldr1 mkAbsCStmts cs
64 -- for fiddling around w/ killing off AbsCNops ... (ToDo)
65 mkAbsCStmts :: AbstractC -> AbstractC -> AbstractC
66 mkAbsCStmts AbsCNop c = c
67 mkAbsCStmts c AbsCNop = c
68 mkAbsCStmts c1 c2 = c1 `AbsCStmts` c2
70 {- Discarded SLPJ June 95; it calls nonemptyAbsC too much!
71 = case (case (nonemptyAbsC abc2) of
73 Just d2 -> d2) of { abc2b ->
75 case (nonemptyAbsC abc1) of {
77 Just d1 -> AbsCStmts d1 abc2b
82 Get the sho' 'nuff statements out of an @AbstractC@.
84 mkAbsCStmtList :: AbstractC -> [AbstractC]
86 mkAbsCStmtList absC = mkAbsCStmtList' absC []
88 -- Optimised a la foldr/build!
90 mkAbsCStmtList' AbsCNop r = r
92 mkAbsCStmtList' (AbsCStmts s1 s2) r
93 = mkAbsCStmtList' s1 (mkAbsCStmtList' s2 r)
95 mkAbsCStmtList' s@(CSimultaneous c) r
96 = if null (mkAbsCStmtList c) then r else s : r
98 mkAbsCStmtList' other r = other : r
102 mkAlgAltsCSwitch :: CAddrMode -> [(ConTag, AbstractC)] -> AbstractC -> AbstractC
104 mkAlgAltsCSwitch scrutinee tagged_alts deflt_absc
105 | isJust (nonemptyAbsC deflt_absc)
106 = CSwitch scrutinee (adjust tagged_alts) deflt_absc
108 = CSwitch scrutinee (adjust rest) first_alt
110 -- it's ok to convert one of the alts into a default if we don't already have
111 -- one, because this is an algebraic case and we're guaranteed that the tag
112 -- will match one of the branches.
113 ((tag,first_alt):rest) = tagged_alts
115 -- Adjust the tags in the switch to start at zero.
116 -- This is the convention used by primitive ops which return algebraic
117 -- data types. Why? Because for two-constructor types, zero is faster
118 -- to create and distinguish from 1 than are 1 and 2.
120 -- We also need to convert to Literals to keep the CSwitch happy
122 = [ (mkMachWord (toInteger (tag - fIRST_TAG)), abs_c)
123 | (tag, abs_c) <- tagged_alts ]
126 %************************************************************************
128 \subsubsection[AbsCUtils-kinds-from-MagicIds]{Kinds from MagicIds}
130 %************************************************************************
133 magicIdPrimRep BaseReg = PtrRep
134 magicIdPrimRep (VanillaReg kind _) = kind
135 magicIdPrimRep (FloatReg _) = FloatRep
136 magicIdPrimRep (DoubleReg _) = DoubleRep
137 magicIdPrimRep (LongReg kind _) = kind
138 magicIdPrimRep Sp = PtrRep
139 magicIdPrimRep Su = PtrRep
140 magicIdPrimRep SpLim = PtrRep
141 magicIdPrimRep Hp = PtrRep
142 magicIdPrimRep HpLim = PtrRep
143 magicIdPrimRep CurCostCentre = CostCentreRep
144 magicIdPrimRep VoidReg = VoidRep
145 magicIdPrimRep CurrentTSO = ThreadIdRep
146 magicIdPrimRep CurrentNursery = PtrRep
149 %************************************************************************
151 \subsection[AbsCUtils-amode-kinds]{Finding @PrimitiveKinds@ of amodes}
153 %************************************************************************
155 See also the return conventions for unboxed things; currently living
156 in @CgCon@ (next to the constructor return conventions).
158 ToDo: tiny tweaking may be in order
160 getAmodeRep :: CAddrMode -> PrimRep
162 getAmodeRep (CVal _ kind) = kind
163 getAmodeRep (CAddr _) = PtrRep
164 getAmodeRep (CReg magic_id) = magicIdPrimRep magic_id
165 getAmodeRep (CTemp uniq kind) = kind
166 getAmodeRep (CLbl _ kind) = kind
167 getAmodeRep (CCharLike _) = PtrRep
168 getAmodeRep (CIntLike _) = PtrRep
169 getAmodeRep (CLit lit) = literalPrimRep lit
170 getAmodeRep (CMacroExpr kind _ _) = kind
171 getAmodeRep (CJoinPoint _) = panic "getAmodeRep:CJoinPoint"
174 @mixedTypeLocn@ tells whether an amode identifies an ``StgWord''
175 location; that is, one which can contain values of various types.
178 mixedTypeLocn :: CAddrMode -> Bool
180 mixedTypeLocn (CVal (NodeRel _) _) = True
181 mixedTypeLocn (CVal (SpRel _) _) = True
182 mixedTypeLocn (CVal (HpRel _) _) = True
183 mixedTypeLocn other = False -- All the rest
186 @mixedPtrLocn@ tells whether an amode identifies a
187 location which can contain values of various pointer types.
190 mixedPtrLocn :: CAddrMode -> Bool
192 mixedPtrLocn (CVal (SpRel _) _) = True
193 mixedPtrLocn other = False -- All the rest
196 %************************************************************************
198 \subsection[AbsCUtils-flattening]{Flatten Abstract~C}
200 %************************************************************************
202 The following bits take ``raw'' Abstract~C, which may have all sorts of
203 nesting, and flattens it into one long @AbsCStmtList@. Mainly,
204 @CClosureInfos@ and code for switches are pulled out to the top level.
206 The various functions herein tend to produce
209 A {\em flattened} \tr{<something>} of interest for ``here'', and
211 Some {\em unflattened} Abstract~C statements to be carried up to the
212 top-level. The only real reason (now) that it is unflattened is
213 because it means the recursive flattening can be done in just one
214 place rather than having to remember lots of places.
217 Care is taken to reduce the occurrence of forward references, while still
218 keeping laziness a much as possible. Essentially, this means that:
221 {\em All} the top-level C statements resulting from flattening a
222 particular AbsC statement (whether the latter is nested or not) appear
223 before {\em any} of the code for a subsequent AbsC statement;
225 but stuff nested within any AbsC statement comes
226 out before the code for the statement itself.
229 The ``stuff to be carried up'' always includes a label: a
230 @CStaticClosure@, @CRetDirect@, @CFlatRetVector@, or
231 @CCodeBlock@. The latter turns into a C function, and is never
232 actually produced by the code generator. Rather it always starts life
233 as a @CCodeBlock@ addressing mode; when such an addr mode is
234 flattened, the ``tops'' stuff is a @CCodeBlock@.
237 flattenAbsC :: UniqSupply -> AbstractC -> AbstractC
240 = case (initFlt us (flatAbsC abs_C)) of { (here, tops) ->
241 here `mkAbsCStmts` tops }
244 %************************************************************************
246 \subsubsection{Flattening monadery}
248 %************************************************************************
250 The flattener is monadised. It's just a @UniqueSupply@.
253 type FlatM result = UniqSupply -> result
255 initFlt :: UniqSupply -> FlatM a -> a
257 initFlt init_us m = m init_us
259 {-# INLINE thenFlt #-}
260 {-# INLINE returnFlt #-}
262 thenFlt :: FlatM a -> (a -> FlatM b) -> FlatM b
265 = case (splitUniqSupply us) of { (s1, s2) ->
266 case (expr s1) of { result ->
269 returnFlt :: a -> FlatM a
270 returnFlt result us = result
272 mapFlt :: (a -> FlatM b) -> [a] -> FlatM [b]
274 mapFlt f [] = returnFlt []
276 = f x `thenFlt` \ r ->
277 mapFlt f xs `thenFlt` \ rs ->
280 mapAndUnzipFlt :: (a -> FlatM (b,c)) -> [a] -> FlatM ([b],[c])
282 mapAndUnzipFlt f [] = returnFlt ([],[])
283 mapAndUnzipFlt f (x:xs)
284 = f x `thenFlt` \ (r1, r2) ->
285 mapAndUnzipFlt f xs `thenFlt` \ (rs1, rs2) ->
286 returnFlt (r1:rs1, r2:rs2)
288 getUniqFlt :: FlatM Unique
289 getUniqFlt us = uniqFromSupply us
291 getUniqsFlt :: Int -> FlatM [Unique]
292 getUniqsFlt i us = uniqsFromSupply i us
295 %************************************************************************
297 \subsubsection{Flattening the top level}
299 %************************************************************************
302 flatAbsC :: AbstractC
303 -> FlatM (AbstractC, -- Stuff to put inline [Both are fully
304 AbstractC) -- Stuff to put at top level flattened]
306 flatAbsC AbsCNop = returnFlt (AbsCNop, AbsCNop)
308 flatAbsC (AbsCStmts s1 s2)
309 = flatAbsC s1 `thenFlt` \ (inline_s1, top_s1) ->
310 flatAbsC s2 `thenFlt` \ (inline_s2, top_s2) ->
311 returnFlt (mkAbsCStmts inline_s1 inline_s2,
312 mkAbsCStmts top_s1 top_s2)
314 flatAbsC (CClosureInfoAndCode cl_info slow maybe_fast descr)
315 = flatAbsC slow `thenFlt` \ (slow_heres, slow_tops) ->
316 flat_maybe maybe_fast `thenFlt` \ (fast_heres, fast_tops) ->
317 returnFlt (AbsCNop, mkAbstractCs [slow_tops, fast_tops,
318 CClosureInfoAndCode cl_info slow_heres fast_heres descr]
321 flatAbsC (CCodeBlock lbl abs_C)
322 = flatAbsC abs_C `thenFlt` \ (absC_heres, absC_tops) ->
323 returnFlt (AbsCNop, absC_tops `mkAbsCStmts` CCodeBlock lbl absC_heres)
325 flatAbsC (CRetDirect uniq slow_code srt liveness)
326 = flatAbsC slow_code `thenFlt` \ (heres, tops) ->
328 mkAbstractCs [ tops, CRetDirect uniq heres srt liveness ])
330 flatAbsC (CSwitch discrim alts deflt)
331 = mapAndUnzipFlt flat_alt alts `thenFlt` \ (flat_alts, flat_alts_tops) ->
332 flatAbsC deflt `thenFlt` \ (flat_def_alt, def_tops) ->
334 CSwitch discrim flat_alts flat_def_alt,
335 mkAbstractCs (def_tops : flat_alts_tops)
339 = flatAbsC absC `thenFlt` \ (alt_heres, alt_tops) ->
340 returnFlt ( (tag, alt_heres), alt_tops )
342 flatAbsC stmt@(COpStmt results (CCallOp ccall@(CCall target is_asm _ _)) args vol_regs)
343 | isCandidate && opt_OutputLanguage == Just "C" -- Urgh
344 = returnFlt (stmt, tdef)
346 = returnFlt (stmt, AbsCNop)
348 isCandidate = is_dynamic || opt_EmitCExternDecls && not is_asm
349 is_dynamic = isDynamicTarget target
351 tdef = CCallTypedef is_dynamic ccall results args
353 flatAbsC stmt@(CSimultaneous abs_c)
354 = flatAbsC abs_c `thenFlt` \ (stmts_here, tops) ->
355 doSimultaneously stmts_here `thenFlt` \ new_stmts_here ->
356 returnFlt (new_stmts_here, tops)
358 flatAbsC stmt@(CCheck macro amodes code)
359 = flatAbsC code `thenFlt` \ (code_here, code_tops) ->
360 returnFlt (CCheck macro amodes code_here, code_tops)
362 -- the TICKY_CTR macro always needs to be hoisted out to the top level.
364 flatAbsC stmt@(CCallProfCtrMacro str amodes)
365 | str == SLIT("TICK_CTR") = returnFlt (AbsCNop, stmt)
366 | otherwise = returnFlt (stmt, AbsCNop)
368 -- Some statements need no flattening at all:
369 flatAbsC stmt@(CMacroStmt macro amodes) = returnFlt (stmt, AbsCNop)
370 flatAbsC stmt@(CCallProfCCMacro str amodes) = returnFlt (stmt, AbsCNop)
371 flatAbsC stmt@(CAssign dest source) = returnFlt (stmt, AbsCNop)
372 flatAbsC stmt@(CJump target) = returnFlt (stmt, AbsCNop)
373 flatAbsC stmt@(CFallThrough target) = returnFlt (stmt, AbsCNop)
374 flatAbsC stmt@(CReturn target return_info) = returnFlt (stmt, AbsCNop)
375 flatAbsC stmt@(CInitHdr a b cc) = returnFlt (stmt, AbsCNop)
376 flatAbsC stmt@(COpStmt results op args vol_regs)= returnFlt (stmt, AbsCNop)
378 -- Some statements only make sense at the top level, so we always float
379 -- them. This probably isn't necessary.
380 flatAbsC stmt@(CStaticClosure _ _ _ _) = returnFlt (AbsCNop, stmt)
381 flatAbsC stmt@(CClosureTbl _) = returnFlt (AbsCNop, stmt)
382 flatAbsC stmt@(CSRT _ _) = returnFlt (AbsCNop, stmt)
383 flatAbsC stmt@(CBitmap _ _) = returnFlt (AbsCNop, stmt)
384 flatAbsC stmt@(CCostCentreDecl _ _) = returnFlt (AbsCNop, stmt)
385 flatAbsC stmt@(CCostCentreStackDecl _) = returnFlt (AbsCNop, stmt)
386 flatAbsC stmt@(CSplitMarker) = returnFlt (AbsCNop, stmt)
387 flatAbsC stmt@(CRetVector _ _ _ _) = returnFlt (AbsCNop, stmt)
388 flatAbsC stmt@(CModuleInitBlock _ _) = returnFlt (AbsCNop, stmt)
392 flat_maybe :: Maybe AbstractC -> FlatM (Maybe AbstractC, AbstractC)
393 flat_maybe Nothing = returnFlt (Nothing, AbsCNop)
394 flat_maybe (Just abs_c) = flatAbsC abs_c `thenFlt` \ (heres, tops) ->
395 returnFlt (Just heres, tops)
398 %************************************************************************
400 \subsection[flat-simultaneous]{Doing things simultaneously}
402 %************************************************************************
405 doSimultaneously :: AbstractC -> FlatM AbstractC
408 Generate code to perform the @CAssign@s and @COpStmt@s in the
409 input simultaneously, using temporary variables when necessary.
411 We use the strongly-connected component algorithm, in which
412 * the vertices are the statements
413 * an edge goes from s1 to s2 iff
414 s1 assigns to something s2 uses
415 that is, if s1 should *follow* s2 in the final order
418 type CVertex = (Int, AbstractC) -- Give each vertex a unique number,
419 -- for fast comparison
421 type CEdge = (CVertex, CVertex)
423 doSimultaneously abs_c
425 enlisted = en_list abs_c
427 case enlisted of -- it's often just one stmt
428 [] -> returnFlt AbsCNop
430 _ -> doSimultaneously1 (zip [(1::Int)..] enlisted)
432 -- en_list puts all the assignments in a list, filtering out Nops and
433 -- assignments which do nothing
435 en_list (AbsCStmts a1 a2) = en_list a1 ++ en_list a2
436 en_list (CAssign am1 am2) | sameAmode am1 am2 = []
437 en_list other = [other]
439 sameAmode :: CAddrMode -> CAddrMode -> Bool
440 -- ToDo: Move this function, or make CAddrMode an instance of Eq
441 -- At the moment we put in just enough to catch the cases we want:
442 -- the second (destination) argument is always a CVal.
443 sameAmode (CReg r1) (CReg r2) = r1 == r2
444 sameAmode (CVal (SpRel r1) _) (CVal (SpRel r2) _) = r1 ==# r2
445 sameAmode other1 other2 = False
447 doSimultaneously1 :: [CVertex] -> FlatM AbstractC
448 doSimultaneously1 vertices
450 edges = [ (vertex, key1, edges_from stmt1)
451 | vertex@(key1, stmt1) <- vertices
453 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
454 stmt1 `should_follow` stmt2
456 components = stronglyConnComp edges
458 -- do_components deal with one strongly-connected component
459 -- Not cyclic, or singleton? Just do it
460 do_component (AcyclicSCC (n,abs_c)) = returnFlt abs_c
461 do_component (CyclicSCC [(n,abs_c)]) = returnFlt abs_c
463 -- Cyclic? Then go via temporaries. Pick one to
464 -- break the loop and try again with the rest.
465 do_component (CyclicSCC ((n,first_stmt) : rest))
466 = doSimultaneously1 rest `thenFlt` \ abs_cs ->
467 go_via_temps first_stmt `thenFlt` \ (to_temps, from_temps) ->
468 returnFlt (mkAbstractCs [to_temps, abs_cs, from_temps])
470 go_via_temps (CAssign dest src)
471 = getUniqFlt `thenFlt` \ uniq ->
473 the_temp = CTemp uniq (getAmodeRep dest)
475 returnFlt (CAssign the_temp src, CAssign dest the_temp)
477 go_via_temps (COpStmt dests op srcs vol_regs)
478 = getUniqsFlt (length dests) `thenFlt` \ uniqs ->
480 the_temps = zipWith (\ u d -> CTemp u (getAmodeRep d)) uniqs dests
482 returnFlt (COpStmt the_temps op srcs vol_regs,
483 mkAbstractCs (zipWith CAssign dests the_temps))
485 mapFlt do_component components `thenFlt` \ abs_cs ->
486 returnFlt (mkAbstractCs abs_cs)
489 should_follow :: AbstractC -> AbstractC -> Bool
490 (CAssign dest1 _) `should_follow` (CAssign _ src2)
491 = dest1 `conflictsWith` src2
492 (COpStmt dests1 _ _ _) `should_follow` (CAssign _ src2)
493 = or [dest1 `conflictsWith` src2 | dest1 <- dests1]
494 (CAssign dest1 _)`should_follow` (COpStmt _ _ srcs2 _)
495 = or [dest1 `conflictsWith` src2 | src2 <- srcs2]
496 (COpStmt dests1 _ _ _) `should_follow` (COpStmt _ _ srcs2 _)
497 = or [dest1 `conflictsWith` src2 | dest1 <- dests1, src2 <- srcs2]
499 -- (COpStmt _ _ _ _ _) `should_follow` (CCallProfCtrMacro _ _) = False
500 -- (CCallProfCtrMacro _ _) `should_follow` (COpStmt _ _ _ _ _) = False
506 @conflictsWith@ tells whether an assignment to its first argument will
507 screw up an access to its second.
510 conflictsWith :: CAddrMode -> CAddrMode -> Bool
511 (CReg reg1) `conflictsWith` (CReg reg2) = reg1 == reg2
512 (CReg reg) `conflictsWith` (CVal reg_rel _) = reg `regConflictsWithRR` reg_rel
513 (CReg reg) `conflictsWith` (CAddr reg_rel) = reg `regConflictsWithRR` reg_rel
514 (CTemp u1 _) `conflictsWith` (CTemp u2 _) = u1 == u2
515 (CVal reg_rel1 k1) `conflictsWith` (CVal reg_rel2 k2)
516 = rrConflictsWithRR (getPrimRepSize k1) (getPrimRepSize k2) reg_rel1 reg_rel2
518 other1 `conflictsWith` other2 = False
519 -- CAddr and literals are impossible on the LHS of an assignment
521 regConflictsWithRR :: MagicId -> RegRelative -> Bool
523 regConflictsWithRR (VanillaReg k _ILIT(1)) (NodeRel _) = True
525 regConflictsWithRR Sp (SpRel _) = True
526 regConflictsWithRR Hp (HpRel _) = True
527 regConflictsWithRR _ _ = False
529 rrConflictsWithRR :: Int -> Int -- Sizes of two things
530 -> RegRelative -> RegRelative -- The two amodes
533 rrConflictsWithRR (I# s1) (I# s2) rr1 rr2 = rr rr1 rr2
535 rr (SpRel o1) (SpRel o2)
536 | s1 ==# _ILIT(0) || s2 ==# _ILIT(0) = False -- No conflict if either is size zero
537 | s1 ==# _ILIT(1) && s2 ==# _ILIT(1) = o1 ==# o2
538 | otherwise = (o1 +# s1) >=# o2 &&
541 rr (NodeRel o1) (NodeRel o2)
542 | s1 ==# _ILIT(0) || s2 ==# _ILIT(0) = False -- No conflict if either is size zero
543 | s1 ==# _ILIT(1) && s2 ==# _ILIT(1) = o1 ==# o2
544 | otherwise = True -- Give up
546 rr (HpRel _) (HpRel _) = True -- Give up (ToDo)
548 rr other1 other2 = False