2 -- The above warning supression flag is a temporary kludge.
3 -- While working on this module you are encouraged to remove it and fix
4 -- any warnings in the module. See
5 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
8 -----------------------------------------------------------------------------
10 -- Code generator utilities; mostly monadic
12 -- (c) The University of Glasgow 2004-2006
14 -----------------------------------------------------------------------------
19 emitDataLits, mkDataLits,
20 emitRODataLits, mkRODataLits,
21 emitIf, emitIfThenElse,
22 emitRtsCall, emitRtsCallWithVols, emitRtsCallWithResult,
25 emitSwitch, emitLitSwitch,
28 callerSaves, callerSaveVolatileRegs, get_GlobalReg_addr,
29 activeStgRegs, fixStgRegisters,
31 cmmAndWord, cmmOrWord, cmmNegate, cmmEqWord, cmmNeWord,
33 cmmOffsetExprW, cmmOffsetExprB,
34 cmmRegOffW, cmmRegOffB,
35 cmmLabelOffW, cmmLabelOffB,
36 cmmOffsetW, cmmOffsetB,
37 cmmOffsetLitW, cmmOffsetLitB,
39 cmmConstrTag, cmmConstrTag1,
41 tagForCon, tagCons, isSmallFamily,
42 cmmUntag, cmmIsTagged, cmmGetTag,
46 mkStringCLit, mkByteStringCLit,
50 getSRTInfo, clHasCafRefs
53 #include "HsVersions.h"
54 #include "../includes/stg/MachRegs.h"
69 import StgSyn (SRT(..))
85 -------------------------------------------------------------------------
87 -- Random small functions
89 -------------------------------------------------------------------------
91 addIdReps :: [Id] -> [(CgRep, Id)]
92 addIdReps ids = [(idCgRep id, id) | id <- ids]
94 -------------------------------------------------------------------------
98 -------------------------------------------------------------------------
100 cgLit :: Literal -> FCode CmmLit
101 cgLit (MachStr s) = mkByteStringCLit (bytesFS s)
102 -- not unpackFS; we want the UTF-8 byte stream.
103 cgLit other_lit = return (mkSimpleLit other_lit)
105 mkSimpleLit :: Literal -> CmmLit
106 mkSimpleLit (MachChar c) = CmmInt (fromIntegral (ord c)) wordWidth
107 mkSimpleLit MachNullAddr = zeroCLit
108 mkSimpleLit (MachInt i) = CmmInt i wordWidth
109 mkSimpleLit (MachInt64 i) = CmmInt i W64
110 mkSimpleLit (MachWord i) = CmmInt i wordWidth
111 mkSimpleLit (MachWord64 i) = CmmInt i W64
112 mkSimpleLit (MachFloat r) = CmmFloat r W32
113 mkSimpleLit (MachDouble r) = CmmFloat r W64
114 mkSimpleLit (MachLabel fs ms fod)
115 = CmmLabel (mkForeignLabel fs ms labelSrc fod)
117 -- TODO: Literal labels might not actually be in the current package...
118 labelSrc = ForeignLabelInThisPackage
120 mkLtOp :: Literal -> MachOp
121 -- On signed literals we must do a signed comparison
122 mkLtOp (MachInt _) = MO_S_Lt wordWidth
123 mkLtOp (MachFloat _) = MO_F_Lt W32
124 mkLtOp (MachDouble _) = MO_F_Lt W64
125 mkLtOp lit = MO_U_Lt (typeWidth (cmmLitType (mkSimpleLit lit)))
128 ---------------------------------------------------
130 -- Cmm data type functions
132 ---------------------------------------------------
134 -----------------------
135 -- The "B" variants take byte offsets
136 cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr
137 cmmRegOffB = cmmRegOff
139 cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr
140 cmmOffsetB = cmmOffset
142 cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr
143 cmmOffsetExprB = cmmOffsetExpr
145 cmmLabelOffB :: CLabel -> ByteOff -> CmmLit
146 cmmLabelOffB = cmmLabelOff
148 cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit
149 cmmOffsetLitB = cmmOffsetLit
151 -----------------------
152 -- The "W" variants take word offsets
153 cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr
154 -- The second arg is a *word* offset; need to change it to bytes
155 cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n)
156 cmmOffsetExprW e wd_off = cmmIndexExpr wordWidth e wd_off
158 cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr
159 cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n)
161 cmmRegOffW :: CmmReg -> WordOff -> CmmExpr
162 cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE)
164 cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit
165 cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off)
167 cmmLabelOffW :: CLabel -> WordOff -> CmmLit
168 cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off)
170 cmmLoadIndexW :: CmmExpr -> Int -> CmmType -> CmmExpr
171 cmmLoadIndexW base off ty = CmmLoad (cmmOffsetW base off) ty
173 -----------------------
174 cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord :: CmmExpr -> CmmExpr -> CmmExpr
175 cmmOrWord e1 e2 = CmmMachOp mo_wordOr [e1, e2]
176 cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2]
177 cmmNeWord e1 e2 = CmmMachOp mo_wordNe [e1, e2]
178 cmmEqWord e1 e2 = CmmMachOp mo_wordEq [e1, e2]
179 cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2]
180 cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2]
181 cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2]
182 --cmmShlWord e1 e2 = CmmMachOp mo_wordShl [e1, e2]
183 --cmmUShrWord e1 e2 = CmmMachOp mo_wordUShr [e1, e2]
184 cmmSubWord e1 e2 = CmmMachOp mo_wordSub [e1, e2]
186 cmmNegate :: CmmExpr -> CmmExpr
187 cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep)
188 cmmNegate e = CmmMachOp (MO_S_Neg (cmmExprWidth e)) [e]
190 blankWord :: CmmStatic
191 blankWord = CmmUninitialised wORD_SIZE
195 --cmmTagBits = CmmLit (mkIntCLit tAG_BITS)
196 cmmTagMask = CmmLit (mkIntCLit tAG_MASK)
197 cmmPointerMask = CmmLit (mkIntCLit (complement tAG_MASK))
199 -- Used to untag a possibly tagged pointer
200 -- A static label need not be untagged
201 cmmUntag e@(CmmLit (CmmLabel _)) = e
203 cmmUntag e = (e `cmmAndWord` cmmPointerMask)
205 cmmGetTag e = (e `cmmAndWord` cmmTagMask)
207 -- Test if a closure pointer is untagged
208 cmmIsTagged e = (e `cmmAndWord` cmmTagMask)
209 `cmmNeWord` CmmLit zeroCLit
211 cmmConstrTag e = (e `cmmAndWord` cmmTagMask) `cmmSubWord` (CmmLit (mkIntCLit 1))
212 -- Get constructor tag, but one based.
213 cmmConstrTag1 e = e `cmmAndWord` cmmTagMask
216 The family size of a data type (the number of constructors)
218 * small, if the family size < 2**tag_bits
221 Small families can have the constructor tag in the tag
223 Big families only use the tag value 1 to represent
226 isSmallFamily fam_size = fam_size <= mAX_PTR_TAG
230 con_tag = dataConTagZ con
231 fam_size = tyConFamilySize (dataConTyCon con)
232 tag | isSmallFamily fam_size = con_tag + 1
235 --Tag an expression, to do: refactor, this appears in some other module.
236 tagCons con expr = cmmOffsetB expr (tagForCon con)
238 -- Copied from CgInfoTbls.hs
239 -- We keep the *zero-indexed* tag in the srt_len field of the info
240 -- table of a data constructor.
241 dataConTagZ :: DataCon -> ConTagZ
242 dataConTagZ con = dataConTag con - fIRST_TAG
244 -----------------------
247 mkWordCLit :: StgWord -> CmmLit
248 mkWordCLit wd = CmmInt (fromIntegral wd) wordWidth
250 packHalfWordsCLit :: (Integral a, Integral b) => a -> b -> CmmLit
251 -- Make a single word literal in which the lower_half_word is
252 -- at the lower address, and the upper_half_word is at the
254 -- ToDo: consider using half-word lits instead
255 -- but be careful: that's vulnerable when reversed
256 packHalfWordsCLit lower_half_word upper_half_word
257 #ifdef WORDS_BIGENDIAN
258 = mkWordCLit ((fromIntegral lower_half_word `shiftL` hALF_WORD_SIZE_IN_BITS)
259 .|. fromIntegral upper_half_word)
261 = mkWordCLit ((fromIntegral lower_half_word)
262 .|. (fromIntegral upper_half_word `shiftL` hALF_WORD_SIZE_IN_BITS))
265 --------------------------------------------------------------------------
267 -- Incrementing a memory location
269 --------------------------------------------------------------------------
271 addToMem :: Width -- rep of the counter
272 -> CmmExpr -- Address
273 -> Int -- What to add (a word)
275 addToMem width ptr n = addToMemE width ptr (CmmLit (CmmInt (toInteger n) width))
277 addToMemE :: Width -- rep of the counter
278 -> CmmExpr -- Address
279 -> CmmExpr -- What to add (a word-typed expression)
281 addToMemE width ptr n
282 = CmmStore ptr (CmmMachOp (MO_Add width) [CmmLoad ptr (cmmBits width), n])
284 -------------------------------------------------------------------------
286 -- Converting a closure tag to a closure for enumeration types
287 -- (this is the implementation of tagToEnum#).
289 -------------------------------------------------------------------------
291 tagToClosure :: TyCon -> CmmExpr -> CmmExpr
292 tagToClosure tycon tag
293 = CmmLoad (cmmOffsetExprW closure_tbl tag) gcWord
294 where closure_tbl = CmmLit (CmmLabel lbl)
295 lbl = mkClosureTableLabel (tyConName tycon) NoCafRefs
297 -------------------------------------------------------------------------
299 -- Conditionals and rts calls
301 -------------------------------------------------------------------------
303 emitIf :: CmmExpr -- Boolean
306 -- Emit (if e then x)
307 -- ToDo: reverse the condition to avoid the extra branch instruction if possible
308 -- (some conditionals aren't reversible. eg. floating point comparisons cannot
309 -- be inverted because there exist some values for which both comparisons
310 -- return False, such as NaN.)
311 emitIf cond then_part
312 = do { then_id <- newLabelC
313 ; join_id <- newLabelC
314 ; stmtC (CmmCondBranch cond then_id)
315 ; stmtC (CmmBranch join_id)
321 emitIfThenElse :: CmmExpr -- Boolean
325 -- Emit (if e then x else y)
326 emitIfThenElse cond then_part else_part
327 = do { then_id <- newLabelC
328 ; join_id <- newLabelC
329 ; stmtC (CmmCondBranch cond then_id)
331 ; stmtC (CmmBranch join_id)
338 -- | Emit code to call a Cmm function.
340 :: PackageId -- ^ package the function is in
341 -> FastString -- ^ name of function
342 -> [CmmHinted CmmExpr] -- ^ function args
343 -> Bool -- ^ whether this is a safe call
344 -> Code -- ^ cmm code
346 emitRtsCall pkg fun args safe = emitRtsCall' [] pkg fun args Nothing safe
347 -- The 'Nothing' says "save all global registers"
349 emitRtsCallWithVols :: PackageId -> FastString -> [CmmHinted CmmExpr] -> [GlobalReg] -> Bool -> Code
350 emitRtsCallWithVols pkg fun args vols safe
351 = emitRtsCall' [] pkg fun args (Just vols) safe
353 emitRtsCallWithResult
354 :: LocalReg -> ForeignHint
355 -> PackageId -> FastString
356 -> [CmmHinted CmmExpr] -> Bool -> Code
357 emitRtsCallWithResult res hint pkg fun args safe
358 = emitRtsCall' [CmmHinted res hint] pkg fun args Nothing safe
360 -- Make a call to an RTS C procedure
362 :: [CmmHinted LocalReg]
365 -> [CmmHinted CmmExpr]
367 -> Bool -- True <=> CmmSafe call
369 emitRtsCall' res pkg fun args vols safe = do
371 then getSRTInfo >>= (return . CmmSafe)
372 else return CmmUnsafe
374 stmtC (CmmCall target res args safety CmmMayReturn)
377 (caller_save, caller_load) = callerSaveVolatileRegs vols
378 target = CmmCallee fun_expr CCallConv
379 fun_expr = mkLblExpr (mkCmmCodeLabel pkg fun)
381 -----------------------------------------------------------------------------
383 -- Caller-Save Registers
385 -----------------------------------------------------------------------------
387 -- Here we generate the sequence of saves/restores required around a
388 -- foreign call instruction.
390 -- TODO: reconcile with includes/Regs.h
391 -- * Regs.h claims that BaseReg should be saved last and loaded first
392 -- * This might not have been tickled before since BaseReg is callee save
393 -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim
394 callerSaveVolatileRegs :: Maybe [GlobalReg] -> ([CmmStmt], [CmmStmt])
395 callerSaveVolatileRegs vols = (caller_save, caller_load)
397 caller_save = foldr ($!) [] (map callerSaveGlobalReg regs_to_save)
398 caller_load = foldr ($!) [] (map callerRestoreGlobalReg regs_to_save)
400 system_regs = [Sp,SpLim,Hp,HpLim,CurrentTSO,CurrentNursery,
401 {-SparkHd,SparkTl,SparkBase,SparkLim,-}BaseReg ]
403 regs_to_save = system_regs ++ vol_list
405 vol_list = case vols of Nothing -> all_of_em; Just regs -> regs
407 all_of_em = [ VanillaReg n VNonGcPtr | n <- [0..mAX_Vanilla_REG] ]
408 -- The VNonGcPtr is a lie, but I don't think it matters
409 ++ [ FloatReg n | n <- [0..mAX_Float_REG] ]
410 ++ [ DoubleReg n | n <- [0..mAX_Double_REG] ]
411 ++ [ LongReg n | n <- [0..mAX_Long_REG] ]
413 callerSaveGlobalReg reg next
415 CmmStore (get_GlobalReg_addr reg)
416 (CmmReg (CmmGlobal reg)) : next
419 callerRestoreGlobalReg reg next
421 CmmAssign (CmmGlobal reg)
422 (CmmLoad (get_GlobalReg_addr reg) (globalRegType reg))
427 -- | Returns @True@ if this global register is stored in a caller-saves
430 callerSaves :: GlobalReg -> Bool
432 #ifdef CALLER_SAVES_Base
433 callerSaves BaseReg = True
435 #ifdef CALLER_SAVES_R1
436 callerSaves (VanillaReg 1 _) = True
438 #ifdef CALLER_SAVES_R2
439 callerSaves (VanillaReg 2 _) = True
441 #ifdef CALLER_SAVES_R3
442 callerSaves (VanillaReg 3 _) = True
444 #ifdef CALLER_SAVES_R4
445 callerSaves (VanillaReg 4 _) = True
447 #ifdef CALLER_SAVES_R5
448 callerSaves (VanillaReg 5 _) = True
450 #ifdef CALLER_SAVES_R6
451 callerSaves (VanillaReg 6 _) = True
453 #ifdef CALLER_SAVES_R7
454 callerSaves (VanillaReg 7 _) = True
456 #ifdef CALLER_SAVES_R8
457 callerSaves (VanillaReg 8 _) = True
459 #ifdef CALLER_SAVES_F1
460 callerSaves (FloatReg 1) = True
462 #ifdef CALLER_SAVES_F2
463 callerSaves (FloatReg 2) = True
465 #ifdef CALLER_SAVES_F3
466 callerSaves (FloatReg 3) = True
468 #ifdef CALLER_SAVES_F4
469 callerSaves (FloatReg 4) = True
471 #ifdef CALLER_SAVES_D1
472 callerSaves (DoubleReg 1) = True
474 #ifdef CALLER_SAVES_D2
475 callerSaves (DoubleReg 2) = True
477 #ifdef CALLER_SAVES_L1
478 callerSaves (LongReg 1) = True
480 #ifdef CALLER_SAVES_Sp
481 callerSaves Sp = True
483 #ifdef CALLER_SAVES_SpLim
484 callerSaves SpLim = True
486 #ifdef CALLER_SAVES_Hp
487 callerSaves Hp = True
489 #ifdef CALLER_SAVES_HpLim
490 callerSaves HpLim = True
492 #ifdef CALLER_SAVES_CurrentTSO
493 callerSaves CurrentTSO = True
495 #ifdef CALLER_SAVES_CurrentNursery
496 callerSaves CurrentNursery = True
498 callerSaves _ = False
501 -- -----------------------------------------------------------------------------
502 -- Information about global registers
504 baseRegOffset :: GlobalReg -> Int
506 baseRegOffset (VanillaReg 1 _) = oFFSET_StgRegTable_rR1
507 baseRegOffset (VanillaReg 2 _) = oFFSET_StgRegTable_rR2
508 baseRegOffset (VanillaReg 3 _) = oFFSET_StgRegTable_rR3
509 baseRegOffset (VanillaReg 4 _) = oFFSET_StgRegTable_rR4
510 baseRegOffset (VanillaReg 5 _) = oFFSET_StgRegTable_rR5
511 baseRegOffset (VanillaReg 6 _) = oFFSET_StgRegTable_rR6
512 baseRegOffset (VanillaReg 7 _) = oFFSET_StgRegTable_rR7
513 baseRegOffset (VanillaReg 8 _) = oFFSET_StgRegTable_rR8
514 baseRegOffset (VanillaReg 9 _) = oFFSET_StgRegTable_rR9
515 baseRegOffset (VanillaReg 10 _) = oFFSET_StgRegTable_rR10
516 baseRegOffset (FloatReg 1) = oFFSET_StgRegTable_rF1
517 baseRegOffset (FloatReg 2) = oFFSET_StgRegTable_rF2
518 baseRegOffset (FloatReg 3) = oFFSET_StgRegTable_rF3
519 baseRegOffset (FloatReg 4) = oFFSET_StgRegTable_rF4
520 baseRegOffset (DoubleReg 1) = oFFSET_StgRegTable_rD1
521 baseRegOffset (DoubleReg 2) = oFFSET_StgRegTable_rD2
522 baseRegOffset Sp = oFFSET_StgRegTable_rSp
523 baseRegOffset SpLim = oFFSET_StgRegTable_rSpLim
524 baseRegOffset (LongReg 1) = oFFSET_StgRegTable_rL1
525 baseRegOffset Hp = oFFSET_StgRegTable_rHp
526 baseRegOffset HpLim = oFFSET_StgRegTable_rHpLim
527 baseRegOffset CurrentTSO = oFFSET_StgRegTable_rCurrentTSO
528 baseRegOffset CurrentNursery = oFFSET_StgRegTable_rCurrentNursery
529 baseRegOffset HpAlloc = oFFSET_StgRegTable_rHpAlloc
530 baseRegOffset EagerBlackholeInfo = oFFSET_stgEagerBlackholeInfo
531 baseRegOffset GCEnter1 = oFFSET_stgGCEnter1
532 baseRegOffset GCFun = oFFSET_stgGCFun
533 baseRegOffset BaseReg = panic "baseRegOffset:BaseReg"
534 baseRegOffset _ = panic "baseRegOffset:other"
537 -------------------------------------------------------------------------
539 -- Strings generate a top-level data block
541 -------------------------------------------------------------------------
543 emitDataLits :: CLabel -> [CmmLit] -> Code
544 -- Emit a data-segment data block
545 emitDataLits lbl lits
546 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
548 mkDataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
549 -- Emit a data-segment data block
551 = CmmData Data (CmmDataLabel lbl : map CmmStaticLit lits)
553 emitRODataLits :: String -> CLabel -> [CmmLit] -> Code
554 -- Emit a read-only data block
555 emitRODataLits caller lbl lits
556 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
557 where section | any needsRelocation lits = RelocatableReadOnlyData
558 | otherwise = ReadOnlyData
559 needsRelocation (CmmLabel _) = True
560 needsRelocation (CmmLabelOff _ _) = True
561 needsRelocation _ = False
563 mkRODataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
564 mkRODataLits lbl lits
565 = CmmData section (CmmDataLabel lbl : map CmmStaticLit lits)
566 where section | any needsRelocation lits = RelocatableReadOnlyData
567 | otherwise = ReadOnlyData
568 needsRelocation (CmmLabel _) = True
569 needsRelocation (CmmLabelOff _ _) = True
570 needsRelocation _ = False
572 mkStringCLit :: String -> FCode CmmLit
573 -- Make a global definition for the string,
574 -- and return its label
575 mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str)
577 mkByteStringCLit :: [Word8] -> FCode CmmLit
578 mkByteStringCLit bytes
579 = do { uniq <- newUnique
580 ; let lbl = mkStringLitLabel uniq
581 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes]
582 ; return (CmmLabel lbl) }
584 -------------------------------------------------------------------------
586 -- Assigning expressions to temporaries
588 -------------------------------------------------------------------------
590 assignTemp :: CmmExpr -> FCode CmmExpr
591 -- For a non-trivial expression, e, create a local
592 -- variable and assign the expression to it
594 | isTrivialCmmExpr e = return e
595 | otherwise = do { reg <- newTemp (cmmExprType e)
596 ; stmtC (CmmAssign (CmmLocal reg) e)
597 ; return (CmmReg (CmmLocal reg)) }
599 newTemp :: CmmType -> FCode LocalReg
600 newTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep) }
602 -------------------------------------------------------------------------
604 -- Building case analysis
606 -------------------------------------------------------------------------
609 :: CmmExpr -- Tag to switch on
610 -> [(ConTagZ, CgStmts)] -- Tagged branches
611 -> Maybe CgStmts -- Default branch (if any)
612 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
613 -- outside this range is undefined
616 -- ONLY A DEFAULT BRANCH: no case analysis to do
617 emitSwitch tag_expr [] (Just stmts) _ _
621 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
622 = -- Just sort the branches before calling mk_sritch
625 Nothing -> return Nothing
626 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
628 ; dflags <- getDynFlags
629 ; let via_C | HscC <- hscTarget dflags = True
632 ; stmts <- mk_switch tag_expr (sortLe le branches)
633 mb_deflt_id lo_tag hi_tag via_C
637 (t1,_) `le` (t2,_) = t1 <= t2
640 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
641 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
644 -- SINGLETON TAG RANGE: no case analysis to do
645 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
647 = ASSERT( tag == lo_tag )
650 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
651 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
653 -- The simplifier might have eliminated a case
654 -- so we may have e.g. case xs of
656 -- In that situation we can be sure the (:) case
657 -- can't happen, so no need to test
659 -- SINGLETON BRANCH: one equality check to do
660 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
661 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
663 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
664 -- We have lo_tag < hi_tag, but there's only one branch,
665 -- so there must be a default
667 -- ToDo: we might want to check for the two branch case, where one of
668 -- the branches is the tag 0, because comparing '== 0' is likely to be
669 -- more efficient than other kinds of comparison.
671 -- DENSE TAG RANGE: use a switch statment.
673 -- We also use a switch uncoditionally when compiling via C, because
674 -- this will get emitted as a C switch statement and the C compiler
675 -- should do a good job of optimising it. Also, older GCC versions
676 -- (2.95 in particular) have problems compiling the complicated
677 -- if-trees generated by this code, so compiling to a switch every
678 -- time works around that problem.
680 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
681 | use_switch -- Use a switch
682 = do { branch_ids <- mapM forkCgStmts (map snd branches)
684 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
686 find_branch :: ConTagZ -> Maybe BlockId
687 find_branch i = assocDefault mb_deflt tagged_blk_ids i
689 -- NB. we have eliminated impossible branches at
690 -- either end of the range (see below), so the first
691 -- tag of a real branch is real_lo_tag (not lo_tag).
692 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
694 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
696 ; ASSERT(not (all isNothing arms))
697 return (oneCgStmt switch_stmt)
700 -- if we can knock off a bunch of default cases with one if, then do so
701 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
702 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
703 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
704 branch = CmmCondBranch cond deflt
705 ; stmts <- mk_switch tag_expr' branches mb_deflt
706 lowest_branch hi_tag via_C
707 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
710 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
711 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
712 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
713 branch = CmmCondBranch cond deflt
714 ; stmts <- mk_switch tag_expr' branches mb_deflt
715 lo_tag highest_branch via_C
716 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
719 | otherwise -- Use an if-tree
720 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
721 -- To avoid duplication
722 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
723 lo_tag (mid_tag-1) via_C
724 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
726 ; hi_id <- forkCgStmts hi_stmts
727 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
728 branch_stmt = CmmCondBranch cond hi_id
729 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
731 -- we test (e >= mid_tag) rather than (e < mid_tag), because
732 -- the former works better when e is a comparison, and there
733 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
734 -- generator can reduce the condition to e itself without
735 -- having to reverse the sense of the comparison: comparisons
736 -- can't always be easily reversed (eg. floating
739 use_switch = {- pprTrace "mk_switch" (
740 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
741 text "branches:" <+> ppr (map fst branches) <+>
742 text "n_branches:" <+> int n_branches <+>
743 text "lo_tag:" <+> int lo_tag <+>
744 text "hi_tag:" <+> int hi_tag <+>
745 text "real_lo_tag:" <+> int real_lo_tag <+>
746 text "real_hi_tag:" <+> int real_hi_tag) $ -}
747 ASSERT( n_branches > 1 && n_tags > 1 )
748 n_tags > 2 && (via_C || (dense && big_enough))
749 -- up to 4 branches we use a decision tree, otherwise
750 -- a switch (== jump table in the NCG). This seems to be
751 -- optimal, and corresponds with what gcc does.
752 big_enough = n_branches > 4
753 dense = n_branches > (n_tags `div` 2)
754 n_branches = length branches
756 -- ignore default slots at each end of the range if there's
757 -- no default branch defined.
758 lowest_branch = fst (head branches)
759 highest_branch = fst (last branches)
762 | isNothing mb_deflt = lowest_branch
766 | isNothing mb_deflt = highest_branch
769 n_tags = real_hi_tag - real_lo_tag + 1
771 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
772 -- lo_tag <= mid_tag < hi_tag
773 -- lo_branches have tags < mid_tag
774 -- hi_branches have tags >= mid_tag
776 (mid_tag,_) = branches !! (n_branches `div` 2)
777 -- 2 branches => n_branches `div` 2 = 1
778 -- => branches !! 1 give the *second* tag
779 -- There are always at least 2 branches here
781 (lo_branches, hi_branches) = span is_lo branches
782 is_lo (t,_) = t < mid_tag
786 | isTrivialCmmExpr e = return (CmmNop, e)
787 | otherwise = do { reg <- newTemp (cmmExprType e)
788 ; return (CmmAssign (CmmLocal reg) e, CmmReg (CmmLocal reg)) }
790 emitLitSwitch :: CmmExpr -- Tag to switch on
791 -> [(Literal, CgStmts)] -- Tagged branches
792 -> CgStmts -- Default branch (always)
793 -> Code -- Emit the code
794 -- Used for general literals, whose size might not be a word,
795 -- where there is always a default case, and where we don't know
796 -- the range of values for certain. For simplicity we always generate a tree.
798 -- ToDo: for integers we could do better here, perhaps by generalising
799 -- mk_switch and using that. --SDM 15/09/2004
800 emitLitSwitch scrut [] deflt
802 emitLitSwitch scrut branches deflt_blk
803 = do { scrut' <- assignTemp scrut
804 ; deflt_blk_id <- forkCgStmts deflt_blk
805 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
808 le (t1,_) (t2,_) = t1 <= t2
810 mk_lit_switch :: CmmExpr -> BlockId
811 -> [(Literal,CgStmts)]
813 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
814 = return (consCgStmt if_stmt blk)
816 cmm_lit = mkSimpleLit lit
817 rep = cmmLitType cmm_lit
818 ne = if isFloatType rep then MO_F_Ne else MO_Ne
819 cond = CmmMachOp (ne (typeWidth rep)) [scrut, CmmLit cmm_lit]
820 if_stmt = CmmCondBranch cond deflt_blk_id
822 mk_lit_switch scrut deflt_blk_id branches
823 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
824 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
825 ; lo_blk_id <- forkCgStmts lo_blk
826 ; let if_stmt = CmmCondBranch cond lo_blk_id
827 ; return (if_stmt `consCgStmt` hi_blk) }
829 n_branches = length branches
830 (mid_lit,_) = branches !! (n_branches `div` 2)
831 -- See notes above re mid_tag
833 (lo_branches, hi_branches) = span is_lo branches
834 is_lo (t,_) = t < mid_lit
836 cond = CmmMachOp (mkLtOp mid_lit)
837 [scrut, CmmLit (mkSimpleLit mid_lit)]
839 -------------------------------------------------------------------------
841 -- Simultaneous assignment
843 -------------------------------------------------------------------------
846 emitSimultaneously :: CmmStmts -> Code
847 -- Emit code to perform the assignments in the
848 -- input simultaneously, using temporary variables when necessary.
850 -- The Stmts must be:
851 -- CmmNop, CmmComment, CmmAssign, CmmStore
855 -- We use the strongly-connected component algorithm, in which
856 -- * the vertices are the statements
857 -- * an edge goes from s1 to s2 iff
858 -- s1 assigns to something s2 uses
859 -- that is, if s1 should *follow* s2 in the final order
861 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
862 -- for fast comparison
864 emitSimultaneously stmts
866 case filterOut isNopStmt (stmtList stmts) of
869 [stmt] -> stmtC stmt -- It's often just one stmt
870 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
872 doSimultaneously1 :: [CVertex] -> Code
873 doSimultaneously1 vertices
875 edges = [ (vertex, key1, edges_from stmt1)
876 | vertex@(key1, stmt1) <- vertices
878 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
879 stmt1 `mustFollow` stmt2
881 components = stronglyConnCompFromEdgedVertices edges
883 -- do_components deal with one strongly-connected component
884 -- Not cyclic, or singleton? Just do it
885 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
886 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
888 -- Cyclic? Then go via temporaries. Pick one to
889 -- break the loop and try again with the rest.
890 do_component (CyclicSCC ((n,first_stmt) : rest))
891 = do { from_temp <- go_via_temp first_stmt
892 ; doSimultaneously1 rest
895 go_via_temp (CmmAssign dest src)
896 = do { tmp <- newTemp (cmmRegType dest) -- TODO FIXME NOW if the pair of assignments move across a call this will be wrong
897 ; stmtC (CmmAssign (CmmLocal tmp) src)
898 ; return (CmmAssign dest (CmmReg (CmmLocal tmp))) }
899 go_via_temp (CmmStore dest src)
900 = do { tmp <- newTemp (cmmExprType src) -- TODO FIXME NOW if the pair of assignemnts move across a call this will be wrong
901 ; stmtC (CmmAssign (CmmLocal tmp) src)
902 ; return (CmmStore dest (CmmReg (CmmLocal tmp))) }
904 mapCs do_component components
906 mustFollow :: CmmStmt -> CmmStmt -> Bool
907 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
908 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprType e)) stmt
909 CmmNop `mustFollow` stmt = False
910 CmmComment _ `mustFollow` stmt = False
913 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
914 -- True if the fn is true of any input of the stmt
915 anySrc p (CmmAssign _ e) = p e
916 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
917 anySrc p (CmmComment _) = False
918 anySrc p CmmNop = False
919 anySrc p other = True -- Conservative
921 locUsedIn :: CmmExpr -> CmmType -> CmmExpr -> Bool
922 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
923 -- 'e'. Returns True if it's not sure.
924 locUsedIn loc rep (CmmLit _) = False
925 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
926 locUsedIn loc rep (CmmReg reg') = False
927 locUsedIn loc rep (CmmRegOff reg' _) = False
928 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
930 possiblySameLoc :: CmmExpr -> CmmType -> CmmExpr -> CmmType -> Bool
931 -- Assumes that distinct registers (eg Hp, Sp) do not
932 -- point to the same location, nor any offset thereof.
933 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
934 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
935 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
936 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
937 = r1==r2 && end1 > start2 && end2 > start1
939 end1 = start1 + widthInBytes (typeWidth rep1)
940 end2 = start2 + widthInBytes (typeWidth rep2)
942 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
943 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative
945 -------------------------------------------------------------------------
947 -- Static Reference Tables
949 -------------------------------------------------------------------------
951 -- There is just one SRT for each top level binding; all the nested
952 -- bindings use sub-sections of this SRT. The label is passed down to
953 -- the nested bindings via the monad.
955 getSRTInfo :: FCode C_SRT
957 srt_lbl <- getSRTLabel
960 -- TODO: Should we panic in this case?
961 -- Someone obviously thinks there should be an SRT
962 NoSRT -> return NoC_SRT
963 SRTEntries {} -> panic "getSRTInfo: SRTEntries. Perhaps you forgot to run SimplStg?"
965 | len > hALF_WORD_SIZE_IN_BITS || bmp == [fromIntegral srt_escape]
966 -> do id <- newUnique
967 let srt_desc_lbl = mkLargeSRTLabel id
968 emitRODataLits "getSRTInfo" srt_desc_lbl
969 ( cmmLabelOffW srt_lbl off
970 : mkWordCLit (fromIntegral len)
971 : map mkWordCLit bmp)
972 return (C_SRT srt_desc_lbl 0 srt_escape)
976 -> return (C_SRT srt_lbl off (fromIntegral (head bmp)))
977 -- The fromIntegral converts to StgHalfWord
979 srt_escape = (-1) :: StgHalfWord
981 clHasCafRefs :: ClosureInfo -> CafInfo
982 clHasCafRefs (ClosureInfo {closureSRT = srt}) =
983 case srt of NoC_SRT -> NoCafRefs
985 clHasCafRefs (ConInfo {}) = NoCafRefs
987 -- -----------------------------------------------------------------------------
991 -- -----------------------------------------------------------------------------
993 -- | Here is where the STG register map is defined for each target arch.
994 -- The order matters (for the llvm backend anyway)! We must make sure to
995 -- maintain the order here with the order used in the LLVM calling conventions.
996 -- Note that also, this isn't all registers, just the ones that are currently
997 -- possbily mapped to real registers.
998 activeStgRegs :: [GlobalReg]
1010 ,VanillaReg 1 VGcPtr
1013 ,VanillaReg 2 VGcPtr
1016 ,VanillaReg 3 VGcPtr
1019 ,VanillaReg 4 VGcPtr
1022 ,VanillaReg 5 VGcPtr
1025 ,VanillaReg 6 VGcPtr
1028 ,VanillaReg 7 VGcPtr
1031 ,VanillaReg 8 VGcPtr
1056 -- | We map STG registers onto appropriate CmmExprs. Either they map
1057 -- to real machine registers or stored as offsets from BaseReg. Given
1058 -- a GlobalReg, get_GlobalReg_addr always produces the
1059 -- register table address for it.
1060 get_GlobalReg_addr :: GlobalReg -> CmmExpr
1061 get_GlobalReg_addr BaseReg = regTableOffset 0
1062 get_GlobalReg_addr mid = get_Regtable_addr_from_offset
1063 (globalRegType mid) (baseRegOffset mid)
1065 -- Calculate a literal representing an offset into the register table.
1066 -- Used when we don't have an actual BaseReg to offset from.
1068 CmmLit (CmmLabelOff mkMainCapabilityLabel (oFFSET_Capability_r + n))
1070 get_Regtable_addr_from_offset :: CmmType -> Int -> CmmExpr
1071 get_Regtable_addr_from_offset rep offset =
1073 CmmRegOff (CmmGlobal BaseReg) offset
1075 regTableOffset offset
1078 -- | Fixup global registers so that they assign to locations within the
1079 -- RegTable if they aren't pinned for the current target.
1080 fixStgRegisters :: RawCmmTop -> RawCmmTop
1081 fixStgRegisters top@(CmmData _ _) = top
1083 fixStgRegisters (CmmProc info lbl (ListGraph blocks)) =
1084 let blocks' = map fixStgRegBlock blocks
1085 in CmmProc info lbl $ ListGraph blocks'
1087 fixStgRegBlock :: CmmBasicBlock -> CmmBasicBlock
1088 fixStgRegBlock (BasicBlock id stmts) =
1089 let stmts' = map fixStgRegStmt stmts
1090 in BasicBlock id stmts'
1092 fixStgRegStmt :: CmmStmt -> CmmStmt
1095 CmmAssign (CmmGlobal reg) src ->
1096 let src' = fixStgRegExpr src
1097 baseAddr = get_GlobalReg_addr reg
1098 in case reg `elem` activeStgRegs of
1099 True -> CmmAssign (CmmGlobal reg) src'
1100 False -> CmmStore baseAddr src'
1102 CmmAssign reg src ->
1103 let src' = fixStgRegExpr src
1104 in CmmAssign reg src'
1106 CmmStore addr src -> CmmStore (fixStgRegExpr addr) (fixStgRegExpr src)
1108 CmmCall target regs args srt returns ->
1109 let target' = case target of
1110 CmmCallee e conv -> CmmCallee (fixStgRegExpr e) conv
1112 args' = map (\(CmmHinted arg hint) ->
1113 (CmmHinted (fixStgRegExpr arg) hint)) args
1114 in CmmCall target' regs args' srt returns
1116 CmmCondBranch test dest -> CmmCondBranch (fixStgRegExpr test) dest
1118 CmmSwitch expr ids -> CmmSwitch (fixStgRegExpr expr) ids
1120 CmmJump addr regs -> CmmJump (fixStgRegExpr addr) regs
1122 -- CmmNop, CmmComment, CmmBranch, CmmReturn
1126 fixStgRegExpr :: CmmExpr -> CmmExpr
1129 CmmLoad addr ty -> CmmLoad (fixStgRegExpr addr) ty
1131 CmmMachOp mop args -> CmmMachOp mop args'
1132 where args' = map fixStgRegExpr args
1134 CmmReg (CmmGlobal reg) ->
1135 -- Replace register leaves with appropriate StixTrees for
1136 -- the given target. MagicIds which map to a reg on this
1137 -- arch are left unchanged. For the rest, BaseReg is taken
1138 -- to mean the address of the reg table in MainCapability,
1139 -- and for all others we generate an indirection to its
1140 -- location in the register table.
1141 case reg `elem` activeStgRegs of
1144 let baseAddr = get_GlobalReg_addr reg
1146 BaseReg -> fixStgRegExpr baseAddr
1147 _other -> fixStgRegExpr
1148 (CmmLoad baseAddr (globalRegType reg))
1150 CmmRegOff (CmmGlobal reg) offset ->
1151 -- RegOf leaves are just a shorthand form. If the reg maps
1152 -- to a real reg, we keep the shorthand, otherwise, we just
1153 -- expand it and defer to the above code.
1154 case reg `elem` activeStgRegs of
1156 False -> fixStgRegExpr (CmmMachOp (MO_Add wordWidth) [
1157 CmmReg (CmmGlobal reg),
1158 CmmLit (CmmInt (fromIntegral offset)
1161 -- CmmLit, CmmReg (CmmLocal), CmmStackSlot