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 callerSaveVolatileRegs, get_GlobalReg_addr,
30 cmmAndWord, cmmOrWord, cmmNegate, cmmEqWord, cmmNeWord,
32 cmmOffsetExprW, cmmOffsetExprB,
33 cmmRegOffW, cmmRegOffB,
34 cmmLabelOffW, cmmLabelOffB,
35 cmmOffsetW, cmmOffsetB,
36 cmmOffsetLitW, cmmOffsetLitB,
38 cmmConstrTag, cmmConstrTag1,
40 tagForCon, tagCons, isSmallFamily,
41 cmmUntag, cmmIsTagged, cmmGetTag,
45 mkStringCLit, mkByteStringCLit,
49 getSRTInfo, clHasCafRefs
52 #include "HsVersions.h"
53 #include "../includes/stg/MachRegs.h"
63 import PprCmm ( {- instances -} )
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) = CmmLabel (mkForeignLabel fs ms is_dyn fod)
116 is_dyn = False -- ToDo: fix me
118 mkLtOp :: Literal -> MachOp
119 -- On signed literals we must do a signed comparison
120 mkLtOp (MachInt _) = MO_S_Lt wordWidth
121 mkLtOp (MachFloat _) = MO_F_Lt W32
122 mkLtOp (MachDouble _) = MO_F_Lt W64
123 mkLtOp lit = MO_U_Lt (typeWidth (cmmLitType (mkSimpleLit lit)))
126 ---------------------------------------------------
128 -- Cmm data type functions
130 ---------------------------------------------------
132 -----------------------
133 -- The "B" variants take byte offsets
134 cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr
135 cmmRegOffB = cmmRegOff
137 cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr
138 cmmOffsetB = cmmOffset
140 cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr
141 cmmOffsetExprB = cmmOffsetExpr
143 cmmLabelOffB :: CLabel -> ByteOff -> CmmLit
144 cmmLabelOffB = cmmLabelOff
146 cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit
147 cmmOffsetLitB = cmmOffsetLit
149 -----------------------
150 -- The "W" variants take word offsets
151 cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr
152 -- The second arg is a *word* offset; need to change it to bytes
153 cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n)
154 cmmOffsetExprW e wd_off = cmmIndexExpr wordWidth e wd_off
156 cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr
157 cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n)
159 cmmRegOffW :: CmmReg -> WordOff -> CmmExpr
160 cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE)
162 cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit
163 cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off)
165 cmmLabelOffW :: CLabel -> WordOff -> CmmLit
166 cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off)
168 cmmLoadIndexW :: CmmExpr -> Int -> CmmType -> CmmExpr
169 cmmLoadIndexW base off ty = CmmLoad (cmmOffsetW base off) ty
171 -----------------------
172 cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord :: CmmExpr -> CmmExpr -> CmmExpr
173 cmmOrWord e1 e2 = CmmMachOp mo_wordOr [e1, e2]
174 cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2]
175 cmmNeWord e1 e2 = CmmMachOp mo_wordNe [e1, e2]
176 cmmEqWord e1 e2 = CmmMachOp mo_wordEq [e1, e2]
177 cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2]
178 cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2]
179 cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2]
180 --cmmShlWord e1 e2 = CmmMachOp mo_wordShl [e1, e2]
181 --cmmUShrWord e1 e2 = CmmMachOp mo_wordUShr [e1, e2]
182 cmmSubWord e1 e2 = CmmMachOp mo_wordSub [e1, e2]
184 cmmNegate :: CmmExpr -> CmmExpr
185 cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep)
186 cmmNegate e = CmmMachOp (MO_S_Neg (cmmExprWidth e)) [e]
188 blankWord :: CmmStatic
189 blankWord = CmmUninitialised wORD_SIZE
193 --cmmTagBits = CmmLit (mkIntCLit tAG_BITS)
194 cmmTagMask = CmmLit (mkIntCLit tAG_MASK)
195 cmmPointerMask = CmmLit (mkIntCLit (complement tAG_MASK))
197 -- Used to untag a possibly tagged pointer
198 -- A static label need not be untagged
199 cmmUntag e@(CmmLit (CmmLabel _)) = e
201 cmmUntag e = (e `cmmAndWord` cmmPointerMask)
203 cmmGetTag e = (e `cmmAndWord` cmmTagMask)
205 -- Test if a closure pointer is untagged
206 cmmIsTagged e = (e `cmmAndWord` cmmTagMask)
207 `cmmNeWord` CmmLit zeroCLit
209 cmmConstrTag e = (e `cmmAndWord` cmmTagMask) `cmmSubWord` (CmmLit (mkIntCLit 1))
210 -- Get constructor tag, but one based.
211 cmmConstrTag1 e = e `cmmAndWord` cmmTagMask
214 The family size of a data type (the number of constructors)
216 * small, if the family size < 2**tag_bits
219 Small families can have the constructor tag in the tag
221 Big families only use the tag value 1 to represent
224 isSmallFamily fam_size = fam_size <= mAX_PTR_TAG
228 con_tag = dataConTagZ con
229 fam_size = tyConFamilySize (dataConTyCon con)
230 tag | isSmallFamily fam_size = con_tag + 1
233 --Tag an expression, to do: refactor, this appears in some other module.
234 tagCons con expr = cmmOffsetB expr (tagForCon con)
236 -- Copied from CgInfoTbls.hs
237 -- We keep the *zero-indexed* tag in the srt_len field of the info
238 -- table of a data constructor.
239 dataConTagZ :: DataCon -> ConTagZ
240 dataConTagZ con = dataConTag con - fIRST_TAG
242 -----------------------
245 mkWordCLit :: StgWord -> CmmLit
246 mkWordCLit wd = CmmInt (fromIntegral wd) wordWidth
248 packHalfWordsCLit :: (Integral a, Integral b) => a -> b -> CmmLit
249 -- Make a single word literal in which the lower_half_word is
250 -- at the lower address, and the upper_half_word is at the
252 -- ToDo: consider using half-word lits instead
253 -- but be careful: that's vulnerable when reversed
254 packHalfWordsCLit lower_half_word upper_half_word
255 #ifdef WORDS_BIGENDIAN
256 = mkWordCLit ((fromIntegral lower_half_word `shiftL` hALF_WORD_SIZE_IN_BITS)
257 .|. fromIntegral upper_half_word)
259 = mkWordCLit ((fromIntegral lower_half_word)
260 .|. (fromIntegral upper_half_word `shiftL` hALF_WORD_SIZE_IN_BITS))
263 --------------------------------------------------------------------------
265 -- Incrementing a memory location
267 --------------------------------------------------------------------------
269 addToMem :: Width -- rep of the counter
270 -> CmmExpr -- Address
271 -> Int -- What to add (a word)
273 addToMem width ptr n = addToMemE width ptr (CmmLit (CmmInt (toInteger n) width))
275 addToMemE :: Width -- rep of the counter
276 -> CmmExpr -- Address
277 -> CmmExpr -- What to add (a word-typed expression)
279 addToMemE width ptr n
280 = CmmStore ptr (CmmMachOp (MO_Add width) [CmmLoad ptr (cmmBits width), n])
282 -------------------------------------------------------------------------
284 -- Converting a closure tag to a closure for enumeration types
285 -- (this is the implementation of tagToEnum#).
287 -------------------------------------------------------------------------
289 tagToClosure :: TyCon -> CmmExpr -> CmmExpr
290 tagToClosure tycon tag
291 = CmmLoad (cmmOffsetExprW closure_tbl tag) gcWord
292 where closure_tbl = CmmLit (CmmLabel lbl)
293 lbl = mkClosureTableLabel (tyConName tycon) NoCafRefs
295 -------------------------------------------------------------------------
297 -- Conditionals and rts calls
299 -------------------------------------------------------------------------
301 emitIf :: CmmExpr -- Boolean
304 -- Emit (if e then x)
305 -- ToDo: reverse the condition to avoid the extra branch instruction if possible
306 -- (some conditionals aren't reversible. eg. floating point comparisons cannot
307 -- be inverted because there exist some values for which both comparisons
308 -- return False, such as NaN.)
309 emitIf cond then_part
310 = do { then_id <- newLabelC
311 ; join_id <- newLabelC
312 ; stmtC (CmmCondBranch cond then_id)
313 ; stmtC (CmmBranch join_id)
319 emitIfThenElse :: CmmExpr -- Boolean
323 -- Emit (if e then x else y)
324 emitIfThenElse cond then_part else_part
325 = do { then_id <- newLabelC
326 ; join_id <- newLabelC
327 ; stmtC (CmmCondBranch cond then_id)
329 ; stmtC (CmmBranch join_id)
336 -- | Emit code to call a Cmm function.
338 :: PackageId -- ^ package the function is in
339 -> FastString -- ^ name of function
340 -> [CmmHinted CmmExpr] -- ^ function args
341 -> Bool -- ^ whether this is a safe call
342 -> Code -- ^ cmm code
344 emitRtsCall pkg fun args safe = emitRtsCall' [] pkg fun args Nothing safe
345 -- The 'Nothing' says "save all global registers"
347 emitRtsCallWithVols :: PackageId -> FastString -> [CmmHinted CmmExpr] -> [GlobalReg] -> Bool -> Code
348 emitRtsCallWithVols pkg fun args vols safe
349 = emitRtsCall' [] pkg fun args (Just vols) safe
351 emitRtsCallWithResult
352 :: LocalReg -> ForeignHint
353 -> PackageId -> FastString
354 -> [CmmHinted CmmExpr] -> Bool -> Code
355 emitRtsCallWithResult res hint pkg fun args safe
356 = emitRtsCall' [CmmHinted res hint] pkg fun args Nothing safe
358 -- Make a call to an RTS C procedure
360 :: [CmmHinted LocalReg]
363 -> [CmmHinted CmmExpr]
365 -> Bool -- True <=> CmmSafe call
367 emitRtsCall' res pkg fun args vols safe = do
369 then getSRTInfo >>= (return . CmmSafe)
370 else return CmmUnsafe
372 stmtC (CmmCall target res args safety CmmMayReturn)
375 (caller_save, caller_load) = callerSaveVolatileRegs vols
376 target = CmmCallee fun_expr CCallConv
377 fun_expr = mkLblExpr (mkCmmCodeLabel pkg fun)
379 -----------------------------------------------------------------------------
381 -- Caller-Save Registers
383 -----------------------------------------------------------------------------
385 -- Here we generate the sequence of saves/restores required around a
386 -- foreign call instruction.
388 -- TODO: reconcile with includes/Regs.h
389 -- * Regs.h claims that BaseReg should be saved last and loaded first
390 -- * This might not have been tickled before since BaseReg is callee save
391 -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim
392 callerSaveVolatileRegs :: Maybe [GlobalReg] -> ([CmmStmt], [CmmStmt])
393 callerSaveVolatileRegs vols = (caller_save, caller_load)
395 caller_save = foldr ($!) [] (map callerSaveGlobalReg regs_to_save)
396 caller_load = foldr ($!) [] (map callerRestoreGlobalReg regs_to_save)
398 system_regs = [Sp,SpLim,Hp,HpLim,CurrentTSO,CurrentNursery,
399 {-SparkHd,SparkTl,SparkBase,SparkLim,-}BaseReg ]
401 regs_to_save = system_regs ++ vol_list
403 vol_list = case vols of Nothing -> all_of_em; Just regs -> regs
405 all_of_em = [ VanillaReg n VNonGcPtr | n <- [0..mAX_Vanilla_REG] ]
406 -- The VNonGcPtr is a lie, but I don't think it matters
407 ++ [ FloatReg n | n <- [0..mAX_Float_REG] ]
408 ++ [ DoubleReg n | n <- [0..mAX_Double_REG] ]
409 ++ [ LongReg n | n <- [0..mAX_Long_REG] ]
411 callerSaveGlobalReg reg next
413 CmmStore (get_GlobalReg_addr reg)
414 (CmmReg (CmmGlobal reg)) : next
417 callerRestoreGlobalReg reg next
419 CmmAssign (CmmGlobal reg)
420 (CmmLoad (get_GlobalReg_addr reg) (globalRegType reg))
424 -- -----------------------------------------------------------------------------
427 -- We map STG registers onto appropriate CmmExprs. Either they map
428 -- to real machine registers or stored as offsets from BaseReg. Given
429 -- a GlobalReg, get_GlobalReg_addr always produces the
430 -- register table address for it.
431 -- (See also get_GlobalReg_reg_or_addr in MachRegs)
433 get_GlobalReg_addr :: GlobalReg -> CmmExpr
434 get_GlobalReg_addr BaseReg = regTableOffset 0
435 get_GlobalReg_addr mid = get_Regtable_addr_from_offset
436 (globalRegType mid) (baseRegOffset mid)
438 -- Calculate a literal representing an offset into the register table.
439 -- Used when we don't have an actual BaseReg to offset from.
441 CmmLit (CmmLabelOff mkMainCapabilityLabel (oFFSET_Capability_r + n))
443 get_Regtable_addr_from_offset :: CmmType -> Int -> CmmExpr
444 get_Regtable_addr_from_offset rep offset =
446 CmmRegOff (CmmGlobal BaseReg) offset
448 regTableOffset offset
452 -- | Returns @True@ if this global register is stored in a caller-saves
455 callerSaves :: GlobalReg -> Bool
457 #ifdef CALLER_SAVES_Base
458 callerSaves BaseReg = True
460 #ifdef CALLER_SAVES_R1
461 callerSaves (VanillaReg 1 _) = True
463 #ifdef CALLER_SAVES_R2
464 callerSaves (VanillaReg 2 _) = True
466 #ifdef CALLER_SAVES_R3
467 callerSaves (VanillaReg 3 _) = True
469 #ifdef CALLER_SAVES_R4
470 callerSaves (VanillaReg 4 _) = True
472 #ifdef CALLER_SAVES_R5
473 callerSaves (VanillaReg 5 _) = True
475 #ifdef CALLER_SAVES_R6
476 callerSaves (VanillaReg 6 _) = True
478 #ifdef CALLER_SAVES_R7
479 callerSaves (VanillaReg 7 _) = True
481 #ifdef CALLER_SAVES_R8
482 callerSaves (VanillaReg 8 _) = True
484 #ifdef CALLER_SAVES_F1
485 callerSaves (FloatReg 1) = True
487 #ifdef CALLER_SAVES_F2
488 callerSaves (FloatReg 2) = True
490 #ifdef CALLER_SAVES_F3
491 callerSaves (FloatReg 3) = True
493 #ifdef CALLER_SAVES_F4
494 callerSaves (FloatReg 4) = True
496 #ifdef CALLER_SAVES_D1
497 callerSaves (DoubleReg 1) = True
499 #ifdef CALLER_SAVES_D2
500 callerSaves (DoubleReg 2) = True
502 #ifdef CALLER_SAVES_L1
503 callerSaves (LongReg 1) = True
505 #ifdef CALLER_SAVES_Sp
506 callerSaves Sp = True
508 #ifdef CALLER_SAVES_SpLim
509 callerSaves SpLim = True
511 #ifdef CALLER_SAVES_Hp
512 callerSaves Hp = True
514 #ifdef CALLER_SAVES_HpLim
515 callerSaves HpLim = True
517 #ifdef CALLER_SAVES_CurrentTSO
518 callerSaves CurrentTSO = True
520 #ifdef CALLER_SAVES_CurrentNursery
521 callerSaves CurrentNursery = True
523 callerSaves _ = False
526 -- -----------------------------------------------------------------------------
527 -- Information about global registers
529 baseRegOffset :: GlobalReg -> Int
531 baseRegOffset (VanillaReg 1 _) = oFFSET_StgRegTable_rR1
532 baseRegOffset (VanillaReg 2 _) = oFFSET_StgRegTable_rR2
533 baseRegOffset (VanillaReg 3 _) = oFFSET_StgRegTable_rR3
534 baseRegOffset (VanillaReg 4 _) = oFFSET_StgRegTable_rR4
535 baseRegOffset (VanillaReg 5 _) = oFFSET_StgRegTable_rR5
536 baseRegOffset (VanillaReg 6 _) = oFFSET_StgRegTable_rR6
537 baseRegOffset (VanillaReg 7 _) = oFFSET_StgRegTable_rR7
538 baseRegOffset (VanillaReg 8 _) = oFFSET_StgRegTable_rR8
539 baseRegOffset (VanillaReg 9 _) = oFFSET_StgRegTable_rR9
540 baseRegOffset (VanillaReg 10 _) = oFFSET_StgRegTable_rR10
541 baseRegOffset (FloatReg 1) = oFFSET_StgRegTable_rF1
542 baseRegOffset (FloatReg 2) = oFFSET_StgRegTable_rF2
543 baseRegOffset (FloatReg 3) = oFFSET_StgRegTable_rF3
544 baseRegOffset (FloatReg 4) = oFFSET_StgRegTable_rF4
545 baseRegOffset (DoubleReg 1) = oFFSET_StgRegTable_rD1
546 baseRegOffset (DoubleReg 2) = oFFSET_StgRegTable_rD2
547 baseRegOffset Sp = oFFSET_StgRegTable_rSp
548 baseRegOffset SpLim = oFFSET_StgRegTable_rSpLim
549 baseRegOffset (LongReg 1) = oFFSET_StgRegTable_rL1
550 baseRegOffset Hp = oFFSET_StgRegTable_rHp
551 baseRegOffset HpLim = oFFSET_StgRegTable_rHpLim
552 baseRegOffset CurrentTSO = oFFSET_StgRegTable_rCurrentTSO
553 baseRegOffset CurrentNursery = oFFSET_StgRegTable_rCurrentNursery
554 baseRegOffset HpAlloc = oFFSET_StgRegTable_rHpAlloc
555 baseRegOffset EagerBlackholeInfo = oFFSET_stgEagerBlackholeInfo
556 baseRegOffset GCEnter1 = oFFSET_stgGCEnter1
557 baseRegOffset GCFun = oFFSET_stgGCFun
558 baseRegOffset BaseReg = panic "baseRegOffset:BaseReg"
559 baseRegOffset _ = panic "baseRegOffset:other"
562 -------------------------------------------------------------------------
564 -- Strings generate a top-level data block
566 -------------------------------------------------------------------------
568 emitDataLits :: CLabel -> [CmmLit] -> Code
569 -- Emit a data-segment data block
570 emitDataLits lbl lits
571 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
573 mkDataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
574 -- Emit a data-segment data block
576 = CmmData Data (CmmDataLabel lbl : map CmmStaticLit lits)
578 emitRODataLits :: String -> CLabel -> [CmmLit] -> Code
579 -- Emit a read-only data block
580 emitRODataLits caller lbl lits
581 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
582 where section | any needsRelocation lits = RelocatableReadOnlyData
583 | otherwise = ReadOnlyData
584 needsRelocation (CmmLabel _) = True
585 needsRelocation (CmmLabelOff _ _) = True
586 needsRelocation _ = False
588 mkRODataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
589 mkRODataLits lbl lits
590 = CmmData section (CmmDataLabel lbl : map CmmStaticLit lits)
591 where section | any needsRelocation lits = RelocatableReadOnlyData
592 | otherwise = ReadOnlyData
593 needsRelocation (CmmLabel _) = True
594 needsRelocation (CmmLabelOff _ _) = True
595 needsRelocation _ = False
597 mkStringCLit :: String -> FCode CmmLit
598 -- Make a global definition for the string,
599 -- and return its label
600 mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str)
602 mkByteStringCLit :: [Word8] -> FCode CmmLit
603 mkByteStringCLit bytes
604 = do { uniq <- newUnique
605 ; let lbl = mkStringLitLabel uniq
606 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes]
607 ; return (CmmLabel lbl) }
609 -------------------------------------------------------------------------
611 -- Assigning expressions to temporaries
613 -------------------------------------------------------------------------
615 assignTemp :: CmmExpr -> FCode CmmExpr
616 -- For a non-trivial expression, e, create a local
617 -- variable and assign the expression to it
619 | isTrivialCmmExpr e = return e
620 | otherwise = do { reg <- newTemp (cmmExprType e)
621 ; stmtC (CmmAssign (CmmLocal reg) e)
622 ; return (CmmReg (CmmLocal reg)) }
624 newTemp :: CmmType -> FCode LocalReg
625 newTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep) }
627 -------------------------------------------------------------------------
629 -- Building case analysis
631 -------------------------------------------------------------------------
634 :: CmmExpr -- Tag to switch on
635 -> [(ConTagZ, CgStmts)] -- Tagged branches
636 -> Maybe CgStmts -- Default branch (if any)
637 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
638 -- outside this range is undefined
641 -- ONLY A DEFAULT BRANCH: no case analysis to do
642 emitSwitch tag_expr [] (Just stmts) _ _
646 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
647 = -- Just sort the branches before calling mk_sritch
650 Nothing -> return Nothing
651 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
653 ; dflags <- getDynFlags
654 ; let via_C | HscC <- hscTarget dflags = True
657 ; stmts <- mk_switch tag_expr (sortLe le branches)
658 mb_deflt_id lo_tag hi_tag via_C
662 (t1,_) `le` (t2,_) = t1 <= t2
665 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
666 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
669 -- SINGLETON TAG RANGE: no case analysis to do
670 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
672 = ASSERT( tag == lo_tag )
675 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
676 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
678 -- The simplifier might have eliminated a case
679 -- so we may have e.g. case xs of
681 -- In that situation we can be sure the (:) case
682 -- can't happen, so no need to test
684 -- SINGLETON BRANCH: one equality check to do
685 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
686 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
688 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
689 -- We have lo_tag < hi_tag, but there's only one branch,
690 -- so there must be a default
692 -- ToDo: we might want to check for the two branch case, where one of
693 -- the branches is the tag 0, because comparing '== 0' is likely to be
694 -- more efficient than other kinds of comparison.
696 -- DENSE TAG RANGE: use a switch statment.
698 -- We also use a switch uncoditionally when compiling via C, because
699 -- this will get emitted as a C switch statement and the C compiler
700 -- should do a good job of optimising it. Also, older GCC versions
701 -- (2.95 in particular) have problems compiling the complicated
702 -- if-trees generated by this code, so compiling to a switch every
703 -- time works around that problem.
705 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
706 | use_switch -- Use a switch
707 = do { branch_ids <- mapM forkCgStmts (map snd branches)
709 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
711 find_branch :: ConTagZ -> Maybe BlockId
712 find_branch i = assocDefault mb_deflt tagged_blk_ids i
714 -- NB. we have eliminated impossible branches at
715 -- either end of the range (see below), so the first
716 -- tag of a real branch is real_lo_tag (not lo_tag).
717 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
719 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
721 ; ASSERT(not (all isNothing arms))
722 return (oneCgStmt switch_stmt)
725 -- if we can knock off a bunch of default cases with one if, then do so
726 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
727 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
728 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
729 branch = CmmCondBranch cond deflt
730 ; stmts <- mk_switch tag_expr' branches mb_deflt
731 lowest_branch hi_tag via_C
732 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
735 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
736 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
737 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
738 branch = CmmCondBranch cond deflt
739 ; stmts <- mk_switch tag_expr' branches mb_deflt
740 lo_tag highest_branch via_C
741 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
744 | otherwise -- Use an if-tree
745 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
746 -- To avoid duplication
747 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
748 lo_tag (mid_tag-1) via_C
749 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
751 ; hi_id <- forkCgStmts hi_stmts
752 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
753 branch_stmt = CmmCondBranch cond hi_id
754 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
756 -- we test (e >= mid_tag) rather than (e < mid_tag), because
757 -- the former works better when e is a comparison, and there
758 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
759 -- generator can reduce the condition to e itself without
760 -- having to reverse the sense of the comparison: comparisons
761 -- can't always be easily reversed (eg. floating
764 use_switch = {- pprTrace "mk_switch" (
765 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
766 text "branches:" <+> ppr (map fst branches) <+>
767 text "n_branches:" <+> int n_branches <+>
768 text "lo_tag:" <+> int lo_tag <+>
769 text "hi_tag:" <+> int hi_tag <+>
770 text "real_lo_tag:" <+> int real_lo_tag <+>
771 text "real_hi_tag:" <+> int real_hi_tag) $ -}
772 ASSERT( n_branches > 1 && n_tags > 1 )
773 n_tags > 2 && (via_C || (dense && big_enough))
774 -- up to 4 branches we use a decision tree, otherwise
775 -- a switch (== jump table in the NCG). This seems to be
776 -- optimal, and corresponds with what gcc does.
777 big_enough = n_branches > 4
778 dense = n_branches > (n_tags `div` 2)
779 n_branches = length branches
781 -- ignore default slots at each end of the range if there's
782 -- no default branch defined.
783 lowest_branch = fst (head branches)
784 highest_branch = fst (last branches)
787 | isNothing mb_deflt = lowest_branch
791 | isNothing mb_deflt = highest_branch
794 n_tags = real_hi_tag - real_lo_tag + 1
796 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
797 -- lo_tag <= mid_tag < hi_tag
798 -- lo_branches have tags < mid_tag
799 -- hi_branches have tags >= mid_tag
801 (mid_tag,_) = branches !! (n_branches `div` 2)
802 -- 2 branches => n_branches `div` 2 = 1
803 -- => branches !! 1 give the *second* tag
804 -- There are always at least 2 branches here
806 (lo_branches, hi_branches) = span is_lo branches
807 is_lo (t,_) = t < mid_tag
811 | isTrivialCmmExpr e = return (CmmNop, e)
812 | otherwise = do { reg <- newTemp (cmmExprType e)
813 ; return (CmmAssign (CmmLocal reg) e, CmmReg (CmmLocal reg)) }
815 emitLitSwitch :: CmmExpr -- Tag to switch on
816 -> [(Literal, CgStmts)] -- Tagged branches
817 -> CgStmts -- Default branch (always)
818 -> Code -- Emit the code
819 -- Used for general literals, whose size might not be a word,
820 -- where there is always a default case, and where we don't know
821 -- the range of values for certain. For simplicity we always generate a tree.
823 -- ToDo: for integers we could do better here, perhaps by generalising
824 -- mk_switch and using that. --SDM 15/09/2004
825 emitLitSwitch scrut [] deflt
827 emitLitSwitch scrut branches deflt_blk
828 = do { scrut' <- assignTemp scrut
829 ; deflt_blk_id <- forkCgStmts deflt_blk
830 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
833 le (t1,_) (t2,_) = t1 <= t2
835 mk_lit_switch :: CmmExpr -> BlockId
836 -> [(Literal,CgStmts)]
838 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
839 = return (consCgStmt if_stmt blk)
841 cmm_lit = mkSimpleLit lit
842 rep = cmmLitType cmm_lit
843 ne = if isFloatType rep then MO_F_Ne else MO_Ne
844 cond = CmmMachOp (ne (typeWidth rep)) [scrut, CmmLit cmm_lit]
845 if_stmt = CmmCondBranch cond deflt_blk_id
847 mk_lit_switch scrut deflt_blk_id branches
848 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
849 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
850 ; lo_blk_id <- forkCgStmts lo_blk
851 ; let if_stmt = CmmCondBranch cond lo_blk_id
852 ; return (if_stmt `consCgStmt` hi_blk) }
854 n_branches = length branches
855 (mid_lit,_) = branches !! (n_branches `div` 2)
856 -- See notes above re mid_tag
858 (lo_branches, hi_branches) = span is_lo branches
859 is_lo (t,_) = t < mid_lit
861 cond = CmmMachOp (mkLtOp mid_lit)
862 [scrut, CmmLit (mkSimpleLit mid_lit)]
864 -------------------------------------------------------------------------
866 -- Simultaneous assignment
868 -------------------------------------------------------------------------
871 emitSimultaneously :: CmmStmts -> Code
872 -- Emit code to perform the assignments in the
873 -- input simultaneously, using temporary variables when necessary.
875 -- The Stmts must be:
876 -- CmmNop, CmmComment, CmmAssign, CmmStore
880 -- We use the strongly-connected component algorithm, in which
881 -- * the vertices are the statements
882 -- * an edge goes from s1 to s2 iff
883 -- s1 assigns to something s2 uses
884 -- that is, if s1 should *follow* s2 in the final order
886 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
887 -- for fast comparison
889 emitSimultaneously stmts
891 case filterOut isNopStmt (stmtList stmts) of
894 [stmt] -> stmtC stmt -- It's often just one stmt
895 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
897 doSimultaneously1 :: [CVertex] -> Code
898 doSimultaneously1 vertices
900 edges = [ (vertex, key1, edges_from stmt1)
901 | vertex@(key1, stmt1) <- vertices
903 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
904 stmt1 `mustFollow` stmt2
906 components = stronglyConnCompFromEdgedVertices edges
908 -- do_components deal with one strongly-connected component
909 -- Not cyclic, or singleton? Just do it
910 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
911 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
913 -- Cyclic? Then go via temporaries. Pick one to
914 -- break the loop and try again with the rest.
915 do_component (CyclicSCC ((n,first_stmt) : rest))
916 = do { from_temp <- go_via_temp first_stmt
917 ; doSimultaneously1 rest
920 go_via_temp (CmmAssign dest src)
921 = do { tmp <- newTemp (cmmRegType dest) -- TODO FIXME NOW if the pair of assignments move across a call this will be wrong
922 ; stmtC (CmmAssign (CmmLocal tmp) src)
923 ; return (CmmAssign dest (CmmReg (CmmLocal tmp))) }
924 go_via_temp (CmmStore dest src)
925 = do { tmp <- newTemp (cmmExprType src) -- TODO FIXME NOW if the pair of assignemnts move across a call this will be wrong
926 ; stmtC (CmmAssign (CmmLocal tmp) src)
927 ; return (CmmStore dest (CmmReg (CmmLocal tmp))) }
929 mapCs do_component components
931 mustFollow :: CmmStmt -> CmmStmt -> Bool
932 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
933 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprType e)) stmt
934 CmmNop `mustFollow` stmt = False
935 CmmComment _ `mustFollow` stmt = False
938 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
939 -- True if the fn is true of any input of the stmt
940 anySrc p (CmmAssign _ e) = p e
941 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
942 anySrc p (CmmComment _) = False
943 anySrc p CmmNop = False
944 anySrc p other = True -- Conservative
946 regUsedIn :: CmmReg -> CmmExpr -> Bool
947 reg `regUsedIn` CmmLit _ = False
948 reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e
949 reg `regUsedIn` CmmReg reg' = reg == reg'
950 reg `regUsedIn` CmmRegOff reg' _ = reg == reg'
951 reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es
953 locUsedIn :: CmmExpr -> CmmType -> CmmExpr -> Bool
954 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
955 -- 'e'. Returns True if it's not sure.
956 locUsedIn loc rep (CmmLit _) = False
957 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
958 locUsedIn loc rep (CmmReg reg') = False
959 locUsedIn loc rep (CmmRegOff reg' _) = False
960 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
962 possiblySameLoc :: CmmExpr -> CmmType -> CmmExpr -> CmmType -> Bool
963 -- Assumes that distinct registers (eg Hp, Sp) do not
964 -- point to the same location, nor any offset thereof.
965 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
966 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
967 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
968 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
969 = r1==r2 && end1 > start2 && end2 > start1
971 end1 = start1 + widthInBytes (typeWidth rep1)
972 end2 = start2 + widthInBytes (typeWidth rep2)
974 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
975 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative
977 -------------------------------------------------------------------------
979 -- Static Reference Tables
981 -------------------------------------------------------------------------
983 -- There is just one SRT for each top level binding; all the nested
984 -- bindings use sub-sections of this SRT. The label is passed down to
985 -- the nested bindings via the monad.
987 getSRTInfo :: FCode C_SRT
989 srt_lbl <- getSRTLabel
992 -- TODO: Should we panic in this case?
993 -- Someone obviously thinks there should be an SRT
994 NoSRT -> return NoC_SRT
995 SRTEntries {} -> panic "getSRTInfo: SRTEntries. Perhaps you forgot to run SimplStg?"
997 | len > hALF_WORD_SIZE_IN_BITS || bmp == [fromIntegral srt_escape]
998 -> do id <- newUnique
999 let srt_desc_lbl = mkLargeSRTLabel id
1000 emitRODataLits "getSRTInfo" srt_desc_lbl
1001 ( cmmLabelOffW srt_lbl off
1002 : mkWordCLit (fromIntegral len)
1003 : map mkWordCLit bmp)
1004 return (C_SRT srt_desc_lbl 0 srt_escape)
1008 -> return (C_SRT srt_lbl off (fromIntegral (head bmp)))
1009 -- The fromIntegral converts to StgHalfWord
1011 srt_escape = (-1) :: StgHalfWord
1013 clHasCafRefs :: ClosureInfo -> CafInfo
1014 clHasCafRefs (ClosureInfo {closureSRT = srt}) =
1015 case srt of NoC_SRT -> NoCafRefs
1017 clHasCafRefs (ConInfo {}) = NoCafRefs