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(..))
84 -------------------------------------------------------------------------
86 -- Random small functions
88 -------------------------------------------------------------------------
90 addIdReps :: [Id] -> [(CgRep, Id)]
91 addIdReps ids = [(idCgRep id, id) | id <- ids]
93 -------------------------------------------------------------------------
97 -------------------------------------------------------------------------
99 cgLit :: Literal -> FCode CmmLit
100 cgLit (MachStr s) = mkByteStringCLit (bytesFS s)
101 -- not unpackFS; we want the UTF-8 byte stream.
102 cgLit other_lit = return (mkSimpleLit other_lit)
104 mkSimpleLit :: Literal -> CmmLit
105 mkSimpleLit (MachChar c) = CmmInt (fromIntegral (ord c)) wordWidth
106 mkSimpleLit MachNullAddr = zeroCLit
107 mkSimpleLit (MachInt i) = CmmInt i wordWidth
108 mkSimpleLit (MachInt64 i) = CmmInt i W64
109 mkSimpleLit (MachWord i) = CmmInt i wordWidth
110 mkSimpleLit (MachWord64 i) = CmmInt i W64
111 mkSimpleLit (MachFloat r) = CmmFloat r W32
112 mkSimpleLit (MachDouble r) = CmmFloat r W64
113 mkSimpleLit (MachLabel fs ms fod) = CmmLabel (mkForeignLabel fs ms is_dyn fod)
115 is_dyn = False -- ToDo: fix me
117 mkLtOp :: Literal -> MachOp
118 -- On signed literals we must do a signed comparison
119 mkLtOp (MachInt _) = MO_S_Lt wordWidth
120 mkLtOp (MachFloat _) = MO_F_Lt W32
121 mkLtOp (MachDouble _) = MO_F_Lt W64
122 mkLtOp lit = MO_U_Lt (typeWidth (cmmLitType (mkSimpleLit lit)))
125 ---------------------------------------------------
127 -- Cmm data type functions
129 ---------------------------------------------------
131 -----------------------
132 -- The "B" variants take byte offsets
133 cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr
134 cmmRegOffB = cmmRegOff
136 cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr
137 cmmOffsetB = cmmOffset
139 cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr
140 cmmOffsetExprB = cmmOffsetExpr
142 cmmLabelOffB :: CLabel -> ByteOff -> CmmLit
143 cmmLabelOffB = cmmLabelOff
145 cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit
146 cmmOffsetLitB = cmmOffsetLit
148 -----------------------
149 -- The "W" variants take word offsets
150 cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr
151 -- The second arg is a *word* offset; need to change it to bytes
152 cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n)
153 cmmOffsetExprW e wd_off = cmmIndexExpr wordWidth e wd_off
155 cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr
156 cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n)
158 cmmRegOffW :: CmmReg -> WordOff -> CmmExpr
159 cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE)
161 cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit
162 cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off)
164 cmmLabelOffW :: CLabel -> WordOff -> CmmLit
165 cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off)
167 cmmLoadIndexW :: CmmExpr -> Int -> CmmType -> CmmExpr
168 cmmLoadIndexW base off ty = CmmLoad (cmmOffsetW base off) ty
170 -----------------------
171 cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord :: CmmExpr -> CmmExpr -> CmmExpr
172 cmmOrWord e1 e2 = CmmMachOp mo_wordOr [e1, e2]
173 cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2]
174 cmmNeWord e1 e2 = CmmMachOp mo_wordNe [e1, e2]
175 cmmEqWord e1 e2 = CmmMachOp mo_wordEq [e1, e2]
176 cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2]
177 cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2]
178 cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2]
179 --cmmShlWord e1 e2 = CmmMachOp mo_wordShl [e1, e2]
180 --cmmUShrWord e1 e2 = CmmMachOp mo_wordUShr [e1, e2]
181 cmmSubWord e1 e2 = CmmMachOp mo_wordSub [e1, e2]
183 cmmNegate :: CmmExpr -> CmmExpr
184 cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep)
185 cmmNegate e = CmmMachOp (MO_S_Neg (cmmExprWidth e)) [e]
187 blankWord :: CmmStatic
188 blankWord = CmmUninitialised wORD_SIZE
192 --cmmTagBits = CmmLit (mkIntCLit tAG_BITS)
193 cmmTagMask = CmmLit (mkIntCLit tAG_MASK)
194 cmmPointerMask = CmmLit (mkIntCLit (complement tAG_MASK))
196 -- Used to untag a possibly tagged pointer
197 -- A static label need not be untagged
198 cmmUntag e@(CmmLit (CmmLabel _)) = e
200 cmmUntag e = (e `cmmAndWord` cmmPointerMask)
202 cmmGetTag e = (e `cmmAndWord` cmmTagMask)
204 -- Test if a closure pointer is untagged
205 cmmIsTagged e = (e `cmmAndWord` cmmTagMask)
206 `cmmNeWord` CmmLit zeroCLit
208 cmmConstrTag e = (e `cmmAndWord` cmmTagMask) `cmmSubWord` (CmmLit (mkIntCLit 1))
209 -- Get constructor tag, but one based.
210 cmmConstrTag1 e = e `cmmAndWord` cmmTagMask
213 The family size of a data type (the number of constructors)
215 * small, if the family size < 2**tag_bits
218 Small families can have the constructor tag in the tag
220 Big families only use the tag value 1 to represent
223 isSmallFamily fam_size = fam_size <= mAX_PTR_TAG
227 con_tag = dataConTagZ con
228 fam_size = tyConFamilySize (dataConTyCon con)
229 tag | isSmallFamily fam_size = con_tag + 1
232 --Tag an expression, to do: refactor, this appears in some other module.
233 tagCons con expr = cmmOffsetB expr (tagForCon con)
235 -- Copied from CgInfoTbls.hs
236 -- We keep the *zero-indexed* tag in the srt_len field of the info
237 -- table of a data constructor.
238 dataConTagZ :: DataCon -> ConTagZ
239 dataConTagZ con = dataConTag con - fIRST_TAG
241 -----------------------
244 mkWordCLit :: StgWord -> CmmLit
245 mkWordCLit wd = CmmInt (fromIntegral wd) wordWidth
247 packHalfWordsCLit :: (Integral a, Integral b) => a -> b -> CmmLit
248 -- Make a single word literal in which the lower_half_word is
249 -- at the lower address, and the upper_half_word is at the
251 -- ToDo: consider using half-word lits instead
252 -- but be careful: that's vulnerable when reversed
253 packHalfWordsCLit lower_half_word upper_half_word
254 #ifdef WORDS_BIGENDIAN
255 = mkWordCLit ((fromIntegral lower_half_word `shiftL` hALF_WORD_SIZE_IN_BITS)
256 .|. fromIntegral upper_half_word)
258 = mkWordCLit ((fromIntegral lower_half_word)
259 .|. (fromIntegral upper_half_word `shiftL` hALF_WORD_SIZE_IN_BITS))
262 --------------------------------------------------------------------------
264 -- Incrementing a memory location
266 --------------------------------------------------------------------------
268 addToMem :: Width -- rep of the counter
269 -> CmmExpr -- Address
270 -> Int -- What to add (a word)
272 addToMem width ptr n = addToMemE width ptr (CmmLit (CmmInt (toInteger n) width))
274 addToMemE :: Width -- rep of the counter
275 -> CmmExpr -- Address
276 -> CmmExpr -- What to add (a word-typed expression)
278 addToMemE width ptr n
279 = CmmStore ptr (CmmMachOp (MO_Add width) [CmmLoad ptr (cmmBits width), n])
281 -------------------------------------------------------------------------
283 -- Converting a closure tag to a closure for enumeration types
284 -- (this is the implementation of tagToEnum#).
286 -------------------------------------------------------------------------
288 tagToClosure :: TyCon -> CmmExpr -> CmmExpr
289 tagToClosure tycon tag
290 = CmmLoad (cmmOffsetExprW closure_tbl tag) gcWord
291 where closure_tbl = CmmLit (CmmLabel lbl)
292 lbl = mkClosureTableLabel (tyConName tycon) NoCafRefs
294 -------------------------------------------------------------------------
296 -- Conditionals and rts calls
298 -------------------------------------------------------------------------
300 emitIf :: CmmExpr -- Boolean
303 -- Emit (if e then x)
304 -- ToDo: reverse the condition to avoid the extra branch instruction if possible
305 -- (some conditionals aren't reversible. eg. floating point comparisons cannot
306 -- be inverted because there exist some values for which both comparisons
307 -- return False, such as NaN.)
308 emitIf cond then_part
309 = do { then_id <- newLabelC
310 ; join_id <- newLabelC
311 ; stmtC (CmmCondBranch cond then_id)
312 ; stmtC (CmmBranch join_id)
318 emitIfThenElse :: CmmExpr -- Boolean
322 -- Emit (if e then x else y)
323 emitIfThenElse cond then_part else_part
324 = do { then_id <- newLabelC
325 ; join_id <- newLabelC
326 ; stmtC (CmmCondBranch cond then_id)
328 ; stmtC (CmmBranch join_id)
334 emitRtsCall :: LitString -> [CmmHinted CmmExpr] -> Bool -> Code
335 emitRtsCall fun args safe = emitRtsCall' [] fun args Nothing safe
336 -- The 'Nothing' says "save all global registers"
338 emitRtsCallWithVols :: LitString -> [CmmHinted CmmExpr] -> [GlobalReg] -> Bool -> Code
339 emitRtsCallWithVols fun args vols safe
340 = emitRtsCall' [] fun args (Just vols) safe
342 emitRtsCallWithResult :: LocalReg -> ForeignHint -> LitString
343 -> [CmmHinted CmmExpr] -> Bool -> Code
344 emitRtsCallWithResult res hint fun args safe
345 = emitRtsCall' [CmmHinted res hint] fun args Nothing safe
347 -- Make a call to an RTS C procedure
349 :: [CmmHinted LocalReg]
351 -> [CmmHinted CmmExpr]
353 -> Bool -- True <=> CmmSafe call
355 emitRtsCall' res fun args vols safe = do
357 then getSRTInfo >>= (return . CmmSafe)
358 else return CmmUnsafe
360 stmtC (CmmCall target res args safety CmmMayReturn)
363 (caller_save, caller_load) = callerSaveVolatileRegs vols
364 target = CmmCallee fun_expr CCallConv
365 fun_expr = mkLblExpr (mkRtsCodeLabel fun)
367 -----------------------------------------------------------------------------
369 -- Caller-Save Registers
371 -----------------------------------------------------------------------------
373 -- Here we generate the sequence of saves/restores required around a
374 -- foreign call instruction.
376 -- TODO: reconcile with includes/Regs.h
377 -- * Regs.h claims that BaseReg should be saved last and loaded first
378 -- * This might not have been tickled before since BaseReg is callee save
379 -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim
380 callerSaveVolatileRegs :: Maybe [GlobalReg] -> ([CmmStmt], [CmmStmt])
381 callerSaveVolatileRegs vols = (caller_save, caller_load)
383 caller_save = foldr ($!) [] (map callerSaveGlobalReg regs_to_save)
384 caller_load = foldr ($!) [] (map callerRestoreGlobalReg regs_to_save)
386 system_regs = [Sp,SpLim,Hp,HpLim,CurrentTSO,CurrentNursery,
387 {-SparkHd,SparkTl,SparkBase,SparkLim,-}BaseReg ]
389 regs_to_save = system_regs ++ vol_list
391 vol_list = case vols of Nothing -> all_of_em; Just regs -> regs
393 all_of_em = [ VanillaReg n VNonGcPtr | n <- [0..mAX_Vanilla_REG] ]
394 -- The VNonGcPtr is a lie, but I don't think it matters
395 ++ [ FloatReg n | n <- [0..mAX_Float_REG] ]
396 ++ [ DoubleReg n | n <- [0..mAX_Double_REG] ]
397 ++ [ LongReg n | n <- [0..mAX_Long_REG] ]
399 callerSaveGlobalReg reg next
401 CmmStore (get_GlobalReg_addr reg)
402 (CmmReg (CmmGlobal reg)) : next
405 callerRestoreGlobalReg reg next
407 CmmAssign (CmmGlobal reg)
408 (CmmLoad (get_GlobalReg_addr reg) (globalRegType reg))
412 -- -----------------------------------------------------------------------------
415 -- We map STG registers onto appropriate CmmExprs. Either they map
416 -- to real machine registers or stored as offsets from BaseReg. Given
417 -- a GlobalReg, get_GlobalReg_addr always produces the
418 -- register table address for it.
419 -- (See also get_GlobalReg_reg_or_addr in MachRegs)
421 get_GlobalReg_addr :: GlobalReg -> CmmExpr
422 get_GlobalReg_addr BaseReg = regTableOffset 0
423 get_GlobalReg_addr mid = get_Regtable_addr_from_offset
424 (globalRegType mid) (baseRegOffset mid)
426 -- Calculate a literal representing an offset into the register table.
427 -- Used when we don't have an actual BaseReg to offset from.
429 CmmLit (CmmLabelOff mkMainCapabilityLabel (oFFSET_Capability_r + n))
431 get_Regtable_addr_from_offset :: CmmType -> Int -> CmmExpr
432 get_Regtable_addr_from_offset rep offset =
434 CmmRegOff (CmmGlobal BaseReg) offset
436 regTableOffset offset
440 -- | Returns @True@ if this global register is stored in a caller-saves
443 callerSaves :: GlobalReg -> Bool
445 #ifdef CALLER_SAVES_Base
446 callerSaves BaseReg = True
448 #ifdef CALLER_SAVES_R1
449 callerSaves (VanillaReg 1 _) = True
451 #ifdef CALLER_SAVES_R2
452 callerSaves (VanillaReg 2 _) = True
454 #ifdef CALLER_SAVES_R3
455 callerSaves (VanillaReg 3 _) = True
457 #ifdef CALLER_SAVES_R4
458 callerSaves (VanillaReg 4 _) = True
460 #ifdef CALLER_SAVES_R5
461 callerSaves (VanillaReg 5 _) = True
463 #ifdef CALLER_SAVES_R6
464 callerSaves (VanillaReg 6 _) = True
466 #ifdef CALLER_SAVES_R7
467 callerSaves (VanillaReg 7 _) = True
469 #ifdef CALLER_SAVES_R8
470 callerSaves (VanillaReg 8 _) = True
472 #ifdef CALLER_SAVES_F1
473 callerSaves (FloatReg 1) = True
475 #ifdef CALLER_SAVES_F2
476 callerSaves (FloatReg 2) = True
478 #ifdef CALLER_SAVES_F3
479 callerSaves (FloatReg 3) = True
481 #ifdef CALLER_SAVES_F4
482 callerSaves (FloatReg 4) = True
484 #ifdef CALLER_SAVES_D1
485 callerSaves (DoubleReg 1) = True
487 #ifdef CALLER_SAVES_D2
488 callerSaves (DoubleReg 2) = True
490 #ifdef CALLER_SAVES_L1
491 callerSaves (LongReg 1) = True
493 #ifdef CALLER_SAVES_Sp
494 callerSaves Sp = True
496 #ifdef CALLER_SAVES_SpLim
497 callerSaves SpLim = True
499 #ifdef CALLER_SAVES_Hp
500 callerSaves Hp = True
502 #ifdef CALLER_SAVES_HpLim
503 callerSaves HpLim = True
505 #ifdef CALLER_SAVES_CurrentTSO
506 callerSaves CurrentTSO = True
508 #ifdef CALLER_SAVES_CurrentNursery
509 callerSaves CurrentNursery = True
511 callerSaves _ = False
514 -- -----------------------------------------------------------------------------
515 -- Information about global registers
517 baseRegOffset :: GlobalReg -> Int
519 baseRegOffset (VanillaReg 1 _) = oFFSET_StgRegTable_rR1
520 baseRegOffset (VanillaReg 2 _) = oFFSET_StgRegTable_rR2
521 baseRegOffset (VanillaReg 3 _) = oFFSET_StgRegTable_rR3
522 baseRegOffset (VanillaReg 4 _) = oFFSET_StgRegTable_rR4
523 baseRegOffset (VanillaReg 5 _) = oFFSET_StgRegTable_rR5
524 baseRegOffset (VanillaReg 6 _) = oFFSET_StgRegTable_rR6
525 baseRegOffset (VanillaReg 7 _) = oFFSET_StgRegTable_rR7
526 baseRegOffset (VanillaReg 8 _) = oFFSET_StgRegTable_rR8
527 baseRegOffset (VanillaReg 9 _) = oFFSET_StgRegTable_rR9
528 baseRegOffset (VanillaReg 10 _) = oFFSET_StgRegTable_rR10
529 baseRegOffset (FloatReg 1) = oFFSET_StgRegTable_rF1
530 baseRegOffset (FloatReg 2) = oFFSET_StgRegTable_rF2
531 baseRegOffset (FloatReg 3) = oFFSET_StgRegTable_rF3
532 baseRegOffset (FloatReg 4) = oFFSET_StgRegTable_rF4
533 baseRegOffset (DoubleReg 1) = oFFSET_StgRegTable_rD1
534 baseRegOffset (DoubleReg 2) = oFFSET_StgRegTable_rD2
535 baseRegOffset Sp = oFFSET_StgRegTable_rSp
536 baseRegOffset SpLim = oFFSET_StgRegTable_rSpLim
537 baseRegOffset (LongReg 1) = oFFSET_StgRegTable_rL1
538 baseRegOffset Hp = oFFSET_StgRegTable_rHp
539 baseRegOffset HpLim = oFFSET_StgRegTable_rHpLim
540 baseRegOffset CurrentTSO = oFFSET_StgRegTable_rCurrentTSO
541 baseRegOffset CurrentNursery = oFFSET_StgRegTable_rCurrentNursery
542 baseRegOffset HpAlloc = oFFSET_StgRegTable_rHpAlloc
543 baseRegOffset EagerBlackholeInfo = oFFSET_stgEagerBlackholeInfo
544 baseRegOffset GCEnter1 = oFFSET_stgGCEnter1
545 baseRegOffset GCFun = oFFSET_stgGCFun
546 baseRegOffset BaseReg = panic "baseRegOffset:BaseReg"
547 baseRegOffset _ = panic "baseRegOffset:other"
550 -------------------------------------------------------------------------
552 -- Strings generate a top-level data block
554 -------------------------------------------------------------------------
556 emitDataLits :: CLabel -> [CmmLit] -> Code
557 -- Emit a data-segment data block
558 emitDataLits lbl lits
559 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
561 mkDataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
562 -- Emit a data-segment data block
564 = CmmData Data (CmmDataLabel lbl : map CmmStaticLit lits)
566 emitRODataLits :: String -> CLabel -> [CmmLit] -> Code
567 -- Emit a read-only data block
568 emitRODataLits caller lbl lits
569 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
570 where section | any needsRelocation lits = RelocatableReadOnlyData
571 | otherwise = ReadOnlyData
572 needsRelocation (CmmLabel _) = True
573 needsRelocation (CmmLabelOff _ _) = True
574 needsRelocation _ = False
576 mkRODataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
577 mkRODataLits lbl lits
578 = CmmData section (CmmDataLabel lbl : map CmmStaticLit lits)
579 where section | any needsRelocation lits = RelocatableReadOnlyData
580 | otherwise = ReadOnlyData
581 needsRelocation (CmmLabel _) = True
582 needsRelocation (CmmLabelOff _ _) = True
583 needsRelocation _ = False
585 mkStringCLit :: String -> FCode CmmLit
586 -- Make a global definition for the string,
587 -- and return its label
588 mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str)
590 mkByteStringCLit :: [Word8] -> FCode CmmLit
591 mkByteStringCLit bytes
592 = do { uniq <- newUnique
593 ; let lbl = mkStringLitLabel uniq
594 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes]
595 ; return (CmmLabel lbl) }
597 -------------------------------------------------------------------------
599 -- Assigning expressions to temporaries
601 -------------------------------------------------------------------------
603 assignTemp :: CmmExpr -> FCode CmmExpr
604 -- For a non-trivial expression, e, create a local
605 -- variable and assign the expression to it
607 | isTrivialCmmExpr e = return e
608 | otherwise = do { reg <- newTemp (cmmExprType e)
609 ; stmtC (CmmAssign (CmmLocal reg) e)
610 ; return (CmmReg (CmmLocal reg)) }
612 newTemp :: CmmType -> FCode LocalReg
613 newTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep) }
615 -------------------------------------------------------------------------
617 -- Building case analysis
619 -------------------------------------------------------------------------
622 :: CmmExpr -- Tag to switch on
623 -> [(ConTagZ, CgStmts)] -- Tagged branches
624 -> Maybe CgStmts -- Default branch (if any)
625 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
626 -- outside this range is undefined
629 -- ONLY A DEFAULT BRANCH: no case analysis to do
630 emitSwitch tag_expr [] (Just stmts) _ _
634 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
635 = -- Just sort the branches before calling mk_sritch
638 Nothing -> return Nothing
639 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
641 ; dflags <- getDynFlags
642 ; let via_C | HscC <- hscTarget dflags = True
645 ; stmts <- mk_switch tag_expr (sortLe le branches)
646 mb_deflt_id lo_tag hi_tag via_C
650 (t1,_) `le` (t2,_) = t1 <= t2
653 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
654 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
657 -- SINGLETON TAG RANGE: no case analysis to do
658 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
660 = ASSERT( tag == lo_tag )
663 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
664 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
666 -- The simplifier might have eliminated a case
667 -- so we may have e.g. case xs of
669 -- In that situation we can be sure the (:) case
670 -- can't happen, so no need to test
672 -- SINGLETON BRANCH: one equality check to do
673 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
674 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
676 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
677 -- We have lo_tag < hi_tag, but there's only one branch,
678 -- so there must be a default
680 -- ToDo: we might want to check for the two branch case, where one of
681 -- the branches is the tag 0, because comparing '== 0' is likely to be
682 -- more efficient than other kinds of comparison.
684 -- DENSE TAG RANGE: use a switch statment.
686 -- We also use a switch uncoditionally when compiling via C, because
687 -- this will get emitted as a C switch statement and the C compiler
688 -- should do a good job of optimising it. Also, older GCC versions
689 -- (2.95 in particular) have problems compiling the complicated
690 -- if-trees generated by this code, so compiling to a switch every
691 -- time works around that problem.
693 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
694 | use_switch -- Use a switch
695 = do { branch_ids <- mapM forkCgStmts (map snd branches)
697 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
699 find_branch :: ConTagZ -> Maybe BlockId
700 find_branch i = assocDefault mb_deflt tagged_blk_ids i
702 -- NB. we have eliminated impossible branches at
703 -- either end of the range (see below), so the first
704 -- tag of a real branch is real_lo_tag (not lo_tag).
705 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
707 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
709 ; ASSERT(not (all isNothing arms))
710 return (oneCgStmt switch_stmt)
713 -- if we can knock off a bunch of default cases with one if, then do so
714 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
715 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
716 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
717 branch = CmmCondBranch cond deflt
718 ; stmts <- mk_switch tag_expr' branches mb_deflt
719 lowest_branch hi_tag via_C
720 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
723 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
724 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
725 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
726 branch = CmmCondBranch cond deflt
727 ; stmts <- mk_switch tag_expr' branches mb_deflt
728 lo_tag highest_branch via_C
729 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
732 | otherwise -- Use an if-tree
733 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
734 -- To avoid duplication
735 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
736 lo_tag (mid_tag-1) via_C
737 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
739 ; hi_id <- forkCgStmts hi_stmts
740 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
741 branch_stmt = CmmCondBranch cond hi_id
742 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
744 -- we test (e >= mid_tag) rather than (e < mid_tag), because
745 -- the former works better when e is a comparison, and there
746 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
747 -- generator can reduce the condition to e itself without
748 -- having to reverse the sense of the comparison: comparisons
749 -- can't always be easily reversed (eg. floating
752 use_switch = {- pprTrace "mk_switch" (
753 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
754 text "branches:" <+> ppr (map fst branches) <+>
755 text "n_branches:" <+> int n_branches <+>
756 text "lo_tag:" <+> int lo_tag <+>
757 text "hi_tag:" <+> int hi_tag <+>
758 text "real_lo_tag:" <+> int real_lo_tag <+>
759 text "real_hi_tag:" <+> int real_hi_tag) $ -}
760 ASSERT( n_branches > 1 && n_tags > 1 )
761 n_tags > 2 && (via_C || (dense && big_enough))
762 -- up to 4 branches we use a decision tree, otherwise
763 -- a switch (== jump table in the NCG). This seems to be
764 -- optimal, and corresponds with what gcc does.
765 big_enough = n_branches > 4
766 dense = n_branches > (n_tags `div` 2)
767 n_branches = length branches
769 -- ignore default slots at each end of the range if there's
770 -- no default branch defined.
771 lowest_branch = fst (head branches)
772 highest_branch = fst (last branches)
775 | isNothing mb_deflt = lowest_branch
779 | isNothing mb_deflt = highest_branch
782 n_tags = real_hi_tag - real_lo_tag + 1
784 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
785 -- lo_tag <= mid_tag < hi_tag
786 -- lo_branches have tags < mid_tag
787 -- hi_branches have tags >= mid_tag
789 (mid_tag,_) = branches !! (n_branches `div` 2)
790 -- 2 branches => n_branches `div` 2 = 1
791 -- => branches !! 1 give the *second* tag
792 -- There are always at least 2 branches here
794 (lo_branches, hi_branches) = span is_lo branches
795 is_lo (t,_) = t < mid_tag
799 | isTrivialCmmExpr e = return (CmmNop, e)
800 | otherwise = do { reg <- newTemp (cmmExprType e)
801 ; return (CmmAssign (CmmLocal reg) e, CmmReg (CmmLocal reg)) }
803 emitLitSwitch :: CmmExpr -- Tag to switch on
804 -> [(Literal, CgStmts)] -- Tagged branches
805 -> CgStmts -- Default branch (always)
806 -> Code -- Emit the code
807 -- Used for general literals, whose size might not be a word,
808 -- where there is always a default case, and where we don't know
809 -- the range of values for certain. For simplicity we always generate a tree.
811 -- ToDo: for integers we could do better here, perhaps by generalising
812 -- mk_switch and using that. --SDM 15/09/2004
813 emitLitSwitch scrut [] deflt
815 emitLitSwitch scrut branches deflt_blk
816 = do { scrut' <- assignTemp scrut
817 ; deflt_blk_id <- forkCgStmts deflt_blk
818 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
821 le (t1,_) (t2,_) = t1 <= t2
823 mk_lit_switch :: CmmExpr -> BlockId
824 -> [(Literal,CgStmts)]
826 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
827 = return (consCgStmt if_stmt blk)
829 cmm_lit = mkSimpleLit lit
830 rep = cmmLitType cmm_lit
831 ne = if isFloatType rep then MO_F_Ne else MO_Ne
832 cond = CmmMachOp (ne (typeWidth rep)) [scrut, CmmLit cmm_lit]
833 if_stmt = CmmCondBranch cond deflt_blk_id
835 mk_lit_switch scrut deflt_blk_id branches
836 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
837 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
838 ; lo_blk_id <- forkCgStmts lo_blk
839 ; let if_stmt = CmmCondBranch cond lo_blk_id
840 ; return (if_stmt `consCgStmt` hi_blk) }
842 n_branches = length branches
843 (mid_lit,_) = branches !! (n_branches `div` 2)
844 -- See notes above re mid_tag
846 (lo_branches, hi_branches) = span is_lo branches
847 is_lo (t,_) = t < mid_lit
849 cond = CmmMachOp (mkLtOp mid_lit)
850 [scrut, CmmLit (mkSimpleLit mid_lit)]
852 -------------------------------------------------------------------------
854 -- Simultaneous assignment
856 -------------------------------------------------------------------------
859 emitSimultaneously :: CmmStmts -> Code
860 -- Emit code to perform the assignments in the
861 -- input simultaneously, using temporary variables when necessary.
863 -- The Stmts must be:
864 -- CmmNop, CmmComment, CmmAssign, CmmStore
868 -- We use the strongly-connected component algorithm, in which
869 -- * the vertices are the statements
870 -- * an edge goes from s1 to s2 iff
871 -- s1 assigns to something s2 uses
872 -- that is, if s1 should *follow* s2 in the final order
874 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
875 -- for fast comparison
877 emitSimultaneously stmts
879 case filterOut isNopStmt (stmtList stmts) of
882 [stmt] -> stmtC stmt -- It's often just one stmt
883 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
885 doSimultaneously1 :: [CVertex] -> Code
886 doSimultaneously1 vertices
888 edges = [ (vertex, key1, edges_from stmt1)
889 | vertex@(key1, stmt1) <- vertices
891 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
892 stmt1 `mustFollow` stmt2
894 components = stronglyConnCompFromEdgedVertices edges
896 -- do_components deal with one strongly-connected component
897 -- Not cyclic, or singleton? Just do it
898 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
899 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
901 -- Cyclic? Then go via temporaries. Pick one to
902 -- break the loop and try again with the rest.
903 do_component (CyclicSCC ((n,first_stmt) : rest))
904 = do { from_temp <- go_via_temp first_stmt
905 ; doSimultaneously1 rest
908 go_via_temp (CmmAssign dest src)
909 = do { tmp <- newTemp (cmmRegType dest) -- TODO FIXME NOW if the pair of assignments move across a call this will be wrong
910 ; stmtC (CmmAssign (CmmLocal tmp) src)
911 ; return (CmmAssign dest (CmmReg (CmmLocal tmp))) }
912 go_via_temp (CmmStore dest src)
913 = do { tmp <- newTemp (cmmExprType src) -- TODO FIXME NOW if the pair of assignemnts move across a call this will be wrong
914 ; stmtC (CmmAssign (CmmLocal tmp) src)
915 ; return (CmmStore dest (CmmReg (CmmLocal tmp))) }
917 mapCs do_component components
919 mustFollow :: CmmStmt -> CmmStmt -> Bool
920 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
921 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprType e)) stmt
922 CmmNop `mustFollow` stmt = False
923 CmmComment _ `mustFollow` stmt = False
926 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
927 -- True if the fn is true of any input of the stmt
928 anySrc p (CmmAssign _ e) = p e
929 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
930 anySrc p (CmmComment _) = False
931 anySrc p CmmNop = False
932 anySrc p other = True -- Conservative
934 regUsedIn :: CmmReg -> CmmExpr -> Bool
935 reg `regUsedIn` CmmLit _ = False
936 reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e
937 reg `regUsedIn` CmmReg reg' = reg == reg'
938 reg `regUsedIn` CmmRegOff reg' _ = reg == reg'
939 reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es
941 locUsedIn :: CmmExpr -> CmmType -> CmmExpr -> Bool
942 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
943 -- 'e'. Returns True if it's not sure.
944 locUsedIn loc rep (CmmLit _) = False
945 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
946 locUsedIn loc rep (CmmReg reg') = False
947 locUsedIn loc rep (CmmRegOff reg' _) = False
948 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
950 possiblySameLoc :: CmmExpr -> CmmType -> CmmExpr -> CmmType -> Bool
951 -- Assumes that distinct registers (eg Hp, Sp) do not
952 -- point to the same location, nor any offset thereof.
953 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
954 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
955 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
956 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
957 = r1==r2 && end1 > start2 && end2 > start1
959 end1 = start1 + widthInBytes (typeWidth rep1)
960 end2 = start2 + widthInBytes (typeWidth rep2)
962 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
963 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative
965 -------------------------------------------------------------------------
967 -- Static Reference Tables
969 -------------------------------------------------------------------------
971 -- There is just one SRT for each top level binding; all the nested
972 -- bindings use sub-sections of this SRT. The label is passed down to
973 -- the nested bindings via the monad.
975 getSRTInfo :: FCode C_SRT
977 srt_lbl <- getSRTLabel
980 -- TODO: Should we panic in this case?
981 -- Someone obviously thinks there should be an SRT
982 NoSRT -> return NoC_SRT
983 SRTEntries {} -> panic "getSRTInfo: SRTEntries. Perhaps you forgot to run SimplStg?"
985 | len > hALF_WORD_SIZE_IN_BITS || bmp == [fromIntegral srt_escape]
986 -> do id <- newUnique
987 let srt_desc_lbl = mkLargeSRTLabel id
988 emitRODataLits "getSRTInfo" srt_desc_lbl
989 ( cmmLabelOffW srt_lbl off
990 : mkWordCLit (fromIntegral len)
991 : map mkWordCLit bmp)
992 return (C_SRT srt_desc_lbl 0 srt_escape)
996 -> return (C_SRT srt_lbl off (fromIntegral (head bmp)))
997 -- The fromIntegral converts to StgHalfWord
999 srt_escape = (-1) :: StgHalfWord
1001 clHasCafRefs :: ClosureInfo -> CafInfo
1002 clHasCafRefs (ClosureInfo {closureSRT = srt}) =
1003 case srt of NoC_SRT -> NoCafRefs
1005 clHasCafRefs (ConInfo {}) = NoCafRefs