1 -----------------------------------------------------------------------------
3 -- Code generator utilities; mostly monadic
5 -- (c) The University of Glasgow 2004-2006
7 -----------------------------------------------------------------------------
10 -- The above warning supression flag is a temporary kludge.
11 -- While working on this module you are encouraged to remove it and fix
12 -- any warnings in the module. See
13 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
19 emitDataLits, mkDataLits,
20 emitRODataLits, mkRODataLits,
21 emitIf, emitIfThenElse,
22 emitRtsCall, emitRtsCallWithVols, emitRtsCallWithResult,
23 assignNonPtrTemp, newNonPtrTemp,
24 assignPtrTemp, newPtrTemp,
26 emitSwitch, emitLitSwitch,
29 callerSaveVolatileRegs, get_GlobalReg_addr,
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,
53 #include "HsVersions.h"
62 import PprCmm ( {- instances -} )
69 import StgSyn (SRT(..))
86 -------------------------------------------------------------------------
88 -- Random small functions
90 -------------------------------------------------------------------------
92 addIdReps :: [Id] -> [(CgRep, Id)]
93 addIdReps ids = [(idCgRep id, id) | id <- ids]
95 -------------------------------------------------------------------------
99 -------------------------------------------------------------------------
101 cgLit :: Literal -> FCode CmmLit
102 cgLit (MachStr s) = mkByteStringCLit (bytesFS s)
103 -- not unpackFS; we want the UTF-8 byte stream.
104 cgLit other_lit = return (mkSimpleLit other_lit)
106 mkSimpleLit :: Literal -> CmmLit
107 mkSimpleLit (MachChar c) = CmmInt (fromIntegral (ord c)) wordRep
108 mkSimpleLit MachNullAddr = zeroCLit
109 mkSimpleLit (MachInt i) = CmmInt i wordRep
110 mkSimpleLit (MachInt64 i) = CmmInt i I64
111 mkSimpleLit (MachWord i) = CmmInt i wordRep
112 mkSimpleLit (MachWord64 i) = CmmInt i I64
113 mkSimpleLit (MachFloat r) = CmmFloat r F32
114 mkSimpleLit (MachDouble r) = CmmFloat r F64
115 mkSimpleLit (MachLabel fs ms) = CmmLabel (mkForeignLabel fs ms is_dyn)
117 is_dyn = False -- ToDo: fix me
119 mkLtOp :: Literal -> MachOp
120 -- On signed literals we must do a signed comparison
121 mkLtOp (MachInt _) = MO_S_Lt wordRep
122 mkLtOp (MachFloat _) = MO_S_Lt F32
123 mkLtOp (MachDouble _) = MO_S_Lt F64
124 mkLtOp lit = MO_U_Lt (cmmLitRep (mkSimpleLit lit))
127 ---------------------------------------------------
129 -- Cmm data type functions
131 ---------------------------------------------------
133 -----------------------
134 -- The "B" variants take byte offsets
135 cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr
136 cmmRegOffB = cmmRegOff
138 cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr
139 cmmOffsetB = cmmOffset
141 cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr
142 cmmOffsetExprB = cmmOffsetExpr
144 cmmLabelOffB :: CLabel -> ByteOff -> CmmLit
145 cmmLabelOffB = cmmLabelOff
147 cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit
148 cmmOffsetLitB = cmmOffsetLit
150 -----------------------
151 -- The "W" variants take word offsets
152 cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr
153 -- The second arg is a *word* offset; need to change it to bytes
154 cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n)
155 cmmOffsetExprW e wd_off = cmmIndexExpr wordRep e wd_off
157 cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr
158 cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n)
160 cmmRegOffW :: CmmReg -> WordOff -> CmmExpr
161 cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE)
163 cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit
164 cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off)
166 cmmLabelOffW :: CLabel -> WordOff -> CmmLit
167 cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off)
169 cmmLoadIndexW :: CmmExpr -> Int -> CmmExpr
170 cmmLoadIndexW base off
171 = CmmLoad (cmmOffsetW base off) wordRep
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 (cmmExprRep 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) wordRep
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 :: MachRep -- rep of the counter
272 -> CmmExpr -- Address
273 -> Int -- What to add (a word)
275 addToMem rep ptr n = addToMemE rep ptr (CmmLit (CmmInt (toInteger n) rep))
277 addToMemE :: MachRep -- rep of the counter
278 -> CmmExpr -- Address
279 -> CmmExpr -- What to add (a word-typed expression)
282 = CmmStore ptr (CmmMachOp (MO_Add rep) [CmmLoad ptr rep, 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) wordRep
294 where closure_tbl = CmmLit (CmmLabel lbl)
295 lbl = mkClosureTableLabel (tyConName tycon)
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 ; else_id <- newLabelC
329 ; join_id <- newLabelC
330 ; stmtC (CmmCondBranch cond then_id)
332 ; stmtC (CmmBranch join_id)
338 emitRtsCall :: LitString -> [(CmmExpr,MachHint)] -> Bool -> Code
339 emitRtsCall fun args safe = emitRtsCall' [] fun args Nothing safe
340 -- The 'Nothing' says "save all global registers"
342 emitRtsCallWithVols :: LitString -> [(CmmExpr,MachHint)] -> [GlobalReg] -> Bool -> Code
343 emitRtsCallWithVols fun args vols safe
344 = emitRtsCall' [] fun args (Just vols) safe
346 emitRtsCallWithResult :: LocalReg -> MachHint -> LitString
347 -> [(CmmExpr,MachHint)] -> Bool -> Code
348 emitRtsCallWithResult res hint fun args safe
349 = emitRtsCall' [(res,hint)] fun args Nothing safe
351 -- Make a call to an RTS C procedure
355 -> [(CmmExpr,MachHint)]
357 -> Bool -- True <=> CmmSafe call
359 emitRtsCall' res fun args vols safe = do
361 then getSRTInfo >>= (return . CmmSafe)
362 else return CmmUnsafe
364 stmtC (CmmCall target res args safety CmmMayReturn)
367 (caller_save, caller_load) = callerSaveVolatileRegs vols
368 target = CmmCallee fun_expr CCallConv
369 fun_expr = mkLblExpr (mkRtsCodeLabel fun)
371 -----------------------------------------------------------------------------
373 -- Caller-Save Registers
375 -----------------------------------------------------------------------------
377 -- Here we generate the sequence of saves/restores required around a
378 -- foreign call instruction.
380 -- TODO: reconcile with includes/Regs.h
381 -- * Regs.h claims that BaseReg should be saved last and loaded first
382 -- * This might not have been tickled before since BaseReg is callee save
383 -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim
384 callerSaveVolatileRegs :: Maybe [GlobalReg] -> ([CmmStmt], [CmmStmt])
385 callerSaveVolatileRegs vols = (caller_save, caller_load)
387 caller_save = foldr ($!) [] (map callerSaveGlobalReg regs_to_save)
388 caller_load = foldr ($!) [] (map callerRestoreGlobalReg regs_to_save)
390 system_regs = [Sp,SpLim,Hp,HpLim,CurrentTSO,CurrentNursery,
391 {-SparkHd,SparkTl,SparkBase,SparkLim,-}BaseReg ]
393 regs_to_save = system_regs ++ vol_list
395 vol_list = case vols of Nothing -> all_of_em; Just regs -> regs
397 all_of_em = [ VanillaReg n | n <- [0..mAX_Vanilla_REG] ]
398 ++ [ FloatReg n | n <- [0..mAX_Float_REG] ]
399 ++ [ DoubleReg n | n <- [0..mAX_Double_REG] ]
400 ++ [ LongReg n | n <- [0..mAX_Long_REG] ]
402 callerSaveGlobalReg reg next
404 CmmStore (get_GlobalReg_addr reg)
405 (CmmReg (CmmGlobal reg)) : next
408 callerRestoreGlobalReg reg next
410 CmmAssign (CmmGlobal reg)
411 (CmmLoad (get_GlobalReg_addr reg) (globalRegRep reg))
415 -- -----------------------------------------------------------------------------
418 -- We map STG registers onto appropriate CmmExprs. Either they map
419 -- to real machine registers or stored as offsets from BaseReg. Given
420 -- a GlobalReg, get_GlobalReg_addr always produces the
421 -- register table address for it.
422 -- (See also get_GlobalReg_reg_or_addr in MachRegs)
424 get_GlobalReg_addr :: GlobalReg -> CmmExpr
425 get_GlobalReg_addr BaseReg = regTableOffset 0
426 get_GlobalReg_addr mid = get_Regtable_addr_from_offset
427 (globalRegRep mid) (baseRegOffset mid)
429 -- Calculate a literal representing an offset into the register table.
430 -- Used when we don't have an actual BaseReg to offset from.
432 CmmLit (CmmLabelOff mkMainCapabilityLabel (oFFSET_Capability_r + n))
434 get_Regtable_addr_from_offset :: MachRep -> Int -> CmmExpr
435 get_Regtable_addr_from_offset rep offset =
437 CmmRegOff (CmmGlobal BaseReg) offset
439 regTableOffset offset
443 -- | Returns 'True' if this global register is stored in a caller-saves
446 callerSaves :: GlobalReg -> Bool
448 #ifdef CALLER_SAVES_Base
449 callerSaves BaseReg = True
451 #ifdef CALLER_SAVES_R1
452 callerSaves (VanillaReg 1) = True
454 #ifdef CALLER_SAVES_R2
455 callerSaves (VanillaReg 2) = True
457 #ifdef CALLER_SAVES_R3
458 callerSaves (VanillaReg 3) = True
460 #ifdef CALLER_SAVES_R4
461 callerSaves (VanillaReg 4) = True
463 #ifdef CALLER_SAVES_R5
464 callerSaves (VanillaReg 5) = True
466 #ifdef CALLER_SAVES_R6
467 callerSaves (VanillaReg 6) = True
469 #ifdef CALLER_SAVES_R7
470 callerSaves (VanillaReg 7) = True
472 #ifdef CALLER_SAVES_R8
473 callerSaves (VanillaReg 8) = True
475 #ifdef CALLER_SAVES_F1
476 callerSaves (FloatReg 1) = True
478 #ifdef CALLER_SAVES_F2
479 callerSaves (FloatReg 2) = True
481 #ifdef CALLER_SAVES_F3
482 callerSaves (FloatReg 3) = True
484 #ifdef CALLER_SAVES_F4
485 callerSaves (FloatReg 4) = True
487 #ifdef CALLER_SAVES_D1
488 callerSaves (DoubleReg 1) = True
490 #ifdef CALLER_SAVES_D2
491 callerSaves (DoubleReg 2) = True
493 #ifdef CALLER_SAVES_L1
494 callerSaves (LongReg 1) = True
496 #ifdef CALLER_SAVES_Sp
497 callerSaves Sp = True
499 #ifdef CALLER_SAVES_SpLim
500 callerSaves SpLim = True
502 #ifdef CALLER_SAVES_Hp
503 callerSaves Hp = True
505 #ifdef CALLER_SAVES_HpLim
506 callerSaves HpLim = True
508 #ifdef CALLER_SAVES_CurrentTSO
509 callerSaves CurrentTSO = True
511 #ifdef CALLER_SAVES_CurrentNursery
512 callerSaves CurrentNursery = True
514 callerSaves _ = False
517 -- -----------------------------------------------------------------------------
518 -- Information about global registers
520 baseRegOffset :: GlobalReg -> Int
522 baseRegOffset (VanillaReg 1) = oFFSET_StgRegTable_rR1
523 baseRegOffset (VanillaReg 2) = oFFSET_StgRegTable_rR2
524 baseRegOffset (VanillaReg 3) = oFFSET_StgRegTable_rR3
525 baseRegOffset (VanillaReg 4) = oFFSET_StgRegTable_rR4
526 baseRegOffset (VanillaReg 5) = oFFSET_StgRegTable_rR5
527 baseRegOffset (VanillaReg 6) = oFFSET_StgRegTable_rR6
528 baseRegOffset (VanillaReg 7) = oFFSET_StgRegTable_rR7
529 baseRegOffset (VanillaReg 8) = oFFSET_StgRegTable_rR8
530 baseRegOffset (VanillaReg 9) = oFFSET_StgRegTable_rR9
531 baseRegOffset (VanillaReg 10) = oFFSET_StgRegTable_rR10
532 baseRegOffset (FloatReg 1) = oFFSET_StgRegTable_rF1
533 baseRegOffset (FloatReg 2) = oFFSET_StgRegTable_rF2
534 baseRegOffset (FloatReg 3) = oFFSET_StgRegTable_rF3
535 baseRegOffset (FloatReg 4) = oFFSET_StgRegTable_rF4
536 baseRegOffset (DoubleReg 1) = oFFSET_StgRegTable_rD1
537 baseRegOffset (DoubleReg 2) = oFFSET_StgRegTable_rD2
538 baseRegOffset Sp = oFFSET_StgRegTable_rSp
539 baseRegOffset SpLim = oFFSET_StgRegTable_rSpLim
540 baseRegOffset (LongReg 1) = oFFSET_StgRegTable_rL1
541 baseRegOffset Hp = oFFSET_StgRegTable_rHp
542 baseRegOffset HpLim = oFFSET_StgRegTable_rHpLim
543 baseRegOffset CurrentTSO = oFFSET_StgRegTable_rCurrentTSO
544 baseRegOffset CurrentNursery = oFFSET_StgRegTable_rCurrentNursery
545 baseRegOffset HpAlloc = oFFSET_StgRegTable_rHpAlloc
546 baseRegOffset GCEnter1 = oFFSET_stgGCEnter1
547 baseRegOffset GCFun = oFFSET_stgGCFun
549 baseRegOffset BaseReg = panic "baseRegOffset:BaseReg"
550 baseRegOffset _ = panic "baseRegOffset:other"
554 -------------------------------------------------------------------------
556 -- Strings generate a top-level data block
558 -------------------------------------------------------------------------
560 emitDataLits :: CLabel -> [CmmLit] -> Code
561 -- Emit a data-segment data block
562 emitDataLits lbl lits
563 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
565 mkDataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
566 -- Emit a data-segment data block
568 = CmmData Data (CmmDataLabel lbl : map CmmStaticLit lits)
570 emitRODataLits :: CLabel -> [CmmLit] -> Code
571 -- Emit a read-only data block
572 emitRODataLits lbl lits
573 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
574 where section | any needsRelocation lits = RelocatableReadOnlyData
575 | otherwise = ReadOnlyData
576 needsRelocation (CmmLabel _) = True
577 needsRelocation (CmmLabelOff _ _) = True
578 needsRelocation _ = False
580 mkRODataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
581 mkRODataLits lbl lits
582 = CmmData section (CmmDataLabel lbl : map CmmStaticLit lits)
583 where section | any needsRelocation lits = RelocatableReadOnlyData
584 | otherwise = ReadOnlyData
585 needsRelocation (CmmLabel _) = True
586 needsRelocation (CmmLabelOff _ _) = True
587 needsRelocation _ = False
589 mkStringCLit :: String -> FCode CmmLit
590 -- Make a global definition for the string,
591 -- and return its label
592 mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str)
594 mkByteStringCLit :: [Word8] -> FCode CmmLit
595 mkByteStringCLit bytes
596 = do { uniq <- newUnique
597 ; let lbl = mkStringLitLabel uniq
598 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes]
599 ; return (CmmLabel lbl) }
601 -------------------------------------------------------------------------
603 -- Assigning expressions to temporaries
605 -------------------------------------------------------------------------
607 assignNonPtrTemp :: CmmExpr -> FCode CmmExpr
608 -- For a non-trivial expression, e, create a local
609 -- variable and assign the expression to it
611 | isTrivialCmmExpr e = return e
612 | otherwise = do { reg <- newNonPtrTemp (cmmExprRep e)
613 ; stmtC (CmmAssign (CmmLocal reg) e)
614 ; return (CmmReg (CmmLocal reg)) }
616 assignPtrTemp :: CmmExpr -> FCode CmmExpr
617 -- For a non-trivial expression, e, create a local
618 -- variable and assign the expression to it
620 | isTrivialCmmExpr e = return e
621 | otherwise = do { reg <- newPtrTemp (cmmExprRep e)
622 ; stmtC (CmmAssign (CmmLocal reg) e)
623 ; return (CmmReg (CmmLocal reg)) }
625 newNonPtrTemp :: MachRep -> FCode LocalReg
626 newNonPtrTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep GCKindNonPtr) }
628 newPtrTemp :: MachRep -> FCode LocalReg
629 newPtrTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep GCKindPtr) }
632 -------------------------------------------------------------------------
634 -- Building case analysis
636 -------------------------------------------------------------------------
639 :: CmmExpr -- Tag to switch on
640 -> [(ConTagZ, CgStmts)] -- Tagged branches
641 -> Maybe CgStmts -- Default branch (if any)
642 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
643 -- outside this range is undefined
646 -- ONLY A DEFAULT BRANCH: no case analysis to do
647 emitSwitch tag_expr [] (Just stmts) _ _
651 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
652 = -- Just sort the branches before calling mk_sritch
655 Nothing -> return Nothing
656 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
658 ; dflags <- getDynFlags
659 ; let via_C | HscC <- hscTarget dflags = True
662 ; stmts <- mk_switch tag_expr (sortLe le branches)
663 mb_deflt_id lo_tag hi_tag via_C
667 (t1,_) `le` (t2,_) = t1 <= t2
670 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
671 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
674 -- SINGLETON TAG RANGE: no case analysis to do
675 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
677 = ASSERT( tag == lo_tag )
680 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
681 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
683 -- The simplifier might have eliminated a case
684 -- so we may have e.g. case xs of
686 -- In that situation we can be sure the (:) case
687 -- can't happen, so no need to test
689 -- SINGLETON BRANCH: one equality check to do
690 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
691 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
693 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
694 -- We have lo_tag < hi_tag, but there's only one branch,
695 -- so there must be a default
697 -- ToDo: we might want to check for the two branch case, where one of
698 -- the branches is the tag 0, because comparing '== 0' is likely to be
699 -- more efficient than other kinds of comparison.
701 -- DENSE TAG RANGE: use a switch statment.
703 -- We also use a switch uncoditionally when compiling via C, because
704 -- this will get emitted as a C switch statement and the C compiler
705 -- should do a good job of optimising it. Also, older GCC versions
706 -- (2.95 in particular) have problems compiling the complicated
707 -- if-trees generated by this code, so compiling to a switch every
708 -- time works around that problem.
710 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
711 | use_switch -- Use a switch
712 = do { branch_ids <- mapM forkCgStmts (map snd branches)
714 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
716 find_branch :: ConTagZ -> Maybe BlockId
717 find_branch i = assocDefault mb_deflt tagged_blk_ids i
719 -- NB. we have eliminated impossible branches at
720 -- either end of the range (see below), so the first
721 -- tag of a real branch is real_lo_tag (not lo_tag).
722 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
724 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
726 ; ASSERT(not (all isNothing arms))
727 return (oneCgStmt switch_stmt)
730 -- if we can knock off a bunch of default cases with one if, then do so
731 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
732 = do { (assign_tag, tag_expr') <- assignNonPtrTemp' tag_expr
733 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
734 branch = CmmCondBranch cond deflt
735 ; stmts <- mk_switch tag_expr' branches mb_deflt
736 lowest_branch hi_tag via_C
737 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
740 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
741 = do { (assign_tag, tag_expr') <- assignNonPtrTemp' tag_expr
742 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
743 branch = CmmCondBranch cond deflt
744 ; stmts <- mk_switch tag_expr' branches mb_deflt
745 lo_tag highest_branch via_C
746 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
749 | otherwise -- Use an if-tree
750 = do { (assign_tag, tag_expr') <- assignNonPtrTemp' tag_expr
751 -- To avoid duplication
752 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
753 lo_tag (mid_tag-1) via_C
754 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
756 ; hi_id <- forkCgStmts hi_stmts
757 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
758 branch_stmt = CmmCondBranch cond hi_id
759 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
761 -- we test (e >= mid_tag) rather than (e < mid_tag), because
762 -- the former works better when e is a comparison, and there
763 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
764 -- generator can reduce the condition to e itself without
765 -- having to reverse the sense of the comparison: comparisons
766 -- can't always be easily reversed (eg. floating
769 use_switch = {- pprTrace "mk_switch" (
770 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
771 text "branches:" <+> ppr (map fst branches) <+>
772 text "n_branches:" <+> int n_branches <+>
773 text "lo_tag:" <+> int lo_tag <+>
774 text "hi_tag:" <+> int hi_tag <+>
775 text "real_lo_tag:" <+> int real_lo_tag <+>
776 text "real_hi_tag:" <+> int real_hi_tag) $ -}
777 ASSERT( n_branches > 1 && n_tags > 1 )
778 n_tags > 2 && (via_C || (dense && big_enough))
779 -- up to 4 branches we use a decision tree, otherwise
780 -- a switch (== jump table in the NCG). This seems to be
781 -- optimal, and corresponds with what gcc does.
782 big_enough = n_branches > 4
783 dense = n_branches > (n_tags `div` 2)
784 n_branches = length branches
786 -- ignore default slots at each end of the range if there's
787 -- no default branch defined.
788 lowest_branch = fst (head branches)
789 highest_branch = fst (last branches)
792 | isNothing mb_deflt = lowest_branch
796 | isNothing mb_deflt = highest_branch
799 n_tags = real_hi_tag - real_lo_tag + 1
801 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
802 -- lo_tag <= mid_tag < hi_tag
803 -- lo_branches have tags < mid_tag
804 -- hi_branches have tags >= mid_tag
806 (mid_tag,_) = branches !! (n_branches `div` 2)
807 -- 2 branches => n_branches `div` 2 = 1
808 -- => branches !! 1 give the *second* tag
809 -- There are always at least 2 branches here
811 (lo_branches, hi_branches) = span is_lo branches
812 is_lo (t,_) = t < mid_tag
816 | isTrivialCmmExpr e = return (CmmNop, e)
817 | otherwise = do { reg <- newNonPtrTemp (cmmExprRep e)
818 ; return (CmmAssign (CmmLocal reg) e, CmmReg (CmmLocal reg)) }
820 emitLitSwitch :: CmmExpr -- Tag to switch on
821 -> [(Literal, CgStmts)] -- Tagged branches
822 -> CgStmts -- Default branch (always)
823 -> Code -- Emit the code
824 -- Used for general literals, whose size might not be a word,
825 -- where there is always a default case, and where we don't know
826 -- the range of values for certain. For simplicity we always generate a tree.
828 -- ToDo: for integers we could do better here, perhaps by generalising
829 -- mk_switch and using that. --SDM 15/09/2004
830 emitLitSwitch scrut [] deflt
832 emitLitSwitch scrut branches deflt_blk
833 = do { scrut' <- assignNonPtrTemp scrut
834 ; deflt_blk_id <- forkCgStmts deflt_blk
835 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
838 le (t1,_) (t2,_) = t1 <= t2
840 mk_lit_switch :: CmmExpr -> BlockId
841 -> [(Literal,CgStmts)]
843 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
844 = return (consCgStmt if_stmt blk)
846 cmm_lit = mkSimpleLit lit
847 rep = cmmLitRep cmm_lit
848 cond = CmmMachOp (MO_Ne rep) [scrut, CmmLit cmm_lit]
849 if_stmt = CmmCondBranch cond deflt_blk_id
851 mk_lit_switch scrut deflt_blk_id branches
852 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
853 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
854 ; lo_blk_id <- forkCgStmts lo_blk
855 ; let if_stmt = CmmCondBranch cond lo_blk_id
856 ; return (if_stmt `consCgStmt` hi_blk) }
858 n_branches = length branches
859 (mid_lit,_) = branches !! (n_branches `div` 2)
860 -- See notes above re mid_tag
862 (lo_branches, hi_branches) = span is_lo branches
863 is_lo (t,_) = t < mid_lit
865 cond = CmmMachOp (mkLtOp mid_lit)
866 [scrut, CmmLit (mkSimpleLit mid_lit)]
868 -------------------------------------------------------------------------
870 -- Simultaneous assignment
872 -------------------------------------------------------------------------
875 emitSimultaneously :: CmmStmts -> Code
876 -- Emit code to perform the assignments in the
877 -- input simultaneously, using temporary variables when necessary.
879 -- The Stmts must be:
880 -- CmmNop, CmmComment, CmmAssign, CmmStore
884 -- We use the strongly-connected component algorithm, in which
885 -- * the vertices are the statements
886 -- * an edge goes from s1 to s2 iff
887 -- s1 assigns to something s2 uses
888 -- that is, if s1 should *follow* s2 in the final order
890 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
891 -- for fast comparison
893 emitSimultaneously stmts
895 case filterOut isNopStmt (stmtList stmts) of
898 [stmt] -> stmtC stmt -- It's often just one stmt
899 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
901 doSimultaneously1 :: [CVertex] -> Code
902 doSimultaneously1 vertices
904 edges = [ (vertex, key1, edges_from stmt1)
905 | vertex@(key1, stmt1) <- vertices
907 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
908 stmt1 `mustFollow` stmt2
910 components = stronglyConnComp edges
912 -- do_components deal with one strongly-connected component
913 -- Not cyclic, or singleton? Just do it
914 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
915 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
917 -- Cyclic? Then go via temporaries. Pick one to
918 -- break the loop and try again with the rest.
919 do_component (CyclicSCC ((n,first_stmt) : rest))
920 = do { from_temp <- go_via_temp first_stmt
921 ; doSimultaneously1 rest
924 go_via_temp (CmmAssign dest src)
925 = do { tmp <- newNonPtrTemp (cmmRegRep dest) -- TODO FIXME NOW if the pair of assignments move across a call this will be wrong
926 ; stmtC (CmmAssign (CmmLocal tmp) src)
927 ; return (CmmAssign dest (CmmReg (CmmLocal tmp))) }
928 go_via_temp (CmmStore dest src)
929 = do { tmp <- newNonPtrTemp (cmmExprRep src) -- TODO FIXME NOW if the pair of assignemnts move across a call this will be wrong
930 ; stmtC (CmmAssign (CmmLocal tmp) src)
931 ; return (CmmStore dest (CmmReg (CmmLocal tmp))) }
933 mapCs do_component components
935 mustFollow :: CmmStmt -> CmmStmt -> Bool
936 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
937 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprRep e)) stmt
938 CmmNop `mustFollow` stmt = False
939 CmmComment _ `mustFollow` stmt = False
942 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
943 -- True if the fn is true of any input of the stmt
944 anySrc p (CmmAssign _ e) = p e
945 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
946 anySrc p (CmmComment _) = False
947 anySrc p CmmNop = False
948 anySrc p other = True -- Conservative
950 regUsedIn :: CmmReg -> CmmExpr -> Bool
951 reg `regUsedIn` CmmLit _ = False
952 reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e
953 reg `regUsedIn` CmmReg reg' = reg == reg'
954 reg `regUsedIn` CmmRegOff reg' _ = reg == reg'
955 reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es
957 locUsedIn :: CmmExpr -> MachRep -> CmmExpr -> Bool
958 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
959 -- 'e'. Returns True if it's not sure.
960 locUsedIn loc rep (CmmLit _) = False
961 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
962 locUsedIn loc rep (CmmReg reg') = False
963 locUsedIn loc rep (CmmRegOff reg' _) = False
964 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
966 possiblySameLoc :: CmmExpr -> MachRep -> CmmExpr -> MachRep -> Bool
967 -- Assumes that distinct registers (eg Hp, Sp) do not
968 -- point to the same location, nor any offset thereof.
969 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
970 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
971 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
972 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
973 = r1==r2 && end1 > start2 && end2 > start1
975 end1 = start1 + machRepByteWidth rep1
976 end2 = start2 + machRepByteWidth rep2
978 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
979 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative
981 -------------------------------------------------------------------------
983 -- Static Reference Tables
985 -------------------------------------------------------------------------
987 -- There is just one SRT for each top level binding; all the nested
988 -- bindings use sub-sections of this SRT. The label is passed down to
989 -- the nested bindings via the monad.
991 getSRTInfo :: FCode C_SRT
993 srt_lbl <- getSRTLabel
996 -- TODO: Should we panic in this case?
997 -- Someone obviously thinks there should be an SRT
998 NoSRT -> return NoC_SRT
1000 | len > hALF_WORD_SIZE_IN_BITS || bmp == [fromIntegral srt_escape]
1001 -> do id <- newUnique
1002 let srt_desc_lbl = mkLargeSRTLabel id
1003 emitRODataLits srt_desc_lbl
1004 ( cmmLabelOffW srt_lbl off
1005 : mkWordCLit (fromIntegral len)
1006 : map mkWordCLit bmp)
1007 return (C_SRT srt_desc_lbl 0 srt_escape)
1011 -> return (C_SRT srt_lbl off (fromIntegral (head bmp)))
1012 -- The fromIntegral converts to StgHalfWord
1014 srt_escape = (-1) :: StgHalfWord