1 -----------------------------------------------------------------------------
3 -- Code generator utilities; mostly monadic
5 -- (c) The University of Glasgow 2004-2006
7 -----------------------------------------------------------------------------
12 emitDataLits, mkDataLits,
13 emitRODataLits, mkRODataLits,
14 emitIf, emitIfThenElse,
15 emitRtsCall, emitRtsCallWithVols, emitRtsCallWithResult,
16 assignNonPtrTemp, newNonPtrTemp,
17 assignPtrTemp, newPtrTemp,
19 emitSwitch, emitLitSwitch,
22 callerSaveVolatileRegs, get_GlobalReg_addr,
24 cmmAndWord, cmmOrWord, cmmNegate, cmmEqWord, cmmNeWord,
26 cmmOffsetExprW, cmmOffsetExprB,
27 cmmRegOffW, cmmRegOffB,
28 cmmLabelOffW, cmmLabelOffB,
29 cmmOffsetW, cmmOffsetB,
30 cmmOffsetLitW, cmmOffsetLitB,
32 cmmConstrTag, cmmConstrTag1,
34 tagForCon, tagCons, isSmallFamily,
35 cmmUntag, cmmIsTagged, cmmGetTag,
39 mkStringCLit, mkByteStringCLit,
46 #include "HsVersions.h"
55 import PprCmm ( {- instances -} )
62 import StgSyn (SRT(..))
79 -------------------------------------------------------------------------
81 -- Random small functions
83 -------------------------------------------------------------------------
85 addIdReps :: [Id] -> [(CgRep, Id)]
86 addIdReps ids = [(idCgRep id, id) | id <- ids]
88 -------------------------------------------------------------------------
92 -------------------------------------------------------------------------
94 cgLit :: Literal -> FCode CmmLit
95 cgLit (MachStr s) = mkByteStringCLit (bytesFS s)
96 -- not unpackFS; we want the UTF-8 byte stream.
97 cgLit other_lit = return (mkSimpleLit other_lit)
99 mkSimpleLit :: Literal -> CmmLit
100 mkSimpleLit (MachChar c) = CmmInt (fromIntegral (ord c)) wordRep
101 mkSimpleLit MachNullAddr = zeroCLit
102 mkSimpleLit (MachInt i) = CmmInt i wordRep
103 mkSimpleLit (MachInt64 i) = CmmInt i I64
104 mkSimpleLit (MachWord i) = CmmInt i wordRep
105 mkSimpleLit (MachWord64 i) = CmmInt i I64
106 mkSimpleLit (MachFloat r) = CmmFloat r F32
107 mkSimpleLit (MachDouble r) = CmmFloat r F64
108 mkSimpleLit (MachLabel fs ms) = CmmLabel (mkForeignLabel fs ms is_dyn)
110 is_dyn = False -- ToDo: fix me
112 mkLtOp :: Literal -> MachOp
113 -- On signed literals we must do a signed comparison
114 mkLtOp (MachInt _) = MO_S_Lt wordRep
115 mkLtOp (MachFloat _) = MO_S_Lt F32
116 mkLtOp (MachDouble _) = MO_S_Lt F64
117 mkLtOp lit = MO_U_Lt (cmmLitRep (mkSimpleLit lit))
120 ---------------------------------------------------
122 -- Cmm data type functions
124 ---------------------------------------------------
126 -----------------------
127 -- The "B" variants take byte offsets
128 cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr
129 cmmRegOffB = cmmRegOff
131 cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr
132 cmmOffsetB = cmmOffset
134 cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr
135 cmmOffsetExprB = cmmOffsetExpr
137 cmmLabelOffB :: CLabel -> ByteOff -> CmmLit
138 cmmLabelOffB = cmmLabelOff
140 cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit
141 cmmOffsetLitB = cmmOffsetLit
143 -----------------------
144 -- The "W" variants take word offsets
145 cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr
146 -- The second arg is a *word* offset; need to change it to bytes
147 cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n)
148 cmmOffsetExprW e wd_off = cmmIndexExpr wordRep e wd_off
150 cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr
151 cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n)
153 cmmRegOffW :: CmmReg -> WordOff -> CmmExpr
154 cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE)
156 cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit
157 cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off)
159 cmmLabelOffW :: CLabel -> WordOff -> CmmLit
160 cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off)
162 cmmLoadIndexW :: CmmExpr -> Int -> CmmExpr
163 cmmLoadIndexW base off
164 = CmmLoad (cmmOffsetW base off) wordRep
166 -----------------------
167 cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord :: CmmExpr -> CmmExpr -> CmmExpr
168 cmmOrWord e1 e2 = CmmMachOp mo_wordOr [e1, e2]
169 cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2]
170 cmmNeWord e1 e2 = CmmMachOp mo_wordNe [e1, e2]
171 cmmEqWord e1 e2 = CmmMachOp mo_wordEq [e1, e2]
172 cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2]
173 cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2]
174 cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2]
175 --cmmShlWord e1 e2 = CmmMachOp mo_wordShl [e1, e2]
176 --cmmUShrWord e1 e2 = CmmMachOp mo_wordUShr [e1, e2]
177 cmmSubWord e1 e2 = CmmMachOp mo_wordSub [e1, e2]
179 cmmNegate :: CmmExpr -> CmmExpr
180 cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep)
181 cmmNegate e = CmmMachOp (MO_S_Neg (cmmExprRep e)) [e]
183 blankWord :: CmmStatic
184 blankWord = CmmUninitialised wORD_SIZE
188 --cmmTagBits = CmmLit (mkIntCLit tAG_BITS)
189 cmmTagMask = CmmLit (mkIntCLit tAG_MASK)
190 cmmPointerMask = CmmLit (mkIntCLit (complement tAG_MASK))
192 -- Used to untag a possibly tagged pointer
193 -- A static label need not be untagged
194 cmmUntag e@(CmmLit (CmmLabel _)) = e
196 cmmUntag e = (e `cmmAndWord` cmmPointerMask)
198 cmmGetTag e = (e `cmmAndWord` cmmTagMask)
200 -- Test if a closure pointer is untagged
201 cmmIsTagged e = (e `cmmAndWord` cmmTagMask)
202 `cmmNeWord` CmmLit zeroCLit
204 cmmConstrTag e = (e `cmmAndWord` cmmTagMask) `cmmSubWord` (CmmLit (mkIntCLit 1))
205 -- Get constructor tag, but one based.
206 cmmConstrTag1 e = e `cmmAndWord` cmmTagMask
209 The family size of a data type (the number of constructors)
211 * small, if the family size < 2**tag_bits
214 Small families can have the constructor tag in the tag
216 Big families only use the tag value 1 to represent
219 isSmallFamily fam_size = fam_size <= mAX_PTR_TAG
223 con_tag = dataConTagZ con
224 fam_size = tyConFamilySize (dataConTyCon con)
225 tag | isSmallFamily fam_size = con_tag + 1
228 --Tag an expression, to do: refactor, this appears in some other module.
229 tagCons con expr = cmmOffsetB expr (tagForCon con)
231 -- Copied from CgInfoTbls.hs
232 -- We keep the *zero-indexed* tag in the srt_len field of the info
233 -- table of a data constructor.
234 dataConTagZ :: DataCon -> ConTagZ
235 dataConTagZ con = dataConTag con - fIRST_TAG
237 -----------------------
240 mkWordCLit :: StgWord -> CmmLit
241 mkWordCLit wd = CmmInt (fromIntegral wd) wordRep
243 packHalfWordsCLit :: (Integral a, Integral b) => a -> b -> CmmLit
244 -- Make a single word literal in which the lower_half_word is
245 -- at the lower address, and the upper_half_word is at the
247 -- ToDo: consider using half-word lits instead
248 -- but be careful: that's vulnerable when reversed
249 packHalfWordsCLit lower_half_word upper_half_word
250 #ifdef WORDS_BIGENDIAN
251 = mkWordCLit ((fromIntegral lower_half_word `shiftL` hALF_WORD_SIZE_IN_BITS)
252 .|. fromIntegral upper_half_word)
254 = mkWordCLit ((fromIntegral lower_half_word)
255 .|. (fromIntegral upper_half_word `shiftL` hALF_WORD_SIZE_IN_BITS))
258 --------------------------------------------------------------------------
260 -- Incrementing a memory location
262 --------------------------------------------------------------------------
264 addToMem :: MachRep -- rep of the counter
265 -> CmmExpr -- Address
266 -> Int -- What to add (a word)
268 addToMem rep ptr n = addToMemE rep ptr (CmmLit (CmmInt (toInteger n) rep))
270 addToMemE :: MachRep -- rep of the counter
271 -> CmmExpr -- Address
272 -> CmmExpr -- What to add (a word-typed expression)
275 = CmmStore ptr (CmmMachOp (MO_Add rep) [CmmLoad ptr rep, n])
277 -------------------------------------------------------------------------
279 -- Converting a closure tag to a closure for enumeration types
280 -- (this is the implementation of tagToEnum#).
282 -------------------------------------------------------------------------
284 tagToClosure :: TyCon -> CmmExpr -> CmmExpr
285 tagToClosure tycon tag
286 = CmmLoad (cmmOffsetExprW closure_tbl tag) wordRep
287 where closure_tbl = CmmLit (CmmLabel lbl)
288 lbl = mkClosureTableLabel (tyConName tycon)
290 -------------------------------------------------------------------------
292 -- Conditionals and rts calls
294 -------------------------------------------------------------------------
296 emitIf :: CmmExpr -- Boolean
299 -- Emit (if e then x)
300 -- ToDo: reverse the condition to avoid the extra branch instruction if possible
301 -- (some conditionals aren't reversible. eg. floating point comparisons cannot
302 -- be inverted because there exist some values for which both comparisons
303 -- return False, such as NaN.)
304 emitIf cond then_part
305 = do { then_id <- newLabelC
306 ; join_id <- newLabelC
307 ; stmtC (CmmCondBranch cond then_id)
308 ; stmtC (CmmBranch join_id)
314 emitIfThenElse :: CmmExpr -- Boolean
318 -- Emit (if e then x else y)
319 emitIfThenElse cond then_part else_part
320 = do { then_id <- newLabelC
321 ; else_id <- newLabelC
322 ; join_id <- newLabelC
323 ; stmtC (CmmCondBranch cond then_id)
325 ; stmtC (CmmBranch join_id)
331 emitRtsCall :: LitString -> [(CmmExpr,MachHint)] -> Bool -> Code
332 emitRtsCall fun args safe = emitRtsCall' [] fun args Nothing safe
333 -- The 'Nothing' says "save all global registers"
335 emitRtsCallWithVols :: LitString -> [(CmmExpr,MachHint)] -> [GlobalReg] -> Bool -> Code
336 emitRtsCallWithVols fun args vols safe
337 = emitRtsCall' [] fun args (Just vols) safe
339 emitRtsCallWithResult :: LocalReg -> MachHint -> LitString
340 -> [(CmmExpr,MachHint)] -> Bool -> Code
341 emitRtsCallWithResult res hint fun args safe
342 = emitRtsCall' [(res,hint)] fun args Nothing safe
344 -- Make a call to an RTS C procedure
348 -> [(CmmExpr,MachHint)]
350 -> Bool -- True <=> CmmSafe call
352 emitRtsCall' res fun args vols safe = do
354 then getSRTInfo >>= (return . CmmSafe)
355 else return CmmUnsafe
357 stmtC (CmmCall target res args safety)
360 (caller_save, caller_load) = callerSaveVolatileRegs vols
361 target = CmmCallee fun_expr CCallConv
362 fun_expr = mkLblExpr (mkRtsCodeLabel fun)
364 -----------------------------------------------------------------------------
366 -- Caller-Save Registers
368 -----------------------------------------------------------------------------
370 -- Here we generate the sequence of saves/restores required around a
371 -- foreign call instruction.
373 -- TODO: reconcile with includes/Regs.h
374 -- * Regs.h claims that BaseReg should be saved last and loaded first
375 -- * This might not have been tickled before since BaseReg is callee save
376 -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim
377 callerSaveVolatileRegs :: Maybe [GlobalReg] -> ([CmmStmt], [CmmStmt])
378 callerSaveVolatileRegs vols = (caller_save, caller_load)
380 caller_save = foldr ($!) [] (map callerSaveGlobalReg regs_to_save)
381 caller_load = foldr ($!) [] (map callerRestoreGlobalReg regs_to_save)
383 system_regs = [Sp,SpLim,Hp,HpLim,CurrentTSO,CurrentNursery,
384 {-SparkHd,SparkTl,SparkBase,SparkLim,-}BaseReg ]
386 regs_to_save = system_regs ++ vol_list
388 vol_list = case vols of Nothing -> all_of_em; Just regs -> regs
390 all_of_em = [ VanillaReg n | n <- [0..mAX_Vanilla_REG] ]
391 ++ [ FloatReg n | n <- [0..mAX_Float_REG] ]
392 ++ [ DoubleReg n | n <- [0..mAX_Double_REG] ]
393 ++ [ LongReg n | n <- [0..mAX_Long_REG] ]
395 callerSaveGlobalReg reg next
397 CmmStore (get_GlobalReg_addr reg)
398 (CmmReg (CmmGlobal reg)) : next
401 callerRestoreGlobalReg reg next
403 CmmAssign (CmmGlobal reg)
404 (CmmLoad (get_GlobalReg_addr reg) (globalRegRep reg))
408 -- -----------------------------------------------------------------------------
411 -- We map STG registers onto appropriate CmmExprs. Either they map
412 -- to real machine registers or stored as offsets from BaseReg. Given
413 -- a GlobalReg, get_GlobalReg_addr always produces the
414 -- register table address for it.
415 -- (See also get_GlobalReg_reg_or_addr in MachRegs)
417 get_GlobalReg_addr :: GlobalReg -> CmmExpr
418 get_GlobalReg_addr BaseReg = regTableOffset 0
419 get_GlobalReg_addr mid = get_Regtable_addr_from_offset
420 (globalRegRep mid) (baseRegOffset mid)
422 -- Calculate a literal representing an offset into the register table.
423 -- Used when we don't have an actual BaseReg to offset from.
425 CmmLit (CmmLabelOff mkMainCapabilityLabel (oFFSET_Capability_r + n))
427 get_Regtable_addr_from_offset :: MachRep -> Int -> CmmExpr
428 get_Regtable_addr_from_offset rep offset =
430 CmmRegOff (CmmGlobal BaseReg) offset
432 regTableOffset offset
436 -- | Returns 'True' if this global register is stored in a caller-saves
439 callerSaves :: GlobalReg -> Bool
441 #ifdef CALLER_SAVES_Base
442 callerSaves BaseReg = True
444 #ifdef CALLER_SAVES_R1
445 callerSaves (VanillaReg 1) = True
447 #ifdef CALLER_SAVES_R2
448 callerSaves (VanillaReg 2) = True
450 #ifdef CALLER_SAVES_R3
451 callerSaves (VanillaReg 3) = True
453 #ifdef CALLER_SAVES_R4
454 callerSaves (VanillaReg 4) = True
456 #ifdef CALLER_SAVES_R5
457 callerSaves (VanillaReg 5) = True
459 #ifdef CALLER_SAVES_R6
460 callerSaves (VanillaReg 6) = True
462 #ifdef CALLER_SAVES_R7
463 callerSaves (VanillaReg 7) = True
465 #ifdef CALLER_SAVES_R8
466 callerSaves (VanillaReg 8) = True
468 #ifdef CALLER_SAVES_F1
469 callerSaves (FloatReg 1) = True
471 #ifdef CALLER_SAVES_F2
472 callerSaves (FloatReg 2) = True
474 #ifdef CALLER_SAVES_F3
475 callerSaves (FloatReg 3) = True
477 #ifdef CALLER_SAVES_F4
478 callerSaves (FloatReg 4) = True
480 #ifdef CALLER_SAVES_D1
481 callerSaves (DoubleReg 1) = True
483 #ifdef CALLER_SAVES_D2
484 callerSaves (DoubleReg 2) = True
486 #ifdef CALLER_SAVES_L1
487 callerSaves (LongReg 1) = True
489 #ifdef CALLER_SAVES_Sp
490 callerSaves Sp = True
492 #ifdef CALLER_SAVES_SpLim
493 callerSaves SpLim = True
495 #ifdef CALLER_SAVES_Hp
496 callerSaves Hp = True
498 #ifdef CALLER_SAVES_HpLim
499 callerSaves HpLim = True
501 #ifdef CALLER_SAVES_CurrentTSO
502 callerSaves CurrentTSO = True
504 #ifdef CALLER_SAVES_CurrentNursery
505 callerSaves CurrentNursery = True
507 callerSaves _ = False
510 -- -----------------------------------------------------------------------------
511 -- Information about global registers
513 baseRegOffset :: GlobalReg -> Int
515 baseRegOffset (VanillaReg 1) = oFFSET_StgRegTable_rR1
516 baseRegOffset (VanillaReg 2) = oFFSET_StgRegTable_rR2
517 baseRegOffset (VanillaReg 3) = oFFSET_StgRegTable_rR3
518 baseRegOffset (VanillaReg 4) = oFFSET_StgRegTable_rR4
519 baseRegOffset (VanillaReg 5) = oFFSET_StgRegTable_rR5
520 baseRegOffset (VanillaReg 6) = oFFSET_StgRegTable_rR6
521 baseRegOffset (VanillaReg 7) = oFFSET_StgRegTable_rR7
522 baseRegOffset (VanillaReg 8) = oFFSET_StgRegTable_rR8
523 baseRegOffset (VanillaReg 9) = oFFSET_StgRegTable_rR9
524 baseRegOffset (VanillaReg 10) = oFFSET_StgRegTable_rR10
525 baseRegOffset (FloatReg 1) = oFFSET_StgRegTable_rF1
526 baseRegOffset (FloatReg 2) = oFFSET_StgRegTable_rF2
527 baseRegOffset (FloatReg 3) = oFFSET_StgRegTable_rF3
528 baseRegOffset (FloatReg 4) = oFFSET_StgRegTable_rF4
529 baseRegOffset (DoubleReg 1) = oFFSET_StgRegTable_rD1
530 baseRegOffset (DoubleReg 2) = oFFSET_StgRegTable_rD2
531 baseRegOffset Sp = oFFSET_StgRegTable_rSp
532 baseRegOffset SpLim = oFFSET_StgRegTable_rSpLim
533 baseRegOffset (LongReg 1) = oFFSET_StgRegTable_rL1
534 baseRegOffset Hp = oFFSET_StgRegTable_rHp
535 baseRegOffset HpLim = oFFSET_StgRegTable_rHpLim
536 baseRegOffset CurrentTSO = oFFSET_StgRegTable_rCurrentTSO
537 baseRegOffset CurrentNursery = oFFSET_StgRegTable_rCurrentNursery
538 baseRegOffset HpAlloc = oFFSET_StgRegTable_rHpAlloc
539 baseRegOffset GCEnter1 = oFFSET_stgGCEnter1
540 baseRegOffset GCFun = oFFSET_stgGCFun
542 baseRegOffset BaseReg = panic "baseRegOffset:BaseReg"
543 baseRegOffset _ = panic "baseRegOffset:other"
547 -------------------------------------------------------------------------
549 -- Strings generate a top-level data block
551 -------------------------------------------------------------------------
553 emitDataLits :: CLabel -> [CmmLit] -> Code
554 -- Emit a data-segment data block
555 emitDataLits lbl lits
556 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
558 mkDataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info stmt
559 -- Emit a data-segment data block
561 = CmmData Data (CmmDataLabel lbl : map CmmStaticLit lits)
563 emitRODataLits :: CLabel -> [CmmLit] -> Code
564 -- Emit a read-only data block
565 emitRODataLits lbl lits
566 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
567 where section | any needsRelocation lits = RelocatableReadOnlyData
568 | otherwise = ReadOnlyData
569 needsRelocation (CmmLabel _) = True
570 needsRelocation (CmmLabelOff _ _) = True
571 needsRelocation _ = False
573 mkRODataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info stmt
574 mkRODataLits lbl lits
575 = CmmData section (CmmDataLabel lbl : map CmmStaticLit lits)
576 where section | any needsRelocation lits = RelocatableReadOnlyData
577 | otherwise = ReadOnlyData
578 needsRelocation (CmmLabel _) = True
579 needsRelocation (CmmLabelOff _ _) = True
580 needsRelocation _ = False
582 mkStringCLit :: String -> FCode CmmLit
583 -- Make a global definition for the string,
584 -- and return its label
585 mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str)
587 mkByteStringCLit :: [Word8] -> FCode CmmLit
588 mkByteStringCLit bytes
589 = do { uniq <- newUnique
590 ; let lbl = mkStringLitLabel uniq
591 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes]
592 ; return (CmmLabel lbl) }
594 -------------------------------------------------------------------------
596 -- Assigning expressions to temporaries
598 -------------------------------------------------------------------------
600 assignNonPtrTemp :: CmmExpr -> FCode CmmExpr
601 -- For a non-trivial expression, e, create a local
602 -- variable and assign the expression to it
604 | isTrivialCmmExpr e = return e
605 | otherwise = do { reg <- newNonPtrTemp (cmmExprRep e)
606 ; stmtC (CmmAssign (CmmLocal reg) e)
607 ; return (CmmReg (CmmLocal reg)) }
609 assignPtrTemp :: CmmExpr -> FCode CmmExpr
610 -- For a non-trivial expression, e, create a local
611 -- variable and assign the expression to it
613 | isTrivialCmmExpr e = return e
614 | otherwise = do { reg <- newPtrTemp (cmmExprRep e)
615 ; stmtC (CmmAssign (CmmLocal reg) e)
616 ; return (CmmReg (CmmLocal reg)) }
618 newNonPtrTemp :: MachRep -> FCode LocalReg
619 newNonPtrTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep KindNonPtr) }
621 newPtrTemp :: MachRep -> FCode LocalReg
622 newPtrTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep KindPtr) }
625 -------------------------------------------------------------------------
627 -- Building case analysis
629 -------------------------------------------------------------------------
632 :: CmmExpr -- Tag to switch on
633 -> [(ConTagZ, CgStmts)] -- Tagged branches
634 -> Maybe CgStmts -- Default branch (if any)
635 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
636 -- outside this range is undefined
639 -- ONLY A DEFAULT BRANCH: no case analysis to do
640 emitSwitch tag_expr [] (Just stmts) _ _
644 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
645 = -- Just sort the branches before calling mk_sritch
648 Nothing -> return Nothing
649 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
651 ; dflags <- getDynFlags
652 ; let via_C | HscC <- hscTarget dflags = True
655 ; stmts <- mk_switch tag_expr (sortLe le branches)
656 mb_deflt_id lo_tag hi_tag via_C
660 (t1,_) `le` (t2,_) = t1 <= t2
663 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
664 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
667 -- SINGLETON TAG RANGE: no case analysis to do
668 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
670 = ASSERT( tag == lo_tag )
673 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
674 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
676 -- The simplifier might have eliminated a case
677 -- so we may have e.g. case xs of
679 -- In that situation we can be sure the (:) case
680 -- can't happen, so no need to test
682 -- SINGLETON BRANCH: one equality check to do
683 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
684 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
686 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
687 -- We have lo_tag < hi_tag, but there's only one branch,
688 -- so there must be a default
690 -- ToDo: we might want to check for the two branch case, where one of
691 -- the branches is the tag 0, because comparing '== 0' is likely to be
692 -- more efficient than other kinds of comparison.
694 -- DENSE TAG RANGE: use a switch statment.
696 -- We also use a switch uncoditionally when compiling via C, because
697 -- this will get emitted as a C switch statement and the C compiler
698 -- should do a good job of optimising it. Also, older GCC versions
699 -- (2.95 in particular) have problems compiling the complicated
700 -- if-trees generated by this code, so compiling to a switch every
701 -- time works around that problem.
703 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
704 | use_switch -- Use a switch
705 = do { branch_ids <- mapM forkCgStmts (map snd branches)
707 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
709 find_branch :: ConTagZ -> Maybe BlockId
710 find_branch i = assocDefault mb_deflt tagged_blk_ids i
712 -- NB. we have eliminated impossible branches at
713 -- either end of the range (see below), so the first
714 -- tag of a real branch is real_lo_tag (not lo_tag).
715 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
717 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
719 ; ASSERT(not (all isNothing arms))
720 return (oneCgStmt switch_stmt)
723 -- if we can knock off a bunch of default cases with one if, then do so
724 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
725 = do { (assign_tag, tag_expr') <- assignNonPtrTemp' tag_expr
726 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
727 branch = CmmCondBranch cond deflt
728 ; stmts <- mk_switch tag_expr' branches mb_deflt
729 lowest_branch hi_tag via_C
730 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
733 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
734 = do { (assign_tag, tag_expr') <- assignNonPtrTemp' tag_expr
735 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
736 branch = CmmCondBranch cond deflt
737 ; stmts <- mk_switch tag_expr' branches mb_deflt
738 lo_tag highest_branch via_C
739 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
742 | otherwise -- Use an if-tree
743 = do { (assign_tag, tag_expr') <- assignNonPtrTemp' tag_expr
744 -- To avoid duplication
745 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
746 lo_tag (mid_tag-1) via_C
747 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
749 ; hi_id <- forkCgStmts hi_stmts
750 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
751 branch_stmt = CmmCondBranch cond hi_id
752 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
754 -- we test (e >= mid_tag) rather than (e < mid_tag), because
755 -- the former works better when e is a comparison, and there
756 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
757 -- generator can reduce the condition to e itself without
758 -- having to reverse the sense of the comparison: comparisons
759 -- can't always be easily reversed (eg. floating
762 use_switch = {- pprTrace "mk_switch" (
763 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
764 text "branches:" <+> ppr (map fst branches) <+>
765 text "n_branches:" <+> int n_branches <+>
766 text "lo_tag:" <+> int lo_tag <+>
767 text "hi_tag:" <+> int hi_tag <+>
768 text "real_lo_tag:" <+> int real_lo_tag <+>
769 text "real_hi_tag:" <+> int real_hi_tag) $ -}
770 ASSERT( n_branches > 1 && n_tags > 1 )
771 n_tags > 2 && (via_C || (dense && big_enough))
772 -- up to 4 branches we use a decision tree, otherwise
773 -- a switch (== jump table in the NCG). This seems to be
774 -- optimal, and corresponds with what gcc does.
775 big_enough = n_branches > 4
776 dense = n_branches > (n_tags `div` 2)
777 n_branches = length branches
779 -- ignore default slots at each end of the range if there's
780 -- no default branch defined.
781 lowest_branch = fst (head branches)
782 highest_branch = fst (last branches)
785 | isNothing mb_deflt = lowest_branch
789 | isNothing mb_deflt = highest_branch
792 n_tags = real_hi_tag - real_lo_tag + 1
794 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
795 -- lo_tag <= mid_tag < hi_tag
796 -- lo_branches have tags < mid_tag
797 -- hi_branches have tags >= mid_tag
799 (mid_tag,_) = branches !! (n_branches `div` 2)
800 -- 2 branches => n_branches `div` 2 = 1
801 -- => branches !! 1 give the *second* tag
802 -- There are always at least 2 branches here
804 (lo_branches, hi_branches) = span is_lo branches
805 is_lo (t,_) = t < mid_tag
809 | isTrivialCmmExpr e = return (CmmNop, e)
810 | otherwise = do { reg <- newNonPtrTemp (cmmExprRep e)
811 ; return (CmmAssign (CmmLocal reg) e, CmmReg (CmmLocal reg)) }
813 emitLitSwitch :: CmmExpr -- Tag to switch on
814 -> [(Literal, CgStmts)] -- Tagged branches
815 -> CgStmts -- Default branch (always)
816 -> Code -- Emit the code
817 -- Used for general literals, whose size might not be a word,
818 -- where there is always a default case, and where we don't know
819 -- the range of values for certain. For simplicity we always generate a tree.
821 -- ToDo: for integers we could do better here, perhaps by generalising
822 -- mk_switch and using that. --SDM 15/09/2004
823 emitLitSwitch scrut [] deflt
825 emitLitSwitch scrut branches deflt_blk
826 = do { scrut' <- assignNonPtrTemp scrut
827 ; deflt_blk_id <- forkCgStmts deflt_blk
828 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
831 le (t1,_) (t2,_) = t1 <= t2
833 mk_lit_switch :: CmmExpr -> BlockId
834 -> [(Literal,CgStmts)]
836 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
837 = return (consCgStmt if_stmt blk)
839 cmm_lit = mkSimpleLit lit
840 rep = cmmLitRep cmm_lit
841 cond = CmmMachOp (MO_Ne rep) [scrut, CmmLit cmm_lit]
842 if_stmt = CmmCondBranch cond deflt_blk_id
844 mk_lit_switch scrut deflt_blk_id branches
845 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
846 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
847 ; lo_blk_id <- forkCgStmts lo_blk
848 ; let if_stmt = CmmCondBranch cond lo_blk_id
849 ; return (if_stmt `consCgStmt` hi_blk) }
851 n_branches = length branches
852 (mid_lit,_) = branches !! (n_branches `div` 2)
853 -- See notes above re mid_tag
855 (lo_branches, hi_branches) = span is_lo branches
856 is_lo (t,_) = t < mid_lit
858 cond = CmmMachOp (mkLtOp mid_lit)
859 [scrut, CmmLit (mkSimpleLit mid_lit)]
861 -------------------------------------------------------------------------
863 -- Simultaneous assignment
865 -------------------------------------------------------------------------
868 emitSimultaneously :: CmmStmts -> Code
869 -- Emit code to perform the assignments in the
870 -- input simultaneously, using temporary variables when necessary.
872 -- The Stmts must be:
873 -- CmmNop, CmmComment, CmmAssign, CmmStore
877 -- We use the strongly-connected component algorithm, in which
878 -- * the vertices are the statements
879 -- * an edge goes from s1 to s2 iff
880 -- s1 assigns to something s2 uses
881 -- that is, if s1 should *follow* s2 in the final order
883 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
884 -- for fast comparison
886 emitSimultaneously stmts
888 case filterOut isNopStmt (stmtList stmts) of
891 [stmt] -> stmtC stmt -- It's often just one stmt
892 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
894 doSimultaneously1 :: [CVertex] -> Code
895 doSimultaneously1 vertices
897 edges = [ (vertex, key1, edges_from stmt1)
898 | vertex@(key1, stmt1) <- vertices
900 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
901 stmt1 `mustFollow` stmt2
903 components = stronglyConnComp edges
905 -- do_components deal with one strongly-connected component
906 -- Not cyclic, or singleton? Just do it
907 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
908 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
910 -- Cyclic? Then go via temporaries. Pick one to
911 -- break the loop and try again with the rest.
912 do_component (CyclicSCC ((n,first_stmt) : rest))
913 = do { from_temp <- go_via_temp first_stmt
914 ; doSimultaneously1 rest
917 go_via_temp (CmmAssign dest src)
918 = do { tmp <- newNonPtrTemp (cmmRegRep dest) -- TODO FIXME NOW if the pair of assignments move across a call this will be wrong
919 ; stmtC (CmmAssign (CmmLocal tmp) src)
920 ; return (CmmAssign dest (CmmReg (CmmLocal tmp))) }
921 go_via_temp (CmmStore dest src)
922 = do { tmp <- newNonPtrTemp (cmmExprRep src) -- TODO FIXME NOW if the pair of assignemnts move across a call this will be wrong
923 ; stmtC (CmmAssign (CmmLocal tmp) src)
924 ; return (CmmStore dest (CmmReg (CmmLocal tmp))) }
926 mapCs do_component components
928 mustFollow :: CmmStmt -> CmmStmt -> Bool
929 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
930 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprRep e)) stmt
931 CmmNop `mustFollow` stmt = False
932 CmmComment _ `mustFollow` stmt = False
935 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
936 -- True if the fn is true of any input of the stmt
937 anySrc p (CmmAssign _ e) = p e
938 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
939 anySrc p (CmmComment _) = False
940 anySrc p CmmNop = False
941 anySrc p other = True -- Conservative
943 regUsedIn :: CmmReg -> CmmExpr -> Bool
944 reg `regUsedIn` CmmLit _ = False
945 reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e
946 reg `regUsedIn` CmmReg reg' = reg == reg'
947 reg `regUsedIn` CmmRegOff reg' _ = reg == reg'
948 reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es
950 locUsedIn :: CmmExpr -> MachRep -> CmmExpr -> Bool
951 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
952 -- 'e'. Returns True if it's not sure.
953 locUsedIn loc rep (CmmLit _) = False
954 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
955 locUsedIn loc rep (CmmReg reg') = False
956 locUsedIn loc rep (CmmRegOff reg' _) = False
957 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
959 possiblySameLoc :: CmmExpr -> MachRep -> CmmExpr -> MachRep -> Bool
960 -- Assumes that distinct registers (eg Hp, Sp) do not
961 -- point to the same location, nor any offset thereof.
962 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
963 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
964 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
965 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
966 = r1==r2 && end1 > start2 && end2 > start1
968 end1 = start1 + machRepByteWidth rep1
969 end2 = start2 + machRepByteWidth rep2
971 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
972 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative
974 -------------------------------------------------------------------------
976 -- Static Reference Tables
978 -------------------------------------------------------------------------
980 -- There is just one SRT for each top level binding; all the nested
981 -- bindings use sub-sections of this SRT. The label is passed down to
982 -- the nested bindings via the monad.
984 getSRTInfo :: FCode C_SRT
986 srt_lbl <- getSRTLabel
989 -- TODO: Should we panic in this case?
990 -- Someone obviously thinks there should be an SRT
991 NoSRT -> return NoC_SRT
993 | len > hALF_WORD_SIZE_IN_BITS || bmp == [fromIntegral srt_escape]
994 -> do id <- newUnique
995 let srt_desc_lbl = mkLargeSRTLabel id
996 emitRODataLits srt_desc_lbl
997 ( cmmLabelOffW srt_lbl off
998 : mkWordCLit (fromIntegral len)
999 : map mkWordCLit bmp)
1000 return (C_SRT srt_desc_lbl 0 srt_escape)
1004 -> return (C_SRT srt_lbl off (fromIntegral (head bmp)))
1005 -- The fromIntegral converts to StgHalfWord
1007 srt_escape = (-1) :: StgHalfWord