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/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) = CmmLabel (mkForeignLabel fs ms is_dyn)
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 ; else_id <- newLabelC
326 ; join_id <- newLabelC
327 ; stmtC (CmmCondBranch cond then_id)
329 ; stmtC (CmmBranch join_id)
335 emitRtsCall :: LitString -> [CmmHinted CmmExpr] -> Bool -> Code
336 emitRtsCall fun args safe = emitRtsCall' [] fun args Nothing safe
337 -- The 'Nothing' says "save all global registers"
339 emitRtsCallWithVols :: LitString -> [CmmHinted CmmExpr] -> [GlobalReg] -> Bool -> Code
340 emitRtsCallWithVols fun args vols safe
341 = emitRtsCall' [] fun args (Just vols) safe
343 emitRtsCallWithResult :: LocalReg -> ForeignHint -> LitString
344 -> [CmmHinted CmmExpr] -> Bool -> Code
345 emitRtsCallWithResult res hint fun args safe
346 = emitRtsCall' [CmmHinted res hint] fun args Nothing safe
348 -- Make a call to an RTS C procedure
350 :: [CmmHinted LocalReg]
352 -> [CmmHinted CmmExpr]
354 -> Bool -- True <=> CmmSafe call
356 emitRtsCall' res fun args vols safe = do
358 then getSRTInfo >>= (return . CmmSafe)
359 else return CmmUnsafe
361 stmtC (CmmCall target res args safety CmmMayReturn)
364 (caller_save, caller_load) = callerSaveVolatileRegs vols
365 target = CmmCallee fun_expr CCallConv
366 fun_expr = mkLblExpr (mkRtsCodeLabel fun)
368 -----------------------------------------------------------------------------
370 -- Caller-Save Registers
372 -----------------------------------------------------------------------------
374 -- Here we generate the sequence of saves/restores required around a
375 -- foreign call instruction.
377 -- TODO: reconcile with includes/Regs.h
378 -- * Regs.h claims that BaseReg should be saved last and loaded first
379 -- * This might not have been tickled before since BaseReg is callee save
380 -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim
381 callerSaveVolatileRegs :: Maybe [GlobalReg] -> ([CmmStmt], [CmmStmt])
382 callerSaveVolatileRegs vols = (caller_save, caller_load)
384 caller_save = foldr ($!) [] (map callerSaveGlobalReg regs_to_save)
385 caller_load = foldr ($!) [] (map callerRestoreGlobalReg regs_to_save)
387 system_regs = [Sp,SpLim,Hp,HpLim,CurrentTSO,CurrentNursery,
388 {-SparkHd,SparkTl,SparkBase,SparkLim,-}BaseReg ]
390 regs_to_save = system_regs ++ vol_list
392 vol_list = case vols of Nothing -> all_of_em; Just regs -> regs
394 all_of_em = [ VanillaReg n VNonGcPtr | n <- [0..mAX_Vanilla_REG] ]
395 -- The VNonGcPtr is a lie, but I don't think it matters
396 ++ [ FloatReg n | n <- [0..mAX_Float_REG] ]
397 ++ [ DoubleReg n | n <- [0..mAX_Double_REG] ]
398 ++ [ LongReg n | n <- [0..mAX_Long_REG] ]
400 callerSaveGlobalReg reg next
402 CmmStore (get_GlobalReg_addr reg)
403 (CmmReg (CmmGlobal reg)) : next
406 callerRestoreGlobalReg reg next
408 CmmAssign (CmmGlobal reg)
409 (CmmLoad (get_GlobalReg_addr reg) (globalRegType reg))
413 -- -----------------------------------------------------------------------------
416 -- We map STG registers onto appropriate CmmExprs. Either they map
417 -- to real machine registers or stored as offsets from BaseReg. Given
418 -- a GlobalReg, get_GlobalReg_addr always produces the
419 -- register table address for it.
420 -- (See also get_GlobalReg_reg_or_addr in MachRegs)
422 get_GlobalReg_addr :: GlobalReg -> CmmExpr
423 get_GlobalReg_addr BaseReg = regTableOffset 0
424 get_GlobalReg_addr mid = get_Regtable_addr_from_offset
425 (globalRegType mid) (baseRegOffset mid)
427 -- Calculate a literal representing an offset into the register table.
428 -- Used when we don't have an actual BaseReg to offset from.
430 CmmLit (CmmLabelOff mkMainCapabilityLabel (oFFSET_Capability_r + n))
432 get_Regtable_addr_from_offset :: CmmType -> Int -> CmmExpr
433 get_Regtable_addr_from_offset rep offset =
435 CmmRegOff (CmmGlobal BaseReg) offset
437 regTableOffset offset
441 -- | Returns @True@ if this global register is stored in a caller-saves
444 callerSaves :: GlobalReg -> Bool
446 #ifdef CALLER_SAVES_Base
447 callerSaves BaseReg = True
449 #ifdef CALLER_SAVES_R1
450 callerSaves (VanillaReg 1 _) = True
452 #ifdef CALLER_SAVES_R2
453 callerSaves (VanillaReg 2 _) = True
455 #ifdef CALLER_SAVES_R3
456 callerSaves (VanillaReg 3 _) = True
458 #ifdef CALLER_SAVES_R4
459 callerSaves (VanillaReg 4 _) = True
461 #ifdef CALLER_SAVES_R5
462 callerSaves (VanillaReg 5 _) = True
464 #ifdef CALLER_SAVES_R6
465 callerSaves (VanillaReg 6 _) = True
467 #ifdef CALLER_SAVES_R7
468 callerSaves (VanillaReg 7 _) = True
470 #ifdef CALLER_SAVES_R8
471 callerSaves (VanillaReg 8 _) = True
473 #ifdef CALLER_SAVES_F1
474 callerSaves (FloatReg 1) = True
476 #ifdef CALLER_SAVES_F2
477 callerSaves (FloatReg 2) = True
479 #ifdef CALLER_SAVES_F3
480 callerSaves (FloatReg 3) = True
482 #ifdef CALLER_SAVES_F4
483 callerSaves (FloatReg 4) = True
485 #ifdef CALLER_SAVES_D1
486 callerSaves (DoubleReg 1) = True
488 #ifdef CALLER_SAVES_D2
489 callerSaves (DoubleReg 2) = True
491 #ifdef CALLER_SAVES_L1
492 callerSaves (LongReg 1) = True
494 #ifdef CALLER_SAVES_Sp
495 callerSaves Sp = True
497 #ifdef CALLER_SAVES_SpLim
498 callerSaves SpLim = True
500 #ifdef CALLER_SAVES_Hp
501 callerSaves Hp = True
503 #ifdef CALLER_SAVES_HpLim
504 callerSaves HpLim = True
506 #ifdef CALLER_SAVES_CurrentTSO
507 callerSaves CurrentTSO = True
509 #ifdef CALLER_SAVES_CurrentNursery
510 callerSaves CurrentNursery = True
512 callerSaves _ = False
515 -- -----------------------------------------------------------------------------
516 -- Information about global registers
518 baseRegOffset :: GlobalReg -> Int
520 baseRegOffset (VanillaReg 1 _) = oFFSET_StgRegTable_rR1
521 baseRegOffset (VanillaReg 2 _) = oFFSET_StgRegTable_rR2
522 baseRegOffset (VanillaReg 3 _) = oFFSET_StgRegTable_rR3
523 baseRegOffset (VanillaReg 4 _) = oFFSET_StgRegTable_rR4
524 baseRegOffset (VanillaReg 5 _) = oFFSET_StgRegTable_rR5
525 baseRegOffset (VanillaReg 6 _) = oFFSET_StgRegTable_rR6
526 baseRegOffset (VanillaReg 7 _) = oFFSET_StgRegTable_rR7
527 baseRegOffset (VanillaReg 8 _) = oFFSET_StgRegTable_rR8
528 baseRegOffset (VanillaReg 9 _) = oFFSET_StgRegTable_rR9
529 baseRegOffset (VanillaReg 10 _) = oFFSET_StgRegTable_rR10
530 baseRegOffset (FloatReg 1) = oFFSET_StgRegTable_rF1
531 baseRegOffset (FloatReg 2) = oFFSET_StgRegTable_rF2
532 baseRegOffset (FloatReg 3) = oFFSET_StgRegTable_rF3
533 baseRegOffset (FloatReg 4) = oFFSET_StgRegTable_rF4
534 baseRegOffset (DoubleReg 1) = oFFSET_StgRegTable_rD1
535 baseRegOffset (DoubleReg 2) = oFFSET_StgRegTable_rD2
536 baseRegOffset Sp = oFFSET_StgRegTable_rSp
537 baseRegOffset SpLim = oFFSET_StgRegTable_rSpLim
538 baseRegOffset (LongReg 1) = oFFSET_StgRegTable_rL1
539 baseRegOffset Hp = oFFSET_StgRegTable_rHp
540 baseRegOffset HpLim = oFFSET_StgRegTable_rHpLim
541 baseRegOffset CurrentTSO = oFFSET_StgRegTable_rCurrentTSO
542 baseRegOffset CurrentNursery = oFFSET_StgRegTable_rCurrentNursery
543 baseRegOffset HpAlloc = oFFSET_StgRegTable_rHpAlloc
544 baseRegOffset EagerBlackholeInfo = oFFSET_stgEagerBlackholeInfo
545 baseRegOffset GCEnter1 = oFFSET_stgGCEnter1
546 baseRegOffset GCFun = oFFSET_stgGCFun
547 baseRegOffset BaseReg = panic "baseRegOffset:BaseReg"
548 baseRegOffset _ = panic "baseRegOffset:other"
551 -------------------------------------------------------------------------
553 -- Strings generate a top-level data block
555 -------------------------------------------------------------------------
557 emitDataLits :: CLabel -> [CmmLit] -> Code
558 -- Emit a data-segment data block
559 emitDataLits lbl lits
560 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
562 mkDataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
563 -- Emit a data-segment data block
565 = CmmData Data (CmmDataLabel lbl : map CmmStaticLit lits)
567 emitRODataLits :: String -> CLabel -> [CmmLit] -> Code
568 -- Emit a read-only data block
569 emitRODataLits caller lbl lits
570 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
571 where section | any needsRelocation lits = RelocatableReadOnlyData
572 | otherwise = ReadOnlyData
573 needsRelocation (CmmLabel _) = True
574 needsRelocation (CmmLabelOff _ _) = True
575 needsRelocation _ = False
577 mkRODataLits :: CLabel -> [CmmLit] -> GenCmmTop CmmStatic info graph
578 mkRODataLits lbl lits
579 = CmmData section (CmmDataLabel lbl : map CmmStaticLit lits)
580 where section | any needsRelocation lits = RelocatableReadOnlyData
581 | otherwise = ReadOnlyData
582 needsRelocation (CmmLabel _) = True
583 needsRelocation (CmmLabelOff _ _) = True
584 needsRelocation _ = False
586 mkStringCLit :: String -> FCode CmmLit
587 -- Make a global definition for the string,
588 -- and return its label
589 mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str)
591 mkByteStringCLit :: [Word8] -> FCode CmmLit
592 mkByteStringCLit bytes
593 = do { uniq <- newUnique
594 ; let lbl = mkStringLitLabel uniq
595 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes]
596 ; return (CmmLabel lbl) }
598 -------------------------------------------------------------------------
600 -- Assigning expressions to temporaries
602 -------------------------------------------------------------------------
604 assignTemp :: CmmExpr -> FCode CmmExpr
605 -- For a non-trivial expression, e, create a local
606 -- variable and assign the expression to it
608 | isTrivialCmmExpr e = return e
609 | otherwise = do { reg <- newTemp (cmmExprType e)
610 ; stmtC (CmmAssign (CmmLocal reg) e)
611 ; return (CmmReg (CmmLocal reg)) }
613 newTemp :: CmmType -> FCode LocalReg
614 newTemp rep = do { uniq <- newUnique; return (LocalReg uniq rep) }
616 -------------------------------------------------------------------------
618 -- Building case analysis
620 -------------------------------------------------------------------------
623 :: CmmExpr -- Tag to switch on
624 -> [(ConTagZ, CgStmts)] -- Tagged branches
625 -> Maybe CgStmts -- Default branch (if any)
626 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
627 -- outside this range is undefined
630 -- ONLY A DEFAULT BRANCH: no case analysis to do
631 emitSwitch tag_expr [] (Just stmts) _ _
635 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
636 = -- Just sort the branches before calling mk_sritch
639 Nothing -> return Nothing
640 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
642 ; dflags <- getDynFlags
643 ; let via_C | HscC <- hscTarget dflags = True
646 ; stmts <- mk_switch tag_expr (sortLe le branches)
647 mb_deflt_id lo_tag hi_tag via_C
651 (t1,_) `le` (t2,_) = t1 <= t2
654 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
655 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
658 -- SINGLETON TAG RANGE: no case analysis to do
659 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
661 = ASSERT( tag == lo_tag )
664 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
665 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
667 -- The simplifier might have eliminated a case
668 -- so we may have e.g. case xs of
670 -- In that situation we can be sure the (:) case
671 -- can't happen, so no need to test
673 -- SINGLETON BRANCH: one equality check to do
674 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
675 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
677 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
678 -- We have lo_tag < hi_tag, but there's only one branch,
679 -- so there must be a default
681 -- ToDo: we might want to check for the two branch case, where one of
682 -- the branches is the tag 0, because comparing '== 0' is likely to be
683 -- more efficient than other kinds of comparison.
685 -- DENSE TAG RANGE: use a switch statment.
687 -- We also use a switch uncoditionally when compiling via C, because
688 -- this will get emitted as a C switch statement and the C compiler
689 -- should do a good job of optimising it. Also, older GCC versions
690 -- (2.95 in particular) have problems compiling the complicated
691 -- if-trees generated by this code, so compiling to a switch every
692 -- time works around that problem.
694 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
695 | use_switch -- Use a switch
696 = do { branch_ids <- mapM forkCgStmts (map snd branches)
698 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
700 find_branch :: ConTagZ -> Maybe BlockId
701 find_branch i = assocDefault mb_deflt tagged_blk_ids i
703 -- NB. we have eliminated impossible branches at
704 -- either end of the range (see below), so the first
705 -- tag of a real branch is real_lo_tag (not lo_tag).
706 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
708 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
710 ; ASSERT(not (all isNothing arms))
711 return (oneCgStmt switch_stmt)
714 -- if we can knock off a bunch of default cases with one if, then do so
715 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
716 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
717 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
718 branch = CmmCondBranch cond deflt
719 ; stmts <- mk_switch tag_expr' branches mb_deflt
720 lowest_branch hi_tag via_C
721 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
724 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
725 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
726 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
727 branch = CmmCondBranch cond deflt
728 ; stmts <- mk_switch tag_expr' branches mb_deflt
729 lo_tag highest_branch via_C
730 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
733 | otherwise -- Use an if-tree
734 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
735 -- To avoid duplication
736 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
737 lo_tag (mid_tag-1) via_C
738 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
740 ; hi_id <- forkCgStmts hi_stmts
741 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
742 branch_stmt = CmmCondBranch cond hi_id
743 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
745 -- we test (e >= mid_tag) rather than (e < mid_tag), because
746 -- the former works better when e is a comparison, and there
747 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
748 -- generator can reduce the condition to e itself without
749 -- having to reverse the sense of the comparison: comparisons
750 -- can't always be easily reversed (eg. floating
753 use_switch = {- pprTrace "mk_switch" (
754 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
755 text "branches:" <+> ppr (map fst branches) <+>
756 text "n_branches:" <+> int n_branches <+>
757 text "lo_tag:" <+> int lo_tag <+>
758 text "hi_tag:" <+> int hi_tag <+>
759 text "real_lo_tag:" <+> int real_lo_tag <+>
760 text "real_hi_tag:" <+> int real_hi_tag) $ -}
761 ASSERT( n_branches > 1 && n_tags > 1 )
762 n_tags > 2 && (via_C || (dense && big_enough))
763 -- up to 4 branches we use a decision tree, otherwise
764 -- a switch (== jump table in the NCG). This seems to be
765 -- optimal, and corresponds with what gcc does.
766 big_enough = n_branches > 4
767 dense = n_branches > (n_tags `div` 2)
768 n_branches = length branches
770 -- ignore default slots at each end of the range if there's
771 -- no default branch defined.
772 lowest_branch = fst (head branches)
773 highest_branch = fst (last branches)
776 | isNothing mb_deflt = lowest_branch
780 | isNothing mb_deflt = highest_branch
783 n_tags = real_hi_tag - real_lo_tag + 1
785 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
786 -- lo_tag <= mid_tag < hi_tag
787 -- lo_branches have tags < mid_tag
788 -- hi_branches have tags >= mid_tag
790 (mid_tag,_) = branches !! (n_branches `div` 2)
791 -- 2 branches => n_branches `div` 2 = 1
792 -- => branches !! 1 give the *second* tag
793 -- There are always at least 2 branches here
795 (lo_branches, hi_branches) = span is_lo branches
796 is_lo (t,_) = t < mid_tag
800 | isTrivialCmmExpr e = return (CmmNop, e)
801 | otherwise = do { reg <- newTemp (cmmExprType e)
802 ; return (CmmAssign (CmmLocal reg) e, CmmReg (CmmLocal reg)) }
804 emitLitSwitch :: CmmExpr -- Tag to switch on
805 -> [(Literal, CgStmts)] -- Tagged branches
806 -> CgStmts -- Default branch (always)
807 -> Code -- Emit the code
808 -- Used for general literals, whose size might not be a word,
809 -- where there is always a default case, and where we don't know
810 -- the range of values for certain. For simplicity we always generate a tree.
812 -- ToDo: for integers we could do better here, perhaps by generalising
813 -- mk_switch and using that. --SDM 15/09/2004
814 emitLitSwitch scrut [] deflt
816 emitLitSwitch scrut branches deflt_blk
817 = do { scrut' <- assignTemp scrut
818 ; deflt_blk_id <- forkCgStmts deflt_blk
819 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
822 le (t1,_) (t2,_) = t1 <= t2
824 mk_lit_switch :: CmmExpr -> BlockId
825 -> [(Literal,CgStmts)]
827 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
828 = return (consCgStmt if_stmt blk)
830 cmm_lit = mkSimpleLit lit
831 rep = cmmLitType cmm_lit
832 ne = if isFloatType rep then MO_F_Ne else MO_Ne
833 cond = CmmMachOp (ne (typeWidth rep)) [scrut, CmmLit cmm_lit]
834 if_stmt = CmmCondBranch cond deflt_blk_id
836 mk_lit_switch scrut deflt_blk_id branches
837 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
838 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
839 ; lo_blk_id <- forkCgStmts lo_blk
840 ; let if_stmt = CmmCondBranch cond lo_blk_id
841 ; return (if_stmt `consCgStmt` hi_blk) }
843 n_branches = length branches
844 (mid_lit,_) = branches !! (n_branches `div` 2)
845 -- See notes above re mid_tag
847 (lo_branches, hi_branches) = span is_lo branches
848 is_lo (t,_) = t < mid_lit
850 cond = CmmMachOp (mkLtOp mid_lit)
851 [scrut, CmmLit (mkSimpleLit mid_lit)]
853 -------------------------------------------------------------------------
855 -- Simultaneous assignment
857 -------------------------------------------------------------------------
860 emitSimultaneously :: CmmStmts -> Code
861 -- Emit code to perform the assignments in the
862 -- input simultaneously, using temporary variables when necessary.
864 -- The Stmts must be:
865 -- CmmNop, CmmComment, CmmAssign, CmmStore
869 -- We use the strongly-connected component algorithm, in which
870 -- * the vertices are the statements
871 -- * an edge goes from s1 to s2 iff
872 -- s1 assigns to something s2 uses
873 -- that is, if s1 should *follow* s2 in the final order
875 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
876 -- for fast comparison
878 emitSimultaneously stmts
880 case filterOut isNopStmt (stmtList stmts) of
883 [stmt] -> stmtC stmt -- It's often just one stmt
884 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
886 doSimultaneously1 :: [CVertex] -> Code
887 doSimultaneously1 vertices
889 edges = [ (vertex, key1, edges_from stmt1)
890 | vertex@(key1, stmt1) <- vertices
892 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
893 stmt1 `mustFollow` stmt2
895 components = stronglyConnCompFromEdgedVertices edges
897 -- do_components deal with one strongly-connected component
898 -- Not cyclic, or singleton? Just do it
899 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
900 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
902 -- Cyclic? Then go via temporaries. Pick one to
903 -- break the loop and try again with the rest.
904 do_component (CyclicSCC ((n,first_stmt) : rest))
905 = do { from_temp <- go_via_temp first_stmt
906 ; doSimultaneously1 rest
909 go_via_temp (CmmAssign dest src)
910 = do { tmp <- newTemp (cmmRegType dest) -- TODO FIXME NOW if the pair of assignments move across a call this will be wrong
911 ; stmtC (CmmAssign (CmmLocal tmp) src)
912 ; return (CmmAssign dest (CmmReg (CmmLocal tmp))) }
913 go_via_temp (CmmStore dest src)
914 = do { tmp <- newTemp (cmmExprType src) -- TODO FIXME NOW if the pair of assignemnts move across a call this will be wrong
915 ; stmtC (CmmAssign (CmmLocal tmp) src)
916 ; return (CmmStore dest (CmmReg (CmmLocal tmp))) }
918 mapCs do_component components
920 mustFollow :: CmmStmt -> CmmStmt -> Bool
921 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
922 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprType e)) stmt
923 CmmNop `mustFollow` stmt = False
924 CmmComment _ `mustFollow` stmt = False
927 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
928 -- True if the fn is true of any input of the stmt
929 anySrc p (CmmAssign _ e) = p e
930 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
931 anySrc p (CmmComment _) = False
932 anySrc p CmmNop = False
933 anySrc p other = True -- Conservative
935 regUsedIn :: CmmReg -> CmmExpr -> Bool
936 reg `regUsedIn` CmmLit _ = False
937 reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e
938 reg `regUsedIn` CmmReg reg' = reg == reg'
939 reg `regUsedIn` CmmRegOff reg' _ = reg == reg'
940 reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es
942 locUsedIn :: CmmExpr -> CmmType -> CmmExpr -> Bool
943 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
944 -- 'e'. Returns True if it's not sure.
945 locUsedIn loc rep (CmmLit _) = False
946 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
947 locUsedIn loc rep (CmmReg reg') = False
948 locUsedIn loc rep (CmmRegOff reg' _) = False
949 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
951 possiblySameLoc :: CmmExpr -> CmmType -> CmmExpr -> CmmType -> Bool
952 -- Assumes that distinct registers (eg Hp, Sp) do not
953 -- point to the same location, nor any offset thereof.
954 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
955 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
956 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
957 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
958 = r1==r2 && end1 > start2 && end2 > start1
960 end1 = start1 + widthInBytes (typeWidth rep1)
961 end2 = start2 + widthInBytes (typeWidth rep2)
963 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
964 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative
966 -------------------------------------------------------------------------
968 -- Static Reference Tables
970 -------------------------------------------------------------------------
972 -- There is just one SRT for each top level binding; all the nested
973 -- bindings use sub-sections of this SRT. The label is passed down to
974 -- the nested bindings via the monad.
976 getSRTInfo :: FCode C_SRT
978 srt_lbl <- getSRTLabel
981 -- TODO: Should we panic in this case?
982 -- Someone obviously thinks there should be an SRT
983 NoSRT -> return NoC_SRT
984 SRTEntries {} -> panic "getSRTInfo: SRTEntries. Perhaps you forgot to run SimplStg?"
986 | len > hALF_WORD_SIZE_IN_BITS || bmp == [fromIntegral srt_escape]
987 -> do id <- newUnique
988 let srt_desc_lbl = mkLargeSRTLabel id
989 emitRODataLits "getSRTInfo" srt_desc_lbl
990 ( cmmLabelOffW srt_lbl off
991 : mkWordCLit (fromIntegral len)
992 : map mkWordCLit bmp)
993 return (C_SRT srt_desc_lbl 0 srt_escape)
997 -> return (C_SRT srt_lbl off (fromIntegral (head bmp)))
998 -- The fromIntegral converts to StgHalfWord
1000 srt_escape = (-1) :: StgHalfWord
1002 clHasCafRefs :: ClosureInfo -> CafInfo
1003 clHasCafRefs (ClosureInfo {closureSRT = srt}) =
1004 case srt of NoC_SRT -> NoCafRefs
1006 clHasCafRefs (ConInfo {}) = NoCafRefs