1 -----------------------------------------------------------------------------
3 -- Code generator utilities; mostly monadic
5 -- (c) The University of Glasgow 2004
7 -----------------------------------------------------------------------------
12 emitDataLits, emitRODataLits, emitIf, emitIfThenElse,
13 emitRtsCall, emitRtsCallWithVols, emitRtsCallWithResult,
16 emitSwitch, emitLitSwitch,
19 cmmAndWord, cmmOrWord, cmmNegate, cmmEqWord, cmmNeWord,
20 cmmOffsetExprW, cmmOffsetExprB,
21 cmmRegOffW, cmmRegOffB,
22 cmmLabelOffW, cmmLabelOffB,
23 cmmOffsetW, cmmOffsetB,
24 cmmOffsetLitW, cmmOffsetLitB,
34 #include "HsVersions.h"
37 import TyCon ( TyCon, tyConName )
39 import Constants ( wORD_SIZE )
40 import SMRep ( CgRep, StgWord, hALF_WORD_SIZE_IN_BITS, ByteOff,
42 import PprCmm ( {- instances -} )
46 import MachOp ( MachRep(..), wordRep, MachOp(..), MachHint(..),
47 mo_wordOr, mo_wordAnd, mo_wordNe, mo_wordEq,
48 mo_wordULt, mo_wordUGt, mo_wordUGe, machRepByteWidth )
49 import ForeignCall ( CCallConv(..) )
50 import Literal ( Literal(..) )
51 import CLabel ( CLabel, mkStringLitLabel )
52 import Digraph ( SCC(..), stronglyConnComp )
53 import ListSetOps ( assocDefault )
54 import Util ( filterOut, sortLe )
55 import DynFlags ( DynFlags(..), HscTarget(..) )
56 import Packages ( HomeModules )
57 import FastString ( LitString, FastString, bytesFS )
62 import DATA_WORD ( Word8 )
63 import Maybe ( isNothing )
65 -------------------------------------------------------------------------
67 -- Random small functions
69 -------------------------------------------------------------------------
71 addIdReps :: [Id] -> [(CgRep, Id)]
72 addIdReps ids = [(idCgRep id, id) | id <- ids]
74 -------------------------------------------------------------------------
78 -------------------------------------------------------------------------
80 cgLit :: Literal -> FCode CmmLit
81 cgLit (MachStr s) = mkByteStringCLit (bytesFS s)
82 -- not unpackFS; we want the UTF-8 byte stream.
83 cgLit other_lit = return (mkSimpleLit other_lit)
85 mkSimpleLit :: Literal -> CmmLit
86 mkSimpleLit (MachChar c) = CmmInt (fromIntegral (ord c)) wordRep
87 mkSimpleLit MachNullAddr = zeroCLit
88 mkSimpleLit (MachInt i) = CmmInt i wordRep
89 mkSimpleLit (MachInt64 i) = CmmInt i I64
90 mkSimpleLit (MachWord i) = CmmInt i wordRep
91 mkSimpleLit (MachWord64 i) = CmmInt i I64
92 mkSimpleLit (MachFloat r) = CmmFloat r F32
93 mkSimpleLit (MachDouble r) = CmmFloat r F64
94 mkSimpleLit (MachLabel fs ms) = CmmLabel (mkForeignLabel fs ms is_dyn)
96 is_dyn = False -- ToDo: fix me
98 mkLtOp :: Literal -> MachOp
99 -- On signed literals we must do a signed comparison
100 mkLtOp (MachInt _) = MO_S_Lt wordRep
101 mkLtOp (MachFloat _) = MO_S_Lt F32
102 mkLtOp (MachDouble _) = MO_S_Lt F64
103 mkLtOp lit = MO_U_Lt (cmmLitRep (mkSimpleLit lit))
106 ---------------------------------------------------
108 -- Cmm data type functions
110 ---------------------------------------------------
112 -----------------------
113 -- The "B" variants take byte offsets
114 cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr
115 cmmRegOffB = cmmRegOff
117 cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr
118 cmmOffsetB = cmmOffset
120 cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr
121 cmmOffsetExprB = cmmOffsetExpr
123 cmmLabelOffB :: CLabel -> ByteOff -> CmmLit
124 cmmLabelOffB = cmmLabelOff
126 cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit
127 cmmOffsetLitB = cmmOffsetLit
129 -----------------------
130 -- The "W" variants take word offsets
131 cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr
132 -- The second arg is a *word* offset; need to change it to bytes
133 cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n)
134 cmmOffsetExprW e wd_off = cmmIndexExpr wordRep e wd_off
136 cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr
137 cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n)
139 cmmRegOffW :: CmmReg -> WordOff -> CmmExpr
140 cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE)
142 cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit
143 cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off)
145 cmmLabelOffW :: CLabel -> WordOff -> CmmLit
146 cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off)
148 cmmLoadIndexW :: CmmExpr -> Int -> CmmExpr
149 cmmLoadIndexW base off
150 = CmmLoad (cmmOffsetW base off) wordRep
152 -----------------------
153 cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord :: CmmExpr -> CmmExpr -> CmmExpr
154 cmmOrWord e1 e2 = CmmMachOp mo_wordOr [e1, e2]
155 cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2]
156 cmmNeWord e1 e2 = CmmMachOp mo_wordNe [e1, e2]
157 cmmEqWord e1 e2 = CmmMachOp mo_wordEq [e1, e2]
158 cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2]
159 cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2]
160 cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2]
162 cmmNegate :: CmmExpr -> CmmExpr
163 cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep)
164 cmmNegate e = CmmMachOp (MO_S_Neg (cmmExprRep e)) [e]
166 blankWord :: CmmStatic
167 blankWord = CmmUninitialised wORD_SIZE
169 -----------------------
172 mkWordCLit :: StgWord -> CmmLit
173 mkWordCLit wd = CmmInt (fromIntegral wd) wordRep
175 packHalfWordsCLit :: (Integral a, Integral b) => a -> b -> CmmLit
176 -- Make a single word literal in which the lower_half_word is
177 -- at the lower address, and the upper_half_word is at the
179 -- ToDo: consider using half-word lits instead
180 -- but be careful: that's vulnerable when reversed
181 packHalfWordsCLit lower_half_word upper_half_word
182 #ifdef WORDS_BIGENDIAN
183 = mkWordCLit ((fromIntegral lower_half_word `shiftL` hALF_WORD_SIZE_IN_BITS)
184 .|. fromIntegral upper_half_word)
186 = mkWordCLit ((fromIntegral lower_half_word)
187 .|. (fromIntegral upper_half_word `shiftL` hALF_WORD_SIZE_IN_BITS))
190 --------------------------------------------------------------------------
192 -- Incrementing a memory location
194 --------------------------------------------------------------------------
196 addToMem :: MachRep -- rep of the counter
197 -> CmmExpr -- Address
198 -> Int -- What to add (a word)
200 addToMem rep ptr n = addToMemE rep ptr (CmmLit (CmmInt (toInteger n) rep))
202 addToMemE :: MachRep -- rep of the counter
203 -> CmmExpr -- Address
204 -> CmmExpr -- What to add (a word-typed expression)
207 = CmmStore ptr (CmmMachOp (MO_Add rep) [CmmLoad ptr rep, n])
209 -------------------------------------------------------------------------
211 -- Converting a closure tag to a closure for enumeration types
212 -- (this is the implementation of tagToEnum#).
214 -------------------------------------------------------------------------
216 tagToClosure :: HomeModules -> TyCon -> CmmExpr -> CmmExpr
217 tagToClosure hmods tycon tag
218 = CmmLoad (cmmOffsetExprW closure_tbl tag) wordRep
219 where closure_tbl = CmmLit (CmmLabel lbl)
220 lbl = mkClosureTableLabel hmods (tyConName tycon)
222 -------------------------------------------------------------------------
224 -- Conditionals and rts calls
226 -------------------------------------------------------------------------
228 emitIf :: CmmExpr -- Boolean
231 -- Emit (if e then x)
232 -- ToDo: reverse the condition to avoid the extra branch instruction if possible
233 -- (some conditionals aren't reversible. eg. floating point comparisons cannot
234 -- be inverted because there exist some values for which both comparisons
235 -- return False, such as NaN.)
236 emitIf cond then_part
237 = do { then_id <- newLabelC
238 ; join_id <- newLabelC
239 ; stmtC (CmmCondBranch cond then_id)
240 ; stmtC (CmmBranch join_id)
246 emitIfThenElse :: CmmExpr -- Boolean
250 -- Emit (if e then x else y)
251 emitIfThenElse cond then_part else_part
252 = do { then_id <- newLabelC
253 ; else_id <- newLabelC
254 ; join_id <- newLabelC
255 ; stmtC (CmmCondBranch cond then_id)
257 ; stmtC (CmmBranch join_id)
263 emitRtsCall :: LitString -> [(CmmExpr,MachHint)] -> Code
264 emitRtsCall fun args = emitRtsCall' [] fun args Nothing
265 -- The 'Nothing' says "save all global registers"
267 emitRtsCallWithVols :: LitString -> [(CmmExpr,MachHint)] -> [GlobalReg] -> Code
268 emitRtsCallWithVols fun args vols
269 = emitRtsCall' [] fun args (Just vols)
271 emitRtsCallWithResult :: CmmReg -> MachHint -> LitString
272 -> [(CmmExpr,MachHint)] -> Code
273 emitRtsCallWithResult res hint fun args
274 = emitRtsCall' [(res,hint)] fun args Nothing
276 -- Make a call to an RTS C procedure
278 :: [(CmmReg,MachHint)]
280 -> [(CmmExpr,MachHint)]
283 emitRtsCall' res fun args vols = stmtC (CmmCall target res args vols)
285 target = CmmForeignCall fun_expr CCallConv
286 fun_expr = mkLblExpr (mkRtsCodeLabel fun)
289 -------------------------------------------------------------------------
291 -- Strings gnerate a top-level data block
293 -------------------------------------------------------------------------
295 emitDataLits :: CLabel -> [CmmLit] -> Code
296 -- Emit a data-segment data block
297 emitDataLits lbl lits
298 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
300 emitRODataLits :: CLabel -> [CmmLit] -> Code
301 -- Emit a read-only data block
302 emitRODataLits lbl lits
303 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
304 where section | any needsRelocation lits = RelocatableReadOnlyData
305 | otherwise = ReadOnlyData
306 needsRelocation (CmmLabel _) = True
307 needsRelocation (CmmLabelOff _ _) = True
308 needsRelocation _ = False
310 mkStringCLit :: String -> FCode CmmLit
311 -- Make a global definition for the string,
312 -- and return its label
313 mkStringCLit str = mkByteStringCLit (map (fromIntegral.ord) str)
315 mkByteStringCLit :: [Word8] -> FCode CmmLit
316 mkByteStringCLit bytes
317 = do { uniq <- newUnique
318 ; let lbl = mkStringLitLabel uniq
319 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString bytes]
320 ; return (CmmLabel lbl) }
322 -------------------------------------------------------------------------
324 -- Assigning expressions to temporaries
326 -------------------------------------------------------------------------
328 assignTemp :: CmmExpr -> FCode CmmExpr
329 -- For a non-trivial expression, e, create a local
330 -- variable and assign the expression to it
332 | isTrivialCmmExpr e = return e
333 | otherwise = do { reg <- newTemp (cmmExprRep e)
334 ; stmtC (CmmAssign reg e)
335 ; return (CmmReg reg) }
338 newTemp :: MachRep -> FCode CmmReg
339 newTemp rep = do { uniq <- newUnique; return (CmmLocal (LocalReg uniq rep)) }
342 -------------------------------------------------------------------------
344 -- Building case analysis
346 -------------------------------------------------------------------------
349 :: CmmExpr -- Tag to switch on
350 -> [(ConTagZ, CgStmts)] -- Tagged branches
351 -> Maybe CgStmts -- Default branch (if any)
352 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
353 -- outside this range is undefined
356 -- ONLY A DEFAULT BRANCH: no case analysis to do
357 emitSwitch tag_expr [] (Just stmts) _ _
361 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
362 = -- Just sort the branches before calling mk_sritch
365 Nothing -> return Nothing
366 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
368 ; dflags <- getDynFlags
369 ; let via_C | HscC <- hscTarget dflags = True
372 ; stmts <- mk_switch tag_expr (sortLe le branches)
373 mb_deflt_id lo_tag hi_tag via_C
377 (t1,_) `le` (t2,_) = t1 <= t2
380 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
381 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
384 -- SINGLETON TAG RANGE: no case analysis to do
385 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
387 = ASSERT( tag == lo_tag )
390 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
391 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
393 -- The simplifier might have eliminated a case
394 -- so we may have e.g. case xs of
396 -- In that situation we can be sure the (:) case
397 -- can't happen, so no need to test
399 -- SINGLETON BRANCH: one equality check to do
400 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
401 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
403 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
404 -- We have lo_tag < hi_tag, but there's only one branch,
405 -- so there must be a default
407 -- ToDo: we might want to check for the two branch case, where one of
408 -- the branches is the tag 0, because comparing '== 0' is likely to be
409 -- more efficient than other kinds of comparison.
411 -- DENSE TAG RANGE: use a switch statment.
413 -- We also use a switch uncoditionally when compiling via C, because
414 -- this will get emitted as a C switch statement and the C compiler
415 -- should do a good job of optimising it. Also, older GCC versions
416 -- (2.95 in particular) have problems compiling the complicated
417 -- if-trees generated by this code, so compiling to a switch every
418 -- time works around that problem.
420 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
421 | use_switch -- Use a switch
422 = do { branch_ids <- mapM forkCgStmts (map snd branches)
424 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
426 find_branch :: ConTagZ -> Maybe BlockId
427 find_branch i = assocDefault mb_deflt tagged_blk_ids i
429 -- NB. we have eliminated impossible branches at
430 -- either end of the range (see below), so the first
431 -- tag of a real branch is real_lo_tag (not lo_tag).
432 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
434 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
436 ; ASSERT(not (all isNothing arms))
437 return (oneCgStmt switch_stmt)
440 -- if we can knock off a bunch of default cases with one if, then do so
441 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
442 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
443 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
444 branch = CmmCondBranch cond deflt
445 ; stmts <- mk_switch tag_expr' branches mb_deflt
446 lowest_branch hi_tag via_C
447 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
450 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
451 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
452 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
453 branch = CmmCondBranch cond deflt
454 ; stmts <- mk_switch tag_expr' branches mb_deflt
455 lo_tag highest_branch via_C
456 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
459 | otherwise -- Use an if-tree
460 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
461 -- To avoid duplication
462 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
463 lo_tag (mid_tag-1) via_C
464 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
466 ; hi_id <- forkCgStmts hi_stmts
467 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
468 branch_stmt = CmmCondBranch cond hi_id
469 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
471 -- we test (e >= mid_tag) rather than (e < mid_tag), because
472 -- the former works better when e is a comparison, and there
473 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
474 -- generator can reduce the condition to e itself without
475 -- having to reverse the sense of the comparison: comparisons
476 -- can't always be easily reversed (eg. floating
479 use_switch = {- pprTrace "mk_switch" (
480 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
481 text "n_branches:" <+> int n_branches <+>
482 text "lo_tag: " <+> int lo_tag <+>
483 text "hi_tag: " <+> int hi_tag <+>
484 text "real_lo_tag: " <+> int real_lo_tag <+>
485 text "real_hi_tag: " <+> int real_hi_tag) $ -}
486 ASSERT( n_branches > 1 && n_tags > 1 )
487 n_tags > 2 && (small || dense || via_C)
488 -- a 2-branch switch always turns into an if.
490 dense = n_branches > (n_tags `div` 2)
491 exhaustive = n_tags == n_branches
492 n_branches = length branches
494 -- ignore default slots at each end of the range if there's
495 -- no default branch defined.
496 lowest_branch = fst (head branches)
497 highest_branch = fst (last branches)
500 | isNothing mb_deflt = lowest_branch
504 | isNothing mb_deflt = highest_branch
507 n_tags = real_hi_tag - real_lo_tag + 1
509 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
510 -- lo_tag <= mid_tag < hi_tag
511 -- lo_branches have tags < mid_tag
512 -- hi_branches have tags >= mid_tag
514 (mid_tag,_) = branches !! (n_branches `div` 2)
515 -- 2 branches => n_branches `div` 2 = 1
516 -- => branches !! 1 give the *second* tag
517 -- There are always at least 2 branches here
519 (lo_branches, hi_branches) = span is_lo branches
520 is_lo (t,_) = t < mid_tag
524 | isTrivialCmmExpr e = return (CmmNop, e)
525 | otherwise = do { reg <- newTemp (cmmExprRep e)
526 ; return (CmmAssign reg e, CmmReg reg) }
529 emitLitSwitch :: CmmExpr -- Tag to switch on
530 -> [(Literal, CgStmts)] -- Tagged branches
531 -> CgStmts -- Default branch (always)
532 -> Code -- Emit the code
533 -- Used for general literals, whose size might not be a word,
534 -- where there is always a default case, and where we don't know
535 -- the range of values for certain. For simplicity we always generate a tree.
537 -- ToDo: for integers we could do better here, perhaps by generalising
538 -- mk_switch and using that. --SDM 15/09/2004
539 emitLitSwitch scrut [] deflt
541 emitLitSwitch scrut branches deflt_blk
542 = do { scrut' <- assignTemp scrut
543 ; deflt_blk_id <- forkCgStmts deflt_blk
544 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
547 le (t1,_) (t2,_) = t1 <= t2
549 mk_lit_switch :: CmmExpr -> BlockId
550 -> [(Literal,CgStmts)]
552 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
553 = return (consCgStmt if_stmt blk)
555 cmm_lit = mkSimpleLit lit
556 rep = cmmLitRep cmm_lit
557 cond = CmmMachOp (MO_Ne rep) [scrut, CmmLit cmm_lit]
558 if_stmt = CmmCondBranch cond deflt_blk_id
560 mk_lit_switch scrut deflt_blk_id branches
561 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
562 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
563 ; lo_blk_id <- forkCgStmts lo_blk
564 ; let if_stmt = CmmCondBranch cond lo_blk_id
565 ; return (if_stmt `consCgStmt` hi_blk) }
567 n_branches = length branches
568 (mid_lit,_) = branches !! (n_branches `div` 2)
569 -- See notes above re mid_tag
571 (lo_branches, hi_branches) = span is_lo branches
572 is_lo (t,_) = t < mid_lit
574 cond = CmmMachOp (mkLtOp mid_lit)
575 [scrut, CmmLit (mkSimpleLit mid_lit)]
577 -------------------------------------------------------------------------
579 -- Simultaneous assignment
581 -------------------------------------------------------------------------
584 emitSimultaneously :: CmmStmts -> Code
585 -- Emit code to perform the assignments in the
586 -- input simultaneously, using temporary variables when necessary.
588 -- The Stmts must be:
589 -- CmmNop, CmmComment, CmmAssign, CmmStore
593 -- We use the strongly-connected component algorithm, in which
594 -- * the vertices are the statements
595 -- * an edge goes from s1 to s2 iff
596 -- s1 assigns to something s2 uses
597 -- that is, if s1 should *follow* s2 in the final order
599 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
600 -- for fast comparison
602 emitSimultaneously stmts
604 case filterOut isNopStmt (stmtList stmts) of
607 [stmt] -> stmtC stmt -- It's often just one stmt
608 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
610 doSimultaneously1 :: [CVertex] -> Code
611 doSimultaneously1 vertices
613 edges = [ (vertex, key1, edges_from stmt1)
614 | vertex@(key1, stmt1) <- vertices
616 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
617 stmt1 `mustFollow` stmt2
619 components = stronglyConnComp edges
621 -- do_components deal with one strongly-connected component
622 -- Not cyclic, or singleton? Just do it
623 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
624 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
626 -- Cyclic? Then go via temporaries. Pick one to
627 -- break the loop and try again with the rest.
628 do_component (CyclicSCC ((n,first_stmt) : rest))
629 = do { from_temp <- go_via_temp first_stmt
630 ; doSimultaneously1 rest
633 go_via_temp (CmmAssign dest src)
634 = do { tmp <- newTemp (cmmRegRep dest)
635 ; stmtC (CmmAssign tmp src)
636 ; return (CmmAssign dest (CmmReg tmp)) }
637 go_via_temp (CmmStore dest src)
638 = do { tmp <- newTemp (cmmExprRep src)
639 ; stmtC (CmmAssign tmp src)
640 ; return (CmmStore dest (CmmReg tmp)) }
642 mapCs do_component components
644 mustFollow :: CmmStmt -> CmmStmt -> Bool
645 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
646 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprRep e)) stmt
647 CmmNop `mustFollow` stmt = False
648 CmmComment _ `mustFollow` stmt = False
651 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
652 -- True if the fn is true of any input of the stmt
653 anySrc p (CmmAssign _ e) = p e
654 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
655 anySrc p (CmmComment _) = False
656 anySrc p CmmNop = False
657 anySrc p other = True -- Conservative
659 regUsedIn :: CmmReg -> CmmExpr -> Bool
660 reg `regUsedIn` CmmLit _ = False
661 reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e
662 reg `regUsedIn` CmmReg reg' = reg == reg'
663 reg `regUsedIn` CmmRegOff reg' _ = reg == reg'
664 reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es
666 locUsedIn :: CmmExpr -> MachRep -> CmmExpr -> Bool
667 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
668 -- 'e'. Returns True if it's not sure.
669 locUsedIn loc rep (CmmLit _) = False
670 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
671 locUsedIn loc rep (CmmReg reg') = False
672 locUsedIn loc rep (CmmRegOff reg' _) = False
673 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
675 possiblySameLoc :: CmmExpr -> MachRep -> CmmExpr -> MachRep -> Bool
676 -- Assumes that distinct registers (eg Hp, Sp) do not
677 -- point to the same location, nor any offset thereof.
678 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
679 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
680 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
681 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
682 = r1==r2 && end1 > start2 && end2 > start1
684 end1 = start1 + machRepByteWidth rep1
685 end2 = start2 + machRepByteWidth rep2
687 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
688 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative