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 FastString ( LitString, FastString, unpackFS )
61 import Maybe ( isNothing )
63 -------------------------------------------------------------------------
65 -- Random small functions
67 -------------------------------------------------------------------------
69 addIdReps :: [Id] -> [(CgRep, Id)]
70 addIdReps ids = [(idCgRep id, id) | id <- ids]
72 -------------------------------------------------------------------------
76 -------------------------------------------------------------------------
78 cgLit :: Literal -> FCode CmmLit
79 cgLit (MachStr s) = mkStringCLit (unpackFS s)
80 cgLit other_lit = return (mkSimpleLit other_lit)
82 mkSimpleLit :: Literal -> CmmLit
83 mkSimpleLit (MachChar c) = CmmInt (fromIntegral (ord c)) wordRep
84 mkSimpleLit MachNullAddr = zeroCLit
85 mkSimpleLit (MachInt i) = CmmInt i wordRep
86 mkSimpleLit (MachInt64 i) = CmmInt i I64
87 mkSimpleLit (MachWord i) = CmmInt i wordRep
88 mkSimpleLit (MachWord64 i) = CmmInt i I64
89 mkSimpleLit (MachFloat r) = CmmFloat r F32
90 mkSimpleLit (MachDouble r) = CmmFloat r F64
91 mkSimpleLit (MachLabel fs ms) = CmmLabel (mkForeignLabel fs ms is_dyn)
93 is_dyn = False -- ToDo: fix me
95 mkLtOp :: Literal -> MachOp
96 -- On signed literals we must do a signed comparison
97 mkLtOp (MachInt _) = MO_S_Lt wordRep
98 mkLtOp (MachFloat _) = MO_S_Lt F32
99 mkLtOp (MachDouble _) = MO_S_Lt F64
100 mkLtOp lit = MO_U_Lt (cmmLitRep (mkSimpleLit lit))
103 ---------------------------------------------------
105 -- Cmm data type functions
107 ---------------------------------------------------
109 -----------------------
110 -- The "B" variants take byte offsets
111 cmmRegOffB :: CmmReg -> ByteOff -> CmmExpr
112 cmmRegOffB = cmmRegOff
114 cmmOffsetB :: CmmExpr -> ByteOff -> CmmExpr
115 cmmOffsetB = cmmOffset
117 cmmOffsetExprB :: CmmExpr -> CmmExpr -> CmmExpr
118 cmmOffsetExprB = cmmOffsetExpr
120 cmmLabelOffB :: CLabel -> ByteOff -> CmmLit
121 cmmLabelOffB = cmmLabelOff
123 cmmOffsetLitB :: CmmLit -> ByteOff -> CmmLit
124 cmmOffsetLitB = cmmOffsetLit
126 -----------------------
127 -- The "W" variants take word offsets
128 cmmOffsetExprW :: CmmExpr -> CmmExpr -> CmmExpr
129 -- The second arg is a *word* offset; need to change it to bytes
130 cmmOffsetExprW e (CmmLit (CmmInt n _)) = cmmOffsetW e (fromInteger n)
131 cmmOffsetExprW e wd_off = cmmIndexExpr wordRep e wd_off
133 cmmOffsetW :: CmmExpr -> WordOff -> CmmExpr
134 cmmOffsetW e n = cmmOffsetB e (wORD_SIZE * n)
136 cmmRegOffW :: CmmReg -> WordOff -> CmmExpr
137 cmmRegOffW reg wd_off = cmmRegOffB reg (wd_off * wORD_SIZE)
139 cmmOffsetLitW :: CmmLit -> WordOff -> CmmLit
140 cmmOffsetLitW lit wd_off = cmmOffsetLitB lit (wORD_SIZE * wd_off)
142 cmmLabelOffW :: CLabel -> WordOff -> CmmLit
143 cmmLabelOffW lbl wd_off = cmmLabelOffB lbl (wORD_SIZE * wd_off)
145 cmmLoadIndexW :: CmmExpr -> Int -> CmmExpr
146 cmmLoadIndexW base off
147 = CmmLoad (cmmOffsetW base off) wordRep
149 -----------------------
150 cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord :: CmmExpr -> CmmExpr -> CmmExpr
151 cmmOrWord e1 e2 = CmmMachOp mo_wordOr [e1, e2]
152 cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2]
153 cmmNeWord e1 e2 = CmmMachOp mo_wordNe [e1, e2]
154 cmmEqWord e1 e2 = CmmMachOp mo_wordEq [e1, e2]
155 cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2]
156 cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2]
157 cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2]
159 cmmNegate :: CmmExpr -> CmmExpr
160 cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep)
161 cmmNegate e = CmmMachOp (MO_S_Neg (cmmExprRep e)) [e]
163 blankWord :: CmmStatic
164 blankWord = CmmUninitialised wORD_SIZE
166 -----------------------
169 mkWordCLit :: StgWord -> CmmLit
170 mkWordCLit wd = CmmInt (fromIntegral wd) wordRep
172 packHalfWordsCLit :: (Integral a, Integral b) => a -> b -> CmmLit
173 -- Make a single word literal in which the lower_half_word is
174 -- at the lower address, and the upper_half_word is at the
176 -- ToDo: consider using half-word lits instead
177 -- but be careful: that's vulnerable when reversed
178 packHalfWordsCLit lower_half_word upper_half_word
179 #ifdef WORDS_BIGENDIAN
180 = mkWordCLit ((fromIntegral lower_half_word `shiftL` hALF_WORD_SIZE_IN_BITS)
181 .|. fromIntegral upper_half_word)
183 = mkWordCLit ((fromIntegral lower_half_word)
184 .|. (fromIntegral upper_half_word `shiftL` hALF_WORD_SIZE_IN_BITS))
187 --------------------------------------------------------------------------
189 -- Incrementing a memory location
191 --------------------------------------------------------------------------
193 addToMem :: MachRep -- rep of the counter
194 -> CmmExpr -- Address
195 -> Int -- What to add (a word)
197 addToMem rep ptr n = addToMemE rep ptr (CmmLit (CmmInt (toInteger n) rep))
199 addToMemE :: MachRep -- rep of the counter
200 -> CmmExpr -- Address
201 -> CmmExpr -- What to add (a word-typed expression)
204 = CmmStore ptr (CmmMachOp (MO_Add rep) [CmmLoad ptr rep, n])
206 -------------------------------------------------------------------------
208 -- Converting a closure tag to a closure for enumeration types
209 -- (this is the implementation of tagToEnum#).
211 -------------------------------------------------------------------------
213 tagToClosure :: DynFlags -> TyCon -> CmmExpr -> CmmExpr
214 tagToClosure dflags tycon tag
215 = CmmLoad (cmmOffsetExprW closure_tbl tag) wordRep
216 where closure_tbl = CmmLit (CmmLabel lbl)
217 lbl = mkClosureTableLabel dflags (tyConName tycon)
219 -------------------------------------------------------------------------
221 -- Conditionals and rts calls
223 -------------------------------------------------------------------------
225 emitIf :: CmmExpr -- Boolean
228 -- Emit (if e then x)
229 -- ToDo: reverse the condition to avoid the extra branch instruction if possible
230 -- (some conditionals aren't reversible. eg. floating point comparisons cannot
231 -- be inverted because there exist some values for which both comparisons
232 -- return False, such as NaN.)
233 emitIf cond then_part
234 = do { then_id <- newLabelC
235 ; join_id <- newLabelC
236 ; stmtC (CmmCondBranch cond then_id)
237 ; stmtC (CmmBranch join_id)
243 emitIfThenElse :: CmmExpr -- Boolean
247 -- Emit (if e then x else y)
248 emitIfThenElse cond then_part else_part
249 = do { then_id <- newLabelC
250 ; else_id <- newLabelC
251 ; join_id <- newLabelC
252 ; stmtC (CmmCondBranch cond then_id)
254 ; stmtC (CmmBranch join_id)
260 emitRtsCall :: LitString -> [(CmmExpr,MachHint)] -> Code
261 emitRtsCall fun args = emitRtsCall' [] fun args Nothing
262 -- The 'Nothing' says "save all global registers"
264 emitRtsCallWithVols :: LitString -> [(CmmExpr,MachHint)] -> [GlobalReg] -> Code
265 emitRtsCallWithVols fun args vols
266 = emitRtsCall' [] fun args (Just vols)
268 emitRtsCallWithResult :: CmmReg -> MachHint -> LitString
269 -> [(CmmExpr,MachHint)] -> Code
270 emitRtsCallWithResult res hint fun args
271 = emitRtsCall' [(res,hint)] fun args Nothing
273 -- Make a call to an RTS C procedure
275 :: [(CmmReg,MachHint)]
277 -> [(CmmExpr,MachHint)]
280 emitRtsCall' res fun args vols = stmtC (CmmCall target res args vols)
282 target = CmmForeignCall fun_expr CCallConv
283 fun_expr = mkLblExpr (mkRtsCodeLabel fun)
286 -------------------------------------------------------------------------
288 -- Strings gnerate a top-level data block
290 -------------------------------------------------------------------------
292 emitDataLits :: CLabel -> [CmmLit] -> Code
293 -- Emit a data-segment data block
294 emitDataLits lbl lits
295 = emitData Data (CmmDataLabel lbl : map CmmStaticLit lits)
297 emitRODataLits :: CLabel -> [CmmLit] -> Code
298 -- Emit a read-only data block
299 emitRODataLits lbl lits
300 = emitData section (CmmDataLabel lbl : map CmmStaticLit lits)
301 where section | any needsRelocation lits = RelocatableReadOnlyData
302 | otherwise = ReadOnlyData
303 needsRelocation (CmmLabel _) = True
304 needsRelocation (CmmLabelOff _ _) = True
305 needsRelocation _ = False
307 mkStringCLit :: String -> FCode CmmLit
308 -- Make a global definition for the string,
309 -- and return its label
311 = do { uniq <- newUnique
312 ; let lbl = mkStringLitLabel uniq
313 ; emitData ReadOnlyData [CmmDataLabel lbl, CmmString str]
314 ; return (CmmLabel lbl) }
316 -------------------------------------------------------------------------
318 -- Assigning expressions to temporaries
320 -------------------------------------------------------------------------
322 assignTemp :: CmmExpr -> FCode CmmExpr
323 -- For a non-trivial expression, e, create a local
324 -- variable and assign the expression to it
326 | isTrivialCmmExpr e = return e
327 | otherwise = do { reg <- newTemp (cmmExprRep e)
328 ; stmtC (CmmAssign reg e)
329 ; return (CmmReg reg) }
332 newTemp :: MachRep -> FCode CmmReg
333 newTemp rep = do { uniq <- newUnique; return (CmmLocal (LocalReg uniq rep)) }
336 -------------------------------------------------------------------------
338 -- Building case analysis
340 -------------------------------------------------------------------------
343 :: CmmExpr -- Tag to switch on
344 -> [(ConTagZ, CgStmts)] -- Tagged branches
345 -> Maybe CgStmts -- Default branch (if any)
346 -> ConTagZ -> ConTagZ -- Min and Max possible values; behaviour
347 -- outside this range is undefined
350 -- ONLY A DEFAULT BRANCH: no case analysis to do
351 emitSwitch tag_expr [] (Just stmts) _ _
355 emitSwitch tag_expr branches mb_deflt lo_tag hi_tag
356 = -- Just sort the branches before calling mk_sritch
359 Nothing -> return Nothing
360 Just stmts -> do id <- forkCgStmts stmts; return (Just id)
362 ; dflags <- getDynFlags
363 ; let via_C | HscC <- hscTarget dflags = True
366 ; stmts <- mk_switch tag_expr (sortLe le branches)
367 mb_deflt_id lo_tag hi_tag via_C
371 (t1,_) `le` (t2,_) = t1 <= t2
374 mk_switch :: CmmExpr -> [(ConTagZ, CgStmts)]
375 -> Maybe BlockId -> ConTagZ -> ConTagZ -> Bool
378 -- SINGLETON TAG RANGE: no case analysis to do
379 mk_switch tag_expr [(tag,stmts)] _ lo_tag hi_tag via_C
381 = ASSERT( tag == lo_tag )
384 -- SINGLETON BRANCH, NO DEFUALT: no case analysis to do
385 mk_switch tag_expr [(tag,stmts)] Nothing lo_tag hi_tag via_C
387 -- The simplifier might have eliminated a case
388 -- so we may have e.g. case xs of
390 -- In that situation we can be sure the (:) case
391 -- can't happen, so no need to test
393 -- SINGLETON BRANCH: one equality check to do
394 mk_switch tag_expr [(tag,stmts)] (Just deflt) lo_tag hi_tag via_C
395 = return (CmmCondBranch cond deflt `consCgStmt` stmts)
397 cond = cmmNeWord tag_expr (CmmLit (mkIntCLit tag))
398 -- We have lo_tag < hi_tag, but there's only one branch,
399 -- so there must be a default
401 -- ToDo: we might want to check for the two branch case, where one of
402 -- the branches is the tag 0, because comparing '== 0' is likely to be
403 -- more efficient than other kinds of comparison.
405 -- DENSE TAG RANGE: use a switch statment.
407 -- We also use a switch uncoditionally when compiling via C, because
408 -- this will get emitted as a C switch statement and the C compiler
409 -- should do a good job of optimising it. Also, older GCC versions
410 -- (2.95 in particular) have problems compiling the complicated
411 -- if-trees generated by this code, so compiling to a switch every
412 -- time works around that problem.
414 mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
415 | use_switch || via_C -- Use a switch
416 = do { branch_ids <- mapM forkCgStmts (map snd branches)
418 tagged_blk_ids = zip (map fst branches) (map Just branch_ids)
420 find_branch :: ConTagZ -> Maybe BlockId
421 find_branch i = assocDefault mb_deflt tagged_blk_ids i
423 -- NB. we have eliminated impossible branches at
424 -- either end of the range (see below), so the first
425 -- tag of a real branch is real_lo_tag (not lo_tag).
426 arms = [ find_branch i | i <- [real_lo_tag..real_hi_tag]]
428 switch_stmt = CmmSwitch (cmmOffset tag_expr (- real_lo_tag)) arms
430 ; ASSERT(not (all isNothing arms))
431 return (oneCgStmt switch_stmt)
434 -- if we can knock off a bunch of default cases with one if, then do so
435 | Just deflt <- mb_deflt, (lowest_branch - lo_tag) >= n_branches
436 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
437 ; let cond = cmmULtWord tag_expr' (CmmLit (mkIntCLit lowest_branch))
438 branch = CmmCondBranch cond deflt
439 ; stmts <- mk_switch tag_expr' branches mb_deflt
440 lowest_branch hi_tag via_C
441 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
444 | Just deflt <- mb_deflt, (hi_tag - highest_branch) >= n_branches
445 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
446 ; let cond = cmmUGtWord tag_expr' (CmmLit (mkIntCLit highest_branch))
447 branch = CmmCondBranch cond deflt
448 ; stmts <- mk_switch tag_expr' branches mb_deflt
449 lo_tag highest_branch via_C
450 ; return (assign_tag `consCgStmt` (branch `consCgStmt` stmts))
453 | otherwise -- Use an if-tree
454 = do { (assign_tag, tag_expr') <- assignTemp' tag_expr
455 -- To avoid duplication
456 ; lo_stmts <- mk_switch tag_expr' lo_branches mb_deflt
457 lo_tag (mid_tag-1) via_C
458 ; hi_stmts <- mk_switch tag_expr' hi_branches mb_deflt
460 ; hi_id <- forkCgStmts hi_stmts
461 ; let cond = cmmUGeWord tag_expr' (CmmLit (mkIntCLit mid_tag))
462 branch_stmt = CmmCondBranch cond hi_id
463 ; return (assign_tag `consCgStmt` (branch_stmt `consCgStmt` lo_stmts))
465 -- we test (e >= mid_tag) rather than (e < mid_tag), because
466 -- the former works better when e is a comparison, and there
467 -- are two tags 0 & 1 (mid_tag == 1). In this case, the code
468 -- generator can reduce the condition to e itself without
469 -- having to reverse the sense of the comparison: comparisons
470 -- can't always be easily reversed (eg. floating
473 use_switch = {- pprTrace "mk_switch" (
474 ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
475 text "n_branches:" <+> int n_branches <+>
476 text "lo_tag: " <+> int lo_tag <+>
477 text "hi_tag: " <+> int hi_tag <+>
478 text "real_lo_tag: " <+> int real_lo_tag <+>
479 text "real_hi_tag: " <+> int real_hi_tag) $ -}
480 ASSERT( n_branches > 1 && n_tags > 1 )
481 n_tags > 2 && (small || dense)
482 -- a 2-branch switch always turns into an if.
484 dense = n_branches > (n_tags `div` 2)
485 exhaustive = n_tags == n_branches
486 n_branches = length branches
488 -- ignore default slots at each end of the range if there's
489 -- no default branch defined.
490 lowest_branch = fst (head branches)
491 highest_branch = fst (last branches)
494 | isNothing mb_deflt = lowest_branch
498 | isNothing mb_deflt = highest_branch
501 n_tags = real_hi_tag - real_lo_tag + 1
503 -- INVARIANT: Provided hi_tag > lo_tag (which is true)
504 -- lo_tag <= mid_tag < hi_tag
505 -- lo_branches have tags < mid_tag
506 -- hi_branches have tags >= mid_tag
508 (mid_tag,_) = branches !! (n_branches `div` 2)
509 -- 2 branches => n_branches `div` 2 = 1
510 -- => branches !! 1 give the *second* tag
511 -- There are always at least 2 branches here
513 (lo_branches, hi_branches) = span is_lo branches
514 is_lo (t,_) = t < mid_tag
518 | isTrivialCmmExpr e = return (CmmNop, e)
519 | otherwise = do { reg <- newTemp (cmmExprRep e)
520 ; return (CmmAssign reg e, CmmReg reg) }
523 emitLitSwitch :: CmmExpr -- Tag to switch on
524 -> [(Literal, CgStmts)] -- Tagged branches
525 -> CgStmts -- Default branch (always)
526 -> Code -- Emit the code
527 -- Used for general literals, whose size might not be a word,
528 -- where there is always a default case, and where we don't know
529 -- the range of values for certain. For simplicity we always generate a tree.
531 -- ToDo: for integers we could do better here, perhaps by generalising
532 -- mk_switch and using that. --SDM 15/09/2004
533 emitLitSwitch scrut [] deflt
535 emitLitSwitch scrut branches deflt_blk
536 = do { scrut' <- assignTemp scrut
537 ; deflt_blk_id <- forkCgStmts deflt_blk
538 ; blk <- mk_lit_switch scrut' deflt_blk_id (sortLe le branches)
541 le (t1,_) (t2,_) = t1 <= t2
543 mk_lit_switch :: CmmExpr -> BlockId
544 -> [(Literal,CgStmts)]
546 mk_lit_switch scrut deflt_blk_id [(lit,blk)]
547 = return (consCgStmt if_stmt blk)
549 cmm_lit = mkSimpleLit lit
550 rep = cmmLitRep cmm_lit
551 cond = CmmMachOp (MO_Ne rep) [scrut, CmmLit cmm_lit]
552 if_stmt = CmmCondBranch cond deflt_blk_id
554 mk_lit_switch scrut deflt_blk_id branches
555 = do { hi_blk <- mk_lit_switch scrut deflt_blk_id hi_branches
556 ; lo_blk <- mk_lit_switch scrut deflt_blk_id lo_branches
557 ; lo_blk_id <- forkCgStmts lo_blk
558 ; let if_stmt = CmmCondBranch cond lo_blk_id
559 ; return (if_stmt `consCgStmt` hi_blk) }
561 n_branches = length branches
562 (mid_lit,_) = branches !! (n_branches `div` 2)
563 -- See notes above re mid_tag
565 (lo_branches, hi_branches) = span is_lo branches
566 is_lo (t,_) = t < mid_lit
568 cond = CmmMachOp (mkLtOp mid_lit)
569 [scrut, CmmLit (mkSimpleLit mid_lit)]
571 -------------------------------------------------------------------------
573 -- Simultaneous assignment
575 -------------------------------------------------------------------------
578 emitSimultaneously :: CmmStmts -> Code
579 -- Emit code to perform the assignments in the
580 -- input simultaneously, using temporary variables when necessary.
582 -- The Stmts must be:
583 -- CmmNop, CmmComment, CmmAssign, CmmStore
587 -- We use the strongly-connected component algorithm, in which
588 -- * the vertices are the statements
589 -- * an edge goes from s1 to s2 iff
590 -- s1 assigns to something s2 uses
591 -- that is, if s1 should *follow* s2 in the final order
593 type CVertex = (Int, CmmStmt) -- Give each vertex a unique number,
594 -- for fast comparison
596 emitSimultaneously stmts
598 case filterOut isNopStmt (stmtList stmts) of
601 [stmt] -> stmtC stmt -- It's often just one stmt
602 stmt_list -> doSimultaneously1 (zip [(1::Int)..] stmt_list)
604 doSimultaneously1 :: [CVertex] -> Code
605 doSimultaneously1 vertices
607 edges = [ (vertex, key1, edges_from stmt1)
608 | vertex@(key1, stmt1) <- vertices
610 edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices,
611 stmt1 `mustFollow` stmt2
613 components = stronglyConnComp edges
615 -- do_components deal with one strongly-connected component
616 -- Not cyclic, or singleton? Just do it
617 do_component (AcyclicSCC (n,stmt)) = stmtC stmt
618 do_component (CyclicSCC [(n,stmt)]) = stmtC stmt
620 -- Cyclic? Then go via temporaries. Pick one to
621 -- break the loop and try again with the rest.
622 do_component (CyclicSCC ((n,first_stmt) : rest))
623 = do { from_temp <- go_via_temp first_stmt
624 ; doSimultaneously1 rest
627 go_via_temp (CmmAssign dest src)
628 = do { tmp <- newTemp (cmmRegRep dest)
629 ; stmtC (CmmAssign tmp src)
630 ; return (CmmAssign dest (CmmReg tmp)) }
631 go_via_temp (CmmStore dest src)
632 = do { tmp <- newTemp (cmmExprRep src)
633 ; stmtC (CmmAssign tmp src)
634 ; return (CmmStore dest (CmmReg tmp)) }
636 mapCs do_component components
638 mustFollow :: CmmStmt -> CmmStmt -> Bool
639 CmmAssign reg _ `mustFollow` stmt = anySrc (reg `regUsedIn`) stmt
640 CmmStore loc e `mustFollow` stmt = anySrc (locUsedIn loc (cmmExprRep e)) stmt
641 CmmNop `mustFollow` stmt = False
642 CmmComment _ `mustFollow` stmt = False
645 anySrc :: (CmmExpr -> Bool) -> CmmStmt -> Bool
646 -- True if the fn is true of any input of the stmt
647 anySrc p (CmmAssign _ e) = p e
648 anySrc p (CmmStore e1 e2) = p e1 || p e2 -- Might be used in either side
649 anySrc p (CmmComment _) = False
650 anySrc p CmmNop = False
651 anySrc p other = True -- Conservative
653 regUsedIn :: CmmReg -> CmmExpr -> Bool
654 reg `regUsedIn` CmmLit _ = False
655 reg `regUsedIn` CmmLoad e _ = reg `regUsedIn` e
656 reg `regUsedIn` CmmReg reg' = reg == reg'
657 reg `regUsedIn` CmmRegOff reg' _ = reg == reg'
658 reg `regUsedIn` CmmMachOp _ es = any (reg `regUsedIn`) es
660 locUsedIn :: CmmExpr -> MachRep -> CmmExpr -> Bool
661 -- (locUsedIn a r e) checks whether writing to r[a] could affect the value of
662 -- 'e'. Returns True if it's not sure.
663 locUsedIn loc rep (CmmLit _) = False
664 locUsedIn loc rep (CmmLoad e ld_rep) = possiblySameLoc loc rep e ld_rep
665 locUsedIn loc rep (CmmReg reg') = False
666 locUsedIn loc rep (CmmRegOff reg' _) = False
667 locUsedIn loc rep (CmmMachOp _ es) = any (locUsedIn loc rep) es
669 possiblySameLoc :: CmmExpr -> MachRep -> CmmExpr -> MachRep -> Bool
670 -- Assumes that distinct registers (eg Hp, Sp) do not
671 -- point to the same location, nor any offset thereof.
672 possiblySameLoc (CmmReg r1) rep1 (CmmReg r2) rep2 = r1==r2
673 possiblySameLoc (CmmReg r1) rep1 (CmmRegOff r2 0) rep2 = r1==r2
674 possiblySameLoc (CmmRegOff r1 0) rep1 (CmmReg r2) rep2 = r1==r2
675 possiblySameLoc (CmmRegOff r1 start1) rep1 (CmmRegOff r2 start2) rep2
676 = r1==r2 && end1 > start2 && end2 > start1
678 end1 = start1 + machRepByteWidth rep1
679 end2 = start2 + machRepByteWidth rep2
681 possiblySameLoc l1 rep1 (CmmLit _) rep2 = False
682 possiblySameLoc l1 rep1 l2 rep2 = True -- Conservative