StgCmmHeap.hs 20.7 KB
Newer Older
1
2
3
4
5
6
7
8
9
-----------------------------------------------------------------------------
--
-- Stg to C--: heap management functions
--
-- (c) The University of Glasgow 2004-2006
--
-----------------------------------------------------------------------------

module StgCmmHeap (
10
11
        getVirtHp, setVirtHp, setRealHp,
        getHpRelOffset, hpRel,
12

13
        entryHeapCheck, altHeapCheck,
14

15
16
        mkVirtHeapOffsets, mkVirtConstrOffsets,
        mkStaticClosureFields, mkStaticClosure,
17

18
        allocDynClosure, allocDynClosureCmm, emitSetDynHdr
19
20
21
22
    ) where

#include "HsVersions.h"

23
import CmmType
24
25
26
27
28
29
30
31
32
33
34
import StgSyn
import CLabel
import StgCmmLayout
import StgCmmUtils
import StgCmmMonad
import StgCmmProf
import StgCmmTicky
import StgCmmGran
import StgCmmClosure
import StgCmmEnv

35
import MkGraph
36
37

import SMRep
38
import Cmm
39
40
41
import CmmUtils
import CostCentre
import Outputable
42
import IdInfo( CafInfo(..), mayHaveCafRefs )
43
import Module
44
import FastString( mkFastString, fsLit )
45
import Constants
46
import DynFlags
47
48

-----------------------------------------------------------
49
--              Initialise dynamic heap objects
50
51
52
-----------------------------------------------------------

allocDynClosure
Simon Marlow's avatar
Simon Marlow committed
53
54
        :: CmmInfoTable
        -> LambdaFormInfo
55
56
57
58
59
60
61
62
63
64
        -> CmmExpr              -- Cost Centre to stick in the object
        -> CmmExpr              -- Cost Centre to blame for this alloc
                                -- (usually the same; sometimes "OVERHEAD")

        -> [(NonVoid StgArg, VirtualHpOffset)]  -- Offsets from start of object
                                                -- ie Info ptr has offset zero.
                                                -- No void args in here
        -> FCode (LocalReg, CmmAGraph)

allocDynClosureCmm
Simon Marlow's avatar
Simon Marlow committed
65
        :: CmmInfoTable -> LambdaFormInfo -> CmmExpr -> CmmExpr
66
67
68
69
        -> [(CmmExpr, VirtualHpOffset)]
        -> FCode (LocalReg, CmmAGraph)

-- allocDynClosure allocates the thing in the heap,
70
-- and modifies the virtual Hp to account for this.
71
72
73
-- The second return value is the graph that sets the value of the
-- returned LocalReg, which should point to the closure after executing
-- the graph.
74
75
76
77
78

-- Note [Return a LocalReg]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- allocDynClosure returns a LocalReg, not a (Hp+8) CmmExpr.
-- Reason:
79
80
81
82
83
--      ...allocate object...
--      obj = Hp + 8
--      y = f(z)
--      ...here obj is still valid,
--         but Hp+8 means something quite different...
84
85


Simon Marlow's avatar
Simon Marlow committed
86
allocDynClosure info_tbl lf_info use_cc _blame_cc args_w_offsets
87
88
  = do  { let (args, offsets) = unzip args_w_offsets
        ; cmm_args <- mapM getArgAmode args     -- No void args
Simon Marlow's avatar
Simon Marlow committed
89
90
        ; allocDynClosureCmm info_tbl lf_info
                             use_cc _blame_cc (zip cmm_args offsets)
91
92
        }

Simon Marlow's avatar
Simon Marlow committed
93
allocDynClosureCmm info_tbl lf_info use_cc _blame_cc amodes_w_offsets
94
95
96
  = do  { virt_hp <- getVirtHp

        -- SAY WHAT WE ARE ABOUT TO DO
Simon Marlow's avatar
Simon Marlow committed
97
98
99
        ; let rep = cit_rep info_tbl
        ; tickyDynAlloc rep lf_info
        ; profDynAlloc rep use_cc
100
101
102
103
104
105
106
107

        -- FIND THE OFFSET OF THE INFO-PTR WORD
        ; let   info_offset = virt_hp + 1
                -- info_offset is the VirtualHpOffset of the first
                -- word of the new object
                -- Remember, virtHp points to last allocated word,
                -- ie 1 *before* the info-ptr word of new object.

Simon Marlow's avatar
Simon Marlow committed
108
                info_ptr = CmmLit (CmmLabel (cit_lbl info_tbl))
109
110
111

        -- ALLOCATE THE OBJECT
        ; base <- getHpRelOffset info_offset
112
        ; emitComment $ mkFastString "allocDynClosure"
113
114
115
116
117
        ; emitSetDynHdr base info_ptr  use_cc
        ; let (cmm_args, offsets) = unzip amodes_w_offsets
        ; hpStore base cmm_args offsets

        -- BUMP THE VIRTUAL HEAP POINTER
Simon Marlow's avatar
Simon Marlow committed
118
        ; setVirtHp (virt_hp + heapClosureSize rep)
119
120
121
122
123

        -- Assign to a temporary and return
        -- Note [Return a LocalReg]
        ; hp_rel <- getHpRelOffset info_offset
        ; getCodeR $ assignTemp hp_rel }
124
125

emitSetDynHdr :: CmmExpr -> CmmExpr -> CmmExpr -> FCode ()
126
emitSetDynHdr base info_ptr ccs
127
128
129
130
  = hpStore base header [0..]
  where
    header :: [CmmExpr]
    header = [info_ptr] ++ dynProfHdr ccs
131
132
133
        -- ToDo: Gransim stuff
        -- ToDo: Parallel stuff
        -- No ticky header
134
135
136
137
138
139

hpStore :: CmmExpr -> [CmmExpr] -> [VirtualHpOffset] -> FCode ()
-- Store the item (expr,off) in base[off]
hpStore base vals offs
  = emit (catAGraphs (zipWith mk_store vals offs))
  where
140
    mk_store val off = mkStore (cmmOffsetW base off) val
141
142
143


-----------------------------------------------------------
144
--              Layout of static closures
145
146
147
148
149
-----------------------------------------------------------

-- Make a static closure, adding on any extra padding needed for CAFs,
-- and adding a static link field if necessary.

150
mkStaticClosureFields
Simon Marlow's avatar
Simon Marlow committed
151
        :: CmmInfoTable
152
        -> CostCentreStack
153
        -> CafInfo
154
155
        -> [CmmLit]             -- Payload
        -> [CmmLit]             -- The full closure
Simon Marlow's avatar
Simon Marlow committed
156
mkStaticClosureFields info_tbl ccs caf_refs payload
157
158
  = mkStaticClosure info_lbl ccs payload padding
        static_link_field saved_info_field
159
  where
Simon Marlow's avatar
Simon Marlow committed
160
    info_lbl = cit_lbl info_tbl
161
162
163
164
165
166
167
168
169

    -- CAFs must have consistent layout, regardless of whether they
    -- are actually updatable or not.  The layout of a CAF is:
    --
    --        3 saved_info
    --        2 static_link
    --        1 indirectee
    --        0 info ptr
    --
Simon Marlow's avatar
Simon Marlow committed
170
171
172
    -- the static_link and saved_info fields must always be in the
    -- same place.  So we use isThunkRep rather than closureUpdReqd
    -- here:
173

Simon Marlow's avatar
Simon Marlow committed
174
    is_caf = isThunkRep (cit_rep info_tbl)
175

176
177
178
    padding
        | not is_caf = []
        | otherwise  = ASSERT(null payload) [mkIntCLit 0]
179
180

    static_link_field
Simon Marlow's avatar
Simon Marlow committed
181
182
        | is_caf || staticClosureNeedsLink info_tbl = [static_link_value]
        | otherwise                                 = []
183
184

    saved_info_field
185
186
        | is_caf     = [mkIntCLit 0]
        | otherwise  = []
187

188
        -- For a static constructor which has NoCafRefs, we set the
189
190
        -- static link field to a non-zero value so the garbage
        -- collector will ignore it.
191
    static_link_value
192
193
        | mayHaveCafRefs caf_refs  = mkIntCLit 0
        | otherwise                = mkIntCLit 1  -- No CAF refs
194
195
196
197


mkStaticClosure :: CLabel -> CostCentreStack -> [CmmLit]
  -> [CmmLit] -> [CmmLit] -> [CmmLit] -> [CmmLit]
198
mkStaticClosure info_lbl ccs payload padding static_link_field saved_info_field
199
200
  =  [CmmLabel info_lbl]
  ++ variable_header_words
201
  ++ concatMap padLitToWord payload
202
  ++ padding
203
204
205
206
  ++ static_link_field
  ++ saved_info_field
  where
    variable_header_words
207
208
209
210
        =  staticGranHdr
        ++ staticParHdr
        ++ staticProfHdr ccs
        ++ staticTickyHdr
211

212
213
-- JD: Simon had ellided this padding, but without it the C back end asserts
-- failure. Maybe it's a bad assertion, and this padding is indeed unnecessary?
214
215
216
217
218
219
220
221
222
223
224
padLitToWord :: CmmLit -> [CmmLit]
padLitToWord lit = lit : padding pad_length
  where width = typeWidth (cmmLitType lit)
        pad_length = wORD_SIZE - widthInBytes width :: Int

        padding n | n <= 0 = []
                  | n `rem` 2 /= 0 = CmmInt 0 W8  : padding (n-1)
                  | n `rem` 4 /= 0 = CmmInt 0 W16 : padding (n-2)
                  | n `rem` 8 /= 0 = CmmInt 0 W32 : padding (n-4)
                  | otherwise      = CmmInt 0 W64 : padding (n-8)

225
-----------------------------------------------------------
226
--              Heap overflow checking
227
228
229
230
231
232
233
234
235
236
237
238
-----------------------------------------------------------

{- Note [Heap checks]
   ~~~~~~~~~~~~~~~~~~
Heap checks come in various forms.  We provide the following entry
points to the runtime system, all of which use the native C-- entry
convention.

  * gc() performs garbage collection and returns
    nothing to its caller

  * A series of canned entry points like
239
        r = gc_1p( r )
240
241
    where r is a pointer.  This performs gc, and
    then returns its argument r to its caller.
242

243
  * A series of canned entry points like
244
        gcfun_2p( f, x, y )
245
246
247
248
249
250
251
252
253
    where f is a function closure of arity 2
    This performs garbage collection, keeping alive the
    three argument ptrs, and then tail-calls f(x,y)

These are used in the following circumstances

* entryHeapCheck: Function entry
    (a) With a canned GC entry sequence
        f( f_clo, x:ptr, y:ptr ) {
254
255
256
             Hp = Hp+8
             if Hp > HpLim goto L
             ...
257
258
259
          L: HpAlloc = 8
             jump gcfun_2p( f_clo, x, y ) }
     Note the tail call to the garbage collector;
260
     it should do no register shuffling
261
262
263

    (b) No canned sequence
        f( f_clo, x:ptr, y:ptr, ...etc... ) {
264
265
266
          T: Hp = Hp+8
             if Hp > HpLim goto L
             ...
267
          L: HpAlloc = 8
268
269
             call gc()  -- Needs an info table
             goto T }
270
271

* altHeapCheck: Immediately following an eval
272
273
  Started as
        case f x y of r { (p,q) -> rhs }
274
275
276
  (a) With a canned sequence for the results of f
       (which is the very common case since
       all boxed cases return just one pointer
277
278
279
280
281
282
           ...
           r = f( x, y )
        K:      -- K needs an info table
           Hp = Hp+8
           if Hp > HpLim goto L
           ...code for rhs...
283

284
285
        L: r = gc_1p( r )
           goto K }
286

287
288
289
290
        Here, the info table needed by the call
        to gc_1p should be the *same* as the
        one for the call to f; the C-- optimiser
        spots this sharing opportunity)
291
292
293

   (b) No canned sequence for results of f
       Note second info table
294
295
296
297
298
299
           ...
           (r1,r2,r3) = call f( x, y )
        K:
           Hp = Hp+8
           if Hp > HpLim goto L
           ...code for rhs...
300

301
302
        L: call gc()    -- Extra info table here
           goto K
303
304
305

* generalHeapCheck: Anywhere else
  e.g. entry to thunk
306
       case branch *not* following eval,
307
308
309
       or let-no-escape
  Exactly the same as the previous case:

310
311
312
313
        K:      -- K needs an info table
           Hp = Hp+8
           if Hp > HpLim goto L
           ...
314

315
316
        L: call gc()
           goto K
317
318
319
320
321
-}

--------------------------------------------------------------
-- A heap/stack check at a function or thunk entry point.

322
323
324
325
326
327
328
entryHeapCheck :: ClosureInfo
               -> Int            -- Arg Offset
               -> Maybe LocalReg -- Function (closure environment)
               -> Int            -- Arity -- not same as len args b/c of voids
               -> [LocalReg]     -- Non-void args (empty for thunk)
               -> FCode ()
               -> FCode ()
329

330
entryHeapCheck cl_info offset nodeSet arity args code
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
  = do dflags <- getDynFlags

       let platform = targetPlatform dflags

           is_thunk = arity == 0
           is_fastf = case closureFunInfo cl_info of
                           Just (_, ArgGen _) -> False
                           _otherwise         -> True

           args' = map (CmmReg . CmmLocal) args
           setN = case nodeSet of
                          Just n  -> mkAssign nodeReg (CmmReg $ CmmLocal n)
                          Nothing -> mkAssign nodeReg $
                              CmmLit (CmmLabel $ staticClosureLabel platform cl_info)

           {- Thunks:          Set R1 = node, jump GCEnter1
              Function (fast): Set R1 = node, jump GCFun
              Function (slow): Set R1 = node, call generic_gc -}
           gc_call upd = setN <*> gc_lbl upd
           gc_lbl upd
               | is_thunk  = mkDirectJump (CmmReg $ CmmGlobal GCEnter1) [] sp
               | is_fastf  = mkDirectJump (CmmReg $ CmmGlobal GCFun) [] sp
               | otherwise = mkForeignJump Slow (CmmReg $ CmmGlobal GCFun) args' upd
               where sp = max offset upd
           {- DT (12/08/10) This is a little fishy, mainly the sp fix up amount.
            - This is since the ncg inserts spills before the stack/heap check.
            - This should be fixed up and then we won't need to fix up the Sp on
            - GC calls, but until then this fishy code works -}

       updfr_sz <- getUpdFrameOff
361
362
363
364
365
366
367
368
369
370
       heapCheck True (gc_call updfr_sz) code

{-
    -- This code is slightly outdated now and we could easily keep the above
    -- GC methods. However, there may be some performance gains to be made by
    -- using more specialised GC entry points. Since the semi generic GCFun
    -- entry needs to check the node and figure out what registers to save...
    -- if we provided and used more specialised GC entry points then these
    -- runtime decisions could be turned into compile time decisions.

371
372
    args'     = case fun of Just f  -> f : args
                            Nothing -> args
373
    arg_exprs = map (CmmReg . CmmLocal) args'
374
    gc_call updfr_sz
375
        | arity == 0 = mkJumpGC (CmmReg (CmmGlobal GCEnter1)) arg_exprs updfr_sz
376
377
378
379
380
381
        | otherwise =
            case gc_lbl args' of
                Just _lbl -> panic "StgCmmHeap.entryHeapCheck: not finished"
                            -- mkJumpGC (CmmLit (CmmLabel (mkRtsCodeLabel lbl)))
                            --         arg_exprs updfr_sz
                Nothing  -> mkCall generic_gc (GC, GC) [] [] updfr_sz
382

383
    gc_lbl :: [LocalReg] -> Maybe FastString
384
    gc_lbl [reg]
385
386
387
388
389
390
391
392
393
394
395
        | isGcPtrType ty  = Just (sLit "stg_gc_unpt_r1") -- "stg_gc_fun_1p"
        | isFloatType ty  = case width of
                              W32 -> Just (sLit "stg_gc_f1")
                              W64 -> Just (sLit "stg_gc_d1")
                              _other -> Nothing
        | width == wordWidth = Just (mkGcLabel "stg_gc_unbx_r1")
        | width == W64       = Just (mkGcLabel "stg_gc_l1")
        | otherwise          = Nothing
        where
          ty = localRegType reg
          width = typeWidth ty
396
397
398

    gc_lbl regs = gc_lbl_ptrs (map (isGcPtrType . localRegType) regs)

399
    gc_lbl_ptrs :: [Bool] -> Maybe FastString
400
    -- JD: TEMPORARY -- UNTIL THESE FUNCTIONS EXIST...
401
402
403
    --gc_lbl_ptrs [True,True]      = Just (sLit "stg_gc_fun_2p")
    --gc_lbl_ptrs [True,True,True] = Just (sLit "stg_gc_fun_3p")
    gc_lbl_ptrs _ = Nothing
404
405
406
407
408
-}


--------------------------------------------------------------
-- A heap/stack check at in a case alternative
409

410
411
altHeapCheck :: [LocalReg] -> FCode a -> FCode a
altHeapCheck regs code
412
  = do updfr_sz <- getUpdFrameOff
413
414
       gc_call_code <- gc_call updfr_sz
       heapCheck False gc_call_code code
415

416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
  where
    reg_exprs = map (CmmReg . CmmLocal) regs

    gc_call sp =
        case rts_label regs of
             Just gc -> mkCall (CmmLit gc) (GC, GC) regs reg_exprs sp
             Nothing -> mkCall generic_gc (GC, GC) [] [] sp

    rts_label [reg]
        | isGcPtrType ty = Just (mkGcLabel "stg_gc_unpt_r1")
        | isFloatType ty = case width of
                                W32       -> Just (mkGcLabel "stg_gc_f1")
                                W64       -> Just (mkGcLabel "stg_gc_d1")
                                _         -> Nothing

        | width == wordWidth = Just (mkGcLabel "stg_gc_unbx_r1")
        | width == W64       = Just (mkGcLabel "stg_gc_l1")
        | otherwise          = Nothing
        where
            ty = localRegType reg
            width = typeWidth ty
437
438
439
440

    rts_label _ = Nothing


441
442
443
444
445
446
447
-- | The generic GC procedure; no params, no results
generic_gc :: CmmExpr
generic_gc = CmmLit $ mkGcLabel "stg_gc_noregs"

-- | Create a CLabel for calling a garbage collector entry point
mkGcLabel :: String -> CmmLit
mkGcLabel = (CmmLabel . (mkCmmCodeLabel rtsPackageId) . fsLit)
448
449

-------------------------------
450
451
heapCheck :: Bool -> CmmAGraph -> FCode a -> FCode a
heapCheck checkStack do_gc code
452
  = getHeapUsage $ \ hpHw ->
453
454
    -- Emit heap checks, but be sure to do it lazily so
    -- that the conditionals on hpHw don't cause a black hole
455
    do  { codeOnly $ do_checks checkStack hpHw do_gc
456
457
458
459
        ; tickyAllocHeap hpHw
        ; doGranAllocate hpHw
        ; setRealHp hpHw
        ; code }
460

461
do_checks :: Bool       -- Should we check the stack?
462
463
          -> WordOff    -- Heap headroom
          -> CmmAGraph  -- What to do on failure
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
          -> FCode ()
do_checks checkStack alloc do_gc = do
  loop_id <- newLabelC
  gc_id <- newLabelC
  emitLabel loop_id
  hp_check <- if alloc == 0
                 then return mkNop
                 else do
                   ifthen <- mkCmmIfThen hp_oflo (alloc_n <*> mkBranch gc_id)
                   return (mkAssign hpReg bump_hp <*> ifthen)

  if checkStack
     then emit =<< mkCmmIfThenElse sp_oflo (mkBranch gc_id) hp_check
     else emit hp_check

  emit $ mkComment (mkFastString "outOfLine should follow:")

  emitOutOfLine gc_id $
     mkComment (mkFastString "outOfLine here") <*>
     do_gc <*>
     mkBranch loop_id
485
486
487
488
489
490
                -- Test for stack pointer exhaustion, then
                -- bump heap pointer, and test for heap exhaustion
                -- Note that we don't move the heap pointer unless the
                -- stack check succeeds.  Otherwise we might end up
                -- with slop at the end of the current block, which can
                -- confuse the LDV profiler.
491
  where
492
    alloc_lit = CmmLit (mkIntCLit (alloc*wORD_SIZE)) -- Bytes
493
494
    bump_hp   = cmmOffsetExprB (CmmReg hpReg) alloc_lit

495
496
497
    -- Sp overflow if (Sp - CmmHighStack < SpLim)
    sp_oflo = CmmMachOp mo_wordULt
                  [CmmMachOp (MO_Sub (typeWidth (cmmRegType spReg)))
498
499
                             [CmmReg spReg, CmmLit CmmHighStackMark],
                   CmmReg spLimReg]
500

501
502
503
504
505
506
507
    -- Hp overflow if (Hp > HpLim)
    -- (Hp has been incremented by now)
    -- HpLim points to the LAST WORD of valid allocation space.
    hp_oflo = CmmMachOp mo_wordUGt
                  [CmmReg hpReg, CmmReg (CmmGlobal HpLim)]

    alloc_n = mkAssign (CmmGlobal HpAlloc) alloc_lit
508
509
510
511
512
513
514
515
516
517

{-

{- Unboxed tuple alternatives and let-no-escapes (the two most annoying
constructs to generate code for!)  For unboxed tuple returns, there
are an arbitrary number of possibly unboxed return values, some of
which will be in registers, and the others will be on the stack.  We
always organise the stack-resident fields into pointers &
non-pointers, and pass the number of each to the heap check code. -}

518
519
520
521
522
523
524
unbxTupleHeapCheck
        :: [(Id, GlobalReg)]    -- Live registers
        -> WordOff      -- no. of stack slots containing ptrs
        -> WordOff      -- no. of stack slots containing nonptrs
        -> CmmAGraph    -- code to insert in the failure path
        -> FCode ()
        -> FCode ()
525
526

unbxTupleHeapCheck regs ptrs nptrs fail_code code
527
  -- We can't manage more than 255 pointers/non-pointers
528
529
  -- in a generic heap check.
  | ptrs > 255 || nptrs > 255 = panic "altHeapCheck"
530
  | otherwise
531
  = initHeapUsage $ \ hpHw -> do
532
533
534
535
536
        { codeOnly $ do { do_checks 0 {- no stack check -} hpHw
                                    full_fail_code rts_label
                        ; tickyAllocHeap hpHw }
        ; setRealHp hpHw
        ; code }
537
538
  where
    full_fail_code  = fail_code `plusStmts` oneStmt assign_liveness
539
540
541
542
    assign_liveness = CmmAssign (CmmGlobal (VanillaReg 9))      -- Ho ho ho!
                                (CmmLit (mkWordCLit liveness))
    liveness        = mkRegLiveness regs ptrs nptrs
    rts_label       = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "stg_gc_ut")))
543
544


545
{- Old Gransim com -- I have no idea whether it still makes sense (SLPJ Sep07)
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
For GrAnSim the code for doing a heap check and doing a context switch
has been separated. Especially, the HEAP_CHK macro only performs a
heap check. THREAD_CONTEXT_SWITCH should be used for doing a context
switch. GRAN_FETCH_AND_RESCHEDULE must be put at the beginning of
every slow entry code in order to simulate the fetching of
closures. If fetching is necessary (i.e. current closure is not local)
then an automatic context switch is done. -}


When failing a check, we save a return address on the stack and
jump to a pre-compiled code fragment that saves the live registers
and returns to the scheduler.

The return address in most cases will be the beginning of the basic
block in which the check resides, since we need to perform the check
again on re-entry because someone else might have stolen the resource
in the meantime.

%************************************************************************
565
%*                                                                      *
566
     Generic Heap/Stack Checks - used in the RTS
567
%*                                                                      *
568
569
570
571
572
573
574
575
%************************************************************************

\begin{code}
hpChkGen :: CmmExpr -> CmmExpr -> CmmExpr -> FCode ()
hpChkGen bytes liveness reentry
  = do_checks' bytes True assigns stg_gc_gen
  where
    assigns = mkStmts [
576
577
578
                CmmAssign (CmmGlobal (VanillaReg 9))  liveness,
                CmmAssign (CmmGlobal (VanillaReg 10)) reentry
                ]
579
580
581
582
583
584
585
586
587
588
589
590

-- a heap check where R1 points to the closure to enter on return, and
-- we want to assign to Sp[0] on failure (used in AutoApply.cmm:BUILD_PAP).
hpChkNodePointsAssignSp0 :: CmmExpr -> CmmExpr -> FCode ()
hpChkNodePointsAssignSp0 bytes sp0
  = do_checks' bytes True assign stg_gc_enter1
  where assign = oneStmt (CmmStore (CmmReg spReg) sp0)

stg_gc_gen    = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "stg_gc_gen")))
\end{code}

-}