1 -----------------------------------------------------------------------------
3 -- Monad for Stg to C-- code generation
5 -- (c) The University of Glasgow 2004-2006
7 -----------------------------------------------------------------------------
12 initC, thenC, thenFC, listCs, listFCs, mapCs, mapFCs,
13 returnFC, fixC, nopC, whenC,
14 newUnique, newUniqSupply,
16 emit, emitData, emitProc, emitProcWithConvention, emitSimpleProc,
18 getCmm, cgStmtsToBlocks,
19 getCodeR, getCode, getHeapUsage,
21 forkClosureBody, forkStatics, forkAlts, forkProc, codeOnly,
26 withSequel, getSequel,
28 setSRTLabel, getSRTLabel,
29 setTickyCtrLabel, getTickyCtrLabel,
31 withUpdFrameOff, getUpdFrameOff, initUpdFrameOff,
33 HeapUsage(..), VirtualHpOffset, initHpUsage,
34 getHpUsage, setHpUsage, heapHWM,
35 setVirtHp, getVirtHp, setRealHp,
39 -- ideally we wouldn't export these, but some other modules access internal state
40 getState, setState, getInfoDown, getDynFlags, getThisPackage,
42 -- more localised access to monad state
43 CgIdInfo(..), CgLoc(..),
44 getBinds, setBinds, getStaticBinds,
46 -- out of general friendliness, we also export ...
47 CgInfoDownwards(..), CgState(..) -- non-abstract
50 #include "HsVersions.h"
55 import ZipCfgCmmRep (UpdFrameOffset)
59 import TyCon ( PrimRep )
68 import FastString(sLit)
73 import Prelude hiding( sequence )
74 import qualified Prelude( sequence )
76 infixr 9 `thenC` -- Right-associative!
80 --------------------------------------------------------
81 -- The FCode monad and its types
82 --------------------------------------------------------
84 newtype FCode a = FCode (CgInfoDownwards -> CgState -> (a, CgState))
86 instance Monad FCode where
92 {-# INLINE returnFC #-}
94 initC :: DynFlags -> Module -> FCode a -> IO a
95 initC dflags mod (FCode code)
96 = do { uniqs <- mkSplitUniqSupply 'c'
97 ; case code (initCgInfoDown dflags mod) (initCgState uniqs) of
98 (res, _) -> return res
101 returnFC :: a -> FCode a
102 returnFC val = FCode (\_info_down state -> (val, state))
104 thenC :: FCode () -> FCode a -> FCode a
105 thenC (FCode m) (FCode k) =
106 FCode (\info_down state -> let (_,new_state) = m info_down state in
107 k info_down new_state)
112 whenC :: Bool -> FCode () -> FCode ()
113 whenC True code = code
114 whenC False _code = nopC
116 listCs :: [FCode ()] -> FCode ()
117 listCs [] = return ()
122 mapCs :: (a -> FCode ()) -> [a] -> FCode ()
125 thenFC :: FCode a -> (a -> FCode c) -> FCode c
126 thenFC (FCode m) k = FCode (
129 (m_result, new_state) = m info_down state
130 (FCode kcode) = k m_result
132 kcode info_down new_state
135 listFCs :: [FCode a] -> FCode [a]
136 listFCs = Prelude.sequence
138 mapFCs :: (a -> FCode b) -> [a] -> FCode [b]
141 fixC :: (a -> FCode a) -> FCode a
146 result@(v,_) = fc info_down state
153 --------------------------------------------------------
154 -- The code generator environment
155 --------------------------------------------------------
157 -- This monadery has some information that it only passes
158 -- *downwards*, as well as some ``state'' which is modified
161 data CgInfoDownwards -- information only passed *downwards* by the monad
163 cgd_dflags :: DynFlags,
164 cgd_mod :: Module, -- Module being compiled
165 cgd_statics :: CgBindings, -- [Id -> info] : static environment
166 cgd_srt_lbl :: CLabel, -- Label of the current top-level SRT
167 cgd_updfr_off :: UpdFrameOffset, -- Size of current update frame
168 cgd_ticky :: CLabel, -- Current destination for ticky counts
169 cgd_sequel :: Sequel -- What to do at end of basic block
172 type CgBindings = IdEnv CgIdInfo
176 { cg_id :: Id -- Id that this is the info for
177 -- Can differ from the Id at occurrence sites by
178 -- virtue of being externalised, for splittable C
179 , cg_lf :: LambdaFormInfo
180 , cg_loc :: CgLoc -- CmmExpr for the *tagged* value
181 , cg_rep :: PrimRep -- Cache for (idPrimRep id)
182 , cg_tag :: {-# UNPACK #-} !DynTag -- Cache for (lfDynTag cg_lf)
186 = CmmLoc CmmExpr -- A stable CmmExpr; that is, one not mentioning
187 -- Hp, so that it remains valid across calls
189 | LneLoc BlockId [LocalReg] -- A join point
190 -- A join point (= let-no-escape) should only
191 -- be tail-called, and in a saturated way.
192 -- To tail-call it, assign to these locals,
193 -- and branch to the block id
195 instance Outputable CgIdInfo where
196 ppr (CgIdInfo { cg_id = id, cg_loc = loc })
197 = ppr id <+> ptext (sLit "-->") <+> ppr loc
199 instance Outputable CgLoc where
200 ppr (CmmLoc e) = ptext (sLit "cmm") <+> ppr e
201 ppr (LneLoc b rs) = ptext (sLit "lne") <+> ppr b <+> ppr rs
204 -- Sequel tells what to do with the result of this expression
206 = Return Bool -- Return result(s) to continuation found on the stack
207 -- True <=> the continuation is update code (???)
210 [LocalReg] -- Put result(s) in these regs and fall through
211 -- NB: no void arguments here
212 Bool -- Should we adjust the heap pointer back to recover
213 -- space that's unused on this path?
214 -- We need to do this only if the expression may
215 -- allocate (e.g. it's a foreign call or allocating primOp)
216 instance Show Sequel where
217 show (Return _) = "Sequel: Return"
218 show (AssignTo _ _) = "Sequel: Assign"
220 initCgInfoDown :: DynFlags -> Module -> CgInfoDownwards
221 initCgInfoDown dflags mod
222 = MkCgInfoDown { cgd_dflags = dflags,
224 cgd_statics = emptyVarEnv,
225 cgd_srt_lbl = error "initC: srt_lbl",
226 cgd_updfr_off = initUpdFrameOff,
227 cgd_ticky = mkTopTickyCtrLabel,
228 cgd_sequel = initSequel }
231 initSequel = Return False
233 initUpdFrameOff :: UpdFrameOffset
234 initUpdFrameOff = widthInBytes wordWidth -- space for the RA
237 --------------------------------------------------------
238 -- The code generator state
239 --------------------------------------------------------
243 cgs_stmts :: CmmAGraph, -- Current procedure
245 cgs_tops :: OrdList CmmTopZ,
246 -- Other procedures and data blocks in this compilation unit
247 -- Both are ordered only so that we can
248 -- reduce forward references, when it's easy to do so
250 cgs_binds :: CgBindings, -- [Id -> info] : *local* bindings environment
251 -- Bindings for top-level things are given in
252 -- the info-down part
254 cgs_hp_usg :: HeapUsage,
256 cgs_uniqs :: UniqSupply }
260 virtHp :: VirtualHpOffset, -- Virtual offset of highest-allocated word
261 realHp :: VirtualHpOffset -- realHp: Virtual offset of real heap ptr
264 type VirtualHpOffset = WordOff
266 initCgState :: UniqSupply -> CgState
268 = MkCgState { cgs_stmts = mkNop, cgs_tops = nilOL,
269 cgs_binds = emptyVarEnv,
270 cgs_hp_usg = initHpUsage,
273 stateIncUsage :: CgState -> CgState -> CgState
274 -- stateIncUsage@ e1 e2 incorporates in e1
275 -- the heap high water mark found in e2.
276 stateIncUsage s1 s2@(MkCgState { cgs_hp_usg = hp_usg })
277 = s1 { cgs_hp_usg = cgs_hp_usg s1 `maxHpHw` virtHp hp_usg }
278 `addCodeBlocksFrom` s2
280 addCodeBlocksFrom :: CgState -> CgState -> CgState
281 -- Add code blocks from the latter to the former
282 -- (The cgs_stmts will often be empty, but not always; see codeOnly)
283 s1 `addCodeBlocksFrom` s2
284 = s1 { cgs_stmts = cgs_stmts s1 <*> cgs_stmts s2,
285 cgs_tops = cgs_tops s1 `appOL` cgs_tops s2 }
288 -- The heap high water mark is the larger of virtHp and hwHp. The latter is
289 -- only records the high water marks of forked-off branches, so to find the
290 -- heap high water mark you have to take the max of virtHp and hwHp. Remember,
291 -- virtHp never retreats!
293 -- Note Jan 04: ok, so why do we only look at the virtual Hp??
295 heapHWM :: HeapUsage -> VirtualHpOffset
298 initHpUsage :: HeapUsage
299 initHpUsage = HeapUsage { virtHp = 0, realHp = 0 }
301 maxHpHw :: HeapUsage -> VirtualHpOffset -> HeapUsage
302 hp_usg `maxHpHw` hw = hp_usg { virtHp = virtHp hp_usg `max` hw }
305 --------------------------------------------------------
306 -- Operators for getting and setting the state and "info_down".
307 --------------------------------------------------------
309 getState :: FCode CgState
310 getState = FCode $ \_info_down state -> (state,state)
312 setState :: CgState -> FCode ()
313 setState state = FCode $ \_info_down _ -> ((),state)
315 getHpUsage :: FCode HeapUsage
318 return $ cgs_hp_usg state
320 setHpUsage :: HeapUsage -> FCode ()
321 setHpUsage new_hp_usg = do
323 setState $ state {cgs_hp_usg = new_hp_usg}
325 setVirtHp :: VirtualHpOffset -> FCode ()
327 = do { hp_usage <- getHpUsage
328 ; setHpUsage (hp_usage {virtHp = new_virtHp}) }
330 getVirtHp :: FCode VirtualHpOffset
332 = do { hp_usage <- getHpUsage
333 ; return (virtHp hp_usage) }
335 setRealHp :: VirtualHpOffset -> FCode ()
337 = do { hp_usage <- getHpUsage
338 ; setHpUsage (hp_usage {realHp = new_realHp}) }
340 getBinds :: FCode CgBindings
343 return $ cgs_binds state
345 setBinds :: CgBindings -> FCode ()
346 setBinds new_binds = do
348 setState $ state {cgs_binds = new_binds}
350 getStaticBinds :: FCode CgBindings
353 return (cgd_statics info)
355 withState :: FCode a -> CgState -> FCode (a,CgState)
356 withState (FCode fcode) newstate = FCode $ \info_down state ->
357 let (retval, state2) = fcode info_down newstate in ((retval,state2), state)
359 newUniqSupply :: FCode UniqSupply
362 let (us1, us2) = splitUniqSupply (cgs_uniqs state)
363 setState $ state { cgs_uniqs = us1 }
366 newUnique :: FCode Unique
369 return (uniqFromSupply us)
372 getInfoDown :: FCode CgInfoDownwards
373 getInfoDown = FCode $ \info_down state -> (info_down,state)
375 getDynFlags :: FCode DynFlags
376 getDynFlags = liftM cgd_dflags getInfoDown
378 getThisPackage :: FCode PackageId
379 getThisPackage = liftM thisPackage getDynFlags
381 withInfoDown :: FCode a -> CgInfoDownwards -> FCode a
382 withInfoDown (FCode fcode) info_down = FCode $ \_ state -> fcode info_down state
384 doFCode :: FCode a -> CgInfoDownwards -> CgState -> (a,CgState)
385 doFCode (FCode fcode) info_down state = fcode info_down state
388 -- ----------------------------------------------------------------------------
389 -- Get the current module name
391 getModuleName :: FCode Module
392 getModuleName = do { info <- getInfoDown; return (cgd_mod info) }
394 -- ----------------------------------------------------------------------------
395 -- Get/set the end-of-block info
397 withSequel :: Sequel -> FCode () -> FCode ()
398 withSequel sequel code
399 = do { info <- getInfoDown
400 ; withInfoDown code (info {cgd_sequel = sequel }) }
402 getSequel :: FCode Sequel
403 getSequel = do { info <- getInfoDown
404 ; return (cgd_sequel info) }
406 -- ----------------------------------------------------------------------------
407 -- Get/set the current SRT label
409 -- There is just one SRT for each top level binding; all the nested
410 -- bindings use sub-sections of this SRT. The label is passed down to
411 -- the nested bindings via the monad.
413 getSRTLabel :: FCode CLabel -- Used only by cgPanic
414 getSRTLabel = do info <- getInfoDown
415 return (cgd_srt_lbl info)
417 setSRTLabel :: CLabel -> FCode a -> FCode a
418 setSRTLabel srt_lbl code
419 = do info <- getInfoDown
420 withInfoDown code (info { cgd_srt_lbl = srt_lbl})
422 -- ----------------------------------------------------------------------------
423 -- Get/set the size of the update frame
425 -- We keep track of the size of the update frame so that we
426 -- can set the stack pointer to the proper address on return
427 -- (or tail call) from the closure.
428 -- There should be at most one update frame for each closure.
429 -- Note: I'm including the size of the original return address
430 -- in the size of the update frame -- hence the default case on `get'.
432 withUpdFrameOff :: UpdFrameOffset -> FCode () -> FCode ()
433 withUpdFrameOff size code
434 = do { info <- getInfoDown
435 ; withInfoDown code (info {cgd_updfr_off = size }) }
437 getUpdFrameOff :: FCode UpdFrameOffset
439 = do { info <- getInfoDown
440 ; return $ cgd_updfr_off info }
442 -- ----------------------------------------------------------------------------
443 -- Get/set the current ticky counter label
445 getTickyCtrLabel :: FCode CLabel
446 getTickyCtrLabel = do
448 return (cgd_ticky info)
450 setTickyCtrLabel :: CLabel -> FCode () -> FCode ()
451 setTickyCtrLabel ticky code = do
453 withInfoDown code (info {cgd_ticky = ticky})
456 --------------------------------------------------------
458 --------------------------------------------------------
460 forkClosureBody :: FCode () -> FCode ()
461 -- forkClosureBody takes a code, $c$, and compiles it in a
462 -- fresh environment, except that:
463 -- - compilation info and statics are passed in unchanged.
464 -- - local bindings are passed in unchanged
465 -- (it's up to the enclosed code to re-bind the
466 -- free variables to a field of the closure)
468 -- The current state is passed on completely unaltered, except that
469 -- C-- from the fork is incorporated.
471 forkClosureBody body_code
472 = do { info <- getInfoDown
473 ; us <- newUniqSupply
475 ; let body_info_down = info { cgd_sequel = initSequel
476 , cgd_updfr_off = initUpdFrameOff }
477 fork_state_in = (initCgState us) { cgs_binds = cgs_binds state }
479 = doFCode body_code body_info_down fork_state_in
480 ; setState $ state `addCodeBlocksFrom` fork_state_out }
482 forkStatics :: FCode a -> FCode a
483 -- @forkStatics@ $fc$ compiles $fc$ in an environment whose *statics* come
484 -- from the current *local bindings*, but which is otherwise freshly initialised.
485 -- The Abstract~C returned is attached to the current state, but the
486 -- bindings and usage information is otherwise unchanged.
487 forkStatics body_code
488 = do { info <- getInfoDown
489 ; us <- newUniqSupply
491 ; let rhs_info_down = info { cgd_statics = cgs_binds state
492 , cgd_sequel = initSequel
493 , cgd_updfr_off = initUpdFrameOff }
494 (result, fork_state_out) = doFCode body_code rhs_info_down
496 ; setState (state `addCodeBlocksFrom` fork_state_out)
499 forkProc :: FCode a -> FCode a
500 -- 'forkProc' takes a code and compiles it in the *current* environment,
501 -- returning the graph thus constructed.
503 -- The current environment is passed on completely unchanged to
504 -- the successor. In particular, any heap usage from the enclosed
505 -- code is discarded; it should deal with its own heap consumption
507 = do { info_down <- getInfoDown
508 ; us <- newUniqSupply
510 ; let info_down' = info_down -- { cgd_sequel = initSequel }
511 fork_state_in = (initCgState us) { cgs_binds = cgs_binds state }
512 (result, fork_state_out) = doFCode body_code info_down' fork_state_in
513 ; setState $ state `addCodeBlocksFrom` fork_state_out
516 codeOnly :: FCode () -> FCode ()
517 -- Emit any code from the inner thing into the outer thing
518 -- Do not affect anything else in the outer state
519 -- Used in almost-circular code to prevent false loop dependencies
521 = do { info_down <- getInfoDown
522 ; us <- newUniqSupply
524 ; let fork_state_in = (initCgState us) { cgs_binds = cgs_binds state,
525 cgs_hp_usg = cgs_hp_usg state }
526 ((), fork_state_out) = doFCode body_code info_down fork_state_in
527 ; setState $ state `addCodeBlocksFrom` fork_state_out }
529 forkAlts :: [FCode a] -> FCode [a]
530 -- (forkAlts' bs d) takes fcodes 'bs' for the branches of a 'case', and
531 -- an fcode for the default case 'd', and compiles each in the current
532 -- environment. The current environment is passed on unmodified, except
533 -- that the virtual Hp is moved on to the worst virtual Hp for the branches
535 forkAlts branch_fcodes
536 = do { info_down <- getInfoDown
537 ; us <- newUniqSupply
539 ; let compile us branch
540 = (us2, doFCode branch info_down branch_state)
542 (us1,us2) = splitUniqSupply us
543 branch_state = (initCgState us1) {
544 cgs_binds = cgs_binds state,
545 cgs_hp_usg = cgs_hp_usg state }
547 (_us, results) = mapAccumL compile us branch_fcodes
548 (branch_results, branch_out_states) = unzip results
549 ; setState $ foldl stateIncUsage state branch_out_states
550 -- NB foldl. state is the *left* argument to stateIncUsage
551 ; return branch_results }
553 -- collect the code emitted by an FCode computation
554 getCodeR :: FCode a -> FCode (a, CmmAGraph)
556 = do { state1 <- getState
557 ; (a, state2) <- withState fcode (state1 { cgs_stmts = mkNop })
558 ; setState $ state2 { cgs_stmts = cgs_stmts state1 }
559 ; return (a, cgs_stmts state2) }
561 getCode :: FCode a -> FCode CmmAGraph
562 getCode fcode = do { (_,stmts) <- getCodeR fcode; return stmts }
564 -- 'getHeapUsage' applies a function to the amount of heap that it uses.
565 -- It initialises the heap usage to zeros, and passes on an unchanged
568 -- It is usually a prelude to performing a GC check, so everything must
569 -- be in a tidy and consistent state.
571 -- Note the slightly subtle fixed point behaviour needed here
573 getHeapUsage :: (VirtualHpOffset -> FCode a) -> FCode a
575 = do { info_down <- getInfoDown
577 ; let fstate_in = state { cgs_hp_usg = initHpUsage }
578 (r, fstate_out) = doFCode (fcode hp_hw) info_down fstate_in
579 hp_hw = heapHWM (cgs_hp_usg fstate_out) -- Loop here!
581 ; setState $ fstate_out { cgs_hp_usg = cgs_hp_usg state }
584 -- ----------------------------------------------------------------------------
585 -- Combinators for emitting code
587 emit :: CmmAGraph -> FCode ()
589 = do { state <- getState
590 ; setState $ state { cgs_stmts = cgs_stmts state <*> ag } }
592 emitData :: Section -> [CmmStatic] -> FCode ()
594 = do { state <- getState
595 ; setState $ state { cgs_tops = cgs_tops state `snocOL` data_block } }
597 data_block = CmmData sect lits
599 emitProcWithConvention :: Convention -> CmmInfo -> CLabel -> CmmFormals ->
600 CmmAGraph -> FCode ()
601 emitProcWithConvention conv info lbl args blocks
602 = do { us <- newUniqSupply
603 ; let (offset, entry) = mkEntry (mkBlockId $ uniqFromSupply us) conv args
604 blks = initUs_ us $ lgraphOfAGraph $ entry <*> blocks
605 ; let proc_block = CmmProc info lbl args ((offset, Just initUpdFrameOff), blks)
607 ; setState $ state { cgs_tops = cgs_tops state `snocOL` proc_block } }
609 emitProc :: CmmInfo -> CLabel -> CmmFormals -> CmmAGraph -> FCode ()
610 emitProc = emitProcWithConvention Native
612 emitSimpleProc :: CLabel -> CmmAGraph -> FCode ()
613 emitSimpleProc lbl code =
614 emitProc (CmmInfo Nothing Nothing CmmNonInfoTable) lbl [] code
616 getCmm :: FCode () -> FCode CmmZ
617 -- Get all the CmmTops (there should be no stmts)
618 -- Return a single Cmm which may be split from other Cmms by
619 -- object splitting (at a later stage)
621 = do { state1 <- getState
622 ; ((), state2) <- withState code (state1 { cgs_tops = nilOL })
623 ; setState $ state2 { cgs_tops = cgs_tops state1 }
624 ; return (Cmm (fromOL (cgs_tops state2))) }
626 -- ----------------------------------------------------------------------------
629 -- These functions deal in terms of CgStmts, which is an abstract type
630 -- representing the code in the current proc.
632 -- turn CgStmts into [CmmBasicBlock], for making a new proc.
633 cgStmtsToBlocks :: CmmAGraph -> FCode CmmGraph
634 cgStmtsToBlocks stmts
635 = do { us <- newUniqSupply
636 ; return (initUs_ us (lgraphOfAGraph stmts)) }