SMRep.lhs 12.9 KB
Newer Older
1
%
Simon Marlow's avatar
Simon Marlow committed
2
% (c) The University of Glasgow 2006
3
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4
%
Simon Marlow's avatar
Simon Marlow committed
5 6

Storage manager representation of closures
7 8 9 10 11

This is here, rather than in ClosureInfo, just to keep nhc happy.
Other modules should access this info through ClosureInfo.

\begin{code}
Ian Lynagh's avatar
Ian Lynagh committed
12 13 14 15 16 17 18
{-# OPTIONS -fno-warn-tabs #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and
-- detab the module (please do the detabbing in a separate patch). See
--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
-- for details

19
module SMRep (
Simon Marlow's avatar
Simon Marlow committed
20
        -- * Words and bytes
21 22 23
	StgWord, StgHalfWord, 
	hALF_WORD_SIZE, hALF_WORD_SIZE_IN_BITS,
	WordOff, ByteOff,
24
        roundUpToWords,
25

Simon Marlow's avatar
Simon Marlow committed
26
        -- * Closure repesentation
27 28 29 30
        SMRep(..),	-- CmmInfo sees the rep; no one else does
        IsStatic, 
        ClosureTypeInfo(..), ArgDescr(..), Liveness,
        ConstrDescription, 
Simon Marlow's avatar
Simon Marlow committed
31 32

        -- ** Construction
33
        mkHeapRep, blackHoleRep, mkStackRep, mkRTSRep,
34

Simon Marlow's avatar
Simon Marlow committed
35
        -- ** Predicates
Simon Marlow's avatar
Simon Marlow committed
36
        isStaticRep, isConRep, isThunkRep, isFunRep, isStaticNoCafCon,
Simon Marlow's avatar
Simon Marlow committed
37 38

        -- ** Size-related things
39 40 41 42
        heapClosureSize,
        fixedHdrSize, arrWordsHdrSize, arrPtrsHdrSize,
        profHdrSize, thunkHdrSize, nonHdrSize,

Simon Marlow's avatar
Simon Marlow committed
43 44
        -- ** RTS closure types
        rtsClosureType, rET_SMALL, rET_BIG,
45 46
        aRG_GEN, aRG_GEN_BIG,

Simon Marlow's avatar
Simon Marlow committed
47
        -- * Operations over [Word8] strings that don't belong here
48
	pprWord8String, stringToWord8s
49 50
    ) where

51
#include "../HsVersions.h"
52
#include "../includes/MachDeps.h"
53

Simon Marlow's avatar
Simon Marlow committed
54
import StaticFlags
55
import Constants
sof's avatar
sof committed
56
import Outputable
57
import FastString
58

59
import Data.Char( ord )
Simon Marlow's avatar
Simon Marlow committed
60
import Data.Word
61
import Data.Bits
62 63
\end{code}

64 65 66 67 68 69 70 71 72 73

%************************************************************************
%*									*
		Words and bytes
%*									*
%************************************************************************

\begin{code}
type WordOff = Int	-- Word offset, or word count
type ByteOff = Int	-- Byte offset, or byte count
74 75 76

roundUpToWords :: ByteOff -> ByteOff
roundUpToWords n = (n + (wORD_SIZE - 1)) .&. (complement (wORD_SIZE - 1))
77 78 79 80 81 82 83 84
\end{code}

StgWord is a type representing an StgWord on the target platform.

\begin{code}
#if SIZEOF_HSWORD == 4
type StgWord     = Word32
type StgHalfWord = Word16
Ian Lynagh's avatar
Ian Lynagh committed
85 86 87 88
hALF_WORD_SIZE :: ByteOff
hALF_WORD_SIZE = 2
hALF_WORD_SIZE_IN_BITS :: Int
hALF_WORD_SIZE_IN_BITS = 16
89 90 91
#elif SIZEOF_HSWORD == 8
type StgWord     = Word64
type StgHalfWord = Word32
Ian Lynagh's avatar
Ian Lynagh committed
92 93 94 95
hALF_WORD_SIZE :: ByteOff
hALF_WORD_SIZE = 4
hALF_WORD_SIZE_IN_BITS :: Int
hALF_WORD_SIZE_IN_BITS = 32
96 97 98 99 100
#else
#error unknown SIZEOF_HSWORD
#endif
\end{code}

101

102 103 104 105 106 107 108
%************************************************************************
%*									*
\subsubsection[SMRep-datatype]{@SMRep@---storage manager representation}
%*									*
%************************************************************************

\begin{code}
109 110
-- | A description of the layout of a closure.  Corresponds directly
-- to the closure types in includes/rts/storage/ClosureTypes.h.
111
data SMRep
112 113 114 115 116 117 118 119 120
  = HeapRep              -- GC routines consult sizes in info tbl
        IsStatic
        !WordOff         --  # ptr words
        !WordOff         --  # non-ptr words INCLUDING SLOP (see mkHeapRep below)
        ClosureTypeInfo  -- type-specific info

  | StackRep            -- Stack frame (RET_SMALL or RET_BIG)
        Liveness

121 122 123 124
  | RTSRep              -- The RTS needs to declare info tables with specific
        StgHalfWord     -- type tags, so this form lets us override the default
        SMRep           -- tag for an SMRep.

125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180
-- | True <=> This is a static closure.  Affects how we garbage-collect it.
-- Static closure have an extra static link field at the end.
type IsStatic = Bool

-- From an SMRep you can get to the closure type defined in
-- includes/rts/storage/ClosureTypes.h. Described by the function
-- rtsClosureType below.

data ClosureTypeInfo
  = Constr        ConstrTag ConstrDescription
  | Fun           FunArity ArgDescr
  | Thunk
  | ThunkSelector SelectorOffset
  | BlackHole

type ConstrTag         = StgHalfWord
type ConstrDescription = [Word8] -- result of dataConIdentity
type FunArity          = StgHalfWord
type SelectorOffset    = StgWord

-------------------------
-- We represent liveness bitmaps as a Bitmap (whose internal
-- representation really is a bitmap).  These are pinned onto case return
-- vectors to indicate the state of the stack for the garbage collector.
-- 
-- In the compiled program, liveness bitmaps that fit inside a single
-- word (StgWord) are stored as a single word, while larger bitmaps are
-- stored as a pointer to an array of words. 

type Liveness = [Bool]   -- One Bool per word; True  <=> non-ptr or dead
                         --                    False <=> ptr

-------------------------
-- An ArgDescr describes the argument pattern of a function

data ArgDescr
  = ArgSpec		-- Fits one of the standard patterns
	!StgHalfWord	-- RTS type identifier ARG_P, ARG_N, ...

  | ArgGen	 	-- General case
	Liveness	-- Details about the arguments


-----------------------------------------------------------------------------
-- Construction

mkHeapRep :: IsStatic -> WordOff -> WordOff -> ClosureTypeInfo -> SMRep
mkHeapRep is_static ptr_wds nonptr_wds cl_type_info
  = HeapRep is_static
            ptr_wds
            (nonptr_wds + slop_wds)
            cl_type_info
  where
     slop_wds
      | is_static = 0
      | otherwise = max 0 (minClosureSize - (hdr_size + payload_size))
181

182 183
     hdr_size     = closureTypeHdrSize cl_type_info
     payload_size = ptr_wds + nonptr_wds
184

185 186
mkRTSRep :: StgHalfWord -> SMRep -> SMRep
mkRTSRep = RTSRep
187 188

mkStackRep :: [Bool] -> SMRep
189
mkStackRep liveness = StackRep liveness
190 191 192 193

blackHoleRep :: SMRep
blackHoleRep = HeapRep False 0 0 BlackHole

Simon Marlow's avatar
Simon Marlow committed
194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211
-----------------------------------------------------------------------------
-- Predicates

isStaticRep :: SMRep -> IsStatic
isStaticRep (HeapRep is_static _ _ _) = is_static
isStaticRep (StackRep {})             = False
isStaticRep (RTSRep _ rep)            = isStaticRep rep

isConRep :: SMRep -> Bool
isConRep (HeapRep _ _ _ Constr{}) = True
isConRep _                        = False

isThunkRep :: SMRep -> Bool
isThunkRep (HeapRep _ _ _ Thunk{})         = True
isThunkRep (HeapRep _ _ _ ThunkSelector{}) = True
isThunkRep (HeapRep _ _ _ BlackHole{})     = True
isThunkRep _                               = False

Simon Marlow's avatar
Simon Marlow committed
212 213 214 215
isFunRep :: SMRep -> Bool
isFunRep (HeapRep _ _ _ Fun{}) = True
isFunRep _                     = False

Simon Marlow's avatar
Simon Marlow committed
216 217 218 219 220 221 222
isStaticNoCafCon :: SMRep -> Bool
-- This should line up exactly with CONSTR_NOCAF_STATIC above
-- See Note [Static NoCaf constructors]
isStaticNoCafCon (HeapRep True 0 _ Constr{}) = True
isStaticNoCafCon _                           = False


223 224 225 226
-----------------------------------------------------------------------------
-- Size-related things

-- | Size of a closure header (StgHeader in includes/rts/storage/Closures.h)
227
fixedHdrSize :: WordOff
Simon Marlow's avatar
Simon Marlow committed
228
fixedHdrSize = sTD_HDR_SIZE + profHdrSize
229

230 231
-- | Size of the profiling part of a closure header
-- (StgProfHeader in includes/rts/storage/Closures.h)
232
profHdrSize  :: WordOff
233 234
profHdrSize  | opt_SccProfilingOn   = pROF_HDR_SIZE
	     | otherwise	    = 0
235

236 237 238 239
-- | The garbage collector requires that every closure is at least as big as this.
minClosureSize :: WordOff
minClosureSize = fixedHdrSize + mIN_PAYLOAD_SIZE

240 241
arrWordsHdrSize   :: ByteOff
arrWordsHdrSize   = fixedHdrSize*wORD_SIZE + sIZEOF_StgArrWords_NoHdr
242

243 244
arrPtrsHdrSize    :: ByteOff
arrPtrsHdrSize    = fixedHdrSize*wORD_SIZE + sIZEOF_StgMutArrPtrs_NoHdr
245 246 247 248

-- Thunks have an extra header word on SMP, so the update doesn't 
-- splat the payload.
thunkHdrSize :: WordOff
249
thunkHdrSize = fixedHdrSize + smp_hdr
250
	where smp_hdr = sIZEOF_StgSMPThunkHeader `quot` wORD_SIZE
251

252

253 254 255
nonHdrSize :: SMRep -> WordOff
nonHdrSize (HeapRep _ p np _) = p + np
nonHdrSize (StackRep bs)      = length bs
256
nonHdrSize (RTSRep _ rep)     = nonHdrSize rep
257

258 259 260
heapClosureSize :: SMRep -> WordOff
heapClosureSize (HeapRep _ p np ty) = closureTypeHdrSize ty + p + np
heapClosureSize _ = panic "SMRep.heapClosureSize"
261

262 263 264 265 266 267 268 269 270 271 272
closureTypeHdrSize :: ClosureTypeInfo -> WordOff
closureTypeHdrSize ty = case ty of
                  Thunk{}         -> thunkHdrSize
                  ThunkSelector{} -> thunkHdrSize
                  BlackHole{}     -> thunkHdrSize
                  _               -> fixedHdrSize
	-- All thunks use thunkHdrSize, even if they are non-updatable.
	-- this is because we don't have separate closure types for
	-- updatable vs. non-updatable thunks, so the GC can't tell the
	-- difference.  If we ever have significant numbers of non-
	-- updatable thunks, it might be worth fixing this.
273

274 275
-----------------------------------------------------------------------------
-- deriving the RTS closure type from an SMRep
276

277 278 279
#include "../includes/rts/storage/ClosureTypes.h"
#include "../includes/rts/storage/FunTypes.h"
-- Defines CONSTR, CONSTR_1_0 etc
280

281 282
-- | Derives the RTS closure type from an 'SMRep'
rtsClosureType :: SMRep -> StgHalfWord
283 284
rtsClosureType (RTSRep ty _)  = ty

285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325
rtsClosureType (HeapRep False 1 0 Constr{}) = CONSTR_1_0
rtsClosureType (HeapRep False 0 1 Constr{}) = CONSTR_0_1
rtsClosureType (HeapRep False 2 0 Constr{}) = CONSTR_2_0
rtsClosureType (HeapRep False 1 1 Constr{}) = CONSTR_1_1
rtsClosureType (HeapRep False 0 2 Constr{}) = CONSTR_0_2
rtsClosureType (HeapRep False _ _ Constr{}) = CONSTR

rtsClosureType (HeapRep False 1 0 Fun{}) = FUN_1_0
rtsClosureType (HeapRep False 0 1 Fun{}) = FUN_0_1
rtsClosureType (HeapRep False 2 0 Fun{}) = FUN_2_0
rtsClosureType (HeapRep False 1 1 Fun{}) = FUN_1_1
rtsClosureType (HeapRep False 0 2 Fun{}) = FUN_0_2
rtsClosureType (HeapRep False _ _ Fun{}) = FUN

rtsClosureType (HeapRep False 1 0 Thunk{}) = THUNK_1_0
rtsClosureType (HeapRep False 0 1 Thunk{}) = THUNK_0_1
rtsClosureType (HeapRep False 2 0 Thunk{}) = THUNK_2_0
rtsClosureType (HeapRep False 1 1 Thunk{}) = THUNK_1_1
rtsClosureType (HeapRep False 0 2 Thunk{}) = THUNK_0_2
rtsClosureType (HeapRep False _ _ Thunk{}) = THUNK

rtsClosureType (HeapRep False _ _ ThunkSelector{}) =  THUNK_SELECTOR

-- Approximation: we use the CONSTR_NOCAF_STATIC type for static constructors
-- that have no pointer words only.
rtsClosureType (HeapRep True 0 _ Constr{}) = CONSTR_NOCAF_STATIC  -- See isStaticNoCafCon below
rtsClosureType (HeapRep True _ _ Constr{}) = CONSTR_STATIC
rtsClosureType (HeapRep True _ _ Fun{})    = FUN_STATIC
rtsClosureType (HeapRep True _ _ Thunk{})  = THUNK_STATIC

rtsClosureType (HeapRep False _ _ BlackHole{}) =  BLACKHOLE

rtsClosureType _ = panic "rtsClosureType"

-- We export these ones
rET_SMALL, rET_BIG, aRG_GEN, aRG_GEN_BIG :: StgHalfWord
rET_SMALL   = RET_SMALL
rET_BIG     = RET_BIG
aRG_GEN     = ARG_GEN
aRG_GEN_BIG = ARG_GEN_BIG
\end{code}
326

327 328 329 330 331 332 333
Note [Static NoCaf constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If we know that a top-level binding 'x' is not Caffy (ie no CAFs are 
reachable from 'x'), then a statically allocated constructor (Just x)
is also not Caffy, and the garbage collector need not follow its
argument fields.  Exploiting this would require two static info tables
for Just, for the two cases where the argument was Caffy or non-Caffy.
334

335 336
Currently we don't do this; instead we treat nullary constructors 
as non-Caffy, and the others as potentially Caffy.
337

338

339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361
%************************************************************************
%*									*
             Pretty printing of SMRep and friends
%*									*
%************************************************************************

\begin{code}
instance Outputable ClosureTypeInfo where
   ppr = pprTypeInfo

instance Outputable SMRep where
   ppr (HeapRep static ps nps tyinfo)
     = hang (header <+> lbrace) 2 (ppr tyinfo <+> rbrace)
     where
       header = ptext (sLit "HeapRep")
                <+> if static then ptext (sLit "static") else empty
                <+> pp_n "ptrs" ps <+> pp_n "nonptrs" nps
       pp_n :: String -> Int -> SDoc
       pp_n _ 0 = empty
       pp_n s n = int n <+> text s

   ppr (StackRep bs) = ptext (sLit "StackRep") <+> ppr bs

362 363
   ppr (RTSRep ty rep) = ptext (sLit "tag:") <> ppr ty <+> ppr rep

364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384
instance Outputable ArgDescr where
  ppr (ArgSpec n) = ptext (sLit "ArgSpec") <+> integer (toInteger n)
  ppr (ArgGen ls) = ptext (sLit "ArgGen") <+> ppr ls
  
pprTypeInfo :: ClosureTypeInfo -> SDoc
pprTypeInfo (Constr tag descr)
  = ptext (sLit "Con") <+> 
    braces (sep [ ptext (sLit "tag:") <+> integer (toInteger tag)
                , ptext (sLit "descr:") <> text (show descr) ])

pprTypeInfo (Fun arity args)
  = ptext (sLit "Fun") <+> 
    braces (sep [ ptext (sLit "arity:") <+> integer (toInteger arity)
                , ptext (sLit ("fun_type:")) <+> ppr args ])

pprTypeInfo (ThunkSelector offset) 
  = ptext (sLit "ThunkSel") <+> integer (toInteger offset)

pprTypeInfo Thunk     = ptext (sLit "Thunk")
pprTypeInfo BlackHole = ptext (sLit "BlackHole")

Simon Marlow's avatar
Simon Marlow committed
385
-- XXX Does not belong here!!
386 387 388 389 390 391 392
stringToWord8s :: String -> [Word8]
stringToWord8s s = map (fromIntegral . ord) s

pprWord8String :: [Word8] -> SDoc
-- Debug printing.  Not very clever right now.
pprWord8String ws = text (show ws)
\end{code}