-- (c) The University of Glasgow 2006 -- (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 -- -- Storage manager representation of closures {-# LANGUAGE CPP,GeneralizedNewtypeDeriving #-} module GHC.Runtime.Heap.Layout ( -- * Words and bytes WordOff, ByteOff, wordsToBytes, bytesToWordsRoundUp, roundUpToWords, roundUpTo, StgWord, fromStgWord, toStgWord, StgHalfWord, fromStgHalfWord, toStgHalfWord, halfWordSize, halfWordSizeInBits, -- * Closure representation SMRep(..), -- CmmInfo sees the rep; no one else does IsStatic, ClosureTypeInfo(..), ArgDescr(..), Liveness, ConstrDescription, -- ** Construction mkHeapRep, blackHoleRep, indStaticRep, mkStackRep, mkRTSRep, arrPtrsRep, smallArrPtrsRep, arrWordsRep, -- ** Predicates isStaticRep, isConRep, isThunkRep, isFunRep, isStaticNoCafCon, isStackRep, -- ** Size-related things heapClosureSizeW, fixedHdrSizeW, arrWordsHdrSize, arrWordsHdrSizeW, arrPtrsHdrSize, arrPtrsHdrSizeW, profHdrSize, thunkHdrSize, nonHdrSize, nonHdrSizeW, smallArrPtrsHdrSize, smallArrPtrsHdrSizeW, hdrSize, hdrSizeW, fixedHdrSize, -- ** RTS closure types rtsClosureType, rET_SMALL, rET_BIG, aRG_GEN, aRG_GEN_BIG, -- ** Arrays card, cardRoundUp, cardTableSizeB, cardTableSizeW ) where import GHC.Prelude import GHC.Types.Basic( ConTagZ ) import GHC.Driver.Session import GHC.Platform import GHC.Platform.Profile import GHC.Data.FastString import GHC.StgToCmm.Types import GHC.Utils.Outputable import GHC.Utils.Panic import Data.Word import Data.ByteString (ByteString) {- ************************************************************************ * * Words and bytes * * ************************************************************************ -} -- | Byte offset, or byte count type ByteOff = Int -- | Round up the given byte count to the next byte count that's a -- multiple of the machine's word size. roundUpToWords :: Platform -> ByteOff -> ByteOff roundUpToWords platform n = roundUpTo n (platformWordSizeInBytes platform) -- | Round up @base@ to a multiple of @size@. roundUpTo :: ByteOff -> ByteOff -> ByteOff roundUpTo base size = (base + (size - 1)) .&. (complement (size - 1)) -- | Convert the given number of words to a number of bytes. -- -- This function morally has type @WordOff -> ByteOff@, but uses @Num -- a@ to allow for overloading. wordsToBytes :: Num a => Platform -> a -> a wordsToBytes platform n = fromIntegral (platformWordSizeInBytes platform) * n {-# SPECIALIZE wordsToBytes :: Platform -> Int -> Int #-} {-# SPECIALIZE wordsToBytes :: Platform -> Word -> Word #-} {-# SPECIALIZE wordsToBytes :: Platform -> Integer -> Integer #-} -- | First round the given byte count up to a multiple of the -- machine's word size and then convert the result to words. bytesToWordsRoundUp :: Platform -> ByteOff -> WordOff bytesToWordsRoundUp platform n = (n + word_size - 1) `quot` word_size where word_size = platformWordSizeInBytes platform -- StgWord is a type representing an StgWord on the target platform. -- A Word64 is large enough to hold a Word for either a 32bit or 64bit platform newtype StgWord = StgWord Word64 deriving (Eq, Bits) fromStgWord :: StgWord -> Integer fromStgWord (StgWord i) = toInteger i toStgWord :: Platform -> Integer -> StgWord toStgWord platform i = case platformWordSize platform of -- These conversions mean that things like toStgWord (-1) -- do the right thing PW4 -> StgWord (fromIntegral (fromInteger i :: Word32)) PW8 -> StgWord (fromInteger i) instance Outputable StgWord where ppr (StgWord i) = integer (toInteger i) -- -- A Word32 is large enough to hold half a Word for either a 32bit or -- 64bit platform newtype StgHalfWord = StgHalfWord Word32 deriving Eq fromStgHalfWord :: StgHalfWord -> Integer fromStgHalfWord (StgHalfWord w) = toInteger w toStgHalfWord :: Platform -> Integer -> StgHalfWord toStgHalfWord platform i = case platformWordSize platform of -- These conversions mean that things like toStgHalfWord (-1) -- do the right thing PW4 -> StgHalfWord (fromIntegral (fromInteger i :: Word16)) PW8 -> StgHalfWord (fromInteger i :: Word32) instance Outputable StgHalfWord where ppr (StgHalfWord w) = integer (toInteger w) -- | Half word size in bytes halfWordSize :: Platform -> ByteOff halfWordSize platform = platformWordSizeInBytes platform `div` 2 halfWordSizeInBits :: Platform -> Int halfWordSizeInBits platform = platformWordSizeInBits platform `div` 2 {- ************************************************************************ * * \subsubsection[SMRep-datatype]{@SMRep@---storage manager representation} * * ************************************************************************ -} -- | A description of the layout of a closure. Corresponds directly -- to the closure types in includes\/rts\/storage\/ClosureTypes.h. data SMRep = 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 | ArrayPtrsRep !WordOff -- # ptr words !WordOff -- # card table words | SmallArrayPtrsRep !WordOff -- # ptr words | ArrayWordsRep !WordOff -- # bytes expressed in words, rounded up | StackRep -- Stack frame (RET_SMALL or RET_BIG) Liveness | RTSRep -- The RTS needs to declare info tables with specific Int -- type tags, so this form lets us override the default SMRep -- tag for an SMRep. -- | True \<=> This is a static closure. Affects how we garbage-collect it. -- Static closure have an extra static link field at the end. -- Constructors do not have a static variant; see Note [static constructors] 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 ConTagZ ConstrDescription | Fun FunArity ArgDescr | Thunk | ThunkSelector SelectorOffset | BlackHole | IndStatic type ConstrDescription = ByteString -- result of dataConIdentity type FunArity = Int type SelectorOffset = Int ----------------------------------------------------------------------------- -- Construction mkHeapRep :: Profile -> IsStatic -> WordOff -> WordOff -> ClosureTypeInfo -> SMRep mkHeapRep profile 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 profile - (hdr_size + payload_size)) hdr_size = closureTypeHdrSize profile cl_type_info payload_size = ptr_wds + nonptr_wds mkRTSRep :: Int -> SMRep -> SMRep mkRTSRep = RTSRep mkStackRep :: [Bool] -> SMRep mkStackRep liveness = StackRep liveness blackHoleRep :: SMRep blackHoleRep = HeapRep False 0 0 BlackHole indStaticRep :: SMRep indStaticRep = HeapRep True 1 0 IndStatic arrPtrsRep :: Platform -> WordOff -> SMRep arrPtrsRep platform elems = ArrayPtrsRep elems (cardTableSizeW platform elems) smallArrPtrsRep :: WordOff -> SMRep smallArrPtrsRep elems = SmallArrayPtrsRep elems arrWordsRep :: Platform -> ByteOff -> SMRep arrWordsRep platform bytes = ArrayWordsRep (bytesToWordsRoundUp platform bytes) ----------------------------------------------------------------------------- -- Predicates isStaticRep :: SMRep -> IsStatic isStaticRep (HeapRep is_static _ _ _) = is_static isStaticRep (RTSRep _ rep) = isStaticRep rep isStaticRep _ = False isStackRep :: SMRep -> Bool isStackRep StackRep{} = True isStackRep (RTSRep _ rep) = isStackRep rep isStackRep _ = False 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 (HeapRep _ _ _ IndStatic) = True isThunkRep _ = False isFunRep :: SMRep -> Bool isFunRep (HeapRep _ _ _ Fun{}) = True isFunRep _ = False isStaticNoCafCon :: SMRep -> Bool -- This should line up exactly with CONSTR_NOCAF below -- See Note [Static NoCaf constructors] isStaticNoCafCon (HeapRep _ 0 _ Constr{}) = True isStaticNoCafCon _ = False ----------------------------------------------------------------------------- -- Size-related things fixedHdrSize :: Profile -> ByteOff fixedHdrSize profile = wordsToBytes (profilePlatform profile) (fixedHdrSizeW profile) -- | Size of a closure header (StgHeader in includes\/rts\/storage\/Closures.h) fixedHdrSizeW :: Profile -> WordOff fixedHdrSizeW profile = pc_STD_HDR_SIZE (profileConstants profile) + profHdrSize profile -- | Size of the profiling part of a closure header -- (StgProfHeader in includes\/rts\/storage\/Closures.h) profHdrSize :: Profile -> WordOff profHdrSize profile = if profileIsProfiling profile then pc_PROF_HDR_SIZE (profileConstants profile) else 0 -- | The garbage collector requires that every closure is at least as -- big as this. minClosureSize :: Profile -> WordOff minClosureSize profile = fixedHdrSizeW profile + pc_MIN_PAYLOAD_SIZE (profileConstants profile) arrWordsHdrSize :: Profile -> ByteOff arrWordsHdrSize profile = fixedHdrSize profile + pc_SIZEOF_StgArrBytes_NoHdr (profileConstants profile) arrWordsHdrSizeW :: Profile -> WordOff arrWordsHdrSizeW profile = fixedHdrSizeW profile + (pc_SIZEOF_StgArrBytes_NoHdr (profileConstants profile) `quot` platformWordSizeInBytes (profilePlatform profile)) arrPtrsHdrSize :: Profile -> ByteOff arrPtrsHdrSize profile = fixedHdrSize profile + pc_SIZEOF_StgMutArrPtrs_NoHdr (profileConstants profile) arrPtrsHdrSizeW :: Profile -> WordOff arrPtrsHdrSizeW profile = fixedHdrSizeW profile + (pc_SIZEOF_StgMutArrPtrs_NoHdr (profileConstants profile) `quot` platformWordSizeInBytes (profilePlatform profile)) smallArrPtrsHdrSize :: Profile -> ByteOff smallArrPtrsHdrSize profile = fixedHdrSize profile + pc_SIZEOF_StgSmallMutArrPtrs_NoHdr (profileConstants profile) smallArrPtrsHdrSizeW :: Profile -> WordOff smallArrPtrsHdrSizeW profile = fixedHdrSizeW profile + (pc_SIZEOF_StgSmallMutArrPtrs_NoHdr (profileConstants profile) `quot` platformWordSizeInBytes (profilePlatform profile)) -- Thunks have an extra header word on SMP, so the update doesn't -- splat the payload. thunkHdrSize :: Profile -> WordOff thunkHdrSize profile = fixedHdrSizeW profile + smp_hdr where platform = profilePlatform profile smp_hdr = pc_SIZEOF_StgSMPThunkHeader (platformConstants platform) `quot` platformWordSizeInBytes platform hdrSize :: Profile -> SMRep -> ByteOff hdrSize profile rep = wordsToBytes (profilePlatform profile) (hdrSizeW profile rep) hdrSizeW :: Profile -> SMRep -> WordOff hdrSizeW profile (HeapRep _ _ _ ty) = closureTypeHdrSize profile ty hdrSizeW profile (ArrayPtrsRep _ _) = arrPtrsHdrSizeW profile hdrSizeW profile (SmallArrayPtrsRep _) = smallArrPtrsHdrSizeW profile hdrSizeW profile (ArrayWordsRep _) = arrWordsHdrSizeW profile hdrSizeW _ _ = panic "GHC.Runtime.Heap.Layout.hdrSizeW" nonHdrSize :: Platform -> SMRep -> ByteOff nonHdrSize platform rep = wordsToBytes platform (nonHdrSizeW rep) nonHdrSizeW :: SMRep -> WordOff nonHdrSizeW (HeapRep _ p np _) = p + np nonHdrSizeW (ArrayPtrsRep elems ct) = elems + ct nonHdrSizeW (SmallArrayPtrsRep elems) = elems nonHdrSizeW (ArrayWordsRep words) = words nonHdrSizeW (StackRep bs) = length bs nonHdrSizeW (RTSRep _ rep) = nonHdrSizeW rep -- | The total size of the closure, in words. heapClosureSizeW :: Profile -> SMRep -> WordOff heapClosureSizeW profile rep = case rep of HeapRep _ p np ty -> closureTypeHdrSize profile ty + p + np ArrayPtrsRep elems ct -> arrPtrsHdrSizeW profile + elems + ct SmallArrayPtrsRep elems -> smallArrPtrsHdrSizeW profile + elems ArrayWordsRep words -> arrWordsHdrSizeW profile + words _ -> panic "GHC.Runtime.Heap.Layout.heapClosureSize" closureTypeHdrSize :: Profile -> ClosureTypeInfo -> WordOff closureTypeHdrSize profile ty = case ty of Thunk -> thunkHdrSize profile ThunkSelector{} -> thunkHdrSize profile BlackHole -> thunkHdrSize profile IndStatic -> thunkHdrSize profile _ -> fixedHdrSizeW profile -- 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. -- --------------------------------------------------------------------------- -- Arrays -- | The byte offset into the card table of the card for a given element card :: Platform -> Int -> Int card platform i = i `shiftR` pc_MUT_ARR_PTRS_CARD_BITS (platformConstants platform) -- | Convert a number of elements to a number of cards, rounding up cardRoundUp :: Platform -> Int -> Int cardRoundUp platform i = card platform (i + ((1 `shiftL` pc_MUT_ARR_PTRS_CARD_BITS (platformConstants platform)) - 1)) -- | The size of a card table, in bytes cardTableSizeB :: Platform -> Int -> ByteOff cardTableSizeB platform elems = cardRoundUp platform elems -- | The size of a card table, in words cardTableSizeW :: Platform -> Int -> WordOff cardTableSizeW platform elems = bytesToWordsRoundUp platform (cardTableSizeB platform elems) ----------------------------------------------------------------------------- -- deriving the RTS closure type from an SMRep #include "../includes/rts/storage/ClosureTypes.h" #include "../includes/rts/storage/FunTypes.h" -- Defines CONSTR, CONSTR_1_0 etc -- | Derives the RTS closure type from an 'SMRep' rtsClosureType :: SMRep -> Int rtsClosureType rep = case rep of RTSRep ty _ -> ty -- See Note [static constructors] HeapRep _ 1 0 Constr{} -> CONSTR_1_0 HeapRep _ 0 1 Constr{} -> CONSTR_0_1 HeapRep _ 2 0 Constr{} -> CONSTR_2_0 HeapRep _ 1 1 Constr{} -> CONSTR_1_1 HeapRep _ 0 2 Constr{} -> CONSTR_0_2 HeapRep _ 0 _ Constr{} -> CONSTR_NOCAF -- See Note [Static NoCaf constructors] HeapRep _ _ _ Constr{} -> CONSTR HeapRep False 1 0 Fun{} -> FUN_1_0 HeapRep False 0 1 Fun{} -> FUN_0_1 HeapRep False 2 0 Fun{} -> FUN_2_0 HeapRep False 1 1 Fun{} -> FUN_1_1 HeapRep False 0 2 Fun{} -> FUN_0_2 HeapRep False _ _ Fun{} -> FUN HeapRep False 1 0 Thunk -> THUNK_1_0 HeapRep False 0 1 Thunk -> THUNK_0_1 HeapRep False 2 0 Thunk -> THUNK_2_0 HeapRep False 1 1 Thunk -> THUNK_1_1 HeapRep False 0 2 Thunk -> THUNK_0_2 HeapRep False _ _ Thunk -> THUNK HeapRep False _ _ ThunkSelector{} -> THUNK_SELECTOR HeapRep True _ _ Fun{} -> FUN_STATIC HeapRep True _ _ Thunk -> THUNK_STATIC HeapRep False _ _ BlackHole -> BLACKHOLE HeapRep False _ _ IndStatic -> IND_STATIC _ -> panic "rtsClosureType" -- We export these ones rET_SMALL, rET_BIG, aRG_GEN, aRG_GEN_BIG :: Int rET_SMALL = RET_SMALL rET_BIG = RET_BIG aRG_GEN = ARG_GEN aRG_GEN_BIG = ARG_GEN_BIG {- Note [static constructors] ~~~~~~~~~~~~~~~~~~~~~~~~~~ We used to have a CONSTR_STATIC closure type, and each constructor had two info tables: one with CONSTR (or CONSTR_1_0 etc.), and one with CONSTR_STATIC. This distinction was removed, because when copying a data structure into a compact region, we must copy static constructors into the compact region too. If we didn't do this, we would need to track the references from the compact region out to the static constructors, because they might (indirectly) refer to CAFs. Since static constructors will be copied to the heap, if we wanted to use different info tables for static and dynamic constructors, we would have to switch the info pointer when copying the constructor into the compact region, which means we would need an extra field of the static info table to point to the dynamic one. However, since the distinction between static and dynamic closure types is never actually needed (other than for assertions), we can just drop the distinction and use the same info table for both. The GC *does* need to distinguish between static and dynamic closures, but it does this using the HEAP_ALLOCED() macro which checks whether the address of the closure resides within the dynamic heap. HEAP_ALLOCED() doesn't read the closure's info table. 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. Currently we don't do this; instead we treat nullary constructors as non-Caffy, and the others as potentially Caffy. ************************************************************************ * * Pretty printing of SMRep and friends * * ************************************************************************ -} 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 = text "HeapRep" <+> if static then text "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 (ArrayPtrsRep size _) = text "ArrayPtrsRep" <+> ppr size ppr (SmallArrayPtrsRep size) = text "SmallArrayPtrsRep" <+> ppr size ppr (ArrayWordsRep words) = text "ArrayWordsRep" <+> ppr words ppr (StackRep bs) = text "StackRep" <+> ppr bs ppr (RTSRep ty rep) = text "tag:" <> ppr ty <+> ppr rep pprTypeInfo :: ClosureTypeInfo -> SDoc pprTypeInfo (Constr tag descr) = text "Con" <+> braces (sep [ text "tag:" <+> ppr tag , text "descr:" <> text (show descr) ]) pprTypeInfo (Fun arity args) = text "Fun" <+> braces (sep [ text "arity:" <+> ppr arity , ptext (sLit ("fun_type:")) <+> ppr args ]) pprTypeInfo (ThunkSelector offset) = text "ThunkSel" <+> ppr offset pprTypeInfo Thunk = text "Thunk" pprTypeInfo BlackHole = text "BlackHole" pprTypeInfo IndStatic = text "IndStatic"