Copyright	(c) 2012 Joachim Breitner
License	BSD3
Maintainer	Joachim Breitner <mail@joachim-breitner.de>
Safe Haskell	None
Language	Haskell2010

GHC.Exts.Heap

Contents

Closure types
Info Table types
Closure inspection
Boxes

Description

With this module, you can investigate the heap representation of Haskell values, i.e. to investigate sharing and lazy evaluation.

Synopsis

type Closure = GenClosure Box
data GenClosure b
- = ConstrClosure {
  - info :: !StgInfoTable
  - ptrArgs :: ![b]
  - dataArgs :: ![Word]
  - pkg :: !String
  - modl :: !String
  - name :: !String
  }
- | FunClosure {
  - info :: !StgInfoTable
  - ptrArgs :: ![b]
  - dataArgs :: ![Word]
  }
- | ThunkClosure {
  - info :: !StgInfoTable
  - ptrArgs :: ![b]
  - dataArgs :: ![Word]
  }
- | SelectorClosure {
  - info :: !StgInfoTable
  - selectee :: !b
  }
- | PAPClosure {
  - info :: !StgInfoTable
  - arity :: !HalfWord
  - n_args :: !HalfWord
  - fun :: !b
  - payload :: ![b]
  }
- | APClosure {
  - info :: !StgInfoTable
  - arity :: !HalfWord
  - n_args :: !HalfWord
  - fun :: !b
  - payload :: ![b]
  }
- | APStackClosure {
  - info :: !StgInfoTable
  - fun :: !b
  - payload :: ![b]
  }
- | IndClosure {
  - info :: !StgInfoTable
  - indirectee :: !b
  }
- | BCOClosure {
  - info :: !StgInfoTable
  - instrs :: !b
  - literals :: !b
  - bcoptrs :: !b
  - arity :: !HalfWord
  - size :: !HalfWord
  - bitmap :: ![Word]
  }
- | BlackholeClosure {
  - info :: !StgInfoTable
  - indirectee :: !b
  }
- | ArrWordsClosure {
  - info :: !StgInfoTable
  - bytes :: !Word
  - arrWords :: ![Word]
  }
- | MutArrClosure {
  - info :: !StgInfoTable
  - mccPtrs :: !Word
  - mccSize :: !Word
  - mccPayload :: ![b]
  }
- | MVarClosure {
  - info :: !StgInfoTable
  - queueHead :: !b
  - queueTail :: !b
  - value :: !b
  }
- | MutVarClosure {
  - info :: !StgInfoTable
  - var :: !b
  }
- | BlockingQueueClosure {
  - info :: !StgInfoTable
  - link :: !b
  - blackHole :: !b
  - owner :: !b
  - queue :: !b
  }
- | IntClosure {
  - ptipe :: PrimType
  - intVal :: !Int
  }
- | WordClosure {
  - ptipe :: PrimType
  - wordVal :: !Word
  }
- | Int64Closure {
  - ptipe :: PrimType
  - int64Val :: !Int64
  }
- | Word64Closure {
  - ptipe :: PrimType
  - word64Val :: !Word64
  }
- | AddrClosure {
  - ptipe :: PrimType
  - addrVal :: !Int
  }
- | FloatClosure {
  - ptipe :: PrimType
  - floatVal :: !Float
  }
- | DoubleClosure {
  - ptipe :: PrimType
  - doubleVal :: !Double
  }
- | OtherClosure {
  - info :: !StgInfoTable
  - hvalues :: ![b]
  - rawWords :: ![Word]
  }
- | UnsupportedClosure {
  - info :: !StgInfoTable
  }
data ClosureType
- = INVALID_OBJECT
- | CONSTR
- | CONSTR_1_0
- | CONSTR_0_1
- | CONSTR_2_0
- | CONSTR_1_1
- | CONSTR_0_2
- | CONSTR_NOCAF
- | FUN
- | FUN_1_0
- | FUN_0_1
- | FUN_2_0
- | FUN_1_1
- | FUN_0_2
- | FUN_STATIC
- | THUNK
- | THUNK_1_0
- | THUNK_0_1
- | THUNK_2_0
- | THUNK_1_1
- | THUNK_0_2
- | THUNK_STATIC
- | THUNK_SELECTOR
- | BCO
- | AP
- | PAP
- | AP_STACK
- | IND
- | IND_STATIC
- | RET_BCO
- | RET_SMALL
- | RET_BIG
- | RET_FUN
- | UPDATE_FRAME
- | CATCH_FRAME
- | UNDERFLOW_FRAME
- | STOP_FRAME
- | BLOCKING_QUEUE
- | BLACKHOLE
- | MVAR_CLEAN
- | MVAR_DIRTY
- | TVAR
- | ARR_WORDS
- | MUT_ARR_PTRS_CLEAN
- | MUT_ARR_PTRS_DIRTY
- | MUT_ARR_PTRS_FROZEN_DIRTY
- | MUT_ARR_PTRS_FROZEN_CLEAN
- | MUT_VAR_CLEAN
- | MUT_VAR_DIRTY
- | WEAK
- | PRIM
- | MUT_PRIM
- | TSO
- | STACK
- | TREC_CHUNK
- | ATOMICALLY_FRAME
- | CATCH_RETRY_FRAME
- | CATCH_STM_FRAME
- | WHITEHOLE
- | SMALL_MUT_ARR_PTRS_CLEAN
- | SMALL_MUT_ARR_PTRS_DIRTY
- | SMALL_MUT_ARR_PTRS_FROZEN_DIRTY
- | SMALL_MUT_ARR_PTRS_FROZEN_CLEAN
- | COMPACT_NFDATA
- | N_CLOSURE_TYPES
data PrimType
- = PInt
- | PWord
- | PInt64
- | PWord64
- | PAddr
- | PFloat
- | PDouble
class HasHeapRep (a :: TYPE rep) where
- getClosureData :: a -> IO Closure
data StgInfoTable = StgInfoTable {
- entry :: Maybe EntryFunPtr
- ptrs :: HalfWord
- nptrs :: HalfWord
- tipe :: ClosureType
- srtlen :: HalfWord
- code :: Maybe ItblCodes
}
type EntryFunPtr = FunPtr (Ptr () -> IO (Ptr ()))
type HalfWord = Word32
type ItblCodes = Either [Word8] [Word32]
itblSize :: Int
peekItbl :: Ptr StgInfoTable -> IO StgInfoTable
pokeItbl :: Ptr StgInfoTable -> StgInfoTable -> IO ()
getBoxedClosureData :: Box -> IO Closure
allClosures :: GenClosure b -> [b]
data Box = Box Any
asBox :: a -> Box
areBoxesEqual :: Box -> Box -> IO Bool

Closure types

type Closure = GenClosure Box Source #

data GenClosure b Source #

This is the representation of a Haskell value on the heap. It reflects http://hackage.haskell.org/trac/ghc/browser/includes/rts/storage/Closures.h

The data type is parametrized by the type to store references in. Usually this is a Box with the type synonym Closure.

All Heap objects have the same basic layout. A header containing a pointer to the info table and a payload with various fields. The info field below always refers to the info table pointed to by the header. The remaining fields are the payload.

See https://ghc.haskell.org/trac/ghc/wiki/Commentary/Rts/Storage/HeapObjects for more information.

Constructors

ConstrClosure	A data constructor
Fields info :: !StgInfoTable ptrArgs :: ![b] Pointer arguments dataArgs :: ![Word] Non-pointer arguments pkg :: !String Package name modl :: !String Module name name :: !String Constructor name
FunClosure	A function
Fields info :: !StgInfoTable ptrArgs :: ![b] Pointer arguments dataArgs :: ![Word] Non-pointer arguments
ThunkClosure	A thunk, an expression not obviously in head normal form
Fields info :: !StgInfoTable ptrArgs :: ![b] Pointer arguments dataArgs :: ![Word] Non-pointer arguments
SelectorClosure	A thunk which performs a simple selection operation
Fields info :: !StgInfoTable selectee :: !b Pointer to the object being selected from
PAPClosure	An unsaturated function application
Fields info :: !StgInfoTable arity :: !HalfWord Arity of the partial application n_args :: !HalfWord Size of the payload in words fun :: !b Pointer to a `FunClosure` payload :: ![b] Sequence of already applied arguments
APClosure	A function application
Fields info :: !StgInfoTable arity :: !HalfWord Arity of the partial application n_args :: !HalfWord Size of the payload in words fun :: !b Pointer to a `FunClosure` payload :: ![b] Sequence of already applied arguments
APStackClosure	A suspended thunk evaluation
Fields info :: !StgInfoTable fun :: !b Pointer to a `FunClosure` payload :: ![b] Sequence of already applied arguments
IndClosure	A pointer to another closure, introduced when a thunk is updated to point at its value
Fields info :: !StgInfoTable indirectee :: !b Target closure
BCOClosure	A byte-code object (BCO) which can be interpreted by GHC's byte-code interpreter (e.g. as used by GHCi)
Fields info :: !StgInfoTable instrs :: !b A pointer to an ArrWords of instructions literals :: !b A pointer to an ArrWords of literals bcoptrs :: !b A pointer to an ArrWords of byte code objects arity :: !HalfWord Arity of the partial application size :: !HalfWord The size of this BCO in words bitmap :: ![Word] An StgLargeBitmap describing the pointerhood of its args/free vars
BlackholeClosure	A thunk under evaluation by another thread
Fields info :: !StgInfoTable indirectee :: !b Target closure
ArrWordsClosure	A `ByteArray#`
Fields info :: !StgInfoTable bytes :: !Word Size of array in bytes arrWords :: ![Word] Array payload
MutArrClosure	A `MutableByteArray#`
Fields info :: !StgInfoTable mccPtrs :: !Word Number of pointers mccSize :: !Word ?? Closures.h vs ClosureMacros.h mccPayload :: ![b] Array payload Card table ignored
MVarClosure	An `MVar#`, with a queue of thread state objects blocking on them
Fields info :: !StgInfoTable queueHead :: !b Pointer to head of queue queueTail :: !b Pointer to tail of queue value :: !b Pointer to closure
MutVarClosure	A `MutVar#`
Fields info :: !StgInfoTable var :: !b Pointer to closure
BlockingQueueClosure	An STM blocking queue.
Fields info :: !StgInfoTable link :: !b ?? Here so it looks like an IND blackHole :: !b The blackhole closure owner :: !b The owning thread state object queue :: !b ??
IntClosure	Primitive Int
Fields ptipe :: PrimType intVal :: !Int
WordClosure	Primitive Word
Fields ptipe :: PrimType wordVal :: !Word
Int64Closure	Primitive Int64
Fields ptipe :: PrimType int64Val :: !Int64
Word64Closure	Primitive Word64
Fields ptipe :: PrimType word64Val :: !Word64
AddrClosure	Primitive Addr
Fields ptipe :: PrimType addrVal :: !Int
FloatClosure	Primitive Float
Fields ptipe :: PrimType floatVal :: !Float
DoubleClosure	Primitive Double
Fields ptipe :: PrimType doubleVal :: !Double
OtherClosure	Another kind of closure
Fields info :: !StgInfoTable hvalues :: ![b] rawWords :: ![Word]
UnsupportedClosure
Fields info :: !StgInfoTable

Instances

Show b => Show (GenClosure b) #
Instance details Defined in GHC.Exts.Heap.Closures Methods showsPrec :: Int -> GenClosure b -> ShowS Source # show :: GenClosure b -> String Source # showList :: [GenClosure b] -> ShowS Source #

data ClosureType Source #

Constructors

INVALID_OBJECT
CONSTR
CONSTR_1_0
CONSTR_0_1
CONSTR_2_0
CONSTR_1_1
CONSTR_0_2
CONSTR_NOCAF
FUN
FUN_1_0
FUN_0_1
FUN_2_0
FUN_1_1
FUN_0_2
FUN_STATIC
THUNK
THUNK_1_0
THUNK_0_1
THUNK_2_0
THUNK_1_1
THUNK_0_2
THUNK_STATIC
THUNK_SELECTOR
BCO
AP
PAP
AP_STACK
IND
IND_STATIC
RET_BCO
RET_SMALL
RET_BIG
RET_FUN
UPDATE_FRAME
CATCH_FRAME
UNDERFLOW_FRAME
STOP_FRAME
BLOCKING_QUEUE
BLACKHOLE
MVAR_CLEAN
MVAR_DIRTY
TVAR
ARR_WORDS
MUT_ARR_PTRS_CLEAN
MUT_ARR_PTRS_DIRTY
MUT_ARR_PTRS_FROZEN_DIRTY
MUT_ARR_PTRS_FROZEN_CLEAN
MUT_VAR_CLEAN
MUT_VAR_DIRTY
WEAK
PRIM
MUT_PRIM
TSO
STACK
TREC_CHUNK
ATOMICALLY_FRAME
CATCH_RETRY_FRAME
CATCH_STM_FRAME
WHITEHOLE
SMALL_MUT_ARR_PTRS_CLEAN
SMALL_MUT_ARR_PTRS_DIRTY
SMALL_MUT_ARR_PTRS_FROZEN_DIRTY
SMALL_MUT_ARR_PTRS_FROZEN_CLEAN
COMPACT_NFDATA
N_CLOSURE_TYPES

Instances

Enum ClosureType #
Instance details Defined in GHC.Exts.Heap.ClosureTypes Methods succ :: ClosureType -> ClosureType Source # pred :: ClosureType -> ClosureType Source # toEnum :: Int -> ClosureType Source # fromEnum :: ClosureType -> Int Source # enumFrom :: ClosureType -> [ClosureType] Source # enumFromThen :: ClosureType -> ClosureType -> [ClosureType] Source # enumFromTo :: ClosureType -> ClosureType -> [ClosureType] Source # enumFromThenTo :: ClosureType -> ClosureType -> ClosureType -> [ClosureType] Source #
Eq ClosureType #
Instance details Defined in GHC.Exts.Heap.ClosureTypes Methods (==) :: ClosureType -> ClosureType -> Bool Source # (/=) :: ClosureType -> ClosureType -> Bool Source #
Ord ClosureType #
Instance details Defined in GHC.Exts.Heap.ClosureTypes Methods compare :: ClosureType -> ClosureType -> Ordering Source # (<) :: ClosureType -> ClosureType -> Bool Source # (<=) :: ClosureType -> ClosureType -> Bool Source # (>) :: ClosureType -> ClosureType -> Bool Source # (>=) :: ClosureType -> ClosureType -> Bool Source # max :: ClosureType -> ClosureType -> ClosureType Source # min :: ClosureType -> ClosureType -> ClosureType Source #
Show ClosureType #
Instance details Defined in GHC.Exts.Heap.ClosureTypes Methods showsPrec :: Int -> ClosureType -> ShowS Source # show :: ClosureType -> String Source # showList :: [ClosureType] -> ShowS Source #

data PrimType Source #

Constructors

PInt
PWord
PInt64
PWord64
PAddr
PFloat
PDouble

Instances

Eq PrimType #
Instance details Defined in GHC.Exts.Heap.Closures Methods (==) :: PrimType -> PrimType -> Bool Source # (/=) :: PrimType -> PrimType -> Bool Source #
Show PrimType #
Instance details Defined in GHC.Exts.Heap.Closures Methods showsPrec :: Int -> PrimType -> ShowS Source # show :: PrimType -> String Source # showList :: [PrimType] -> ShowS Source #

class HasHeapRep (a :: TYPE rep) where Source #

Methods

getClosureData :: a -> IO Closure Source #

Instances

HasHeapRep (a :: Type) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
HasHeapRep (a :: TYPE UnliftedRep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
Int# ~ a => HasHeapRep (a :: TYPE IntRep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
Word# ~ a => HasHeapRep (a :: TYPE WordRep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
Int64# ~ a => HasHeapRep (a :: TYPE Int64Rep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
Word64# ~ a => HasHeapRep (a :: TYPE Word64Rep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
Addr# ~ a => HasHeapRep (a :: TYPE AddrRep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
Float# ~ a => HasHeapRep (a :: TYPE FloatRep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #
Double# ~ a => HasHeapRep (a :: TYPE DoubleRep) #
Instance details Defined in GHC.Exts.Heap Methods getClosureData :: a -> IO Closure Source #

Info Table types

data StgInfoTable Source #

This is a somewhat faithful representation of an info table. See http://hackage.haskell.org/trac/ghc/browser/includes/rts/storage/InfoTables.h for more details on this data structure.

Constructors

StgInfoTable
Fields entry :: Maybe EntryFunPtr ptrs :: HalfWord nptrs :: HalfWord tipe :: ClosureType srtlen :: HalfWord code :: Maybe ItblCodes

Instances

Show StgInfoTable #
Instance details Defined in GHC.Exts.Heap.InfoTable.Types Methods showsPrec :: Int -> StgInfoTable -> ShowS Source # show :: StgInfoTable -> String Source # showList :: [StgInfoTable] -> ShowS Source #

type EntryFunPtr = FunPtr (Ptr () -> IO (Ptr ())) Source #

type HalfWord = Word32 Source #

type ItblCodes = Either [Word8] [Word32] Source #

itblSize :: Int Source #

Size in bytes of a standard InfoTable

peekItbl :: Ptr StgInfoTable -> IO StgInfoTable Source #

Read an InfoTable from the heap into a haskell type. WARNING: This code assumes it is passed a pointer to a "standard" info table. If tables_next_to_code is enabled, it will look 1 byte before the start for the entry field.

pokeItbl :: Ptr StgInfoTable -> StgInfoTable -> IO () Source #

Closure inspection

getBoxedClosureData :: Box -> IO Closure Source #

Like getClosureData, but taking a Box, so it is easier to work with.

allClosures :: GenClosure b -> [b] Source #

For generic code, this function returns all referenced closures.

Boxes

data Box Source #

An arbitrary Haskell value in a safe Box. The point is that even unevaluated thunks can safely be moved around inside the Box, and when required, e.g. in getBoxedClosureData, the function knows how far it has to evaluate the argument.

Constructors

Box Any

Instances

Show Box #
Instance details Defined in GHC.Exts.Heap.Closures Methods showsPrec :: Int -> Box -> ShowS Source # show :: Box -> String Source # showList :: [Box] -> ShowS Source #

asBox :: a -> Box Source #

This takes an arbitrary value and puts it into a box. Note that calls like

asBox (head list)

will put the thunk "head list" into the box, not the element at the head of the list. For that, use careful case expressions:

case list of x:_ -> asBox x

areBoxesEqual :: Box -> Box -> IO Bool Source #

Boxes can be compared, but this is not pure, as different heap objects can, after garbage collection, become the same object.