ghc-7.10.2: The GHC API

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Words and bytes

type WordOff = Int Source

Word offset, or word count

type ByteOff = Int Source

Byte offset, or byte count

wordsToBytes :: Num a => DynFlags -> a -> a Source

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.

bytesToWordsRoundUp :: DynFlags -> ByteOff -> WordOff Source

First round the given byte count up to a multiple of the machine's word size and then convert the result to words.

roundUpToWords :: DynFlags -> ByteOff -> ByteOff Source

Round up the given byte count to the next byte count that's a multiple of the machine's word size.

Closure repesentation

data SMRep Source

A description of the layout of a closure. Corresponds directly to the closure types in includesrtsstorage/ClosureTypes.h.


type IsStatic = Bool Source

True = This is a static closure. Affects how we garbage-collect it. Static closure have an extra static link field at the end.

data ClosureTypeInfo Source


Constr ConstrTag ConstrDescription 
Fun FunArity ArgDescr 
ThunkSelector SelectorOffset 



Size-related things

heapClosureSizeW :: DynFlags -> SMRep -> WordOff Source

The total size of the closure, in words.

fixedHdrSizeW :: DynFlags -> WordOff Source

Size of a closure header (StgHeader in includesrtsstorage/Closures.h)

profHdrSize :: DynFlags -> WordOff Source

Size of the profiling part of a closure header (StgProfHeader in includesrtsstorage/Closures.h)

RTS closure types

rtsClosureType :: SMRep -> Int Source

Derives the RTS closure type from an SMRep


card :: DynFlags -> Int -> Int Source

The byte offset into the card table of the card for a given element

cardRoundUp :: DynFlags -> Int -> Int Source

Convert a number of elements to a number of cards, rounding up

cardTableSizeB :: DynFlags -> Int -> ByteOff Source

The size of a card table, in bytes

cardTableSizeW :: DynFlags -> Int -> WordOff Source

The size of a card table, in words

Operations over [Word8] strings that don't belong here