GHC.Runtime.Heap.Layout

Word offset, or word count

Byte offset, or byte count

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.

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

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

Round up base to a multiple of size.

Half word size in bytes

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

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]

An ArgDescr describes the argument pattern of a function

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.