GHC.Cmm.Graph

CmmAGraph is a chunk of code consisting of:

• ordinary statements (assignments, stores etc.)

• jumps

• labels

• out-of-line labelled blocks

The semantics is that control falls through labels and out-of-line blocks. Everything after a jump up to the next label is by definition unreachable code, and will be discarded.

Two CmmAGraphs can be stuck together with *, with the meaning that control flows from the first to the second.

A CmmAGraph can be turned into a CmmGraph (closed at both ends) by providing a label for the entry point and a tick scope; see labelAGraph.

Unlabeled graph with tick scope

creates a sequence "goto id; id:" as an AGraph

creates an open AGraph from a given node

creates a closed AGraph from a given node

A labelled code block; should end in a last node

allocate a fresh label for the entry point

use the given BlockId as the label of the entry point

Assumes natural alignment

A jump where the caller says what the live GlobalRegs are. Used for low-level hand-written Cmm.

Construct a CmmUnwind node for the given register and unwinding expression.