## Expand description

Compute dominators of a control-flow graph.

## The Dominance Relation

In a directed graph with a root node **R**, a node **A** is said to *dominate* a
node **B** iff every path from **R** to **B** contains **A**.

The node **A** is said to *strictly dominate* the node **B** iff **A** dominates
**B** and **A ≠ B**.

The node **A** is said to be the *immediate dominator* of a node **B** iff it
strictly dominates **B** and there does not exist any node **C** where **A**
dominates **C** and **C** dominates **B**.

## Structs

- Iterator for nodes dominated by a given node.
- The dominance relation for some graph and root.
- Iterator for a node’s dominators.

## Functions

- This is an implementation of the engineered “Simple, Fast Dominance Algorithm” discovered by Cooper et al.