Add dominator Tree

[kevaundray]

Problem

Dominator trees store the dominance relation between basic blocks in a function.

A dominance tree allows us to quickly compute:

• The dominance frontier
• Immediate dominators for a node

The dominator tree is very useful in figuring out which nodes are not dominated by the entry block and for example, can be used for reachability analysis.

Proposed solution

Implement a dominator tree in a modular way with comments and tests

Alternatives considered

No response

Additional context

No response

Submission Checklist

• Once I hit submit, I will assign this issue to the Project Board with the appropriate tags.

[guipublic]

For the record, we already have the dominator tree implemented in the BasicBlock structure where blocks reference their direct dominator.