Phase 2: Building a dominator tree

Goal: Build a dominator tree using the approach from the paper by
Cooper et al., Software - Practice and Experience, 2001. Run your
implementation on each CFG from Phase 1. Recall that in these CFGs,
(1) every CFG node must be reachable from ENTRY, and (2) EXIT must be
reachable from every CFG node. In the resulting tree, ENTRY is the
root and EXIT is one of the leaves.

Your implementation MUST use the 'doms' data structure described in
the paper. As discussed in the paper, this data structure implicitly
represents DOM sets - you should NOT represent such sets explicitly.
Note that in this data structure, the nodes are represented by their
postorder numbers - more precisely, a node is encoded by its
"finishing time" from the standard DFS traversal algorithm. See the
examples in the paper for more details. 

After computing the dominator tree for the CFG, calculate a set of
numbers {count_0, count_1, count_2, ... }. count_0 is the number of
nodes with 0 children in the dominator tree (i.e., the number of
leaves). count_1 is the number of nodes with 1 child in the dominator
tree. In general, count_k is the number of nodes with k children in
the tree. Obviously, there exists some point after which count_k = 0
(for sufficiently large k). Compute the counts only up to the largest
non-zero value. As a sanity check, make sure that the sum of all
counts is equal to the number of nodes in the CFG.

Once all CFGs are processed and their individual sets {count_0,
count_1, count_2, ... } are computed, add all count_0 values for all
CFGs to obtain a single number COUNT_0 for the entire
program. Similarly, compute COUNT_1, COUNT_2, etc.

By 11:59 pm on Tuesday, October 19, submit the source code 
together a single text file report.txt containing:

COUNT_0: ...
COUNT_1: ...
COUNT_2: ...
...

all the way up to the largest non-zero COUNT_k. 

Submit your project using something like

submit c788ac lab2 MyTransform.java MyTreeBuilder.java ... report.txt

IMPORTANT: As with Phase 1, the code MUST be anonymized.