Partial Load Store Elimination

Add partial load-store elimination to the LSE pass. Partial LSE will
move object allocations which only escape along certain execution
paths closer to the escape point and allow more values to be
eliminated. It does this by creating new predicated load and store
instructions that are used when an object has only escaped some of the
time. In cases where the object has not escaped a default value will
be used.

Test: ./test.py --host
Test: ./test.py --target
Bug: 67037140

Change-Id: Idde67eb59ec90de79747cde17b552eec05b58497
29 files changed