I put in a simple fixup pass (MarkUninitializedFixup) for staging purposes. I
don't expect it to be in tree long. I just did not feel comfortable fixing up in
1 commit all of the passes up to DI.
rdar://31521023
The peephole causes the the formal access to the source and destination to
overlap. This results in unwanted exclusive access conflicts when assigning
from one struct stored property to another.
At John's suggestion I've added an isObviouslyNonConflicting() helper
method on LValue that tells when when it is safe to use the peephole
even when exclusivity enforcement enabled. For now, the helper is toothless. It
can be extended to claw back some of the peephole opportunities.
