The pass is already not being run during normal compilation scenarios today
since it bails on OSSA except in certain bit-rot situations where a test wasn't
updated and so was inadvertently invoking the pass. I discovered these while
originally just trying to eliminate the pass from the diagnostic pipeline. The
reason why I am doing this in one larger change is that I found there were a
bunch of sil tests inadvertently relying on guaranteed arc opts to eliminate
copy traffic. So, if I just removed this and did this in two steps, I would
basically be unoptimizing then re-optimizing the tests.
Some notes:
1. The new guaranteed arc opts is based off of SemanticARCOpts and runs only on
ossa. Specifically, in this new pass, we just perform simple
canonicalizations that do not involve any significant analysis. Some
examples: a copy_value all of whose uses are destroys. This will do what the
original pass did and more without more compile time. I did a conservative
first approximation, but we can probably tune this a bit.
2. the reason why I am doing this now is that I was trying to eliminate the
enable-ownership-stripping-after-serialization flag and discovered that the
test opaque_value_mandatory implicitly depends on this since sil-opt by
default was the only place left in the compiler with that option set to false
by default. So I am eliminating that dependency before I land the larger
change.
* rename "Name" to "Description" in the pass definition, because it's not really the pass name, but the description of a pass
* remove the getName() from Transforms (which actually returned the description of a pass)
* in debug printing, print the pass ID and not the pass description. It makes it easier to correlate the debug output to the actual pass implementation.
* remove the iteration numbering in the pass manager, because we only run a single iteration anyway.
