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.
Ensure that we use the correct python to run the python based tools.
This also allows these tools to run on Windows which will not
necessarily associate the python script with an interpreter (python).
Recent changes that eliminated the -sil-serialize-all mode and adding this check to IRGen allow us to get rid of ExternalFunctionDefinitionsElimination and ExternalDefsToDecls passes, which are not needed anymore.
This enables one to dump the various passpipelines in a yaml format. Other
pretty print formats can be added in the future as well if desired. Its intended
usage is to provide a source of pass pipeline information for external python
bug-reducing tools. By integrating this as a compiler-tool, we are guaranteed to
never have to update any of these tools in the face of passpipeline changes.
