Summary:
Add a new plugin API. This closes the gap between pass registration and out-of-tree passes for the new PassManager.
Unlike with the existing API, interaction with a plugin is always
initiated from the tools perspective. I.e., when a plugin is loaded, it
resolves and calls a well-known symbol `llvmGetPassPluginInfo` to obtain
details about the plugin. The fundamental motivation is to get rid of as
many global constructors as possible. The API exposed by the plugin
info is kept intentionally minimal.
Reviewers: chandlerc
Reviewed By: chandlerc
Subscribers: bollu, grosser, lksbhm, mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D35258
llvm-svn: 329273