Before elimination of mostly empty block it makes sense to remove dead PHI nodes.
It open more opportunity for elimination plus eliminates dead code itself.
It appeared that change results in failing many unit tests and some of
them I've updated and for another one I disable this optimization.
The pattern I observed in the tests is that there is a infinite loop
without side effects. As a result after elimination of dead phi node all other
related instruction are also removed and tests stops to check what it is expected.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D158503
The LIT test cases were migrated with the script provided by
Nikita Popov. Due to the size of the change it is split into
several parts.
Reviewed By: nemanja, nikic
Differential Revision: https://reviews.llvm.org/D135474
PowerPC can model these instructions, so we don't need this flag set.
Reviewed By: shchenz, jsji
Differential Revision: https://reviews.llvm.org/D71983
