First step after e113317958,
in these tests, DomTree is valid afterwards, so mark them as such,
so that they don't regress.
In further steps, SimplifyCFG transforms shall taught to preserve DomTree,
in as small steps as possible.
-debug-pass is a legacy PM only option.
Some tests checks that the pass returned that it made a change,
which is not relevant to the NPM, since passes return PreservedAnalyses.
Some tests check that passes are freed at the proper time, which is also
not relevant to the NPM.
Reviewed By: asbirlea
Differential Revision: https://reviews.llvm.org/D87945
SimplifyCFG was incorrectly reporting to the pass manager that it had not made
changes after folding away a PHI. This is detected in the EXPENSIVE_CHECKS
build when the function's hash changes.
Differential Revision: https://reviews.llvm.org/D83985
Roman Lebedev