Previously the script emitted output using plain CHECK directives. This
can result in a test passing even if there are some instructions between
CHECK directives that should have been removed. It also makes debugging
tests that have the output in a different order more difficult since
FileCheck can match with a later line and then complain about the "wrong"
directive not being found.
This will cause quite large diffs when updating existing tests, but I'm not sure we need an opt-in flag here.
Depends on D109765 (pre-commit tests)
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D109767
817e23d481