[clang] [llvm] update_test_checks: add new --filter-out-after option (PR #129739)

[David Sherwood via llvm-commits]

david-arm wrote:

> I'd be fine with limiting it to update_test_checks, just wanted to make sure that it works in the instances where it's available. Of course, if we can get it in the other scripts for free that's great, too! That said, for update_test_checks, does the regex match the input or output? Maybe it would be good with a test case where the input has anonymous instructions, and the output is after running `instnamer`? Then matching against something that is only in the input but not the output, or vice versa.

Thanks for the suggestions! I've added a test for update_cc_test_checks to show that the filtering happens only on the output when checking C files. I've also added a filter-out-after3.ll test for update_test_checks using your instname suggestion, which demonstrates that filtering does not work on the input IR.

https://github.com/llvm/llvm-project/pull/129739