Compatibility of -fsanitize-coverage and CFI

I’ve been poking back through commit history and the mailing lists and I can’t find any explanation of why CFI is not allowed to be combined with sancov. It even appears to me that CFI w/ diagnostics uses ubsan which links in sancov and initializes coverage. Is CFI actually incompatible with sancov or should I try to allow them together and add tests for this?