This patch addresses two TODOs in RISCVISAInfo::checkDependency:
- Report error when both e and f (or d) extensions are specified in -march
- Report error when q extension is specified when rv64 is unavailable
- Corresponding unit tests are also updated
Currently, I cannot add a test about the q extension case because there's no q extension registered in either supported extensions or experimental extensions,
but the code added here should work fine if we have a proper q implementation in the future.
I think the comment is outdated here. E can be combined with all other extensions according to spec:
And, please see also D70401 for more context.