RISC-V LLVM sync-up call 22nd July 2021

For background on these calls, see

Reminder: the purpose is to coordinate between active contributors.
If you have support questions etc then it's best to post to llvm-dev.

We have a call every alternate Thursday at 4pm BST, via
<https://meet.google.com/ske-zcog-spp&gt;\. If you have topics to discuss,
please email me ahead of time and I can add them to the agenda.

We have a shared calendar that may help in keeping track, which is
accessible at:
* <https://calendar.google.com/calendar/b/1?cid=bG93cmlzYy5vcmdfMG41cGtlc2ZqY25wMGJoNWhwczFwMGJkODBAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ&gt;
* <https://calendar.google.com/calendar/ical/lowrisc.org_0n5pkesfjcnp0bh5hps1p0bd80%40group.calendar.google.com/public/basic.ics&gt;

* Staging of RVV v1.0-rc changes <Login, and any
  additional thoughts on any need to support multiple RVV versions
* Encoding arch information in a new module flag 'riscv-isa-features'
* Relax ABI mismatch checking <Login;
* Unify arch string parsing logic to RISCVISAInfo
* Add support for -msave-restore with tailcalls
* Patches / PRs to highlight for review
  * Data mapping symbol proposal
  * RISCV64 support for jitlink <Login;
* Any other business