[PATCH] D129013: [RISCV] Enable (scalable) vectorization by default

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

It came to my attention on Friday that the Linux kernel is missing support for vector save/restore.  As a result, if you try to run vector code in a Linux environment on real hardware or qemu-system, all vector instructions will generate illegal instruction faults.  At least some versions of qemu-user do allow execution of vector code; I have been told this might be a bug in qemu-user as the save/restore context may also be missing there as well.  (Not confirmed.)

Its worth noting that this issue applies to *all* vector code, not just the result of auto-vectorization.  As such, we could chose to look at this as a user-error - specifying +v in an environment that doesn't actually support it - but that feels a tad user hostile.  I'm going to chat this around with a few folks, but I'm expecting we will chose to turn off vetorization until the underlying support is widely available.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129013/new/

https://reviews.llvm.org/D129013