[Bug target/117955] GCC generate illegal riscv instruction `vsetvli zero,zero,e64,mf4,ta,ma` with -O2 and -O3

[law at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117955

--- Comment #6 from Jeffrey A. Law <law at gcc dot gnu.org> ---
As I feared, this has just gone latent.  If you revert:

bdbbe5d4b6d495ac06ee762540a1277498f2a7a0
7bef3482f27ce13ba7e6c4f43943f28a49e63a40

This can be triggered again on the trunk.  Given the sensitivity to scheduling
changes I suspect it's ultimately a vsetvl optimization issue.