[Bug target/126426] riscv rvv: Incorrect result with -march=rva23u64 -O2 in libgav1

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126426

--- Comment #3 from Robin Dapp <rdapp at gcc dot gnu.org> ---
-march=rv64gcv works while -march=rva23u64 doesn't.  optimized dump is similar,
so somewhere in the rtl pipeline.