[llvm-branch-commits] [llvm] backport: [RISCV] Sources of vmerge shouldn't overlap V0 (#170070) (PR #170604)

[Luke Lau via llvm-branch-commits]

https://github.com/lukel97 approved this pull request.

LGTM. FWIW this fixes a miscompile, and the test diffs are largely due to permutations in register allocation if that's of any context. But I'll leave it to @wangpc-pp to comment about the urgency of the backport

https://github.com/llvm/llvm-project/pull/170604