That's 5 copies for SVE (had an error in first message - SVE allows up to 2048-bit vectors, not 1024), and 10 copies for RVV if you wanted to target all widths

That's 5 copies for SVE (had an error in first message - SVE allows up to 2048-bit vectors, not 1024), and 10 copies for RVV if you wanted to target all widths (though you'd probably be fine for a decade or a couple by targeting just 128 & 256-bit, and maybe 512-bit). Plus one more for a scalar fallback. And yes, it's not particularly large of a cost, other than it being an extremely pointless waste of space given that it is possible to have just one variant that covers them all. Though, it would become significantly more problematic if you wanted to target different extension groups too (which you would quite likely want to some extent) as those'd multiply with all the length targets - SVE vs SVE2 vs more future extensions, and on RVV there's just a lot (Zvfh & Zvfhmin for FP16, Zvbb for extra bitmanip stuff, many more here[1]; and potentially at some point there could be an extension that uses a wider encoding scheme to inline vsetvl fields & allow masking by registers other than v0, which could benefit everything) [1]: https://github.com/riscv/riscv-crypto/blob/c8ddeb7e64a3444dda0438316af1238aeed72041/doc/vector/riscv-crypto-spec-vector.adoc https://github.com/riscv/riscv-crypto/blob/c8ddeb7e64a3444dd...