> * -mstrict-align: Both scalar and vector misaligned accesses are > unsupported (-mrvv-allow-misalign doesn't matter). I'm not sure if > there's hardware there, but given we have systems that don't support > scalar misaligned accesses it seems reasonable to assume they'll also > not support vector misaligned accesses.
As a data point, and contrary to what I said/hoped before: There are examples where -mstrict-align and -mrvv-allow-misalign vectorizes code and produces unaligned vector accesses. I haven't looked into that area of the vectorizer for a while but it doesn't appear as if we regard STRICT_ALIGNMENT there at all. We keep track of the known misalignments (via peeling etc.) and either handle them via movmisalign or give up. Same for unknown misalignment but all unaffected by -mstrict-align. We could have -mrvv-allow-misalign have an "| STRICT_ALIGNMENT" to get to the behavior you described but right now it's not like that. And AFAICT -mstrict-align behaves the same way for other targets, regardless if they support unaligned vector accesses or not. So, right now, I'd tend towards describing that both flags are independent and affect either only scalar or only vector code. Maybe we should rename the whole thing to -mrvv-strict-align? Might make it even more confusing, though. Regards Robin
