[llvm] [Hexagon] Add missing pattern for v8i1 type (PR #120703)

[Santanu Das via llvm-commits]

quic-santdas wrote:

> > Does this fix #59009 ?
> 
> Kryzsztof's concern there was that the ABI was underspecified, so the fix was not clear, or rather any fix wouldn't be portable.
> 
> > The issue is that we'd need to amend the ABI, to either allow passing/returning boolean vectors, or specify the conversions. At the moment LLVM is (AFAIK) the only compiler targeting Hexagon with HVX, so we could get away with handling it internally to LLVM, but it would make it harder for other potential future compilers/code generators to be binary-compatible with LLVM.

This patch fixes a case of v8i1 mishandling. The issue #59009 is currently being fixed: this one deals with unhandled v8i1 when used as a call operand.

https://github.com/llvm/llvm-project/pull/120703