[llvm] [LangRef] Cap maximum value of vscale at 2^31-1. (PR #144607)

[Philip Reames via llvm-commits]

preames wrote:

> I'm sure restricting the range of vscale will have other benefits but that feels like an independent change and we already have mechanisms to achieve this via vscale_range (and range?) attributes.

I think this is a case of false generality.  We could explore alternate options here, but this patch has the major advantage of being *simple*.  We can come back and revisit this (even reverse it) if needed, but I see no reason not to go with the simple answer for the moment.

https://github.com/llvm/llvm-project/pull/144607