[PATCH] D32737: [Constants][SVE] Represent the runtime length of a scalable vector

[Chris Lattner via Phabricator via llvm-commits]

lattner added a comment.

In https://reviews.llvm.org/D32737#760310, @sanjoy wrote:

> I've only lightly read the spec, but it looks like the vector length can be controlled by writing to the `ZCR_ELn` registers (so, e.g. user code could make a syscall to change the vector length)?  If that's accurate, I think a constant `vscale` is not sufficient.


@rengolin is correct.  The only sensible way to model this feature is with the vector length being a (load time) constant.  Changing while a process is executing is not a useful thing to model or worry about.  I still think this is better modeled with an intrinsic that returns the value, rather than and llvm::Constant.


https://reviews.llvm.org/D32737