[clang] [HLSL] Add _m and _<numeric> based accessors to hlsl::matrix (PR #163220)

[Chris B via cfe-commits]

llvm-beanz wrote:

> I was thinking this wouldn't be to hard to do by generating multiple MatrixSubscriptExpr(s) but your second point about retain source information to recreate this construct would still not be possible.

You can't do it with multiple AST nodes. You need a single l-value of vector type that represents elements arbitrarily dispersed across the matrix.

https://github.com/llvm/llvm-project/pull/163220