Use tablegen to generate the pass constructor.
This pass is supposed to add function attributes so it does not need to
operate on other top level operations.
Add vscale range attirbute for the Scalable Vector Extension (SVE) if
provided on the command-line (options in a previous commit)
If no command-line option is provided, if the target-feature of SVE is
specified and the architecture is AArch64, it defualts to 128-2048. in
other words a vscale-min of 1, vscale-max of 16.
A pass is used to add the atribute to all functions. The vectorizer will
use this attribute to generate the SVE instruction to match the range
specified. The attribute is harmless if there is no vectorizable
operations in the function.
