This change only applies to functions the can be reasonably expected to
use SVE registers.
Modifying vector length in the middle of a function might cause
incorrect stack deallocation if there are callee-saved SVE registers or
incorrect access to SVE stack slots.
Addresses (non-issue) https://github.com/llvm/llvm-project/issues/143670
This adds a new `mlir_arm_runner_utils` library that contains utils
specific to Arm/AArch64. This is for use in MLIR integration tests.
This initial patch adds `setArmVLBits()` and `setArmSVLBits()`. This
allows changing vector length or streaming vector length at runtime (or
setting it to a known minimum, i.e. 128-bits).