JDK-8318650 added the hotspot intrinsifying of subword gather
load APIs for X86 platforms [1]. But the current implementation is not friendly to AArch64 SVE, which supports native vector instructions for subword gather load operations.

To finally add compiler support of subword gather for SVE, we have to make an adjustment of current implementation of this API both in Java and the compiler mid-end part. The goal is to make the operations more efficient and maintainable across different architectures.