When working on JDK-8351140, I witnessed possible misaligned memory access in array fill stub.
We fill by element for short arrays (< 8 bytes), which assumes a heapword alignment. But that is not guaranteed. This issue could be reproduced by running: `make test TEST="micro:vm.compiler.ArrayFill"`
with `@Param("5") private int size;` on riscv platforms with slow misalgned memory accesses.

[1] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp#L2141