• fixed formatting issues

In D28776#647140, @luporl wrote:

It looks great now! Since this changes core libc functions, can you perform a buildworld on a system with the modified libc installed to confirm everything works fine?

• added new execution path in case src and dst are relatively unaligned
• fixed the style issues

In D28776#646080, @luporl wrote:

Before going further with this discussion, it is important to realize that there are actually 2 issues with bcopy to be solved.

The first one is the use of VSX on POWER7 and older CPUs, that causes SIGBUS with unaligned memory.

The second one is unaligned access on cache-inhibited storage, which AFAIK is not allowed on ANY PowerPC CPU.

So, unless we ignore cache-inhibited storage, commonly used for stuff like framebuffers, we just can't allow unaligned accesses to memory.
That's why my suggestion was to do the same as was done with memcpy, of using only byte copies on unaligned memory.

Besides that, source must always be aligned, to prevent issues such as reading across page boundaries, when the upper page memory may not be accessible.

• improved formatting
• solution to the problem outlined by luporl