map: reduce allocations when (un)marshaling keys and values about ebpf

[brycekahle]

• Structs of valid types which have no compiler inserted padding, aka packed structs

Why is the no padding required?

[lmb]

Because the padding is completely invisible to regular Go. Pretty printing a value doesn't show such padding. What happens when we write into the padding via unsafe? Is padding taken into account when comparing values?

The only way I'd be comfortable with this is if we zeroed the padding somehow, but then we wouldn't do that in the fastpath.

[brycekahle]

Ah, we generate Go types using go tool cgo -godefs which includes the padding. So it sounds like that would still work.