[hcs]

I don't think elfshaker actually does do any binary diffing (e.g. xdelta or bsdiff). It works well because it uses pre-link objects which are built to change as little as possible between versions. Then when it compresses similar files together in a pack, Zstandard can recognize the trivial repeats.

[peterwaller-arm]

Author here. This is correct, we set out to do binary diffing but we soon discovered that if you put similar enough object files together in a stream, and then compress the stream, zstandard does a fantastic job at compressing and decompressing quickly with a high compression ratio. The existing binary diffing tools can produce small patches, but they are relatively expensive both to compute the delta and to apply the patches.