"A" does matter a bit. Builds are uploaded to the App Store include bitcode, which Apple strips on distribution.

According to docs, enabling bitcode: "Includes bitcode which allows the App Store to compile your app optimized for the target devices and operating system versions, and may recompile it later to take advantage of specific hardware, software, or compiler changes."

It seems quite likely they have (and probably used) the capability to recompile any app on their platform to benchmark real workloads against prototype silicon changes.