ICU data file builds are non-deterministic

[akoeplinger]

See Rolf's comment on https://github.com/xamarin/xamarin-macios/pull/11983/files#r657759425

This is unintentional, we're using the same filter so they should be identical.

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Issue Details

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See Rolf's comment on https://github.com/xamarin/xamarin-macios/pull/11983/files#r657759425

Author:	akoeplinger
Assignees:	-
Labels:	area-Infrastructure-mono
Milestone:	6.0.0

[akoeplinger]

/cc @steveisok

[filipnavara]

For reference here's a table with some of the sizes: dotnet/designs#225 (comment). They differ even for the same architecture between two platforms. One of my theories is that it's related to the zlib version / default options on the build machine.

[directhex]

The default packaging mode is common, or archive. In this mode, the different data files are bundled together as an architecture-dependent file that can later be memory mapped for use by ICU.

https://linux.die.net/man/1/pkgdata

Emphasis mine.

icudt.dat is arch specific according to the documentation.

[steveisok]

So, are you suggesting "by design" then?

[filipnavara]

Would that explain why the size differs between arm64 on Android and iOS? (ie. essentially same arch) I would also expect x64 and arm64 to be within margin of error, that was not the case.

[directhex]

The ICU docs say it's by design.

[directhex]

@filipnavara I'd need to examine pkgdata.cpp more closely to be able to answer that

[filipnavara]

The iOS one is about 200 Kb (13%) bigger than the Android one. That may be worth another look even if it turns out to be by design.