[release/7.0-rc1] Fix one more Crossgen2 field layout mismatch with runtime #74293
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The field offset mismatch in the test JIT/Regression/JitBlue/Runtime_60035/Runtime_60035.csproj specific to Crossgen2 composite mode is due to the recent proliferation of 16-byte alignment specific to Vector across the runtime repo. Previously, the largest supported alignment was 8 and X86 was the only architecture not respecting it. In general the problem is caused by the fact that the native CoreCLR runtime method table builder calculates field offsets without taking the method table pointer into account; in the particular case of the Runtime_60035 test, the class System.Text.Encodings.Web.OptimizedInboxTextEncoder has a field named _allowedAsciiCodePoints that is 16-aligned that exposes this inconsistency. Thanks Tomas
ghost
added
the
trylek
requested review from
davidwrighton and
jeffschwMSFT
and removed request for
MichalStrehovsky
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Backport of #73978 to release/7.0-rc1
/cc @trylek
Customer Impact
This bug was only found recently due to more widespread use of Vector128 in framework codebase. In classes containing 16-aligned fields, this causes a layout mismatch between Crossgen2 and native runtime with the potential to cause data corruptions, crashes or GC holes.
Testing
Innerloop & Crossgen2 composite testing (the bug was originally observed in Crossgen2 composite runs), as part of the change I wrote two more dedicated Crossgen2 typesystem tests to exercise this behavior.
Risk
Relatively low - most of the actual code logic is pre-existing, the fix only changes how it's applied to the individual architectures.
IMPORTANT: Is this backport for a servicing release? If so and this change touches code that ships in a NuGet package, please make certain that you have added any necessary package authoring and gotten it explicitly reviewed.