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The diffs are relatively minor, the only large regressions are in MinOpts context from coreclr_tests (on some targets).

This fix will significantly simplify the ADDR(FIELD) => FIELD_ADDR transition.

@dotnet/jit-contrib

Reminds me that we used to tolerate this sort of issues and treat pointers to value types as never null.

Although the diffs don't look too bad in FullOpts so presumably it's fine?

Some of the diffs do look to be in some scary functions:

           3 (20.00 % of base) : 3668.dasm - ConfiguredValueTaskAwaiter[System.__Canon]:get_IsCompleted():bool:this
           3 (20.00 % of base) : 3851.dasm - ConfiguredValueTaskAwaiter[System.__Canon]:GetResult():System.__Canon:this
           3 (20.00 % of base) : 26284.dasm - System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder:SetException(System.Exception):this
           3 (20.00 % of base) : 16608.dasm - System.Runtime.CompilerServices.ValueTaskAwaiter`1[System.__Canon]:get_IsCompleted():bool:this
           3 (20.00 % of base) : 16609.dasm - System.Runtime.CompilerServices.ValueTaskAwaiter`1[System.__Canon]:GetResult():System.__Canon:this
           3 (10.00 % of base) : 16777.dasm - System.Runtime.CompilerServices.AsyncTaskMethodBuilder:AwaitUnsafeOnCompleted[YieldAwaiter,<MultipleSerial>d__23[System.__Canon]](byref,byref):this
           3 (0.53 % of base) : 14294.dasm - System.Collections.Generic.Dictionary`2[uint,System.__Canon]:FindValue(uint):byref:this

We should keep an eye on related benchmarks and/or double check that the diffs in these are not impactful.

Some of the diffs do look to be in some scary functions:

           3 (20.00 % of base) : 3668.dasm - ConfiguredValueTaskAwaiter[System.__Canon]:get_IsCompleted():bool:this
           3 (20.00 % of base) : 3851.dasm - ConfiguredValueTaskAwaiter[System.__Canon]:GetResult():System.__Canon:this
           3 (20.00 % of base) : 26284.dasm - System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder:SetException(System.Exception):this
           3 (20.00 % of base) : 16608.dasm - System.Runtime.CompilerServices.ValueTaskAwaiter`1[System.__Canon]:get_IsCompleted():bool:this
           3 (20.00 % of base) : 16609.dasm - System.Runtime.CompilerServices.ValueTaskAwaiter`1[System.__Canon]:GetResult():System.__Canon:this
           3 (10.00 % of base) : 16777.dasm - System.Runtime.CompilerServices.AsyncTaskMethodBuilder:AwaitUnsafeOnCompleted[YieldAwaiter,<MultipleSerial>d__23[System.__Canon]](byref,byref):this
           3 (0.53 % of base) : 14294.dasm - System.Collections.Generic.Dictionary`2[uint,System.__Canon]:FindValue(uint):byref:this

We should keep an eye on related benchmarks and/or double check that the diffs in these are not impactful.

I assume these all are small functions judging by the relative diffs and are inlined in the real world where null-checks might be folded

I assume these all are small functions judging by the relative diffs and are inlined in the real world where null-checks might be folded

That would be my assumption as well. For reference, the large relative diffs mainly come from cases where have a method that immediately tail-calls another (a member function).