Will the CLR optimize and embed this GetHashCode ()?

Let's say we have a type of value like this, where the fields are readonlyinitialized at build time:

public struct SomeValue
{
    private readonly Int32 field1;
    private readonly Int32 field2;

    ...
}

In addition, let's say we have a helper class that allows us to implement GetHashCode()for composite types in a reusable way:

public struct SomeValue
{
    ...

    public override Int32 GetHashCode()
    {
        return HashHelpers.GetHashCode(this.field1, this.field2);
    }
}

Now the compiler must understand that the values โ€‹โ€‹of the fields will never change after the type is created, as they are readonly. Is it possible that the call HashHelpers.GetHashCode()will be inlined in some way when there SomeValue.GetHashCode()is JIT-ed?

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4 answers

HashHelper, , , , .

, JIT . , . , , . , , . GetHashCode.

, const readonly. GetHashCode. . , -, , , , . - - . , , , xor mov.

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inlining (.NET 4, , ). , HashHelpers.GetHashCode , . , readonly - .

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, , readonly, , .

This article discusses some of the heuristics used by the .NET 3.5sp1 jitter. Perhaps this has changed in .NET 4 and may change again in future versions.

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As far as I know, the call to HashHelpers.GetHashCode () will not be inlined, it will just be considered a normal call to this method in CIL. Maybe I'm wrong, but I'm sure it is not.

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Source: https://habr.com/ru/post/1763784/


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