Example of 'volatile' preventing a compiler optimization in C#?

From what I understand, the 'volatile' modifie开发者_StackOverflowr in C# has two effects:

1. Inserts fences as necessary for the target processor
2. Prevents certain compiler optimizations

On x86 / amd64, (1) is irrelevant. Those processors don't require fences for volatile semantics. (ia64 is different, though.)

So, we are down to (2). But, for examples that I tried, volatile does not make any difference to the jit-ted assembly.

My question is: Can you give an example of a C# code sample where adding a 'volatile' modifier on a field results in different jit-ted assembly code?

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Maybe this is what you are looking for.

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Marc Gravell has an repeatable example of how the lack of a volatile keyword can cause problems.

It's also discussed here.

It's worth noting (as Marc does) that the compiler optimisations are only seen when compiled in Release mode.