Re:Classes vs. Structs in .NET. How not to teach about perfo...
by jkulubya on Saturday November 04, 2023 @09:37PM
(#38147131)
Property accessors `.name` and methods `ElementAt(i)` can have side-effects. From just eyeballing the code, that together with the gc issue would make the compiler in my brain wary of removing the loop. I don't personally know if it's possible to convince the C# compiler that it's safe.
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Re:Classes vs. Structs in .NET. How not to teach about perfo...
by to11mtm on Sunday November 05, 2023 @11:27AM
(#38152561)
... I could be wrong, but I -thought- it was possible for the JIT to see there are no side effects and inline on property access (so long as the property is not a virtual call or otherwise able to devirt.)
.ElementAt() OTOH has a chance to throw in most implementations AFAIR so yeah, a bit of a moot point in this case.
Edited to add:
Actually, there -could- still be side effects in the case of .Name on a class, specifically, it's possible that .ElementAt() could return a null. I'm not sure what cases (if any) that the JIT could get around that.
OTOH, in the case of a struct, as long as .ElementAt() -doesn't- throw, .Name will always return regardless of if it is a property or field, and as part of a struct the compiler should do a good job of inlining as long as the access has no side effects (and you don't have too many fields on the struct!)