Might be a decompiler bug. Can you show the real b...

# announcements

[cbruegg]

Might be a decompiler bug. Can you show the real bytecode here?

[itnoles]

I am seeing again with while, isNullOrEmpty and other functions

[itnoles]

https://pastebin.com/JJnLJ3Hx here for bytecode for isNullOrEmpty that is showing boolean var3 = false;
boolean var4 = false;

[cbruegg]

Yeah, that's odd. Looks like it's indeed like this in the bytecode.

[itnoles]

decompiler bug?

[cbruegg]

No, I mean the useless variable indeed seems to be in the bytecode. Unless I'm missing something.

[cbruegg]

You can see ICONST_0 twice followed by ISTORE_3 / ISTORE_4 to store the value 0 (= false) into the variables 3 and 4, but there's no ILOAD_3 / ILOAD_4 to ever load it again.

[Marko Mitic]

I've seen medum article recommending using if instead of let because of extra variable in bytecode.

[cbruegg]

That's not good advice, and generally the article is of low quality. This should be something that's very easy to optimize for the JVM or ART. And even if not, it's a stack allocation, which are really cheap.

[cbruegg]

For reference, this is the article: https://medium.com/@elye.project/kotlin-dont-just-use-let-7e91f544e27f?sk=6d8d04c5c00613f20e20fe057b3ebd51

[Marko Mitic]

I guess kotlin compiler tests don't check for scenarios like these and this slipped in by accident

[Marko Mitic]

I mean, this bytecode is functionally correct, but it's not optimal

[cbruegg]

It's not optimal, but I would be surprised to see an actual performance impact.

[itnoles]

Android Studio has Kotlin Bytecode with Optimizations checked, it still show same as unoptimizations

[cbruegg]

That doesn't include optimizations performed at runtime by ART or the JVM.

[itnoles]

odd

[gildor]

This is not a bug, this variable used for inline functions debugging
See:
https://kotlinlang.slack.com/archives/C7L3JB43G/p1558022163043700?thread_ts=1557907293.041100&cid=C7L3JB43G

[cbruegg]

Ah, thanks! That's clever.