Intentional overlap

[Kamjam66xx]

Hello, im looking for materials to learn about intentional overlap. Where you pass arguements to a function, but leave them at the top and have intentional memory overlap so that you dont have to copy the arguements.

 

C++ is what i prefer.

 

Edit: i heard about them doing this for a vm in android phones.

[reniat]

By "top" do you mean like top of the memory stack?

 

In C++ there are references, pointers, move semantics, initializer lists, copy constructors, all of which are about avoiding unnecessary copies in memory, and you can kind of think of it like "overlapping memory" I guess.

But i'm a bit confused, since as far as i'm aware, most android development is done in Java and that doesn't have anything like these features since it abstracts all memory away from the high level code construction.

[Guest]

https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.3.0/com.ibm.zos.v2r3.cbclx01/cplr233.htm

[Kamjam66xx]

4 hours ago, fpo said:

 

Im looking for an example of how it works on a virtual stack machine. They had a specific way for an android vm that was super efficient!

 

some guy mentioned it at a university of San Francisco lecture but didnt go over much.

[reniat]

17 minutes ago, Kamjam66xx said:

Im looking for an example of how it works on a virtual stack machine. They had a specific way for an android vm that was super efficient!

 

some guy mentioned it at a university of San Francisco lecture but didnt go over much.

You're gonna need to be more specific (at least for me, maybe someone else has a better idea of what you're asking). If you're talking about how "managing memory in a virtual stack machine" works, that's like asking "How does the JVM handle memory".

 

I can tell you how C++ the language handles memory, but I can't hypothesize how an unknown virtual stack machine built for android might manage memory to avoid duplicates. I need some more specificity in the question. 

[Mira Yurizaki]

16 hours ago, Kamjam66xx said:

Hello, im looking for materials to learn about intentional overlap. Where you pass arguements to a function, but leave them at the top and have intentional memory overlap so that you dont have to copy the arguements.

 

C++ is what i prefer.

 

Edit: i heard about them doing this for a vm in android phones.

What's wrong with using pointers?

[Kamjam66xx]

Oops my bad, i was going off memory and remembered it totally wrong. Any info on that would be awesome too. Sorry. It didnt make sense in my head which is why i asked, and now it does.

 

1:38:21 

 

[Mira Yurizaki]

18 minutes ago, Kamjam66xx said:

Oops my bad, i was going off memory and remembered it totally wrong. Any info on that would be awesome too. Sorry. It didnt make sense in my head which is why i asked, and now it does.

What they're talking about sounds like an optimization for process virtual machines like JVM and Dalvik. In actual hardware, a function call would typically push the current state of the registers onto a stack, so the function that was called is given a fresh processor state. In other words, you can't overlap memory like how they described in the video using the processor's registers, because those values were shuffled off somewhere else already.