3 nested for loop

[ichihgo]

in general is there a way I can do the same job of 3 nested for loop but faster

[Midnight]

elaborate.

[MrBucket101]

Recursion?

[Midnight]

Recursion?

 

That's probably slower.

[MrBucket101]

That's probably slower.

Easier to understand though. 3 nested loops just sounds like a mindfuck lol

[Midnight]

Easier to understand though. 3 nested loops just sounds like a mindfuck lol

 

3 nested loops are not so bad tbh.

[Art Vandelay]

You might be able to unroll a loop or just figure out a better way to code it. Those are really your only options

 

Recursion?

When you call, you push ESP and EBP to the stack, along with any parameters... and if you have 3 levels of recursion, that's gonna be a nightmare.

[SSL]

Even if the loops are necessary there are efficient and inefficient ways of implementing them. Do it wrong and you'll get cache thrashing, which will reduce performance by orders of magnitude.

[Art Vandelay]

Even if the loops are necessary there are efficient and inefficient ways of implementing them. Do it wrong and you'll get cache thrashing, which will reduce performance by orders of magnitude.

Any recommendations on not having loops do cache thrashing, other than the obvious like using fewer/smaller variables?

[SSL]

Any recommendations on not having loops do cache thrashing, other than the obvious like using fewer/smaller variables?

 

Well, a basic one is making sure to read multidimensional loops in the right order. When you access memory, a line of memory will be read and stored in the CPU cache. This works great if you are reading across rows in the array. But if you are reading down columns, the CPU will be forced to go to memory for each operation instead of being able to rely on the much faster cache until getting to the next row.

 

Google for loop tiling and strip mining. Compilers will try to do optimizations like this on their own, but the more you help them the better the performance potential.