Optimize NoiseRouter

[adiantek]

Minecraft Version

Mod Loader

Both (NeoForge and Fabric)

Description

I think NoiseRouter could be optimized. My initial idea is to generate a DAG, for example from:

{
  "type": "minecraft:add",
  "argument1": {
    "type": "minecraft:mul",
    "argument1": 5,
    "argument2": 7
  },
  "argument2": {
    "type": "minecraft:mul",
    "argument1": 5,
    "argument2": 7
  }
}

into something like this (for debugging and validation purposes):

[
  { "op": "load", "arg": 5, "idx": 0 },
  { "op": "load", "arg": 7, "idx": 1 },
  { "op": "mul", "arg1": 0, "arg2": 1, "idx": 2 },
  { "op": "add", "arg1": 2, "arg2": 2, "idx": 3 }
]

We could then generate a CompiledDenseFunction using ObjectWeb ASM or Byte Buddy and pass it to NoiseRouter (which is instantiated once per dimension). This approach could allow deduplication of repeated computations. All intermediate values could remain on the stack, avoiding excessive function calls (except for spline and possibly range_choice).

What do you think about this approach? If you're interested, I can prepare a proof of concept and evaluate its performance.

PS: Custom DenseFunctions provided by mods would still be invoked directly using invoke and can be remapped using DensityFunction.Visitor

[adiantek]

I found this repo:

https://github.com/RelativityMC/C2ME-fabric/blob/dev/26.1.1/c2me-opts-dfc/src/main/java/com/ishland/c2me/opts/dfc/ModuleEntryPoint.java

Performance +44,658% (from 1354 seconds to 936 seconds, 15 threads for generating, same seed, 297252 chunks, AMD Ryzen 7 9700X and DDR5 5200 MHz On-Die ECC)

[Spottedleaf]

Using a runtime compiler seems to be the approach to optimising this area. If you do have some ideas in this area (that isn't stealing C2ME's code) and want to implement it, that would acceptable.