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Feature: Erased-generics mode to eliminate monomorphization overhead #30
Description
We can skip monomorphization overhead during compile time by using invokedynamic. This would lead to smaller JAR file sizes and should also improve compilation speed in big crates with a lot of generics.
An agent driven crude and partial implementation is in this branch: https://github.com/AnuthaDev/rustc_codegen_jvm/tree/generic-erasure
The code and markdown files should serve as a good starting point for a proper implementation.
Here are some statistics from that branch, tested on a Macbook M4 pro:
Compilation Time
erased_bench crate:
| Mode | Avg (s) | Min (s) | Max (s) |
|---|---|---|---|
| Native rustc (debug) | 0.476 | 0.47 | 0.48 |
| Native rustc (release) | 0.474 | 0.47 | 0.55 |
| JVM Mono (debug) | 0.219 | 0.21 | 0.28 |
| JVM Erased (debug) | 0.200 | 0.19 | 0.21 |
Binary/Jar Size
| Mode | erased_bench |
|---|---|
| Native (debug) | 503,296 bytes |
| Native (release) | 430,400 bytes |
| JVM Mono | 43,363 bytes (52 classes) |
| JVM Erased | 25,877 bytes (24 classes) |
Activity
IntegralPilot commentedon Jul 13, 2026
Thank you so much for this! I will have a closer look into it when I'm more free to analyse a complex change like this, on the surface though I think erasure would actually be really useful (and had it in my own internal roadmap in my head), so I am really grateful that you helped help out and handle this for me.