Support for AARCH(64)-architecture

[MonsterDruide1]

Well, not much else to say about it ... I'd want to try using this on a decomp project for Nintendo Switch, which uses AARCH64.

I'm currently happy with using asm-differ, so feel free to sort this to being a low-priority issue.

[encounter]

This would be great to add, but the current limiting factor is finding (or creating) a complete enough aarch64 disassembler in Rust. Existing options:

• capstone: API doesn't provide enough information for formatting arguments individually, which objdiff needs in order to diff individual args. Dependency on a C library, which is a problem for compiling objdiff to WASM. (Rust and C use incompatible WASM ABIs)
• bad64: Seems to be missing formatting logic. Also a dependency on a C library.
• disarm64: Seems promising, but missing SIMD support. I assume the Switch makes use of SIMD.
• yaxpeax-arm: Also promising, also missing SIMD support.

Hopefully this changes in the near future, or someone works on finishing SIMD support for one of the above. I guess another question is: Would it still be useful to add ARM64 without SIMD?

[MonsterDruide1]

For automatically diffing the resulting decompiled functions, we're currently using a mix of bad64 and capstone, feel free to look into that: https://github.com/open-ead/nx-decomp-tools/blob/master/viking/Cargo.toml

I assume that SIMD would mean NEON on the Switch. It is used in some very specific functions, but not too heavily across entire games. The only occurence I came over that were not hidden deep within some math-heavy functions were matrix-multiplications, apart from those it always uses the standard floating point registers/functions. So, it would still be useful having the architecture supported without SIMD, although we couldn't use objdiff as full replacement for asm-differ then.

[MonsterDruide1]

Here's something else I ran across today: https://github.com/emproof-com/nyxstone

This seems to provide rust bindings for disassembling any architecture supported by LLVM, which should also include AARCH64.

[encounter]

I realized yaxpeax-arm supports ARMv8 SIMD, so I implemented an experimental backend in 424434edd6564a6c2afaea051d8f2c43ae755d2a. This required a lot of custom code, and not a lot of relocations are handled yet, so please provide feedback if you try it!

[MonsterDruide1]

Thanks for taking care of this! It seems like I need more help setting up the project for me though, is there something like a Discord server for this to allow easier communication?

[encounter]

Yep! https://discord.gg/hKx3FJJgrV