A New Direction for the Mac Arm64 Code Generator

[solidstate1991]

On Saturday, 11 July 2026 at 04:15:16 UTC, Walter Bright wrote:
> I had carefully crafted the Mach object file generation 
> according to how the default Mac compilers worked. I'd compile 
> bits of code with clang, and dump out the object files. 
> Fortunately, there was also a specification for it, and I could 
> compare the specification with what was generated.
>
> Enter the arm64 clang. Well, it throws this out the window, and 
> has their own undocumented variant of the file format. I've 
> spent a lot of time with AI trying to figure out how to make my 
> work still work with the new ld linker.
>
> The AI would give me mostly correct information, but would 
> never quite give me the details of how it was supposed to work. 
> (This is the likely result of a lack of documentation.) Many of 
> its recommendations just resulted in internal linker assert 
> failures. Yes, my object files would crash ld. This is not 
> helpful because I don't know why they crashed it. AI finally 
> recommended to me reading the LLVM linker source code (it's 
> open source).
>
> Well, looking at that undocumented uncommented hellish snarl of 
> C++ code was a moment of unhappy frustration for me.
>
> So I am forced to abandon the documented way to generate object 
> files, and reverse engineer the new way. At least one point in 
> my favor is I can use g++ to generate sample .o files, and then 
> try to conform to what g++ emits.
>
> It's going to be slow going, though.
>
> Given the frequent erroneous assertions AI has made about the 
> object code format, I won't bother trying to use AI to generate 
> the code.

I had similar experiences when working on iota, some API, 
especially on the Linux side, is poorly documented, and often had 
to peek into others' codes, including the kernel source. For 
libevdev, I'm still experimenting with how to get input support 
on par with the Windows side of things. AI - at least what I 
could get for free - was not helpful for me, just retold me 
whatever stuff I could Google otherwise. I have read enough Dune 
to not want to touch a slightly less bad Google, that has the 
chance of rotting my brain.