"Ironically, among the four stages, the compiler (translation to assembly) is the most approachable one for an AI to build. It is mostly about pattern matching and rule application: take C constructs and map them to assembly patterns.

The assembler is harder than it looks. It needs to know the exact binary encoding of every instruction for the target architecture. x86-64 alone has thousands of instruction variants with complex encoding rules (REX prefixes, ModR/M bytes, SIB bytes, displacement sizes). Getting even one bit wrong means the CPU will do something completely unexpected.

The linker is arguably the hardest. It has to handle relocations, symbol resolution across multiple object files, different section types, position-independent code, thread-local storage, dynamic linking and format-specific details of ELF binaries. The Linux kernel linker script alone is hundreds of lines of layout directives that the linker must get exactly right."

I worked on compilers, assemblers and linkers and this is almost exactly backwards