AsmIntGen is a Rust tool that compiles a custom assembly DSL into
native x86_64 or aarch64 assembly (.S files). It reads struct field
offsets from a generated constants file and instruction layouts from
Bytecode.def (via the BytecodeDef crate) to emit platform-specific
code for each bytecode handler.
The DSL provides a portable instruction set with register aliases,
field access syntax, labels, conditionals, and calls. Each backend
(codegen_x86_64.rs, codegen_aarch64.rs) translates this into the
appropriate platform assembly with correct calling conventions
(SysV AMD64, AAPCS64).
