fasm Assembly Emission

AzLang compiles code by emitting a single, human-readable fasm (flat assembler) assembly file, which fasm turns directly into a native ELF executable in one pass.

1. Why fasm?

fasm was chosen because it aligns with AzLang’s minimalist engineering doctrine:

• One Pass, One Binary: fasm assembles and links in a single step — there is no separate as, no ld, no object files.
• Small Footprint: the entire fasm distribution is a single binary of well under 1 MB.
• Readable Output: the emitted .asm is clean, commented-friendly x86_64 assembly you can inspect directly.

2. Sample Assembly Emission

Here is the exact assembly generated for the Hello World program (paths abbreviated; the compiler canonicalizes them to absolute paths):

format ELF64 executable
entry _start

segment readable executable

include "./sdk/src/write.s"
include "./sdk/src/exit.s"

_start:
    push rbp
    mov rbp, rsp
    sub rsp, 8
    mov rax, 1
    push rax
    lea rax, [main_str0]
    push rax
    mov rax, 25
    push rax
    pop rdx
    pop rsi
    pop rdi
    call write
    mov rax, 0
    push rax
    pop rdi
    call exit
    xor edi, edi
    mov eax, 60
    syscall

main_str0 db "Hello World from AzLang!",10,0

AzLang generates this directly from the validated AST:

• Function calls lower to ordinary call <symbol> instructions following the System V AMD64 ABI (register arguments, 16-byte stack alignment).
• String literals become db data directives (escape sequences such as \n are resolved to bytes at emission time).
• @link(...) sources that are actually invoked are pulled in with include, so unused SDK stubs never reach the binary.
• Programs end with a direct sys_exit (rax = 60) — no C runtime, no ret to nowhere.