A disassembler for JITed functions in Racket.

To install:

% raco pkg install disassemble

To use it, try something like this:

[samth@punge:~/sw/disassemble (master) plt] racket
Welcome to Racket v6.0.1.10.
> (require disassemble)
> (define (f x) 1)
> (disassemble f)
       0: 488943f8                       (mov (mem64+ rbx #x-8) rax)
       4: 4883c3f8                       (add rbx #xfffffffffffffff8)
       8: b803000000                     (mov eax #x3)
       d: 4c8b75c8                       (mov r14 (mem64+ rbp #x-38))
      11: 4883c428                       (add rsp #x28)
      15: 415d                           (pop r13)
      17: 415c                           (pop r12)
      19: 5b                             (pop rbx)
      1a: 5d                             (pop rbp)
      1b: c3                             (ret)
>

If you have ndisasm installed (and in your PATH) you can also try:

> (disassemble f #:program 'nasm)
00000000  488943F8          mov [rbx-0x8],rax
00000004  4883C3F8          add rbx,byte -0x8
00000008  B803000000        mov eax,0x3
0000000D  4C8B75C8          mov r14,[rbp-0x38]
00000011  4883C428          add rsp,byte +0x28
00000015  415D              pop r13
00000017  415C              pop r12
00000019  5B                pop rbx
0000001A  5D                pop rbp
0000001B  C3                ret

This works only on x86 or x86-64.

Also, the dump function writes the bytes of the machine code to a file:

> (dump const "file.bin")

To run the expect-based test suite locally:

raco test tests/main.rkt

The tests use the recspecs library to compare disassembly output. If ndisasm is available, additional checks are run. GitHub Actions runs the suite on x64 with stable and current Racket CS and on arm64 with current Racket CS. The compiled-procedure tests run only on x86-64.

Patches, uses, complaints, and suggestions are all welcome.

The disassembly code (when not using NASM) is taken from Göran Weinholt's Machine Code library.