jit

jit is a Go module for executing machine code instructions directly, without having to store instructions in an executable file.

It was inspired by this post: Hello, JIT World: The Joy of Simple JITs.

jit is also an extremely simple programming language.

For a similar project written in Rust, check out machinecode.

Example usage

code := []byte{0xb8, 0x2a, 0x00, 0x00, 0x00, 0xc3}
jit.Execute(code)

The jitrun command

jit includes a small machine code execution program named jitrun that can be installed with Go 1.17 or later:

go install github.com/xyproto/jit/cmd/jitrun@latest

You can provide a file, and run it:

42.mc:

// This program moves 42 into eax and returns

b8 2a 00 00 00  // mov 2a000000 into the eax register. b8 is the "mov eax" part. 0x2a is 42.
c3              // return to the caller (the return value is held in eax)

./jitrun 42.mc

It's possible to pipe the machine code directly to jitrun:

$ echo 'b8 2a 00 00 00 c3' | jitrun -
Stripped source code:
b8 2a 00 00 00 c3

Source bytes:
[184 42 0 0 0 195]

The program returned: 42

jitrun can be run silently with the -s flag:

$ echo 'b8 2a 00 00 00 c3' | jitrun -s -
$ echo $?
42

Here is another example program:

// This program takes the square root of 1024 and returns the answer (in eax), which is 32

b8 00 04 00 00  // mov 1024 (0x400) into eax
f3 0f 2a c0     // mov eax into the xmm0 register
f3 0f 51 c0     // take the square root of the xmm0 register and place it into xmm0
f3 0f 2c c0     // move xmm0 back into eax
c3              // return to the caller (the return value is held in eax)

Dependencies

• cgo for the jit package.
• The hexstring module for the jitrun command.

General info

• License: BSD-3
• Version: 1.0.0
• Author: Alexander F. Rødseth <[email protected]>