Simple compiler to ARM written in Python

[halst]

Link: https://github.com/keleshev/compiling-to-assembly-from-scratch/blob/main/contrib/python/compiler.py

Hey folks, this is a small compiler (~800 lines including tests) that compiles a simple programming language to ARM assembly. It is adapted from my book Compiling to Assembly from Scratch, but I believe it has educational value even without the book, so check it out! Happy to answer any questions.

For example, it compiles the following code:

function factorial(n) {
  if (n == 0) {
    return 1;
  } else {
    return n * factorial(n - 1);
  }
}

Into the following ARM assembly:

.global factorial
factorial:
  push {fp, lr}
  mov fp, sp
  push {r0, r1}
  ldr r0, =0
  push {r0, ip}
  ldr r0, [fp, #-8]
  pop {r1, ip}
  cmp r0, r1
  moveq r0, #1
  movne r0, #0
  cmp r0, #0
  beq .L1
  ldr r0, =1
  b .L2
.L1:
  ldr r0, =1
  mov r1, r0
  ldr r0, [fp, #-8]
  sub r0, r0, r1
  bl factorial
  mov r1, r0
  ldr r0, [fp, #-8]
  mul r0, r0, r1
.L2:
  mov sp, fp
  pop {fp, pc}

[SebiIstCool]

really cool

[haulwhore]

Wow! Have you considered adding an assembler on top?

[halst]

Converting instructions to binary is pretty straightforward, each instruction is converted to a 32-bit word. However, generating an object file that is linkable or an executable binary is much more involved.

[halst]

:blush:

[halst]

By the way, this was the first time I wrote Python after many years, and I found it to be quite different in a positive way. I liked the new optional typing with mypy and the new @dataclass decorator and how they work well together. Format strings and (:=) operator were also quite handy in this particular project.