https://github.com/susji/opl

Toy compiler for PL/0, emits x86-64 assembly for Linux
https://github.com/susji/opl

compilers educational ocaml

Last synced: 27 days ago
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Toy compiler for PL/0, emits x86-64 assembly for Linux

• Host: GitHub
• URL: https://github.com/susji/opl
• Owner: susji
• License: gpl-3.0
• Created: 2021-11-20T10:34:12.000Z (about 3 years ago)
• Default Branch: main
• Last Pushed: 2021-11-20T11:54:42.000Z (about 3 years ago)
• Last Synced: 2023-09-09T14:20:26.657Z (over 1 year ago)
• Topics: compilers, educational, ocaml
• Language: OCaml
• Homepage:
• Size: 36.1 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# opl

This is an attempt at producing x64 AT & T assembly from Wirth's original

PL/0. Some minor extensions might be supported. The code is unlikely to be of

proper ML nature, as this is really an OCaml exercise. The goal is to

successfully compile the attached `test.pl0` which should be an original

example from Wirth's book.

# usage

The following assumes you have `oasis`, `ocaml`, and a suitable x86-64

compiler installed.

	$ make

	$ cat tests/test.pl0 | bin/opl -w -c

	$ cc -static out.s -o test

	$ ./test

There are a few other parameters, see `bin/opl -help` for more.

# Bits and pieces

Lots of unnecessary recursion is being done as all AST visitors operate on

their own pass for simplicity. To get faster compilation, these should be

combined into a single-pass traversal.

# TODO

- [x] parse `test.pl0` and generate the AST

- [x] do scope analysis for visible constants and variables

- [x] search for referring to not-in-scope identifiers

- [ ] a common logging interface with verbosity for AST handlers

- [ ] extend AST types to store source line:column

- [x] constant folding for integer arithmetic

- [x] constant folding for constant conditionals

- [x] common subexpression elimination

- [ ] report AST errors with line:column info

- [ ] loop-invariant hoisting

- [ ] dead store elimination

- [x] search for calling undeclared functions

- [x] search for assigning to constants

- [x] dumb stack machine codegen

- [ ] register-allocating codegen