Porffor NPM | npm.io

Porffor /ˈpɔrfɔr/ (poor-for)

A from-scratch experimental AOT optimizing JS/TS -> Wasm/C engine/compiler/runtime in JS. Not serious/intended for (real) use. (this is a straight forward, honest readme) Age: ~6 months (very on and off)

Design

Porffor is a very unique JS engine, due many wildly different approaches. It is seriously limited, but what it can do, it does pretty well. Key differences:

100% AOT compiled (no JIT)
No constant runtime/preluded code
Least Wasm imports possible (only I/O)

Porffor is primarily built from scratch, the only thing that is not is the parser (using Acorn). Binaryen/etc is not used, we make final wasm binaries ourself. You could imagine it as compiling a language which is a sub (some things unsupported) and super (new/custom apis) set of javascript. Not based on any particular spec version, focusing on function/working over spec compliance.

Usage

Expect nothing to work! Only very limited JS is currently supported. See files in bench for examples.

Setup

Clone this repo (git clone https://github.com/CanadaHonk/porffor.git)
npm install - for parser(s)

Running a file

The repos comes with easy alias files for Unix and Windows, which you can use like so:

Unix: ./porf path/to/script.js
Windows: .\porf path/to/script.js

Please note that further examples below will just use ./porf, you need to use .\porf on Windows. You can also swap out node in the alias to use another runtime like Deno (deno run -A) or Bun (bun ...), or just use it yourself (eg node runner/index.js ..., bun runner/index.js ...). Node and Bun should work great, Deno support is WIP.

Trying a REPL

./porf. Just run it with no script file argument.

Compiling to native binaries

!WARNING Compiling to native binaries uses 2c, Porffor's own Wasm -> C compiler, which is experimental.

./porf native path/to/script.js out(.exe). You can specify the compiler with -compiler=clang/zig/gcc, and which opt level to use with -cO=O3 (Ofast by default). Output binaries are also stripped by default.

Compiling to C

!WARNING Compiling to C uses 2c, Porffor's own Wasm -> C compiler, which is experimental.

./porf c path/to/script.js (out.c). When not including an output file, it will be printed to stdout instead.

Compiling to a Wasm binary

./porf compile path/to/script.js out.wasm. Currently it does not use an import standard like WASI, so it is mostly unusable.

Options

-target=wasm|c|native (default: wasm) to set target output (native compiles c output to binary, see args below)
-target=c|native only:
- -o=out.c|out.exe|out to set file to output c or binary
-target=native only:
- -compiler=clang to set compiler binary (path/name) to use to compile
- -cO=O3 to set compiler opt argument
-parser=acorn|@babel/parser|meriyah|hermes-parser (default: acorn) to set which parser to use
-parse-types to enable parsing type annotations/typescript. if -parser is unset, changes default to @babel/parser. does not type check
-opt-types to perform optimizations using type annotations as compiler hints. does not type check
-valtype=i32|i64|f64 (default: f64) to set valtype
-O0 to disable opt
-O1 (default) to enable basic opt (simplify insts, treeshake wasm imports)
-O2 to enable advanced opt (inlining). unstable
-O3 to enable advanceder opt (precompute const math). unstable
-no-run to not run wasm output, just compile
-opt-log to log some opts
-code-log to log some codegen (you probably want -funcs)
-regex-log to log some regex
-funcs to log funcs
-ast-log to log AST
-opt-funcs to log funcs after opt
-sections to log sections as hex
-opt-no-inline to not inline any funcs
-tail-call to enable tail calls (experimental + not widely implemented)
-compile-hints to enable V8 compilation hints (experimental + doesn't seem to do much?)

Limitations

No full object support yet
Little built-ins/prototype
No async/promise/await
No variables between scopes (except args and globals)
Literal callees only in calls (eg print() works, a = print; a() does not)
No eval() etc (since it is AOT)

Sub-engines

Asur

Asur is Porffor's own Wasm engine; it is an intentionally simple interpreter written in JS. It is very WIP. See its readme for more details.

Rhemyn

Rhemyn is Porffor's own regex engine; it compiles literal regex to Wasm bytecode AOT (remind you of anything?). It is quite basic and WIP. See its readme for more details.

2c

2c is Porffor's own Wasm -> C compiler, using generated Wasm bytecode and internal info to generate specific and efficient/fast C code. Little boilerplate/preluded code or required external files, just for CLI binaries (not like wasm2c very much).

Supported

See optimizations for opts implemented/supported.

Proposals

These include some early (stage 1/0) and/or dead (last commit years ago) proposals but I think they are pretty neat, so.

`Math` proposals (stage 1/0)

Math.clamp Proposal: Math.clamp (stage 0 - last commit april 2023)
Math Extensions Proposal: Math.scale, Math.radians, Math.degrees, Math.RAD_PER_DEG, Math.DEG_PER_RAD (stage 1 - last commit september 2020)
Math.signbit Proposal: Math.signbit (stage 1 - last commit february 2020)

Language

Number literals
Declaring functions
Calling functions literal callees only
return
let/const/var basic declarations
Some basic integer operators (+-/*%)
Some basic integer bitwise operators (&|)
Equality operators (==, !=, etc)
GT/LT operators (>, <, >=, etc)
Some unary operators (!, +, -)
Logical operators (&&, ||)
Declaring multiple variables in one (let a, b = 0)
Global variables (var/none in top scope)
Functions returning 1 number
Bool literals as ints (not real type)
if and if ... else
Anonymous functions
Setting functions using vars (const foo = function() { ... })
Arrow functions
undefined/null as ints (hack)
Update expressions (a++, ++b, c--, etc)
for loops (for (let i = 0; i < N; i++), etc)
Basic objects (hack)
console.log (hack)
while loops
break and continue
Named export funcs
IIFE support
Assignment operators (+=, -=, >>=, &&=, etc)
Conditional/ternary operator (cond ? a : b)
Recursive functions
Bare returns (return)
throw (literals only)
Basic try { ... } catch { ... } (no error given)
Calling functions with non-matching arguments (eg f(a, b); f(0); f(1, 2, 3);)
typeof
Runtime errors for undeclared variables (ReferenceError), not functions (TypeError)
Array creation via [] (eg let arr = [ 1, 2, 3 ])
Array member access via arr[ind] (eg arr[0])
String literals ('hello world')
String member (char) access via str[ind] (eg str[0])
String concat (+) (eg 'a' + 'b')
Truthy/falsy (eg !'' == true)
String comparison (eg 'a' == 'a', 'a' != 'b')
Nullish coalescing operator (??)
for...of (arrays and strings)
Array member setting (arr[0] = 2, arr[0] += 2, etc)
Array constructor (Array(5), new Array(1, 2, 3))
Labelled statements (foo: while (...))

Built-ins

NaN and Infinity (f64 only)
isNaN() and isFinite() (f64 only)
Most of Number (MAX_VALUE, MIN_VALUE, MAX_SAFE_INTEGER, MIN_SAFE_INTEGER, POSITIVE_INFINITY, NEGATIVE_INFINITY, EPSILON, NaN, isNaN, isFinite, isInteger, isSafeInteger) (some f64 only)
Some Math funcs (sqrt, abs, floor, sign, round, trunc, clz32, fround, random) (f64 only)
Basic globalThis support
Basic Boolean and Number
Basic eval for literals
Math.random() using self-made xorshift128+ PRNG
Some of performance (now())
Some of Array.prototype (at, push, pop, shift, fill)
Some of Array (of, isArray)
Some of String.prototype (at, charAt, charCodeAt)
Some of crypto (randomUUID)
escape

Custom

Supports i32, i64, and f64 for valtypes
Start of a SIMD api (docs needed)
Intrinsic functions (see below)
Inlining wasm via asm`...` "macro"

Performance

For the features it supports most of the time, Porffor is blazingly fast compared to most interpreters and common engines running without JIT. For those with JIT, it is usually slower by default, but can catch up with compiler arguments and typed input, even more so when compiling to native binaries.

Optimizations

Mostly for reducing size. I do not really care about compiler perf/time as long as it is reasonable. We do not use/rely on external opt tools (wasm-opt, etc), instead doing optimization inside the compiler itself creating even smaller code sizes than wasm-opt itself can produce as we have more internal information.

Traditional opts

Inlining functions (WIP, limited)
Inline const math ops
Tail calls (behind flag -tail-call)

Wasm transforms

local.set, local.get -> local.tee
i32.const 0, i32.eq -> i32.eqz
i64.extend_i32_s, i32.wrap_i64 ->
f64.convert_i32_u, i32.trunc_sat_f64_s ->
return, end -> end
Change const, convert to const of converted valtype (eg f64.const, i32.trunc_sat_f64_s ->i32.const`)
Remove some redundant sets/gets
Remove unneeded single just used vars
Remove unneeded blocks (no brs inside)
Remove unused imports
Use data segments for initing arrays/strings
(Likely more not documented yet, todo)

Wasm module

Type cache/index (no repeated types)
No main func if empty (and other exports)
No tags if unused/optimized out

Test262

Porffor can run Test262 via some hacks/transforms which remove unsupported features whilst still doing the same asserts (eg simpler error messages using literals only). It currently passes >10% (see latest commit desc for latest and details). Use node test262 to test, it will also show a difference of overall results between the last commit and current results.

Codebase

compiler: contains the compiler itself
- builtins.js: all built-ins of the engine (spec, custom. vars, funcs)
- codegen.js: code (wasm) generation, ast -> wasm. The bulk of the effort
- decompile.js: basic wasm decompiler for debug info
- embedding.js: utils for embedding consts
- encoding.js: utils for encoding things as bytes as wasm expects
- expression.js: mapping most operators to an opcode (advanced are as built-ins eg f64_%)
- index.js: doing all the compiler steps, takes code in, wasm out
- opt.js: self-made wasm bytecode optimizer
- parse.js: parser simply wrapping acorn
- assemble.js: assembles wasm ops and metadata into a wasm module/file
- wasmSpec.js: "enums"/info from wasm spec
- wrap.js: wrapper for compiler which instantiates and produces nice exports
runner: contains utils for running JS with the compiler
- index.js: the main file, you probably want to use this
- info.js: runs with extra info printed
- repl.js: basic repl (uses node:repl)
rhemyn: contains Rhemyn - our regex engine (used by Porffor)
- compile.js: compiles regex ast into wasm bytecode
- parse.js: own regex parser
test: contains many test files for majority of supported features
test262: test262 runner and utils

Usecases

Basically none right now (other than giving people headaches). Potential ideas:

Safety. As Porffor is written in JS, a memory-safe language*, and compiles JS to Wasm, a fully sandboxed environment*, it is quite safe. (* These rely on the underlying implementations being secure. You could also run Wasm, or even Porffor itself, with an interpreter instead of a JIT for bonus security points too.)
Compiling JS to native binaries. This is still very early!
More in future probably?

Todo

No particular order and no guarentees, just what could happen soon™

Arrays
- More of Array prototype
- Arrays/strings inside arrays
- Destructuring
Objects
- Basic object expressions (eg {}, { a: 0 })
Asur
- Support memory
- Support exceptions
More math operators (**, etc)
Typed export inputs (array)
Exceptions
- Rewrite to use actual strings (optional?)
- try { } finally { }
- Rethrowing inside catch
Optimizations
- Rewrite local indexes per func for smallest local header and remove unused idxs
- Smarter inline selection (snapshots?)
- Remove const ifs (if (true), etc)
- Memory alignment
- Add general pref for always using "fast" (non-short circuiting) or/and
Runtime
- WASI target
- Run precompiled Wasm file if given
Docs
- Update codebase readme section
REPL
- Basic polyfill of node:repl for non-Node runtimes to work
Cool proposals
Posts
- Inlining investigation
- JS -> Native
- Precompiled TS built-ins
- Asur
- escape() optimization
Self hosted testing?

VSCode extension

There is a vscode extension in vscode-ext which tweaks JS syntax highlighting to be nicer with porffor features (eg highlighting wasm inside of inline asm).

Isn't this the same as AssemblyScript/other Wasm langs?

No. they are not alike at all internally and have very different goals/ideals:

Porffor is made as a generic JS engine, not for Wasm stuff specifically
Porffor primarily consumes JS
Porffor is written in pure JS and compiles itself, not using Binaryen/etc
(Also I didn't know it existed when I started this, lol)

FAQ

1. Why the name?

purple in Welsh is porffor. Why purple?

No other JS engine is purple colored
Purple is pretty cool
Purple apparently represents "ambition", which is.. one word to describe this project
The hard to speak name is also the noise your brain makes in reaction to this idea!