Add rust n-body version for comparison (#88)

.gitignore

@@ -3,3 +3,4 @@ docs/
 node_modules/
 out/
 raw/
+examples/n-body/rust/target/

examples/n-body/assembly/index.js

@@ -0,0 +1,18 @@
+const fs   = require("fs");
+const path = require("path");
+
+const compiled = new WebAssembly.Module(
+  fs.readFileSync(path.resolve(__dirname, "..", "build", "optimized.wasm"))
+);
+
+const imports = {
+  env: {
+    abort: (filename, line, column) => {
+      throw Error("abort called at " + line + ":" + colum);
+    }
+  }
+};
+
+Object.defineProperty(module, "exports", {
+  get: () => new WebAssembly.Instance(compiled, imports).exports
+});

examples/n-body/index.js

@@ -1,8 +0,0 @@
-const fs = require("fs");
-const compiled = new WebAssembly.Module(fs.readFileSync(__dirname + "/build/optimized.wasm"));
-const imports = {
-  env: { abort: function(filename, line, column) { throw Error("abort called at " + line + ":" + colum); } }
-};
-Object.defineProperty(module, "exports", {
-  get: () => new WebAssembly.Instance(compiled, imports).exports
-});

examples/n-body/rust/Cargo.lock

@@ -0,0 +1,4 @@
+[[package]]
+name = "rust_nbody"
+version = "0.1.0"
+

examples/n-body/rust/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "rust_nbody"
+version = "0.1.0"
+authors = ["MaxGraey <maxgraey@gmail.com>"]
+
+[lib]
+path       = "src/lib.rs"
+crate-type = ["cdylib"]

examples/n-body/rust/README.md

@@ -0,0 +1,7 @@
+### Build
+
+```bash
+cargo build --release --target=wasm32-unknown-unknown
+```
+
+***Next step optimize target wasm via wasm-opt.***

examples/n-body/rust/index.js

@@ -0,0 +1,18 @@
+const fs   = require("fs");
+const path = require("path");
+
+const compiled = new WebAssembly.Module(
+  fs.readFileSync(path.resolve(__dirname, "..", "build", "rust.optimized.wasm"))
+);
+
+const imports = {
+  env: {
+    abort: (filename, line, column) => {
+      throw Error("abort called at " + line + ":" + colum);
+    }
+  }
+};
+
+Object.defineProperty(module, "exports", {
+  get: () => new WebAssembly.Instance(compiled, imports).exports
+});

examples/n-body/rust/src/lib.rs

@@ -0,0 +1,188 @@
+// Code adopted from https://benchmarksgame-team.pages.debian.net/benchmarksgame/program/nbody-rust-1.html
+
+#![feature(core_intrinsics, lang_items)]
+#![no_std]
+
+#[lang = "panic_fmt"]
+extern "C" fn panic_fmt(_args: ::core::fmt::Arguments, _file: &'static str, _line: u32) -> ! {
+  use core::intrinsics;
+  unsafe {
+    intrinsics::abort();
+  }
+}
+
+#[inline(always)]
+fn sqrt(x: f64) -> f64 {
+  use core::intrinsics;
+  unsafe {
+    intrinsics::sqrtf64(x)
+  }
+}
+
+const PI: f64         = 3.141592653589793;
+const SOLAR_MASS: f64 = 4.0 * PI * PI;
+const YEAR: f64       = 365.24;
+const N_BODIES: usize = 5;
+
+static mut BODIES: [Planet; N_BODIES] = [
+  // Sun
+  Planet {
+    x:   0.0,
+    y:   0.0,
+    z:   0.0,
+    vx:  0.0,
+    vy:  0.0,
+    vz:  0.0,
+    mass: SOLAR_MASS,
+  },
+  // Jupiter
+  Planet {
+    x:    4.84143144246472090e+00,
+    y:   -1.16032004402742839e+00,
+    z:   -1.03622044471123109e-01,
+    vx:   1.66007664274403694e-03 * YEAR,
+    vy:   7.69901118419740425e-03 * YEAR,
+    vz:  -6.90460016972063023e-05 * YEAR,
+    mass: 9.54791938424326609e-04 * SOLAR_MASS,
+  },
+  // Saturn
+  Planet {
+    x:    8.34336671824457987e+00,
+    y:    4.12479856412430479e+00,
+    z:   -4.03523417114321381e-01,
+    vx:  -2.76742510726862411e-03 * YEAR,
+    vy:   4.99852801234917238e-03 * YEAR,
+    vz:   2.30417297573763929e-05 * YEAR,
+    mass: 2.85885980666130812e-04 * SOLAR_MASS,
+  },
+  // Uranus
+  Planet {
+    x:    1.28943695621391310e+01,
+    y:   -1.51111514016986312e+01,
+    z:   -2.23307578892655734e-01,
+    vx:   2.96460137564761618e-03 * YEAR,
+    vy:   2.37847173959480950e-03 * YEAR,
+    vz:  -2.96589568540237556e-05 * YEAR,
+    mass: 4.36624404335156298e-05 * SOLAR_MASS,
+  },
+  // Neptune
+  Planet {
+    x:    1.53796971148509165e+01,
+    y:   -2.59193146099879641e+01,
+    z:    1.79258772950371181e-01,
+    vx:   2.68067772490389322e-03 * YEAR,
+    vy:   1.62824170038242295e-03 * YEAR,
+    vz:  -9.51592254519715870e-05 * YEAR,
+    mass: 5.15138902046611451e-05 * SOLAR_MASS,
+  },
+];
+
+#[derive(Clone, Copy)]
+struct Planet {
+  x: f64,
+  y: f64,
+  z: f64,
+  vx: f64,
+  vy: f64,
+  vz: f64,
+  mass: f64,
+}
+
+fn advance(bodies: &mut [Planet; N_BODIES], dt: f64) {
+  let mut b_slice: &mut [_] = bodies;
+  loop {
+    let bi = match shift_mut_ref(&mut b_slice) {
+      Some(bi) => bi,
+      None     => break,
+    };
+
+    for bj in b_slice.iter_mut() {
+      let dx = bi.x - bj.x;
+      let dy = bi.y - bj.y;
+      let dz = bi.z - bj.z;
+
+      let d2  = dx * dx + dy * dy + dz * dz;
+      let mag = dt / (d2 * sqrt(d2));
+
+      let massj_mag = bj.mass * mag;
+      bi.vx -= dx * massj_mag;
+      bi.vy -= dy * massj_mag;
+      bi.vz -= dz * massj_mag;
+
+      let massi_mag = bi.mass * mag;
+      bj.vx += dx * massi_mag;
+      bj.vy += dy * massi_mag;
+      bj.vz += dz * massi_mag;
+    }
+    bi.x += dt * bi.vx;
+    bi.y += dt * bi.vy;
+    bi.z += dt * bi.vz;
+  }
+}
+
+fn energy(bodies: &[Planet; N_BODIES]) -> f64 {
+  let mut e = 0.0;
+  let mut bodies = bodies.iter();
+
+  loop {
+    let bi = match bodies.next() {
+      Some(bi) => bi,
+      None     => break,
+    };
+
+    e += (bi.vx * bi.vx + bi.vy * bi.vy + bi.vz * bi.vz) * bi.mass / 2.0;
+    for bj in bodies.clone() {
+      let dx = bi.x - bj.x;
+      let dy = bi.y - bj.y;
+      let dz = bi.z - bj.z;
+      let dist = sqrt(dx * dx + dy * dy + dz * dz);
+      e -= bi.mass * bj.mass / dist;
+    }
+  }
+  e
+}
+
+fn offset_momentum(bodies: &mut [Planet; N_BODIES]) {
+  let mut px = 0.0;
+  let mut py = 0.0;
+  let mut pz = 0.0;
+  for bi in bodies.iter() {
+    px += bi.vx * bi.mass;
+    py += bi.vy * bi.mass;
+    pz += bi.vz * bi.mass;
+  }
+  let sun = &mut bodies[0];
+  sun.vx = -px / SOLAR_MASS;
+  sun.vy = -py / SOLAR_MASS;
+  sun.vz = -pz / SOLAR_MASS;
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn init() {
+  offset_momentum(&mut BODIES);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn step() -> f64 {
+  advance(&mut BODIES, 0.01);
+  energy(&BODIES)
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn bench(steps: i32) {
+  for _ in 0..steps {
+    advance(&mut BODIES, 0.01);
+  }
+}
+
+/// Pop a mutable reference off the head of a slice, mutating the slice to no
+/// longer contain the mutable reference.
+fn shift_mut_ref<'a, T>(r: &mut &'a mut [T]) -> Option<&'a mut T> {
+  if r.len() == 0 {
+    return None;
+  }
+  let tmp = core::mem::replace(r, &mut []);
+  let (h, t) = tmp.split_at_mut(1);
+  *r = t;
+  Some(&mut h[0])
+}

examples/n-body/tests/index.js

@@ -1,15 +1,17 @@
 const fs = require("fs");
 
 // Load WASM version
-const nbodyWASM = require("../index.js");
+const nbodyAS = require("../assembly/index.js");
+const nbodyRS = require("../rust/index.js");
 
 // Load ASMJS version
-src = fs.readFileSync(__dirname + "/../build/index.asm.js", "utf8");
+var src = fs.readFileSync(__dirname + "/../build/index.asm.js", "utf8");
 if (src.indexOf("var Math_sqrt =") < 0) { // currently missing in asm.js output
   let p = src.indexOf(" var abort = env.abort;");
   src = src.substring(0, p) + " var Math_sqrt = global.Math.sqrt;\n " + src.substring(p);
 }
-var nbodyASMJS = eval("0," + src)({
+
+const nbodyAsmJS = eval("0," + src)({
   Int8Array,
   Int16Array,
   Int32Array,
@@ -20,17 +22,20 @@ var nbodyASMJS = eval("0," + src)({
   Float64Array,
   Math
 }, {
-  abort: function() { throw Error(); }
+  abort: () => { throw Error(); }
 }, new ArrayBuffer(0x10000));
 
 // Load JS version
-var src = fs.readFileSync(__dirname + "/../build/index.js", "utf8");
-var scopeJS = {
-  require: function() {},
-  exports: {},
-  unchecked: function(expr) { return expr }
+src = fs.readFileSync(__dirname + "/../build/index.js", "utf8");
+const scopeJS = {
+  require:   () => {},
+  exports:   {},
+  unchecked: expr => expr
 };
-var nbodyJS = new Function(...Object.keys(scopeJS).concat(src + "\nreturn exports"))(...Object.values(scopeJS));
+
+const nbodyJS = new Function(
+  ...Object.keys(scopeJS).concat(src + "\nreturn exports"))(...Object.values(scopeJS)
+);
 
 function test(nbody, steps) {
   nbody.init();
@@ -42,28 +47,36 @@ function test(nbody, steps) {
 var steps = process.argv.length > 2 ? parseInt(process.argv[2], 10) : 20000000;
 var time;
 
-console.log("Performing " + steps + " steps (WASM) ...");
-time = test(nbodyWASM, steps);
+console.log("Performing " + steps + " steps (AssemblyScript WASM) ...");
+time = test(nbodyAS, steps);
 console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
 
-console.log("Performing " + steps + " steps (ASMJS) ...");
-time = test(nbodyASMJS, steps);
+console.log("Performing " + steps + " steps (AssemblyScript ASMJS) ...");
+time = test(nbodyAsmJS, steps);
 console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
 
 console.log("Performing " + steps + " steps (JS) ...");
 time = test(nbodyJS, steps);
 console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
 
+console.log("Performing " + steps + " steps (Rust WASM) ...");
+time = test(nbodyRS, steps);
+console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
+
 console.log("\nWARMED UP:\n");
 
-console.log("Performing " + steps + " steps (WASM) ...");
-time = test(nbodyWASM, steps);
+console.log("Performing " + steps + " steps (AssemblyScript WASM) ...");
+time = test(nbodyAS, steps);
 console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
 
-console.log("Performing " + steps + " steps (ASMJS) ...");
-time = test(nbodyASMJS, steps);
+console.log("Performing " + steps + " steps (AssemblyScript ASMJS) ...");
+time = test(nbodyAsmJS, steps);
 console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
 
 console.log("Performing " + steps + " steps (JS) ...");
 time = test(nbodyJS, steps);
 console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");
+
+console.log("Performing " + steps + " steps (Rust WASM) ...");
+time = test(nbodyRS, steps);
+console.log("Took " + (time[0] * 1e3 + time[1] / 1e6) + "ms");