src/test/bench/shootout-mandelbrot.rs

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  40
  41 #![feature(core_simd, core)]
  42
  43 // ignore-pretty very bad with line comments
  44
  45 use std::env;
  46 use std::io::prelude::*;
  47 use std::io;
  48 use std::simd::f64x2;
  49 use std::sync::Arc;
  50 use std::thread;
  51
  52 const ITER: usize = 50;
  53 const LIMIT: f64 = 2.0;
  54 const WORKERS: usize = 16;
  55
  56 fn mandelbrot<W: Write>(w: usize, mut out: W) -> io::Result<()> {
  57     assert_eq!(WORKERS % 2, 0);
  58
  59     // Ensure w and h are multiples of 8.
  60     let w = (w + 7) / 8 * 8;
  61     let h = w;
  62
  63     let chunk_size = h / WORKERS;
  64
  65     // Account for remainders in workload division, e.g. 1000 / 16 = 62.5
  66     let last_chunk_size = if h % WORKERS != 0 {
  67         chunk_size + h % WORKERS
  68     } else {
  69         chunk_size
  70     };
  71
  72     // precalc values
  73     let inverse_w_doubled = 2.0 / w as f64;
  74     let inverse_h_doubled = 2.0 / h as f64;
  75     let v_inverses = f64x2(inverse_w_doubled, inverse_h_doubled);
  76     let v_consts = f64x2(1.5, 1.0);
  77
  78     // A lot of this code assumes this (so do other lang benchmarks)
  79     assert_eq!(w, h);
  80     let mut precalc_r = Vec::with_capacity(w);
  81     let mut precalc_i = Vec::with_capacity(h);
  82
  83     let precalc_futures = (0..WORKERS).map(|i| {
  84         thread::spawn(move|| {
  85             let mut rs = Vec::with_capacity(w / WORKERS);
  86             let mut is = Vec::with_capacity(w / WORKERS);
  87
  88             let start = i * chunk_size;
  89             let end = if i == (WORKERS - 1) {
  90                 start + last_chunk_size
  91             } else {
  92                 (i + 1) * chunk_size
  93             };
  94
  95             // This assumes w == h
  96             for x in start..end {
  97                 let xf = x as f64;
  98                 let xy = f64x2(xf, xf);
  99
 100                 let f64x2(r, i) = xy * v_inverses - v_consts;
 101                 rs.push(r);
 102                 is.push(i);
 103             }
 104
 105             (rs, is)
 106         })
 107     }).collect::<Vec<_>>();
 108
 109     for res in precalc_futures {
 110         let (rs, is) = res.join().unwrap();
 111         precalc_r.extend(rs);
 112         precalc_i.extend(is);
 113     }
 114
 115     assert_eq!(precalc_r.len(), w);
 116     assert_eq!(precalc_i.len(), h);
 117
 118     let arc_init_r = Arc::new(precalc_r);
 119     let arc_init_i = Arc::new(precalc_i);
 120
 121     let data = (0..WORKERS).map(|i| {
 122         let vec_init_r = arc_init_r.clone();
 123         let vec_init_i = arc_init_i.clone();
 124
 125         thread::spawn(move|| {
 126             let mut res: Vec<u8> = Vec::with_capacity((chunk_size * w) / 8);
 127             let init_r_slice = vec_init_r;
 128
 129             let start = i * chunk_size;
 130             let end = if i == (WORKERS - 1) {
 131                 start + last_chunk_size
 132             } else {
 133                 (i + 1) * chunk_size
 134             };
 135
 136             for &init_i in &vec_init_i[start..end] {
 137                 write_line(init_i, &init_r_slice, &mut res);
 138             }
 139
 140             res
 141         })
 142     }).collect::<Vec<_>>();
 143
 144     try!(writeln!(&mut out, "P4\n{} {}", w, h));
 145     for res in data {
 146         try!(out.write_all(&res.join().unwrap()));
 147     }
 148     out.flush()
 149 }
 150
 151 fn write_line(init_i: f64, vec_init_r: &[f64], res: &mut Vec<u8>) {
 152     let v_init_i : f64x2 = f64x2(init_i, init_i);
 153     let v_2 : f64x2 = f64x2(2.0, 2.0);
 154     const LIMIT_SQUARED: f64 = LIMIT * LIMIT;
 155
 156     for chunk_init_r in vec_init_r.chunks(8) {
 157         let mut cur_byte = 0xff;
 158         let mut i = 0;
 159
 160         while i < 8 {
 161             let v_init_r = f64x2(chunk_init_r[i], chunk_init_r[i + 1]);
 162             let mut cur_r = v_init_r;
 163             let mut cur_i = v_init_i;
 164             let mut r_sq = v_init_r * v_init_r;
 165             let mut i_sq = v_init_i * v_init_i;
 166
 167             let mut b = 0;
 168             for _ in 0..ITER {
 169                 let r = cur_r;
 170                 let i = cur_i;
 171
 172                 cur_i = v_2 * r * i + v_init_i;
 173                 cur_r = r_sq - i_sq + v_init_r;
 174
 175                 let f64x2(bit1, bit2) = r_sq + i_sq;
 176
 177                 if bit1 > LIMIT_SQUARED {
 178                     b |= 2;
 179                     if b == 3 { break; }
 180                 }
 181
 182                 if bit2 > LIMIT_SQUARED {
 183                     b |= 1;
 184                     if b == 3 { break; }
 185                 }
 186
 187                 r_sq = cur_r * cur_r;
 188                 i_sq = cur_i * cur_i;
 189             }
 190
 191             cur_byte = (cur_byte << 2) + b;
 192             i += 2;
 193         }
 194
 195         res.push(cur_byte^-1);
 196     }
 197 }
 198
 199 fn main() {
 200     let mut args = env::args();
 201     let res = if args.len() < 2 {
 202         println!("Test mode: do not dump the image because it's not utf8, \
 203                   which interferes with the test runner.");
 204         mandelbrot(1000, io::sink())
 205     } else {
 206         mandelbrot(args.nth(1).unwrap().parse().unwrap(), io::stdout())
 207     };
 208     res.unwrap();
 209 }