3 ms·

On my system: gcc -O3 1m40.302s gcc -O3 -ffast-math 0m5.110s rustc -C opt-level=3 0m9.278s gcc (GCC) 6.3.1 20170109 rustc 1.15.1 (021bd294c 201

by walrus 10y ago

On my system: gcc -O3 1m40.302s gcc -O3 -ffast-math 0m5.110s rustc -C opt-level=3 0m9.278s gcc (GCC) 6.3.1 20170109 rustc 1.15.1 (021bd294c 2017-02-08) Edit: Looking into this a bit more, I think 'rustc -C opt-level=3' is optimizing out the actual integration. If I put a println!("{}", x[0][0]) at the end, I end up with 1m43s. Not sure what 'gcc -O3 -ffast-math' is doing; I haven't looked at the disassembly.

marblestation 10y ago
Fantastic, thanks!!!
simias 10y ago
-ffast-math might be a bit cheating here, for scientific work it's not always applicable. Unless rustc uses fast math by default? That would be weird. It's surprising that gcc does such a poor job at -O3 though.
- kibwen 10y ago
  Rust doesn't even have a way to turn on fastmath, AFAIK.
  - dbaupp 10y ago
    It does, for individual operations: https://doc.rust-lang.org/std/?search=fast https://doc.rust-lang.org/std/?search=fast
tom_mellior 10y ago
> If I put a println!("{}", x[0][0]) at the end, I end up with 1m43s. Yes, without that it's basically cheating. There is now a GitHub issue: https://github.com/marblestation/benchmark-leapfrog/issues/6 https://github.com/marblestation/benchmark-leapfrog/issues/6 The submitter writes: "final output [for Rust] is 134 seconds, and also the output is [[NaN, NaN, NaN], [NaN, NaN, NaN]] (batman)"