5 ms·

consistently beating OpenBLAS and having performance comparable with MKL is seriously impressive. I'm wondering how that is possible. I assume it's using the sa

consistently beating OpenBLAS and having performance comparable with MKL is seriously impressive. I'm wondering how that is possible. I assume it's using the same algorithms as other implementations, so the credit goes to the compiler (and to the language to some extent). But the D compiler just uses LLVM for the back end, so is this because LDC produces really good LLVM IR, or is LLVM really good at generating assembly? Either way I'm really impressed they can beat hand-tuned assembly, I'd love to see a comparison between the resulting assembly for Mir GLAS and OpenBLAS.

bachmeier 10y ago
You can get some information from this comment[1] by the author as well as his others on that thread. This is somewhat outside of my area. [1] https://www.reddit.com/r/programming/comments/54kg6v/numeric_age_for_d_mir_glas_is_faster_than/d832t03/ https://www.reddit.com/r/programming/comments/54kg6v/numeric...
kaleidic 10y ago
It's much easier to generate code adapted to that cpu and machine in D because of compile time features. Plus it was an excellent team of a few people working for a few years that built mir. Actually I am joking - mostly one guy working for a few months (with a little help) made mir Blas. A pretty nice example of productivity of D. Also an illustration of the high calibre of person found in the D community.
klickverbot 10y ago
LDC dev here. All the credit for this goes to Ilya Yaroshenko for the expertly crafted implementation and the LLVM developers for efficient low-level code generation (inlining, register allocation and so on, and in some places auto-vectorization). LDC only needs to make sure not to "mess up" things too much. D does play a significant role in this achievement, though – D's very powerful yet easy to use features for generics and introspection make it possible to finely tune the code for different parameters (sizes/dimensions/…) while still being easy to understand and modify.
- openasocket 10y ago
  That's helpful, thanks! I definitely appreciate the power of generics, especially when you can to generics over values instead of just types. But I'm having trouble seeing the value of the compile-time introspection, for the most part it doesn't seem to give you much more power than generics do. Could you give me an example of the "killer feature" introspection gives over generics? Bonus points if you can compare it to Rust-style generics with traits and specialization.
  - nicwilson 10y ago
    Many things, although introspection works glove in hand with generics. Below os a non-exhaustive list. You can 'Write once - automate everywhere' all the boilerplate. See https://github.com/kaleidicassociates/excel-d/ https://github.com/kaleidicassociates/excel-d/ , for an example of automating the interaction between D and Excel. I am in the process of doing something similar for OpenCL and CUDA and will be presenting it at Dconf. You can make at compile time (additional) fast paths by checking to see if a type (or symbol or whatever else) provides a fast primitive to accelerate your algorithm. e.g. if Foo implements fastfoo use that otherwise fallback to a general algorithm. See also Andrei Alexandrescu's 2016(15?) talk (IIRC the relevant section is about half way through https://www.youtube.com/watch?v=4oDK91E3VKs https://www.youtube.com/watch?v=4oDK91E3VKs).

bachmeier 10y ago

You can get some information from this comment[1] by the author as well as his others on that thread. This is somewhat outside of my area. [1] https://www.reddit.com/r/programming/comments/54kg6v/numeric_age_for_d_mir_glas_is_faster_than/d832t03/ https://www.reddit.com/r/programming/comments/54kg6v/numeric...

kaleidic 10y ago

It's much easier to generate code adapted to that cpu and machine in D because of compile time features. Plus it was an excellent team of a few people working for a few years that built mir. Actually I am joking - mostly one guy working for a few months (with a little help) made mir Blas. A pretty nice example of productivity of D. Also an illustration of the high calibre of person found in the D community.

klickverbot 10y ago

LDC dev here. All the credit for this goes to Ilya Yaroshenko for the expertly crafted implementation and the LLVM developers for efficient low-level code generation (inlining, register allocation and so on, and in some places auto-vectorization). LDC only needs to make sure not to "mess up" things too much. D does play a significant role in this achievement, though – D's very powerful yet easy to use features for generics and introspection make it possible to finely tune the code for different parameters (sizes/dimensions/…) while still being easy to understand and modify.

openasocket 10y ago
That's helpful, thanks! I definitely appreciate the power of generics, especially when you can to generics over values instead of just types. But I'm having trouble seeing the value of the compile-time introspection, for the most part it doesn't seem to give you much more power than generics do. Could you give me an example of the "killer feature" introspection gives over generics? Bonus points if you can compare it to Rust-style generics with traits and specialization.
- nicwilson 10y ago
  Many things, although introspection works glove in hand with generics. Below os a non-exhaustive list. You can 'Write once - automate everywhere' all the boilerplate. See https://github.com/kaleidicassociates/excel-d/ https://github.com/kaleidicassociates/excel-d/ , for an example of automating the interaction between D and Excel. I am in the process of doing something similar for OpenCL and CUDA and will be presenting it at Dconf. You can make at compile time (additional) fast paths by checking to see if a type (or symbol or whatever else) provides a fast primitive to accelerate your algorithm. e.g. if Foo implements fastfoo use that otherwise fallback to a general algorithm. See also Andrei Alexandrescu's 2016(15?) talk (IIRC the relevant section is about half way through https://www.youtube.com/watch?v=4oDK91E3VKs https://www.youtube.com/watch?v=4oDK91E3VKs).