Are you making the compiler aware of your machine? Although the obvious point here is vector width (you have AVX-512 from what I can see, however I'm not sure if this is actually a win or not on Skylake W), the compiler is also forced to use a completely generic scheduling model which may or may not yield good code for your procesor. For LDC, you'll want -mcpu=native. Also use cross module inlining if you aren't already.

I also notice in your hot code, you are using function contracts: When contracts are being checked, LDC actually does use them to optimize the code, however in release builds when they are turned off this is not the case. If you are happy to assume that they are true in release builds (I believe you should at least), you can give the compiler this additional information via the use of an intrinsic or similar (with LDC I just use inline IR, on GDC you have __builtin_unreachable()). LDC will assume asserts in release builds as far as I have tested, however this still invokes a branch (just not to a proper assert handler)...

On Thursday, 8 April 2021 at 14:17:09 UTC, Guillaume Piolat wrote:

Also if you don't need the precision: always use powf instead of pow for double, use expf instead of exp for double, etc. Else you pay extra.
In particular, llvm_pow with a float argument is a lot faster.

On Thursday, 8 April 2021 at 16:37:57 UTC, Kyle Ingraham wrote:

No, but you can quite easily:
...
https://dlang.org/phobos/std_parallelism.html#.parallel

On Thursday, 8 April 2021 at 03:27:12 UTC, Max Haughton wrote:

I haven't tried this yet but will give it a go. Ideally I'd want performance independent of compilers but could sprinkle this into the build config for when LDC is used.

Thanks for shining light on a level of optimization that I did not know existed. I've got a lot of learning to do in this area. Do you have any resources you'd recommend?

Thanks for shining light on a level of optimization that I did not know existed. I've got a lot of learning to do in this area. Do you have any resources you'd recommend?