Hello,
I need to use the "popcnt" processor instruction in a performance critical section.
Is there a way to do this in D?

On Tue, 24 Jun 2014 16:34:42 +0000, Archibald wrote:

> Hello,
> I need to use the "popcnt" processor instruction in a performance
> critical section.
> Is there a way to do this in D?

D's inline assembler is described here: http://dlang.org/iasm.html

On Tuesday, 24 June 2014 at 17:05:24 UTC, Justin Whear wrote:
> On Tue, 24 Jun 2014 16:34:42 +0000, Archibald wrote:
>
>> Hello,
>> I need to use the "popcnt" processor instruction in a performance
>> critical section.
>> Is there a way to do this in D?
>
> D's inline assembler is described here: http://dlang.org/iasm.html

There's also an intrinsic in core.bitop:
http://dlang.org/library/core/bitop/popcnt.html

On Tuesday, 24 June 2014 at 17:27:09 UTC, Rene Zwanenburg wrote:
> On Tuesday, 24 June 2014 at 17:05:24 UTC, Justin Whear wrote:
>> On Tue, 24 Jun 2014 16:34:42 +0000, Archibald wrote:
>>
>>> Hello,
>>> I need to use the "popcnt" processor instruction in a performance
>>> critical section.
>>> Is there a way to do this in D?
>>
>> D's inline assembler is described here: http://dlang.org/iasm.html
>
> There's also an intrinsic in core.bitop:
> http://dlang.org/library/core/bitop/popcnt.html


Thanks for the answers.
Unfortunately it seems like popcnt isn't supported by D's inline
assembler.
What if I import it as an external C function, will I get optimal
performance?

On Tue, 24 Jun 2014 19:44:52 +0000, Archibald wrote:

> Thanks for the answers.
> Unfortunately it seems like popcnt isn't supported by D's inline
> assembler.
> What if I import it as an external C function, will I get optimal
> performance?

DMD 2.065 seems to support it.  What compiler are you using and what errors are you getting?

Also, see: http://forum.dlang.org/thread/alirjgygnwpifkijxtjo@forum.dlang.org

On Tuesday, 24 June 2014 at 19:56:29 UTC, Justin Whear wrote:
> Also, see:
> http://forum.dlang.org/thread/alirjgygnwpifkijxtjo@forum.dlang.org

"its not documented on the inline assembler page."
That's why I thought it wasn't supported, it's not in the list of supported opcodes.
Thanks for the help!