[PATCH v2] libstdc++: Add support for POWER9 DARN instruction to std::random_device

Bill Schmidt wschmidt@linux.ibm.com
Fri Nov 5 13:20:31 GMT 2021


On 11/5/21 7:44 AM, Jonathan Wakely wrote:
> On Thu, 4 Nov 2021 at 20:44, Bill Schmidt wrote: For posterity:  This was discussed briefly on IRC, and Segher approved with some simplifications and a request to implement a fail/retry check. Here's what I have now. No more assembler check 
> On Thu, 4 Nov 2021 at 20:44, Bill Schmidt wrote:
>
>     For posterity:  This was discussed briefly on IRC, and Segher approved with some
>     simplifications and a request to implement a fail/retry check.
>
>
> Here's what I have now. No more assembler check in configure, and it uses the 64-bit __builtin_darn() and truncates it to 32-bit, or retries (up to 100 times) if it fails.
>
> I'm doing some more testing now.
>
Those changes look good from my perspective.  Thanks again for this work!  (Not a maintainer, blah blah...)

Bill



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