PPC64: Poor StrictMath performance due to non-optimized compilation

Gustavo Romero gromero at linux.vnet.ibm.com
Tue Nov 22 00:41:34 UTC 2016


Hi Derek,

On 17-11-2016 20:47, White, Derek wrote:
> Hi Joe,
> 
> Although neither a floating point expert (as I think I've proven to you over the years), or a gcc expert, I checked with our in-house gcc expert and got this following answer:
> 
> 	"Yes using -fno-strict-aliasing fixes the issues.  Also there are many forks of fdlibm which has this fixed including the code inside glibc. "

I've tried on PPC64 -O3 and -fno-strict-aliasing but it didn't work. Disabling
the FMA fixed the issue although.

Do you know if the gap between Math and StrictMath is also huge on aarch64?

Thank you.


Regards,
Gustavo:



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