Re: Compiler performance tests on FreeBSD 10.0-CURRENT

From: David Chisnall <theraven_at_FreeBSD.org>
Date: Thu, 6 Sep 2012 11:20:24 +0100
On 6 Sep 2012, at 09:43, Roman Divacky wrote:

> Was this compiled as amd64 or i386? Also, can you send me the test case?
> So that we can explore the difference. The working theory now is SSE vs FPU
> mathematics, but it would be nice to see the testcase.

There may also be a difference in whether -ffast-math is the default on each compiler.  On x86, this will replace a number of libm calls with (much faster, but less accurate) SSE or x87 instructions.  If this is enabled by default with clang and not with gcc, it would account for the difference.  

David
Received on Thu Sep 06 2012 - 08:20:29 UTC

This archive was generated by hypermail 2.4.0 : Wed May 19 2021 - 11:40:30 UTC