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Re: gcc will become the best optimizing x86 compiler


Michael Meissner wrote:
>Memcpy/memset optimizations were added to glibc 2.8, though when your favorite
>distribution will provide it is a different question:
>http://sourceware.org/ml/libc-alpha/2008-04/msg00050.html


I finally got a SUSE with glibc 2.8. I can see that 32-bit memcpy has been modified with an extra misalignment branch, but no significant improvement. Glibc 2.8 is NOT faster than glibc 2.7 in my tests. It still doesn't use XMM registers.

Glibc 2.8 is still almost 5 times slower than the best function libraries for unaligned data on Intel Core 2, and the default builtin function is slower than any other implementation I have seen (copies 1 byte at a time!).

Tarjei Knapstad wrote:
>2008/7/26 Agner Fog <agner@agner.org>:
>>I have libc version 2.7. Can't find version 2.8
>It's in Fedora 9, I have no idea why the source isn't directly
>available from the glibc homepage.

2.8 is not an official final release yet.


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