gcc will become the best optimizing x86 compiler

[Basile STARYNKEVITCH]

Dave Korn wrote:
> Agner Fog wrote on 24 July 2008 09:04:
> 
>> Tim Prince wrote:
>>  >you identify the library you tested only as "ubuntu g++ 4.2.3."
>> Where can I see the libc version?
> 
>   Use whichever package manager ubuntu provides to check the version of the
> glibc package.  Here's an example fron a centos (using rpm):


On most Linux systems, in addition of using the package manager, the 
libc.so file is executable, and when executed, shows info, so on my 
Debian/Sid/AMD64 I'm getting

  % /lib/libc.so.6
GNU C Library stable release version 2.7, by Roland McGrath et al.
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Compiled by GNU CC version 4.3.1 20080523 (prerelease).
Compiled on a Linux >>2.6.25-2-amd64<< system on 2008-06-02.
Available extensions:
         crypt add-on version 2.1 by Michael Glad and others
         GNU Libidn by Simon Josefsson
         Native POSIX Threads Library by Ulrich Drepper et al
         BIND-8.2.3-T5B
For bug reporting instructions, please see:
<http://www.gnu.org/software/libc/bugs.html>.


Of course, on Ubuntu & Debian, you can query the package system
% dpkg -l libc6
Desired=Unknown/Install/Remove/Purge/Hold
| 
Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: 
uppercase=bad)
||/ Name           Version        Description
+++-==============-==============-============================================
ii  libc6          2.7-12         GNU C Library: Shared libraries

Regarding the original thread (performance of GCC & standard functions) 
it should be stressed that gcc would probably compile them better if 
passed machine specific flags.

At last, at the recent (july 2008) GCC summit, someone (sorry I forgot 
who, probably someone from SuSE) proposed in a BOFS to have architecture 
and machine specific hand-tuned (or even hand-written assembly) low 
level libraries for such basic things as memset etc..

Thanks for reading
-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
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