Author: Robert Hyatt
Date: 12:42:16 01/19/05
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On January 19, 2005 at 13:37:16, Rémi Coulom wrote: >On January 19, 2005 at 13:23:50, Robert Hyatt wrote: > >>On January 19, 2005 at 11:55:43, Rémi Coulom wrote: >> >>>Hi, >>> >>>I am porting my chess program to 64 bit on an AMD64 Athlon processor. I have >>>noticed that, with gcc, sizeof(int)=4. I would have expected sizeof(int)=8. On >>>32-bit platforms, 32-bit variables are faster than 16-bit variables. I wonder if >>>64-bit variables are faster than 32-bit variables on 64-bit machines. I have >>>made a few experiments and did not notice much difference. >>> >>>Rémi >> >> >>You aren't running a 64 bit gcc then. And most likely are not running a 64 bit >>operating system which is necessary before you can use a 64 bit compiler... > >Yes, I am using 64 bit gcc on a 64 bit linux. The output of "gcc -v" is: > >Reading specs from /usr/lib64/gcc/x86_64-mandrake-linux-gnu/3.4.1/specs >Configured with: ../configure --prefix=/usr --libdir=/usr/lib64 --with-slibdir=/ >lib64 --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable >-threads=posix --disable-checking --enable-long-long --enable-__cxa_atexit --ena >ble-clocale=gnu --disable-libunwind-exceptions --enable-languages=c,c++,ada,f77, >objc,java --host=x86_64-mandrake-linux-gnu --with-system-zlib >Thread model: posix >gcc version 3.4.1 (Mandrakelinux 10.1 3.4.1-4mdk) > >> >>Not much difference in speed, unless you _need_ 64 bit values. Then having to >>do 2x32 on a 32 bit machine is slower than one 64 bit operation on the opteron. > >Thanks for your reply, > >Rémi I may have been wrong. I believe that on a 64 bit architecture, I use "long" for a 64 bit data type, not int, so I am not sure what an int might be in thinking about this more carefully... I'll test it and see on one of our opteron boxes however.
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