2008/9/22 Brian D. McGrew <brian@xxxxxxxxxxxxx>:> Oops, try gcc -v on the various compilers, not gcc --version... See below, you can see how differently my v4.1.1 versus v4.3.0 are (disregard 32-bit vs. 64-bit).>> Also, I can compile a binary -O2 -g and the two different compilers and get different results. It's not unheard of. Again, it begs the question of source code! The source code is here:http://www.mimuw.edu.pl/~lew/libego_benchmark.tgz And here are the version details:Using built-in specs.Target: i486-linux-gnuConfigured with: ../src/configure -v --with-pkgversion='Ubuntu4.3.2-1ubuntu7'--with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr--enable-shared --with-system-zlib --libexecdir=/usr/lib--without-included-gettext --enable-threads=posix --enable-nls--with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc--enable-mpfr --enable-targets=all --enable-checking=release--build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnuThread model: posixgcc version 4.3.2 (Ubuntu 4.3.2-1ubuntu7) Using built-in specs.Cel: i486-linux-gnuOpcje konfiguracji: ../src/configure -v--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr--enable-shared --with-system-zlib --libexecdir=/usr/lib--without-included-gettext --enable-threads=posix --enable-nls--with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc--enable-mpfr --enable-targets=all --enable-checking=release--build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnuModel wątków: posixgcc wersja 4.2.4 (Ubuntu 4.2.4-1ubuntu1) Lukasz >> -brian>> 20_ gcc -v> Using built-in specs.> Target: i386-redhat-linux> Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=i386-redhat-linux> Thread model: posix> gcc version 4.1.1 20070105 (Red Hat 4.1.1-51)>> And>> 44_ gcc -v> Using built-in specs.> Target: x86_64-redhat-linux> Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-cpu=generic --build=x86_64-redhat-linux> Thread model: posix> gcc version 4.3.0 20080428 (Red Hat 4.3.0-8) (GCC)>> -----Original Message-----> From: Łukasz Lew [mailto:lukasz.lew@xxxxxxxxx]> Sent: Sunday, September 21, 2008 2:41 PM> To: Brian D. McGrew> Cc: gcc-help@xxxxxxxxxxx> Subject: Re: Performance problem>> Thanks for a fast answer,> I use -O3 -march=native -fomit-frame-pointer -DDEBUG -ffast-math> -frename-registers -ggdb3 -Wall -Wextra -Wswitch-enum> but I have the same effect with only -O3>> Versions:> g++-4.2 (GCC) 4.2.4 (Ubuntu 4.2.4-1ubuntu1)> g++-4.3 (Ubuntu 4.3.2-1ubuntu7) 4.3.2>> The original library is here:> http://www.mimuw.edu.pl/~lew/hg/libego/?shortlog> I extracted only the benchmark part:> http://www.mimuw.edu.pl/~lew/libego_benchmark.tgz>> I also found strange one-line difference that degrades performance> of g++-4.2 compiled binary to the level of g++-4.3.>> I don't get it at all ..> If you have any insights please let me know, it is very important to me.> Lukasz>> On Sun, Sep 21, 2008 at 23:24, Brian D. McGrew <brian@xxxxxxxxxxxxx> wrote:>> Source code would be a good start??? Optimization flags??? Architecture flags??? How was gcc-4.3 vs. gcc-4.2 built??? (g++ --version will show this).>>>> -brian>>>> -----Original Message----->> From: gcc-help-owner@xxxxxxxxxxx [mailto:gcc-help-owner@xxxxxxxxxxx] On Behalf Of Lukasz Lew>> Sent: Sunday, September 21, 2008 2:20 PM>> To: gcc-help@xxxxxxxxxxx>> Subject: Performance problem>>>> Hi>>>> I have a program that when compiled with g++-4.3 is 10% slower than with g++-4.2>> I tried to look at the asm output, but its way too different.>> How should I proceed to get my 10% back?>>>> Thanks>> Lukasz>>>
