Re: [Boost-users] g++ compilation is slow with Boost's constructs

On Fri, Sep 10, 2010 at 7:37 PM, OvermindDL1 wrote:

On Thu, Sep 9, 2010 at 10:17 AM, Ilya Murav'jov wrote:

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Jason Merrill пишет:

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On 09/08/2010 07:40 AM, Ilya Murav'jov wrote:

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Dave Abrahams пишет: >> G++4.5 implements O(1) template lookup, which could have a significant >> effect for Boost users.

Thanks for the info. I've built gcc-4.5.1 myself and got not very comforting results: g++4.2 is still 'unbeaten', g++4.5 is 15% slower.

Hmm, that's disappointing.  I grabbed the source file you mentioned, but it seems to depend on other headers from your project; if you send me a preprocessed file I'll try to take a look at what's slowing it down sometime soon.

Jason

After some experiments I've done a clear example. It shows that boost::lambda::bind() invocation cost 0.1 sec. Here is the code:

//////////////////// begin ////////////////////////

#include   // boost::lambda::bind #include      // boost::function

typedef boost::function TestFunctor;

template<int value> struct TestStruct { };

#define IMPL_DEF_(Idx, Type) void Impl ## Idx(Type) {} \ void TestImpl ## Idx()                           \ {                                                \    TestFunctor fnr;                           \    fnr = boost::lambda::bind(&Impl ## Idx, Type());  \ } \ /**/

#define IMPL_DEF(Idx) IMPL_DEF_(Idx, TestStruct<Idx>)

#define IMPL_DEF_10_(Idx) \ IMPL_DEF(Idx ## 0) \ IMPL_DEF(Idx ## 1) \ IMPL_DEF(Idx ## 2) \ IMPL_DEF(Idx ## 3) \ IMPL_DEF(Idx ## 4) \ IMPL_DEF(Idx ## 5) \ IMPL_DEF(Idx ## 6) \ IMPL_DEF(Idx ## 7) \ IMPL_DEF(Idx ## 8) \ IMPL_DEF(Idx ## 9) \ /**/

#define IMPL_DEF_10(Idx) IMPL_DEF_10_(Idx)

IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__) IMPL_DEF_10(__LINE__)

//////////////////// end ////////////////////////

It does 100 invocations of boost::lambda::bind() with various types. Benchmarks with "-c -g -O0 -pipe", Boost 1.44:

G++ 4.2.4: 14.75 sec G++ 4.5.1: 09.57 sec

P.S. It shows that  g++4.5 is quicker, though.  :)  Later I try to do examples with other constructs (BOOST_FOREACH, Boost.Range, B.Function) to find out where g++4.2 is better.

P.S.S. I suggest to make comparison among varios compilers (i.e., clang, msvc, icc) with this test. It is interesting to see the quickest (don't forget to include your CPU).

I have an AMD Phenom II CPU, 3.2ghz, my times:

home:/home/overminddl1/projects/testingrandom# g++ -v Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) home:/home/overminddl1/projects/testingrandom# ~/llvm/Release/bin/clang++ -v clang version 2.8 (trunk 113038) Target: i386-pc-linux-gnu Thread model: posix home:/home/overminddl1/projects/testingrandom# time g++ test.cpp /usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o: In function `_start': (.text+0x18): undefined reference to `main' collect2: ld returned 1 exit status

real    0m8.504s user    0m5.336s sys     0m0.184s home:/home/overminddl1/projects/testingrandom# time ~/llvm/Release/bin/clang++ test.cpp /usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o: In function `_start': (.text+0x18): undefined reference to `main' collect2: ld returned 1 exit status clang: error: linker (via gcc) command failed with exit code 1 (use -v to see invocation)

real    0m3.443s user    0m2.524s sys     0m0.188s

However, clang++ usually does not compile code that runs quite as fast as g++ as of yet, but they are getting close, and yes, I know my g++ is old, it is the stock install.

Guess I should use the same parameters you did, here it is: home:/home/overminddl1/projects/testingrandom# time g++ test.cpp -c -g -O0 -pipe real 0m9.404s user 0m5.500s sys 0m1.608s home:/home/overminddl1/projects/testingrandom# time ~/llvm/Release/bin/clang++ test.cpp -c -g -O0 -pipe real 0m4.644s user 0m2.948s sys 0m0.240s