Hello I have a program with many many inline template functions. It is essential for the execution speed that every (or almost every) function marked as inline, becomes really inlined by the compiler. I already compiled the program with Intel Compiler (ICL) on Visual C++, and it works fine and fast. I verified that the functions are really inlined. But with GCC 3.4 (Linux & Cygwin) the same program is about 5 times slower than the version compiled with ICL. The '-Winline' option of GCC shows me that many functions are not inlined like they should. The compiler considers the 'inline' keyword as an hint, but does not follow it. I tried to set various options of GCC, but nothing is satisfactory as far: -finline-limit 100000000 --param large-function-growth=1000000 --param max-inline-insns-single=1000000 ... I am convicted that the poor performance is due to the lack of inlining because I get slow execution speed with ICL when the functions are not marked as 'inline'. With the '-Winline' option of GCC, I see every not inlined functions. Also the SSE mode should be much quicker than without SIMD, but requires much more inlining. ICL manages it, GCC not at all. Do you know a mean to force GCC to obey the inline statement, or to increase the limits that these compilers internally have? Or do you have an alternative? It is not possible to give a small test program. If you want to test on your own, I propose you download my library at this address, and compile the following test. (No need to compile the library, it is STL-like) http://www.ient.rwth-aachen.de/team/laurent/genial/genial.html #define FFT_LEVEL 32 #include "signal/fft.h" int main() { DenseVector<complex<float> >::self X(32,0); DenseVector<complex<float> >::self Y(X.size(),0); double t0=get_time(); for (int i=0; i<1000000; ++i) fft(X,Y); cout << get_time()-t0 << endl; } The execution time on a Pentium 4, 3.2GHz: With ICL on Windows: -No simd: 0.368s -SSE: 0.126s -SSE3: 0.112s With GCC on Cygwin (-O3 -msse3 -UWIN32 -ftemplate-depth-36 -lstlport) -No SIMD : 0.969s -SSE: 2.069s Thanks Patrick ------------------------------------------------- Patrick LAURENT IENT - Institute for Communications Engineering RWTH - Aachen University of Technology Melatener Strasse 23, 52074 Aachen (Germany) Tel: +49 241/80-27679 Fax: +49 241/80-22196 E-Mail: Laurent@xxxxxxxxxxxxxxxxxxx -------------------------------------------------
