Andreas Kowarz <kowarz@xxxxxxxxxxxxxxxxxx> writes: > we made some interesting experience while implementing and testing a > software package, which makes use of overloaded operators. One aspect > of the implementation is the speed of the resulting binaries. To find > the best solution we have tested the following approaches: normal > overloading and templates. The example (attachment) contains the > source code for 3 programms: > > prog - execution without overloading > progtemp - template based > progover - normal overloading > > Compiled with g++ version 3.2 we got the following runtime: > prog about 2.9 seconds > progtemp about 2.9 seconds > progover about 3.5 seconds > It seems clear that the template based implementation should be the one to use. > > After recompiling with g++ version 3.4.1 we got a complete different result: > prog about 2.9 seconds > progtemp about 15.4 seconds !!! > progover about 3.5 seconds > This time the template version is not really good. :-( > (Same problem with g++ version 3.3.2 on a different machine) > > My questions are: > - Is this a known problem? > - Is there a compiler switch which can solve the problem? This seems to be something target specific; on Alpha, I get the exact same time for all three programs with both 3.3 and 3.4. I guess one would have to look at the assembly to see what causes it... might be register allocation or inlining. You could try changing inline settings and -fomit-frame-pointer and -fnew-ra. -- Falk
