GCC and C vs C++ Speed, Measured

Just to be clear, because this confused me at first:<p>- GCC recently switched from building their own code as C, to building as C++. At the moment they only use the subset of C++ which is C, but this affects compiler behaviour.<p>- People complained that C++ programs couldn't be compiled as efficiently as C programs, and this would make things slower.<p>- This post shows that compiling GCC as C, versus C++, does not result in an appreciable performance change. He benchmarks this by building the kernel using both versions of GCC.

&#62; Using stats –trim-outliers, which throws away best and worse<p>people make this mistake over and over again. there's no point in taking anything but the best time when talking about performance in a preemptive multiprocessing environment. the best time isn't an outlier, every time other than it is!

FWIW, RustyRussell is this Rusty: <a href="http://en.wikipedia.org/wiki/Rusty_Russell" rel="nofollow">http://en.wikipedia.org/wiki/Rusty_Russell</a><p>Nice to see him here - "ciao" from Italy:-)

The results are what I expected and not that interesting. Compiling C as C++ usually yields the exact same native code as compiling it as C, except for some very minor differences.<p>What would be interesting is how long it now takes to compile GCC itself. For code that does not use C++ features, I also expect a very minor difference.

Interesting aside: There are some things that are faster in C++ than C, for example the standard library sort functions are massively faster because the compiler can in-line the comparison.

That is one hell of a misnamed article.

I don't think having a single statistics point is enough to make a judgement here. There are many different programs of which compilers are a very small and relatively rarely used subset.

So 0.3% is a measurable difference and 0.1% is noise. That doesn't sound overly pragmatic to me. Benchmarking is an art, and from his setup 0.3% seems like noise as well.

Aren't the files already cached in memory by the time the C++ compilation happens? Wouldn't flushing memory provide a better measure?

I always ask myself, why are there people who put statistics without charts on the internet.

So python is the fastest?

What is the time difference to compile GCC itself?

Linus will now use LCC

People were complaining that the binaries would be slower? All the complaints I heard were "now it will take 10 times longer to compile gcc", not "now gcc will run slower".