Rohit (@.) on 6/24/10 wrote:
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>? (0xe2.0x9a.0x9b@gmail.com) on 6/24/10 wrote:
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>>Bottom line: Not counting the support for new C/C++ features, how exactly is GCC 4.5 better than GCC 3.4 ?
>>
>
>SSE intrinsics and/or C++ templates improved a lot in 4.2

OK, that is true, but I would put these two things into the bag "new language features". The question I asked is more in the line of: If you can compile a program both with GCC version X *and* without any changes with version Y, is there a difference between GCC-X and GCC-Y?

Let me present some comparison from a project of mine, maybe that will persuade you that the "newer GCC is better than older GCC"-idea suffers from a placebo effect:

Application type: C++ code with some template classes, no floating-point arithmetic, no STL

Compilers: GCC 4.5.0, GCC 4.1.2

Compilation options: identical in both cases

Compilation time: GCC-4.5.0 took 4.4% longer than GCC-4.1.2

Performance of generated code: There do not seem to be any significant differences in performance (well, at least in the places where I am measuring performance). Most certainly, there is *nothing* which would support the conjecture that "4.5.0 produces strictly faster code than 4.1.2".

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So, if I may ask: Do you happen to have a normal Linux application (C/C++ integer code) where you are sure you are seeing GCC-4.5 producing better code than GCC-4.1?