Re: Some benchmark comparison of gcc4.5 and dragonegg (was dragonegg in FSF gcc?)

["Manuel López-Ibáñez" <lopezibanez@gmail.com>]

On 21 April 2010 19:11, Vladimir Makarov <vmakarov@redhat.com> wrote:
> I don't think we should be too much worried about it.  GCC looks good in
> comparison with other industrial compiler with compile time point (and code
> size too) of view (e.g. SunStudio compiler is about 2 times slower and
> generates worse code on x86/x86_64 according to my benchmarking 2 years ago,
> Intel is also slower but generates much better code than gcc).

There is the perception that GCC is too slow and every release it gets
much slower for not significant gain. At some point one has to start
asking whether there is something that can be done to alleviate this.
Either by showing that in fact there is a significant gain, or by
improving compilation speed. But we should be worried.

We have to wait until clang can compile as much C++ code as GCC and
implement a similar feature set, but the differences are going to be
much larger when LLVM uses Clang. [*] This is a major selling point of
Clang/LLVM against GCC. You can choose to ignore it but it is out
there unchallenged and GCC users are listening to it. And it will
probably show that reimplementing GCC FEs using LLVM infrastructure is
an expensive but rewarding project. In fact, given the LLVM/Clang
already has many features that GCC has not, it is not clear what is
the overhead of implementing those features in GCC.

So do you think that the differences in compilation speed can be
explained mostly by lack of optimization features in LLVM?

Cheers,

Manuel.

[*] I also would be very interested on knowing what is the impact of
the integrated assembler approach in compile time:
http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html