Clang LLVM 1.0 vs GCC 4.2

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Clang LLVM 1.0 vs GCC 4.2

Postby XenoPhex » Mon Sep 14, 2009 8:37 pm

I've been reading up on the new compilers that came with 10.6 and I'm trying to figure out what the best way to recompile the latest beta with. I understand LLVM-GCC is a good compiler, but from the benchmarks I've been seeing, it seems to fall short in every way to GCC 4.2. However, I'm having a terribly hard time finding data on Clang LLVM comparisons to GCC. I know GCC has been out so long that the back-end optimizations are probably better then Clang LLVM's but I don't know if that's true in terms of multicore performance when it comes to a higher end multicore machines (in my case with a hyper-threaded 8-core machine).

What's your take on the whole situation?
MacPro 4,1 - 2x Quad-Core Intel Xeon 2.26 GHz on Mac OS X 10.6.2 (10C540) 64-bit Kernel

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Re: Clang LLVM 1.0 vs GCC 4.2

Postby Catfish_Man » Mon Sep 14, 2009 8:58 pm

Compilers are unfortunately not all that relevant in terms of optimization for Adium; Optimizing across objc_msgSend is next to impossible, and most Adium performance issues are algorithmic.

Clang's huge benefit is that it compiles twice as fast and has better error messages :)

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Earth Mk. II
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Re: Clang LLVM 1.0 vs GCC 4.2

Postby Earth Mk. II » Mon Sep 14, 2009 9:02 pm

Agreed entirely with CFM. Primary benefit for us is compilation time.

As a note on status:
Adium itself builds nicely with both clang and llvm-gcc. It's just not the default yet.
Libpurple partially builds with llvm-gcc (breaks on some VV dependancies), but some Autoconfigure generated scripts don't play well with clang yet and it fails miserably.

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