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by berkut 4152 days ago
As the original author of that benchmark, I should point out that that was LLVM SVN (unreleased) against GCC 4.8 & 4.9 - I couldn't get GCC 5.0 SVN to build, so it's possible 5.0 will be faster again than LLVM in certain situations.

However, I would also say that generally I've found LLVM is now producing faster code than GCC in most code I've tested both compilers with.

1 comments

That is very interesting, because LLVM developers themselves admit LLVM generates slower code than GCC (in average). This is plain if you read LLVM Developers' Meeting talks.

I think it is completely possible that LLVM developers are using wrong benchmarks. Benchmarks are mostly SPEC and some large Google C++ codebases; in some sense both are quite atypical. But then, entire problem is to understand how typical codebases look like.

I can hopefully settle this (as a developer of both).

Assuming we stick to x86/x64, nowadays (literally, let's say as of January 2015) GCC and LLVM are within the noise for most people on most code (IE 1-2% of each other).

You can certainly find benchmarks were LLVM does badly. Some are important to some people, some aren't. It is harder to find benchmarks where GCC does badly.