[sanxiyn]

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.

[DannyBee]

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.