Intel Architecture Code Analyzer

Here's an example of the output of IACA: https://gist.github.com/nkurz/0bea9db0cff60ead1686#file-broa...

It's somewhat cumbersome to use since you need to recompile with special asm instructions delimiting the region of interest, but the extensive analysis it gives is amazing for extreme micro-optimization.

The whole Intel Compiler stack is really useful from MKL for math, to VTune, to TBB if you're doing any heavy numerical analysis. It runs about as much as Visual Studio for the professional edition (under a $1k US) which is more than reasonable for what you get. We use Coverity for static analysis, Kcachegrind and ICC in concert in C++ and it's a brilliant stack. Intel PIN(1) is free for everyone and is amazing too. There are a lot of open-source dynamic analysis tools coming out from unis (the UC's, Pitt, CMU in particular which are almost there but not quite).

(1) https://software.intel.com/en-us/articles/pin-a-dynamic-bina...

IACA is a very useful tool. When working on the LLVM compiler I've used it extensively.

I almost put (2012) in the title since it's shown on the page, but the article and docs/binaries were updated in 2013, 2014, and possibly this year.

I spent about an hour looking at the tool. They say that only very few instructions aren't supported (and thus ignored by the tool) but a very popular imul instruction can be ignored.

PS I noticed that gcc with -march=corei7-avx generates more cycles compared to a generic amd64 compilation for an unrolled integer(4) to char[4] conversion.