All modern compilers do this (MSVC, clang, I believe gcc too). Search for "PGO" (Profile Guided Optimization). Also, not just for C++ - PS3 shader compiler did brute force instruction scheduling optimization (using shaderperf instead of profiler).

damn time to refresh my knowledge :-) That's what happens when you do CRUD too long :-)

Last time I optimized code the hard way was using VTune to channel the right operation in the right pipeline.