Agner Fog's resources are amazingly thorough, and some of his documents include information that was completely unknown at the time of publication. If you're trying to optimize for "non-deterministic" Intel chips, there is a wealth of data here.

Thanks for the links. The x86 instruction tables and calling conventions will probably come in handy as a reference for me in the future. Among other things here.

The C++ optimization manual there is in no way out of date. All of the advice and techniques in that manual are even more relevant today than in 2007.

Additionally, the title page says that it was last updated August 2014.