[pkaye]

Hackers Delight is a pretty fun book on low level algorithms. Lots of little tidbits like how to convert a divide by a constant into a multiple by a different constants and a shift. Thought these days the compilers are good enough to do the same thing but now when you look at the resulting assembly you can figure out how they are doing that.

[smabie]

Even if compilers are usually good enough, people (mostly in the market making/HFT space) are still doing this kind of stuff. For example, division (and to a lesser extent, multiplication) is still avoided/hacked around in the fast path for these kinds of strategies.