I'm no x86 assembly expert but what I learned, I learned by reverse engineering. I don't know if that will teach you what you want to learn but I thought it was

I'm no x86 assembly expert but what I learned, I learned by reverse engineering. I don't know if that will teach you what you want to learn but I thought it was useful - I'd learned Atmel AVR assembly years ago so I knew the concepts. I looked at some short functions of Visual C++/gcc-generated assembly then I looked up the instructions and before too long I was familiar enough with the 20 to 30 instructions that most modern compilers use.