This paper is my favorite introduction to compilers, it's short and hands-on, goes from compiling a primitive program that does nothing but returns a single integer to a full-blown implementation of a real programming language in 24 small steps: http://scheme2006.cs.uchicago.edu/11-ghuloum.pdf

There is a book-length expansion of this paper that goes into more detail: https://github.com/IUCompilerCourse/Essentials-of-Compilatio...