tl;dr: Cornell's CS 6120, a PhD-level advanced compilers course taught by Adrian Sampson, is available as a free self-guided online course with video lectures, lecture notes, and open-ended implementation tasks using LLVM and Bril (a custom educational IR). The 14-lesson curriculum covers IRs, data flow, SSA, loop and interprocedural optimization, alias analysis, garbage collection, JITs, and parallelism, interleaved with classic PL research papers. The course is open source on GitHub, though self-guided students miss out on Zulip discussions, deadlines, and the end-of-semester project.