A completely useless LLVM pass. It's for LLVM 9.
Build:
$ cd llvm-pass-skeleton
$ mkdir build
$ cd build
$ cmake ..
$ make
$ cd ..
Run:
$ clang -S -emit-llvm -Xclang -disable-O0-optnone foo.c
$ opt -load build/skeleton/libSkeletonPass.* -skeleton -S foo.ll
The -Xclang -disable-O0-optnone flag ensures that Clang will allow later optimizations even when initially compiling without any.