The complete example can be seen in the source tree at
gcc/jit/docs/examples/tut04-toyvm/toyvm.cc
along with a Makefile and a couple of sample .toy scripts:
$ ls -al drwxrwxr-x. 2 david david 4096 Sep 19 17:46 . drwxrwxr-x. 3 david david 4096 Sep 19 15:26 .. -rw-rw-r--. 1 david david 615 Sep 19 12:43 factorial.toy -rw-rw-r--. 1 david david 834 Sep 19 13:08 fibonacci.toy -rw-rw-r--. 1 david david 238 Sep 19 14:22 Makefile -rw-rw-r--. 1 david david 16457 Sep 19 17:07 toyvm.cc $ make toyvm g++ -Wall -g -o toyvm toyvm.cc -lgccjit $ ./toyvm factorial.toy 10 interpreter result: 3628800 compiler result: 3628800 $ ./toyvm fibonacci.toy 10 interpreter result: 55 compiler result: 55