Arbitrary computation on x86 without using registers. See this article for details.

Requirements: AMD64 Linux with gcc, nasm, and Python.

compiler takes Brainfuck source (not a filename) from the first command line argument or from stdin. It produces a binary named rip, which executes that Brainfuck program without using registers (except for system calls).

Use regclobber to verify this by setting registers to zero after each instruction.

$ gcc -O2 -Wall -o regclobber regclobber.c
$ ./regclobber ./rip
Hello World!

Executed 3268 instructions; clobbered registers 3187 times.