Yeah, it compiles with LLVM git here. However, when run, it locks up X for a
few seconds, displays some snow, and then locks up the kernel. I'm still
working on tracking down a minimal testcase for it, but at least replacing the
main while loop with this:

    child = texelFetch(octree, int(root)).x;

still allows the bug to manifest. Setting child to a constant value does not.
Setting the output of the entire shader to texelFetch(octree, int(root)).x at
the top and immediately returning displays the correct image, so the texture is
correct.