Comment # 4 on bug 84977 from David Heidelberger (okias)

> > Also, problematic swizzle can be seen on instruction 27: in diff wx -> wz.
> 
> .wz is a legal swizzle according to the native_swizzles table.  Can you add
> printfs to lookup_native_swizzle to see why it is not being treated as a
> legal swizzle?

I made printf in lookup_native_swizzle originally.
I probably messed this. It's wz -> wx. (it fails for www after 1. w, same for
wzy, also fails after 1. w).