I missed the point that I was dealing with a ```jl_arrayvar_t```, not a ```jl_array_t```.  Looking at routine ```maybe_alloc_arrayvar```, it appears that ```jl_arrayvar_t:: sizes``` describes a bunch of stack-local variables.  They are definition not related to ```tbaa_array...``` metadata.  If their addresses are not captured in a way that confuses LLVM, then no metadata is necessary.  If they are captured confusingly to LLVM, then some new metadata nodes would be appropriate.