Add an optional attribute referring to a tuple of type and value template parameter nodes to the DIGlobalVariable node. This allows us to record the parameters of template variable specializations.
Generally this looks good, but I'd like for the other to have a look first (at this and the other patch) before accepting.
Might be nice to add a comment here saying what you're doing in this block and below. Looks like the top one is for partial specialization and the bottom one for the general case?
I also suggest to extract TS->getSpecializedTemplateOrPartial() into a variable to make this a little less dense.