[DEBUG_INFO][NVPTX] Generate correct data about variable address class.
Added ability to generate correct debug info data about the variable
address class. Currently, for all the locals and globals the default
values are used, ADDR_local_space(6) for locals and ADDR_global_space(5)
for globals. The values are taken from the table in
https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf. We need to emit correct data for address classes of, at least, shared and constant globals. Currently, all these variables are treated by the cuda-gdb debugger as the variables in the global address space and, thus, it require manual data type casting.
Reviewers: echristo, probinson
Subscribers: jholewinski, aprantl, cfe-commits
Differential Revision: https://reviews.llvm.org/D57162