DWARF is designed to have limited dependency on tools. A linker just has
to concatenate the data sections, resolve symbol and inter-section
relocations. But that does cause lots of repeated data structures (types)
and the linker has to process a lot of references/relocations. To counter
that .debug_types and DebugFission were introduced. First as GNU extensions
then added to DWARF4 and DWARF5. Lots of details changed. These techniques
can be used with separate .dwo files, or since DWARF5 in each .o file.
This does introduce some extra complexity. We have to add various levels
of indirection for types, strings, addresses and inter-section references.
And with split-dwarf between the .o object files, executable and .dwo files.
Some of the de-duplication of data is pushed to the DWARF consumer, or might
need a slightly smarter post-processor to merge the duplication of types
and data (there can be thousands of split-dwarf .dwo files).

We will go over the techniques that are now implemented in GCC. Which
versions of GCC implement what. Why the indirection tables are actually
cheaper than traditional relocations. Where they aren't used yet, but
probably should. The current state of DWARF consumers (gdb, elfutils,
etc.) and auxiliary post-processing tools (dwp and dwz).