In the old (well, current) schema, there are two types of file
references: untagged and tagged (the latter references the former).
!0 = !{!"filename", !"/directory"}
!1 = !{!"0x29", !1} ; DW_TAG_file_type [filename] [/directory]
The interface to `DIBuilder` universally takes the tagged version,
described by `DIFile`. However, most `file:` references actually use
the untagged version directly.
In the new hierarchy, I'm merging this into a single node: `MDFile`.
Originally I'd planned to keep the old schema unchanged until after I
moved the new hierarchy into place.
However, it turns out to be trivial to make `MDFile` match both nodes at
the same time.
- Anyone referencing !1 does so through `DIFile`, whose implementation
I need to gut anyway (as I do the rest of the `DIDescriptor`s).
- Anyone referencing !0 just references an `MDNode`, and expects a
node with two `MDString` operands.
This commit achieves that, and updates all the testcases for the parts
of the new hierarchy that used the two-node schema (I've replaced the
untagged nodes with `distinct !{}` to make the diff clear (otherwise the
metadata all gets renumbered); it might be worthwhile to come back and
delete those nodes and renumber the world, not sure).
llvm-svn: 230057
Duncan P. N. Exon Smith