[llvm] [CLANG][DWARF] Handle DIE offset collision in DW_IDX_parent (PR #95339)

[Alexander Yermolovich via llvm-commits]

ayermolo wrote:

> So the asan fix was replacing `CU->getOutUnitDIE()->getTag() == dwarf::DW_TAG_type_unit` with `CU->getTag() == dwarf::DW_TAG_type_unit)`?
> 
> Also noticed you deleted the default ctor here (which is good). Just to double check, this particular bit is unrelated to the asan issue right?

For the first yes. For parallel dwarf linker it was accessing freed UnitDie. It was allocated on local BumpAllocator in CompileUnit::cloneAndEmit. For followup PR might be a good idea to reset it to nullptr there?

Yes ctor is unrelated. Just a bit of cleanup when I looked at the code "second time". :)

https://github.com/llvm/llvm-project/pull/95339