[Lldb-commits] [PATCH] D46810: 3/3: Fix DWARFUnit::GetUnitDIEPtrOnly stale pointer

Greg Clayton via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Thu May 24 14:37:15 PDT 2018

clayborg added a comment.

In https://reviews.llvm.org/D46810#1111570, @jankratochvil wrote:

> In https://reviews.llvm.org/D46810#1098110, @clayborg wrote:
> > So this problem exists both in the LLDB and LLVM DWARF parsers. I am not sure this fix is safe. I would rather fix this by fixing DWARFDIE class to "do the right thing". We should be able to teach the DWARFDIE class to replace its "m_die" with the updated "m_die" if a method ever causes DWARFDIE to need to expand all DIEs in a DWARFUnit. That seems like a much safer fix. Having m_first_die is not safe because it if you call DWARFDIE::GetFirstChild() it will just add 1 to the "m_die" and we will crash. All parent, sibling and child code just do pointer arithmetic to find their counterparts. So since DWARFDIE has the "DWARFUnit *m_cu;" and "DWARFDebugInfoEntry *m_die;" we should use DWARFDIE to abstract this from users. Anyone playing directly with DWARFDebugInfoEntry must know the rules and do the right thing or just use DWARFDIE.
> Is this statement still valid now with `DWARFBaseDIE`?

Statement isn't valid, but we should cleanup the DIE parsing code so we have dedicated parsing for the unit DIE only and for all DIEs and remove the m_die_array_size() function.


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