CC'ing Felipe Piovezan, who implement this feature, in case he wants to fill in more details.
-- adrian > On Sep 3, 2024, at 10:06 AM, David Blaikie via Dwarf-discuss > <dwarf-discuss@lists.dwarfstd.org> wrote: > > Some context: > https://discourse.llvm.org/t/rfc-improve-dwarf-5-debug-names-type-lookup-parsing-speed/74151/44 > https://github.com/llvm/llvm-project/pull/77457 > > Essentially clang/llvm produces DW_IDX_parent with DW_FORM_flag_present when > the entry has a parent, but that parent isn't indexed (I think this mostly > comes up for the entities that are direct children of the unit DIE). > > This is designed to make it more efficient for consumers (lldb, in > particular) to do quicker comparisons from the index for qualified names. > > My vague recollection is the idea that the consumer needs that info to know > the difference between "this thing may or may not have a parent" and "this > thing has an unnamed/unindexed parent". > > On Sat, Aug 31, 2024 at 1:03 PM David Anderson via Dwarf-discuss > <dwarf-discuss@lists.dwarfstd.org <mailto:dwarf-discuss@lists.dwarfstd.org>> > wrote: >> Dwarf5. The Name Table .debug_names >> >> Background: >> 6.1.1.2, page 141 >> Parent debugging information entry, a reference to the >> index entry for the parent. This is represented as the >> offset of the entry relative to the start of the entry >> pool. >> >> Table 7.232 Name index attribute encodings >> DW_IDX_parent constant >> >> >> However clang version 18.1.8 generates >> >> DW_IDX_parent DW_FORM_flag_present >> when there is no parent entry to refer to. >> >> And that does not seem to match what DWARF5 >> says to do. >> >> So what is 'true' supposed to mean for DW_IDX_parent? >> >> A bit puzzled here. >> Thanks for any insight. >> David Anderson >> >> -- >> Lisp Users: Due to the holiday next >> Monday, there will be no garbage >> collection. --seen on Slashdot >> -- >> Dwarf-discuss mailing list >> Dwarf-discuss@lists.dwarfstd.org <mailto:Dwarf-discuss@lists.dwarfstd.org> >> https://lists.dwarfstd.org/mailman/listinfo/dwarf-discuss > -- > Dwarf-discuss mailing list > Dwarf-discuss@lists.dwarfstd.org > https://lists.dwarfstd.org/mailman/listinfo/dwarf-discuss
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