[all-commits] [llvm/llvm-project] 5153a9: [lldb][DWARF] Change GetAttributes to always visit...

[Michael Buch via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 5153a90453e692b834e38eec247a0c88a0678bfa
      https://github.com/llvm/llvm-project/commit/5153a90453e692b834e38eec247a0c88a0678bfa
  Author: Michael Buch <michaelbuch12 at gmail.com>
  Date:   2025-01-17 (Fri, 17 Jan 2025)

  Changed paths:
    M lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
    M lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h
    M lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
    M lldb/unittests/SymbolFile/DWARF/DWARFDIETest.cpp

  Log Message:
  -----------
  [lldb][DWARF] Change GetAttributes to always visit current DIE before recursing (#123261)

`GetAttributes` returns all attributes on a given DIE, including any
attributes that the DIE references via `DW_AT_abstract_origin` and
`DW_AT_specification`. However, if an attribute exists on both the
referring DIE and the referenced DIE, the first one encountered will be
the one that takes precendence when querying the returned
`DWARFAttributes`. But there was no guarantee in which order those
attributes get visited. That means there's no convenient way of ensuring
that an attribute of a definition doesn't get shadowed by one found on
the declaration. One use-case where we don't want this to happen is for
`DW_AT_object_pointer` (which can exist on both definitions and
declarations, see https://github.com/llvm/llvm-project/pull/123089).

This patch makes sure we visit the current DIE's attributes before
following DIE references. I tried keeping as much of the original
`GetAttributes` unchanged and just add an outer `GetAttributes` that
keeps track of the DIEs we need to visit next.

There's precendent for this iteration order in
`llvm::DWARFDie::findRecursively` and also
`lldb_private::ElaboratingDIEIterator`. We could use the latter to
implement `GetAttributes`, though it also follows `DW_AT_signature` so I
decided to leave it for follow-up.



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