[PATCH] D40156: Fix recursive attribute fetching in DWARFDie

[David Blaikie via llvm-commits]

Do you happen to have minimized source & a specific GCC version (unless
it's just ubiquitous to all/many GCC versions)?

On Thu, Nov 16, 2017 at 4:06 PM Greg Clayton <clayborg at gmail.com> wrote:

> Don't ask me. I just have a GCC generated file that does this.
>
> On Nov 16, 2017, at 4:05 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
> I don't quite follow - why would there be two levels of abstract origin?
> (X -abstract_origin-> Y -abstract_origin-> Z) rather than having X refer to
> Z as its abstract_origin directly?
>
> On Thu, Nov 16, 2017 at 4:01 PM Greg Clayton via Phabricator <
> reviews at reviews.llvm.org> wrote:
>
>> clayborg created this revision.
>> Herald added a subscriber: JDevlieghere.
>>
>> The previous implementation would only look 1 DW_AT_specification or
>> DW_AT_abstract_origin deep. This means DWARFDie::getName() would fail in
>> certain cases. I ran into such a case while creating a tool that used the
>> LLVM DWARF parser to generate a symbolication format so I have seen this in
>> the wild.
>>
>>
>> Repository:
>>   rL LLVM
>>
>> https://reviews.llvm.org/D40156
>>
>> Files:
>>   lib/DebugInfo/DWARF/DWARFDie.cpp
>>   unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
>>
>>
>> Index: unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
>> ===================================================================
>> --- unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
>> +++ unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
>> @@ -1287,12 +1287,16 @@
>>      auto CUDie = CU.getUnitDIE();
>>      auto FuncSpecDie = CUDie.addChild(DW_TAG_subprogram);
>>      auto FuncAbsDie = CUDie.addChild(DW_TAG_subprogram);
>> +    // Put the linkage name in a second abstract origin DIE to ensure we
>> +    // recurse through more than just one DIE when looking for
>> attributes.
>> +    auto FuncAbsDie2 = CUDie.addChild(DW_TAG_subprogram);
>>      auto FuncDie = CUDie.addChild(DW_TAG_subprogram);
>>      auto VarAbsDie = CUDie.addChild(DW_TAG_variable);
>>      auto VarDie = CUDie.addChild(DW_TAG_variable);
>>      FuncSpecDie.addAttribute(DW_AT_name, DW_FORM_strp, SpecDieName);
>> -    FuncAbsDie.addAttribute(DW_AT_linkage_name, DW_FORM_strp,
>> SpecLinkageName);
>> +    FuncAbsDie2.addAttribute(DW_AT_linkage_name, DW_FORM_strp,
>> SpecLinkageName);
>>      FuncAbsDie.addAttribute(DW_AT_specification, DW_FORM_ref4,
>> FuncSpecDie);
>> +    FuncAbsDie.addAttribute(DW_AT_abstract_origin, DW_FORM_ref4,
>> FuncAbsDie2);
>>      FuncDie.addAttribute(DW_AT_abstract_origin, DW_FORM_ref4,
>> FuncAbsDie);
>>      VarAbsDie.addAttribute(DW_AT_name, DW_FORM_strp, AbsDieName);
>>      VarDie.addAttribute(DW_AT_abstract_origin, DW_FORM_ref4, VarAbsDie);
>> @@ -1314,7 +1318,8 @@
>>
>>    auto FuncSpecDie = CUDie.getFirstChild();
>>    auto FuncAbsDie = FuncSpecDie.getSibling();
>> -  auto FuncDie = FuncAbsDie.getSibling();
>> +  auto FuncAbsDie2 = FuncAbsDie.getSibling();
>> +  auto FuncDie = FuncAbsDie2.getSibling();
>>    auto VarAbsDie = FuncDie.getSibling();
>>    auto VarDie = VarAbsDie.getSibling();
>>
>> Index: lib/DebugInfo/DWARF/DWARFDie.cpp
>> ===================================================================
>> --- lib/DebugInfo/DWARF/DWARFDie.cpp
>> +++ lib/DebugInfo/DWARF/DWARFDie.cpp
>> @@ -298,17 +298,16 @@
>>  DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
>>    if (!isValid())
>>      return None;
>> -  auto Die = *this;
>> -  if (auto Value = Die.find(Attrs))
>> +  if (auto Value = find(Attrs))
>>      return Value;
>> -  if (auto D =
>> Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
>> -    Die = D;
>> -  if (auto Value = Die.find(Attrs))
>> -    return Value;
>> -  if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
>> -    Die = D;
>> -  if (auto Value = Die.find(Attrs))
>> -    return Value;
>> +  if (auto Die =
>> getAttributeValueAsReferencedDie(DW_AT_abstract_origin)) {
>> +    if (auto Value = Die.findRecursively(Attrs))
>> +      return Value;
>> +  }
>> +  if (auto Die = getAttributeValueAsReferencedDie(DW_AT_specification)) {
>> +    if (auto Value = Die.findRecursively(Attrs))
>> +      return Value;
>> +  }
>>    return None;
>>  }
>>
>>
>>
>>
>
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