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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - getASTRecordLayout called before that type's base classes are saved"
href="https://bugs.llvm.org/show_bug.cgi?id=50054">50054</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>getASTRecordLayout called before that type's base classes are saved
</td>
</tr>
<tr>
<th>Product</th>
<td>lldb
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>lldb-dev@lists.llvm.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>emrekultursay@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>jdevlieghere@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=24776" name="attach_24776" title="Full stack trace">attachment 24776</a> <a href="attachment.cgi?id=24776&action=edit" title="Full stack trace">[details]</a></span>
Full stack trace
This is a case where LLDB calls `Context.getASTRecordLayout(...)` for a class
BEFORE the `CXXRecordDecl::setBases()` for that same class.
As a result, `getASTRecordLayout()` computes and caches an layout without any
base classes, and subsequent calls use that cached, incorrect result.
This causes a segfault in LLDB due to downstream accesses using FieldNo values
that do not exist in ASTRecordLayout.
I can only reproduce this by attaching to a binary that a customer provided,
and I cannot share that publicly here. However, I hope maybe some LLDB experts
here might be able to guide/help by looking at the stack trace here.
* Topmost frame: Computes and saves the ASTRecordLayout for the problematic
class without any base class information.
* Frame with asterisk(*): Has not processed/saved the base classes for that
same class yet.
<span class="quote">> clang::ASTContext::getASTRecordLayout Line 3339 </span >
`anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203
`anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179
clang::ASTContext::getASTRecordLayout Line 3377
`anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203
`anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179
clang::ASTContext::getASTRecordLayout Line 3377
`anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203
`anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179
clang::ASTContext::getASTRecordLayout Line 3377
`anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203
`anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179
clang::ASTContext::getASTRecordLayout Line 3377
`anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203
`anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179
clang::ASTContext::getASTRecordLayout Line 3377
`anonymous namespace'::EmptySubobjectMap::ComputeEmptySubobjectSizes
Line 203
`anonymous namespace'::EmptySubobjectMap::EmptySubobjectMap Line 179
clang::ASTContext::getASTRecordLayout Line 3377
clang::ASTContext::getTypeInfoImpl Line 2258
clang::ASTContext::getTypeInfo Line 1879
clang::ASTContext::getTypeInfo Line 2116
clang::ASTContext::getTypeSize Line 2122
lldb_private::TypeSystemClang::GetBitSize Line 4588
lldb_private::CompilerType::GetBitSize Line 484
lldb_private::CompilerType::GetByteSize Line 490
DWARFASTParserClang::ParseSingleMember Line 2680
DWARFASTParserClang::ParseChildMembers Line 2801
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseChildMembers Line 2888
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParsePointerToMemberType Line 1362
DWARFASTParserClang::ParseTypeFromDWARF Line 530
...
DWARFASTParserClang::ParseChildParameters Line 3014
DWARFASTParserClang::ParseSubroutine Line 942
DWARFASTParserClang::ParseTypeFromDWARF Line 522
...
DWARFASTParserClang::CompleteRecordType Line 2003
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseSingleMember Line 2562
DWARFASTParserClang::ParseChildMembers Line 2801
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParsePointerToMemberType Line 1362
DWARFASTParserClang::ParseTypeFromDWARF Line 530
...
DWARFASTParserClang::ParseChildParameters Line 3014
DWARFASTParserClang::ParseSubroutine Line 942
DWARFASTParserClang::ParseTypeFromDWARF Line 522
...
DWARFASTParserClang::CompleteRecordType Line 2003
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseSingleMember Line 2562
DWARFASTParserClang::ParseChildMembers Line 2801
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParsePointerToMemberType Line 1362
DWARFASTParserClang::ParseTypeFromDWARF Line 530
...
DWARFASTParserClang::ParseChildParameters Line 3014
DWARFASTParserClang::ParseSubroutine Line 942
DWARFASTParserClang::ParseTypeFromDWARF Line 522
...
DWARFASTParserClang::CompleteRecordType Line 2003
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseSingleMember Line 2562
DWARFASTParserClang::ParseChildMembers Line 2801
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParsePointerToMemberType Line 1362
DWARFASTParserClang::ParseTypeFromDWARF Line 530
...
DWARFASTParserClang::ParseChildParameters Line 3014
DWARFASTParserClang::ParseSubroutine Line 942
DWARFASTParserClang::ParseTypeFromDWARF Line 522
...
DWARFASTParserClang::CompleteRecordType Line 2003
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseSingleMember Line 2562
DWARFASTParserClang::ParseChildMembers Line 2801
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseChildMembers Line 2888
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseChildMembers Line 2888
* DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseSingleMember Line 2562
DWARFASTParserClang::ParseChildMembers Line 2801
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParsePointerToMemberType Line 1362
DWARFASTParserClang::ParseTypeFromDWARF Line 530
...
DWARFASTParserClang::ParseChildParameters Line 3014
DWARFASTParserClang::ParseSubroutine Line 942
DWARFASTParserClang::ParseTypeFromDWARF L
...
DWARFASTParserClang::CompleteRecordType Line 2003
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
...
DWARFASTParserClang::ParseChildMembers Line 2888
DWARFASTParserClang::CompleteRecordType Line 2002
DWARFASTParserClang::CompleteTypeFromDWARF Line 2126
SymbolFileDWARF::CompleteType Line 1484
lldb_private::TypeSystemClang::CompleteTagDecl Line 9100
GetCompleteQualType Line 2607
lldb_private::TypeSystemClang::GetNumChildren Line 5166
lldb_private::TypeSystemClang::GetNumChildren Line 5281
lldb_private::ValueObjectDynamicValue::CalculateNumChildren Line 96
lldb_private::ValueObject::GetNumChildren Line 561
lldb::SBValue::GetNumChildren Line 993
lldb::SBValue::GetNumChildren Line 982
[External Code]
Full stack trace is attached.</pre>
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