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Avoid infinite recursion in GetBitSize/GetBitAlign #3089

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Jul 13, 2021
Merged

Avoid infinite recursion in GetBitSize/GetBitAlign #3089

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23 changes: 19 additions & 4 deletions lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2170,18 +2170,32 @@ TypeSystemSwiftTypeRef::GetBitSize(opaque_compiler_type_t type,
// info for it, so defer to SwiftASTContext.
if (llvm::isa<SwiftASTContextForExpressions>(m_swift_ast_context))
return ReconstructType({this, type}).GetBitSize(exe_scope);
LLDB_LOGF(GetLogIfAllCategoriesSet(LIBLLDB_LOG_TYPES),
"Couldn't compute size of type %s using SwiftLanguageRuntime.",
AsMangledName(type));
return {};
}

// If there is no process, we can still try to get the static size
// information out of DWARF. Because it is stored in the Type
// object we need to look that up by name again.
if (TypeSP type_sp = LookupTypeInModule(type)) {
if (auto byte_size = type_sp->GetByteSize(exe_scope))
struct SwiftType : public Type {
/// Avoid a potential infinite recursion because
/// Type::GetByteSize() may call into this function again.
llvm::Optional<uint64_t> GetStaticByteSize() {
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Thoughts on adding this function directly to Type?

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I did it in this odd way is to minimize the diff between swift-lldb and llvm.org lldb.

if (m_byte_size_has_value)
return m_byte_size;
return {};
}
};
if (auto byte_size =
reinterpret_cast<SwiftType *>(type_sp.get())->GetStaticByteSize())
return *byte_size * 8;
else return {};
}
LLDB_LOGF(GetLogIfAllCategoriesSet(LIBLLDB_LOG_TYPES),
"Couldn't compute size of type %s without a process.",
"Couldn't compute size of type %s using static debug info.",
AsMangledName(type));
return {};
};
Expand Down Expand Up @@ -3179,9 +3193,10 @@ TypeSystemSwiftTypeRef::GetTypeBitAlign(opaque_compiler_type_t type,
// alignment information out of DWARF. Because it is stored in the
// Type object we need to look that up by name again.
if (TypeSP type_sp = LookupTypeInModule(type))
return type_sp->GetLayoutCompilerType().GetTypeBitAlign(exe_scope);
if (type_sp->GetLayoutCompilerType().GetOpaqueQualType() != type)
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Suggestion: a comment saying when/why this inequality happens.

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It's again to avoid an infinite recursion. I'll add a comment.

return type_sp->GetLayoutCompilerType().GetTypeBitAlign(exe_scope);
LLDB_LOGF(GetLogIfAllCategoriesSet(LIBLLDB_LOG_TYPES),
"Couldn't compute alignment of type %s without a process.",
"Couldn't compute alignment of type %s using static debug info.",
AsMangledName(type));
return {};
}
Expand Down