[libcxx-commits] [clang] [libcxxabi] [lldb] [llvm] [lldb][Expression] Add structor variant to LLDB's function call labels (PR #149827)

[Michael Buch via libcxx-commits]

================
@@ -2482,6 +2485,134 @@ bool SymbolFileDWARF::ResolveFunction(const DWARFDIE &orig_die,
   return false;
 }
 
+static int ClangToItaniumCtorKind(clang::CXXCtorType kind) {
+  switch (kind) {
+  case clang::CXXCtorType::Ctor_Complete:
+    return 1;
+  case clang::CXXCtorType::Ctor_Base:
+    return 2;
+  case clang::CXXCtorType::Ctor_CopyingClosure:
+  case clang::CXXCtorType::Ctor_DefaultClosure:
+  case clang::CXXCtorType::Ctor_Comdat:
+    llvm_unreachable("Unexpected constructor kind.");
+  }
+}
+
+static int ClangToItaniumDtorKind(clang::CXXDtorType kind) {
+  switch (kind) {
+  case clang::CXXDtorType::Dtor_Deleting:
+    return 0;
+  case clang::CXXDtorType::Dtor_Complete:
+    return 1;
+  case clang::CXXDtorType::Dtor_Base:
+    return 2;
+  case clang::CXXDtorType::Dtor_Comdat:
+    llvm_unreachable("Unexpected destructor kind.");
+  }
+}
+
+static std::optional<int>
+GetItaniumCtorDtorVariant(llvm::StringRef discriminator) {
+  const bool is_ctor = discriminator.consume_front("C");
+  if (!is_ctor && !discriminator.consume_front("D"))
+    return std::nullopt;
+
+  uint64_t structor_kind;
+  if (!llvm::to_integer(discriminator, structor_kind))
+    return std::nullopt;
+
+  if (is_ctor) {
+    if (structor_kind > clang::CXXCtorType::Ctor_DefaultClosure)
+      return std::nullopt;
+
+    return ClangToItaniumCtorKind(
+        static_cast<clang::CXXCtorType>(structor_kind));
+  }
+
+  if (structor_kind > clang::CXXDtorType::Dtor_Comdat)
+    return std::nullopt;
+
+  return ClangToItaniumDtorKind(static_cast<clang::CXXDtorType>(structor_kind));
+}
+
+DWARFDIE SymbolFileDWARF::FindFunctionDefinition(const FunctionCallLabel &label,
+                                                 const DWARFDIE &declaration) {
+  DWARFDIE definition;
+  llvm::DenseMap<int, DWARFDIE> structor_variant_to_die;
+
+  // eFunctionNameTypeFull for mangled name lookup.
+  // eFunctionNameTypeMethod is required for structor lookups (since we look
+  // those up by DW_AT_name).
+  Module::LookupInfo info(ConstString(label.lookup_name),
+                          lldb::eFunctionNameTypeFull |
+                              lldb::eFunctionNameTypeMethod,
+                          lldb::eLanguageTypeUnknown);
+
+  m_index->GetFunctions(info, *this, {}, [&](DWARFDIE entry) {
+    if (entry.GetAttributeValueAsUnsigned(llvm::dwarf::DW_AT_declaration, 0))
+      return IterationAction::Continue;
+
+    auto spec = entry.GetAttributeValueAsReferenceDIE(DW_AT_specification);
+    if (!spec)
+      return IterationAction::Continue;
+
+    if (spec != declaration)
----------------
Michael137 wrote:

> Getting the information from one module to another would be tricky, but not impossible

But I think it would be one of the pre-requisites to landing this, right? Since that already works today (albeit maybe not completely correctly for all cases), and seems like a common thing people would run into in a non-trivial program.

> That said, the idea to add linkage names to constructors makes perfect sense as well. It aligns with what gcc does for constructors and also aligns with what both gcc and clang do with regular functions. I am slightly worried about what will that do to debug info size, but I can't say if that will be a problem or not.

Let me see what the debug-info size impact of this would be

https://github.com/llvm/llvm-project/pull/149827