================
@@ -2518,6 +2518,59 @@ StringRef CGDebugInfo::getVTableName(const CXXRecordDecl
*RD) {
return internString("_vptr$", RD->getNameAsString());
}
+// Emit symbol for the debugger that points to the vtable address for
+// the given class. The symbol is named as '_vtable$'.
+// The debugger does not need to know any details about the contents of the
+// vtable as it can work this out using its knowledge of the ABI and the
+// existing information in the DWARF. The type is assumed to be 'void *'.
+void CGDebugInfo::emitVTableSymbol(llvm::GlobalVariable *VTable,
+ const CXXRecordDecl *RD) {
+ ASTContext &Context = CGM.getContext();
+ SmallString<64> Buffer;
+ Twine SymbolName = internString("_vtable$");
+ StringRef SymbolNameRef = SymbolName.toStringRef(Buffer);
+ DeclContext *DC = static_cast<DeclContext *>(const_cast<CXXRecordDecl
*>(RD));
+ SourceLocation Loc;
+ QualType VoidPtr = Context.getPointerType(Context.VoidTy);
+
+ // We deal with two different contexts:
+ // - The type for the variable, which is part of the class that has the
+ // vtable, is placed in the context of the DICompositeType metadata.
+ // - The DIGlobalVariable for the vtable is put in the DICompileUnitScope.
+
+ // The created non-member should be mark as 'artificial'. It will be
+ // placed it inside the scope of the C++ class/structure.
+ llvm::DIScope *DContext = getContextDescriptor(cast<Decl>(DC), TheCU);
+ auto *Ctxt = cast<llvm::DICompositeType>(DContext);
+ llvm::DIFile *Unit = getOrCreateFile(Loc);
+ llvm::DIType *VTy = getOrCreateType(VoidPtr, Unit);
+ llvm::DINode::DIFlags Flags = getAccessFlag(AccessSpecifier::AS_private, RD);
+ auto Tag = CGM.getCodeGenOpts().DwarfVersion >= 5
+ ? llvm::dwarf::DW_TAG_variable
+ : llvm::dwarf::DW_TAG_member;
+ llvm::DIDerivedType *OldDT = DBuilder.createStaticMemberType(
+ Ctxt, SymbolNameRef, Unit, /*LineNumber=*/0, VTy, Flags,
+ /*Val=*/nullptr, Tag);
+ llvm::DIDerivedType *DT =
+ static_cast<llvm::DIDerivedType *>(DBuilder.createArtificialType(OldDT));
+
+ // Use the same vtable pointer to global alignment for the symbol.
+ LangAS AS = CGM.GetGlobalVarAddressSpace(nullptr);
+ unsigned PAlign = CGM.getItaniumVTableContext().isRelativeLayout()
+ ? 32
+ : CGM.getTarget().getPointerAlign(AS);
----------------
Michael137 wrote:
Probably also need to guard this behind
`CGM.getTarget().getCXXABI().isItaniumFamily()` or something (or even just
short-circuit this entire function if we're not generating for Itanium?)
https://github.com/llvm/llvm-project/pull/130255
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