[clang] [llvm] [WIP] ABI Lowering Library (PR #140112)

[via llvm-commits]

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@@ -136,9 +136,69 @@ const llvm::abi::Type *QualTypeMapper::convertRecordType(const RecordType *RT) {
 
   if (RD->isUnion())
     return convertUnionType(RD);
+
+  // Handle C++ classes with base classes
+  auto *const CXXRd = dyn_cast<CXXRecordDecl>(RD);
+  if (CXXRd && (CXXRd->getNumBases() > 0 || CXXRd->getNumVBases() > 0)) {
+    return convertCXXRecordType(CXXRd);
+  }
   return convertStructType(RD);
 }
 
+const llvm::abi::StructType *
+QualTypeMapper::convertCXXRecordType(const CXXRecordDecl *RD) {
+  const ASTRecordLayout &Layout = ASTCtx.getASTRecordLayout(RD);
+  SmallVector<llvm::abi::FieldInfo, 16> Fields;
+
+  if (RD->isPolymorphic()) {
+    const llvm::abi::Type *VtablePointer =
+        createPointerTypeForPointee(ASTCtx.VoidPtrTy);
+    Fields.emplace_back(VtablePointer, 0);
+  }
+
+  for (const auto &Base : RD->bases()) {
+    if (Base.isVirtual())
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vortex73 wrote:

I saw that [here](https://github.com/llvm/llvm-project/blob/8ed3cb0e6497944ac7284e88379051b768a426cd/clang/lib/CodeGen/CodeGenTypes.cpp#L812) and emulated that just to be safe.

https://github.com/llvm/llvm-project/pull/140112