[CodeGen] Record if a C++ record is a trivial type

[asmith]

Summary

This has a dependence on D45122

[asmith]

Adding Aleksandr

[zturner]

Why do we only want this for CodeView?

[rnk]

CodeGen/CGDebugInfo.cpp

2842–2843

I think we might as well set it when emitting DWARF for simplicity.

[rnk]

lgtm

I still think we probably want to flag individual constructors and destructors as trivial, so we can decide whether to emit them or not in CodeViewDebug.cpp.

[lebedev.ri]

Test?

CodeGen/CGDebugInfo.cpp

llvm::DICompositeType *CGDebugInfo::CreateLimitedType(const RecordType *Ty) {
 
   // Explicitly record the calling convention for C++ records.
   auto Flags = llvm::DINode::FlagZero;
   if (auto CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
     if (CGM.getCXXABI().getRecordArgABI(CXXRD) == CGCXXABI::RAA_Indirect)
       Flags |= llvm::DINode::FlagTypePassByReference;
     else
       Flags |= llvm::DINode::FlagTypePassByValue;
+
+    // When emitting codeview, record if a C++ record is trivial type.
+    if (CGM.getCodeGenOpts().EmitCodeView) {
+      if (CXXRD->isTrivial())
+        Flags |= llvm::DINode::FlagTrivial;
+    }
   }
 
   llvm::DICompositeType *RealDecl = DBuilder.createReplaceableCompositeType(
       getTagForRecord(RD), RDName, RDContext, DefUnit, Line, 0, Size, Align,
       Flags, FullName);
 
   // Elements of composite types usually have back to the type, creating
   // uniquing cycles.  Distinct nodes are more efficient.