[Clang] Emit type metadata on vtables when IRPGO instrumentation option is on. (#70841)

The motivating use case is to have type metadata on vtables if IR instrumentation is on (without the requirement of`-fwhole-program-vtables` or `-flto`).

A related rfc is in
https://discourse.llvm.org/t/rfc-dynamic-type-profiling-and-optimizations-in-llvm/74600

Author: mingmingl-llvm

clang/lib/CodeGen/CGVTables.cpp

@@ -1312,7 +1312,10 @@ llvm::GlobalObject::VCallVisibility CodeGenModule::GetVCallVisibilityLevel(
 void CodeGenModule::EmitVTableTypeMetadata(const CXXRecordDecl *RD,
                                            llvm::GlobalVariable *VTable,
                                            const VTableLayout &VTLayout) {
-  if (!getCodeGenOpts().LTOUnit)
+  // Emit type metadata on vtables with LTO or IR instrumentation.
+  // In IR instrumentation, the type metadata is used to find out vtable
+  // definitions (for type profiling) among all global variables.
+  if (!getCodeGenOpts().LTOUnit && !getCodeGenOpts().hasProfileIRInstr())
     return;
 
   CharUnits ComponentWidth = GetTargetTypeStoreSize(getVTableComponentType());

clang/lib/CodeGen/MicrosoftCXXABI.cpp

@@ -1673,7 +1673,11 @@ void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF,
 void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info,
                                              const CXXRecordDecl *RD,
                                              llvm::GlobalVariable *VTable) {
-  if (!CGM.getCodeGenOpts().LTOUnit)
+  // Emit type metadata on vtables with LTO or IR instrumentation.
+  // In IR instrumentation, the type metadata could be used to find out vtable
+  // definitions (for type profiling) among all global variables.
+  if (!CGM.getCodeGenOpts().LTOUnit &&
+      !CGM.getCodeGenOpts().hasProfileIRInstr())
     return;
 
   // TODO: Should VirtualFunctionElimination also be supported here?