Introduce the DIEDedupeTopLevelRef CAS Block

DIEDedupeTopLevelRef is a CAS block that holds no data and has
references to DIEDataRef CAS blocks. This makes it easy to check that a
DIETopLevelRef in a CAS is valid, as it should only have 3 references to
it, a DIEDedupeTopLevelRef, a DIEAbbrevSetRef, and a DIEDistinctDataRef

Author: rastogishubham

llvm/include/llvm/MCCAS/MCCASObjectV1.def

@@ -41,6 +41,7 @@ CASV1_SIMPLE_GROUP_REF(SymbolTableRef, mc:symbol_table)
 CASV1_SIMPLE_GROUP_REF(DebugStringSectionRef, mc:debug_string_section)
 CASV1_SIMPLE_GROUP_REF(DIEAbbrevSetRef, mc:debug_DIE_abbrev_set)
 CASV1_SIMPLE_GROUP_REF(DIETopLevelRef, mc:debug_DIE_top_level)
+CASV1_SIMPLE_GROUP_REF(DIEDedupeTopLevelRef, mc:debug_DIE_Dedupe_top_level)
 
 #undef CASV1_SIMPLE_GROUP_REF
 #endif /* CASV1_SIMPLE_GPOUP_REF */

llvm/lib/MCCAS/MCCASObjectV1.cpp

@@ -2918,6 +2918,16 @@ DIETopLevelRef::create(MCCASBuilder &MB, ArrayRef<cas::ObjectRef> Children) {
   return get(B->build());
 }
 
+Expected<DIEDedupeTopLevelRef>
+DIEDedupeTopLevelRef::create(MCCASBuilder &MB,
+                             ArrayRef<cas::ObjectRef> Children) {
+  Expected<Builder> B = Builder::startNode(MB.Schema, KindString);
+  if (!B)
+    return B.takeError();
+  append_range(B->Refs, Children);
+  return get(B->build());
+}
+
 Expected<DIEDataRef> DIEDataRef::create(MCCASBuilder &MB,
                                         ArrayRef<cas::ObjectRef> Children,
                                         ArrayRef<char> Contents) {