reapply r98656 unmodified, which exposed the asmprinter not 
handling constant unions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98680 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index a328837..b9453c9 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -293,6 +293,8 @@
       } else if (ConstantStruct *UserCS = dyn_cast<ConstantStruct>(UserC)) {
         NewC = ConstantStruct::get(Context, &NewOps[0], NewOps.size(),
                                          UserCS->getType()->isPacked());
+      } else if (ConstantUnion *UserCU = dyn_cast<ConstantUnion>(UserC)) {
+        NewC = ConstantUnion::get(UserCU->getType(), NewOps[0]);
       } else if (isa<ConstantVector>(UserC)) {
         NewC = ConstantVector::get(&NewOps[0], NewOps.size());
       } else {
@@ -1015,6 +1017,11 @@
           Elts.push_back(ValueList.getConstantFwdRef(Record[i],
                                                      STy->getElementType(i)));
         V = ConstantStruct::get(STy, Elts);
+      } else if (const UnionType *UnTy = dyn_cast<UnionType>(CurTy)) {
+        uint64_t Index = Record[0];
+        Constant *Val = ValueList.getConstantFwdRef(Record[1],
+                                        UnTy->getElementType(Index));
+        V = ConstantUnion::get(UnTy, Val);
       } else if (const ArrayType *ATy = dyn_cast<ArrayType>(CurTy)) {
         const Type *EltTy = ATy->getElementType();
         for (unsigned i = 0; i != Size; ++i)