[CodeGen] Store element type in RValue

For aggregates, we need to store the element type to be able to
reconstruct the aggregate Address. This increases the size of this
packed structure (as the second value is already used for alignment
in this case), but I did not observe any compile-time or memory
usage regression from this change.

clang/lib/CodeGen/CGValue.h

@@ -47,6 +47,8 @@ class RValue {
   llvm::PointerIntPair<llvm::Value *, 2, Flavor> V1;
   // Stores second value and volatility.
   llvm::PointerIntPair<llvm::Value *, 1, bool> V2;
+  // Stores element type for aggregate values.
+  llvm::Type *ElementType;
 
 public:
   bool isScalar() const { return V1.getInt() == Scalar; }
@@ -71,7 +73,8 @@ class RValue {
   Address getAggregateAddress() const {
     assert(isAggregate() && "Not an aggregate!");
     auto align = reinterpret_cast<uintptr_t>(V2.getPointer()) >> AggAlignShift;
-    return Address(V1.getPointer(), CharUnits::fromQuantity(align));
+    return Address(
+        V1.getPointer(), ElementType, CharUnits::fromQuantity(align));
   }
   llvm::Value *getAggregatePointer() const {
     assert(isAggregate() && "Not an aggregate!");
@@ -108,6 +111,7 @@ class RValue {
     RValue ER;
     ER.V1.setPointer(addr.getPointer());
     ER.V1.setInt(Aggregate);
+    ER.ElementType = addr.getElementType();
 
     auto align = static_cast<uintptr_t>(addr.getAlignment().getQuantity());
     ER.V2.setPointer(reinterpret_cast<llvm::Value*>(align << AggAlignShift));