[OpenCL] Fix address space for base method call (PR43145)

Clang was creating an UncheckedDerivedToBase ImplicitCastExpr that was
also casting between address spaces.  Insert an ImplicitCastExpr node
for doing the address space conversion.

Differential Revision: https://reviews.llvm.org/D69810

clang/lib/Sema/SemaExpr.cpp

@@ -2711,6 +2711,20 @@ Sema::PerformObjectMemberConversion(Expr *From,
       FromRecordType = FromType;
       DestType = DestRecordType;
     }
+
+    LangAS FromAS = FromRecordType.getAddressSpace();
+    LangAS DestAS = DestRecordType.getAddressSpace();
+    if (FromAS != DestAS) {
+      QualType FromRecordTypeWithoutAS =
+          Context.removeAddrSpaceQualType(FromRecordType);
+      QualType FromTypeWithDestAS =
+          Context.getAddrSpaceQualType(FromRecordTypeWithoutAS, DestAS);
+      if (PointerConversions)
+        FromTypeWithDestAS = Context.getPointerType(FromTypeWithDestAS);
+      From = ImpCastExprToType(From, FromTypeWithDestAS,
+                               CK_AddressSpaceConversion, From->getValueKind())
+                 .get();
+    }
   } else {
     // No conversion necessary.
     return From;

clang/test/CodeGenOpenCLCXX/addrspace-derived-base.cl

@@ -28,6 +28,7 @@ void foo() {
 class B2 {
   public:
     void baseMethod() const {  }
+    int &getRef() { return bb; }
     int bb;
 };
 
@@ -46,7 +47,25 @@ void pr43145(const Derived *argDerived) {
 
 void pr43145_2(B *argB) {
   Derived *x = (Derived*)argB;
+  // CHECK-LABEL: @_Z9pr43145_2
+  // CHECK: bitcast %struct.B addrspace(4)* %0 to %class.Derived addrspace(4)*
 }
 
-// CHECK-LABEL: @_Z9pr43145_2
-// CHECK: bitcast %struct.B addrspace(4)* %0 to %class.Derived addrspace(4)*
+// Assigning to reference returned by base class method through derived class.
+
+void pr43145_3(int n) {
+  Derived d;
+  d.getRef() = n;
+
+  // CHECK-LABEL: @_Z9pr43145_3
+  // CHECK: addrspacecast %class.Derived* %d to %class.Derived addrspace(4)*
+  // CHECK: bitcast i8 addrspace(4)* %add.ptr to %class.B2 addrspace(4)*
+  // CHECK: call {{.*}} @_ZNU3AS42B26getRefEv
+
+  private Derived *pd = &d;
+  pd->getRef() = n;
+
+  // CHECK: addrspacecast %class.Derived* %4 to %class.Derived addrspace(4)*
+  // CHECK: bitcast i8 addrspace(4)* %add.ptr1 to %class.B2 addrspace(4)*
+  // CHECK: call {{.*}} @_ZNU3AS42B26getRefEv
+}