[CIR][CIRGen] Fix follow up stores for atomic loads

Author: bcardosolopes

clang/lib/CIR/CodeGen/CIRGenAtomic.cpp

@@ -449,6 +449,14 @@ static void buildAtomicOp(CIRGenFunction &CGF, AtomicExpr *E, Address Dest,
     load->setAttr("mem_order", orderAttr);
     if (E->isVolatile())
       load->setAttr("is_volatile", mlir::UnitAttr::get(builder.getContext()));
+
+    // TODO(cir): this logic should be part of createStore, but doing so
+    // currently breaks CodeGen/union.cpp and CodeGen/union.cpp.
+    auto ptrTy = Dest.getPointer().getType().cast<mlir::cir::PointerType>();
+    if (Dest.getElementType() != ptrTy.getPointee()) {
+      Dest = Dest.withPointer(
+          builder.createPtrBitcast(Dest.getPointer(), Dest.getElementType()));
+    }
     builder.createStore(loc, load->getResult(0), Dest);
     return;
   }

clang/test/CIR/CodeGen/atomic-xchg-field.c

@@ -65,4 +65,18 @@ void structAtomicExchange(unsigned referenceCount, wPtr item) {
 
 // LLVM: [[STORE_OLD]]:
 // LLVM:   store i32 %[[OLD]], ptr
-// LLVM:   br label %[[CONTINUE]]
+// LLVM:   br label %[[CONTINUE]]
+
+void f2(const void *cf);
+
+void structLoad(unsigned referenceCount, wPtr item) {
+  f2(__atomic_load_n(&item->ref, 5));
+}
+
+// CHECK-LABEL: @structLoad
+// CHECK:    %[[ATOMIC_TEMP:.*]] = cir.alloca !cir.ptr<!void>, cir.ptr <!cir.ptr<!void>>, ["atomic-temp"]
+// CHECK:    %[[ATOMIC_LOAD:.*]] = cir.load atomic(seq_cst) %6 : cir.ptr <!u64i>, !u64i
+// CHECK:    %[[RES:.*]] = cir.cast(bitcast, %[[ATOMIC_TEMP]] : !cir.ptr<!cir.ptr<!void>>), !cir.ptr<!u64i>
+// CHECK:    cir.store %[[ATOMIC_LOAD]], %[[RES]] : !u64i, cir.ptr <!u64i>
+
+// No LLVM tests needed for this one, already covered elsewhere.