Make PlaceRef hold a PlaceValue for the non-layout fields (like OperandRef does)

compiler/rustc_codegen_llvm/src/abi.rs

@@ -233,7 +233,7 @@ impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                 bx.store(val, llscratch, scratch_align);
                 // ... and then memcpy it to the intended destination.
                 bx.memcpy(
-                    dst.llval,
+                    dst.val.llval,
                     self.layout.align.abi,
                     llscratch,
                     scratch_align,