[Sol->Yul] Implementing struct copying from storage to memory

test/libsolidity/semanticTests/structs/struct_copy_via_local.sol

@@ -3,6 +3,7 @@ contract c {
         uint256 a;
         uint256 b;
     }
+    uint[75] r;
     Struct data1;
     Struct data2;
 
@@ -15,5 +16,7 @@ contract c {
     }
 }
 
+// ====
+// compileViaYul: also
 // ----
 // test() -> true

test/libsolidity/semanticTests/structs/struct_storage_to_memory.sol

@@ -0,0 +1,26 @@
+pragma experimental ABIEncoderV2;
+
+contract C {
+    struct S {
+        uint32 a;
+        uint128 b;
+        uint256 c;
+    }
+    struct X {
+        uint32 a;
+        S s;
+    }
+
+    uint[79] arr;
+    X x = X(12, S(42, 23, 34));
+
+    function f() external returns (uint32, uint128, uint256) {
+        X memory m = x;
+        return (m.s.a, m.s.b, m.s.c);
+    }
+}
+
+// ====
+// compileViaYul: also
+// ----
+// f() -> 42, 23, 34