Codegen for object access.

test/libyul/objectCompiler/datacopy.yul

@@ -0,0 +1,48 @@
+object "a" {
+  code {
+    datacopy(0, dataoffset("sub"), datasize("sub"))
+    return(0, datasize("sub"))
+  }
+  object "sub" {
+    code {
+      sstore(0, dataoffset("sub"))
+      mstore(0, datasize("data1"))
+    }
+    data "data1" "Hello, World!"
+  }
+}
+// ----
+// Assembly:
+//     /* "source":26:73   */
+//   dataSize(sub_0)
+//   dataOffset(sub_0)
+//     /* "source":35:36   */
+//   0x00
+//     /* "source":26:73   */
+//   codecopy
+//     /* "source":78:104   */
+//   dataSize(sub_0)
+//     /* "source":85:86   */
+//   0x00
+//     /* "source":78:104   */
+//   return
+// stop
+//
+// sub_0: assembly {
+//         /* "source":143:171   */
+//       0x00
+//         /* "source":150:151   */
+//       0x00
+//         /* "source":143:171   */
+//       sstore
+//         /* "source":178:206   */
+//       0x0d
+//         /* "source":185:186   */
+//       0x00
+//         /* "source":178:206   */
+//       mstore
+//     stop
+//     data_acaf3289d7b601cbd114fb36c4d29c85bbfd5e133f14cb355c3fd8d99367964f 48656c6c6f2c20576f726c6421
+// }
+// Bytecode: 600b600d600039600b6000f3fe6000600055600d600052fe
+// Opcodes: PUSH1 0xB PUSH1 0xD PUSH1 0x0 CODECOPY PUSH1 0xB PUSH1 0x0 RETURN INVALID PUSH1 0x0 PUSH1 0x0 SSTORE PUSH1 0xD PUSH1 0x0 MSTORE INVALID