Opcode Suite fails for Scala 2.13.8+

[razajafri]

The Opcode tests in OpcodeSuite.scala fail when using scala.version 2.13.8+ with the following exception

- IFNONNULL opcode *** FAILED ***
  [,z,] did not equal [,z,z] (OpcodeSuite.scala:62)

We need to add support for it in the udf-compiler.

[mattahrens]

@abellina can you triage this issue to understand the potential fix needed?

[abellina]

I've finally gotten to this. I see different bytecode between scala 2.13 and scala 2.12, and that may be part of the issue, but I am not sure yet. Adding some tracing in the Instruction class, we seem to get to: 5: areturn in the scala 2.13 case and then emit the expression. The result ends up being that we pick a in the result instead of picking b. The UDF is invoked with a row of non-null values ["", "z"] and we say "if the first item (a) is null, then we pick a, else we pick b". a is non null, and we are doing something wrong in the compilation as we are picking b and that's why the test fails.

source:

  val myudf: (String, String) => String = (a: String, b: String) => {
    if (null == a) {
      a
    } else {
      b
    }
  }

For the scala 2.13 case, I see:

  public static final java.lang.String $anonfun$myudf$1(java.lang.String, java.lang.String);
    Code:
       0: aload_0
       1: ifnonnull     6
       4: aload_0
       5: areturn
       6: aload_1
       7: areturn

For the scala 2.12 one I see:

  public static final java.lang.String $anonfun$myudf$1(java.lang.String, java.lang.String);
    Code:
       0: aload_0
       1: ifnonnull     8
       4: aload_0
       5: goto          9
       8: aload_1
       9: areturn