[GROOVY-10314] finally block produces long sequence of nop instructions

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 4.0.0-beta-2
• Component/s: class generator, Compiler
• Labels: bytecode
• Assignee: Eric Milles
• Reporter: Eric Milles
• Created: 16/Oct/21 13:47
• Updated: 03/Feb/22 22:32
• Resolved: 16/Oct/21 20:58

Description

Consider the following:

def test() {
  try {
    print 'hello'
  } finally {
    print ' world'
  }
}

For any non-void method where the try/finally is part of the return value, a long sequence of nop bytecode instructions is produced. The sample code from GROOVY-4721 produces 18 nop in a row.

  // Method descriptor #42 ()Ljava/lang/Object;
  // Stack: 2, Locals: 3
  public java.lang.Object test();
     0  aload_0 [this]
     1  ldc <String "hello"> [47]
     3  invokedynamic 1 invoke(Scratch, java.lang.String) : java.lang.Object [53]
     8  astore_1
     9  nop
    10  aload_0 [this]
    11  ldc <String " world"> [55]
    13  invokedynamic 1 invoke(Scratch, java.lang.String) : java.lang.Object [53]
    18  pop
    19  nop
    20  aload_1
    21  areturn
    22  nop
    23  nop
    24  athrow
    25  nop
    26  nop
    27  nop
    28  nop
    29  nop
    30  nop
    31  nop
    32  nop
    33  athrow
    34  nop
    35  nop
    36  athrow
    37  astore_2
    38  aload_0 [this]
    39  ldc <String " world"> [55]
    41  invokedynamic 1 invoke(Scratch, java.lang.String) : java.lang.Object [53]
    46  pop
    47  aload_2
    48  athrow
    49  nop
    50  athrow
      Exception Table:
        [pc: 0, pc: 10] -> 37 when : any
        [pc: 20, pc: 22] -> 37 when : any
      Line numbers:
        [pc: 0, line: 3]
        [pc: 10, line: 5]
        [pc: 49, line: 7]
      Local variable table:
        [pc: 0, pc: 49] local: this index: 0 type: Scratch