Suspending Lambda

[poseidon-mysugr]

Given the following class:

class SuspendingLambda {
    private fun foo(suspendingLambda: suspend () -> Unit) {}
    fun bar() {
        foo {}
    }
}

the Kotlin 1.6.0 compiler generates an inner class SuspendingLambda.$bar.$1 with a function invokeSuspend with the following bytecode:

  public final java.lang.Object invokeSuspend(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Ljava/lang/Object;
    flags: (0x0011) ACC_PUBLIC, ACC_FINAL
    Code:
      stack=3, locals=2, args_size=2
         0: invokestatic  #37                 // Method kotlin/coroutines/intrinsics/IntrinsicsKt.getCOROUTINE_SUSPENDED:()Ljava/lang/Object;
         3: pop
         4: aload_0
         5: getfield      #41                 // Field label:I
         8: tableswitch   { // 0 to 0
                       0: 28
                 default: 36
            }
        28: aload_1
        29: invokestatic  #47                 // Method kotlin/ResultKt.throwOnFailure:(Ljava/lang/Object;)V
        32: getstatic     #53                 // Field kotlin/Unit.INSTANCE:Lkotlin/Unit;
        35: areturn
        36: new           #55                 // class java/lang/IllegalStateException
        39: dup
        40: ldc           #57                 // String call to \'resume\' before \'invoke\' with coroutine
        42: invokespecial #60                 // Method java/lang/IllegalStateException."<init>":(Ljava/lang/String;)V
        45: athrow
      StackMapTable: number_of_entries = 2
        frame_type = 28 /* same */
        frame_type = 7 /* same */
      LineNumberTable:
        line 6: 3
        line 6: 32
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
           32       4     0  this   Lcom/mysugr/SuspendingLambda$bar$1;
           32       4     1 $result   Ljava/lang/Object;
    RuntimeInvisibleAnnotations:
      0: #30()
        org.jetbrains.annotations.Nullable
    RuntimeInvisibleParameterAnnotations:
      parameter 0:
        0: #31()
          org.jetbrains.annotations.NotNull

The tableswitch instruction creates two branches, one of which (instructions 36 to 45) is impossible to cover in test cases, because the Kotlin compiler already takes care that this fault condition doesn't happen.

In this PR, a new filter is introduced to filter both the tableswitch instruction and the branch that throws the IllegalStateException.

Also, new functions nextIsLdc and nextIsLdcStartingWith are introduced to the AbstractMatcher to simplify a few cases where the cst property of the LdcInsnNode is checked against a String or a String prefix.

[ChristopherKoellner]

I have one question.
Other than that it looks good.