Handle withIndex() on Iterables (including progressions) and Sequences

in ForLoopsLowering.

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInDownToWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in (7 downTo 4).withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(7, 6, 5, 4), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInIndicesWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in listOf(4, 5, 6, 7).indices.withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(0, 1, 2, 3), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInRangeToWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in (4..7).withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(4, 5, 6, 7), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInReversedStepWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in ((4..11).reversed() step 2).withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(11, 9, 7, 5), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInReversedWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in (4..7).reversed().withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(7, 6, 5, 4), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInStepReversedWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in (4..11 step 2).reversed().withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(10, 8, 6, 4), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInStepWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in (4..11 step 2).withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(4, 6, 8, 10), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInUntilWithIndex.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in (4 until 8).withIndex()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(4, 5, 6, 7), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInWithIndexNoIndexOrElementVar.kt

@@ -0,0 +1,15 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    var count = 0
+    for ((_, _) in (4..7).withIndex()) {
+        count++
+    }
+    assertEquals(4, count)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInWithIndexNotDestructured.kt

@@ -0,0 +1,19 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for (iv in (4..7).withIndex()) {
+        val (i, v) = iv
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(4, 5, 6, 7), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInWithIndexReversed.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((i, v) in (4..7).withIndex().reversed()) {
+        indexList += i
+        valueList += v
+    }
+    assertEquals(listOf(3, 2, 1, 0), indexList)
+    assertEquals(listOf(7, 6, 5, 4), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInWithIndexWithDestructuringInLoop.kt

@@ -0,0 +1,23 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val indexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    val valueAndIndexList = mutableListOf<Int>()
+    for ((i, v) in (4..7).withIndex()) {
+        val (v2, i2) = Pair(v, i)
+        indexList += i
+        valueList += v
+        valueAndIndexList += v2
+        valueAndIndexList += i2
+    }
+    assertEquals(listOf(0, 1, 2, 3), indexList)
+    assertEquals(listOf(4, 5, 6, 7), valueList)
+    assertEquals(listOf(4, 0, 5, 1, 6, 2, 7, 3), valueAndIndexList)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInProgressionWithIndex/forInWithIndexWithIndex.kt

@@ -0,0 +1,22 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// KJS_WITH_FULL_RUNTIME
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun box(): String {
+    val outerIndexList = mutableListOf<Int>()
+    val innerIndexList = mutableListOf<Int>()
+    val valueList = mutableListOf<Int>()
+    for ((outer, iv) in (4..7).withIndex().withIndex()) {
+        outerIndexList += outer
+        val (inner, v) = iv
+        innerIndexList += inner
+        valueList += v
+    }
+    assertEquals(listOf(0, 1, 2, 3), outerIndexList)
+    assertEquals(listOf(0, 1, 2, 3), innerIndexList)
+    assertEquals(listOf(4, 5, 6, 7), valueList)
+
+    return "OK"
+}

compiler/testData/codegen/bytecodeText/forLoop/forInIterableWithIndex/forInEmptyListWithIndex.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf<Any>()
 
 fun box(): String {
@@ -15,3 +14,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInIterableWithIndex/forInListWithIndex.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d")
 
 fun box(): String {
@@ -18,3 +17,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInIterableWithIndex/forInListWithIndexNoElementVar.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d")
 
 fun box(): String {
@@ -18,3 +17,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInIterableWithIndex/forInListWithIndexNoIndexVar.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d")
 
 fun box(): String {
@@ -18,3 +17,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInIterableWithIndex/forInListWithIndexWithExplicitlyTypedIndexVariable.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d")
 
 fun useAny(x: Any) {}
@@ -21,3 +20,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInDownToWithIndex.kt

@@ -0,0 +1,28 @@
+fun box(): String {
+    for ((i, v) in (7 downTo 4).withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInIndicesWithIndex.kt

@@ -0,0 +1,29 @@
+fun box(): String {
+    for ((i, v) in listOf(4, 5, 6, 7).indices.withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep
+// 0 getIndices

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInRangeToWithIndex.kt

@@ -0,0 +1,28 @@
+fun box(): String {
+    for ((i, v) in (4..7).withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInReversedStepWithIndex.kt

@@ -0,0 +1,30 @@
+fun box(): String {
+    for ((i, v) in ((4..11).reversed() step 2).withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep
+// 0 reversed
+// 0 step

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInReversedWithIndex.kt

@@ -0,0 +1,29 @@
+fun box(): String {
+    for ((i, v) in (4..7).reversed().withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep
+// 0 reversed

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInStepReversedWithIndex.kt

@@ -0,0 +1,30 @@
+fun box(): String {
+    for ((i, v) in (4..11 step 2).reversed().withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep
+// 0 reversed
+// 0 step

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInStepWithIndex.kt

@@ -0,0 +1,29 @@
+fun box(): String {
+    for ((i, v) in (4..11 step 2).withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep
+// 0 step

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInUntilWithIndex.kt

@@ -0,0 +1,28 @@
+fun box(): String {
+    for ((i, v) in (4 until 8).withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInWithIndexNoIndexOrElementVar.kt

@@ -0,0 +1,28 @@
+fun box(): String {
+    for ((_, _) in (4..7).withIndex()) {
+    }
+
+    return "OK"
+}
+
+// 0 withIndex
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0
+
+// JVM_TEMPLATES
+// 1 iterator
+// 1 hasNext
+// 1 next
+
+// JVM_IR_TEMPLATES
+// 0 iterator
+// 0 hasNext
+// 0 next
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+// 0 getStep

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInWithIndexNotDestructured.kt

@@ -0,0 +1,15 @@
+fun box(): String {
+    for (iv in (4..7).withIndex()) {
+    }
+
+    return "OK"
+}
+
+// We do not optimize `withIndex()` if the loop variable is not destructured
+
+// 1 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 0 component1
+// 0 component2

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInWithIndexReversed.kt

@@ -0,0 +1,16 @@
+fun box(): String {
+    for ((i, v) in (4..7).withIndex().reversed()) {
+    }
+
+    return "OK"
+}
+
+// We do not optimize `withIndex().reversed()`
+
+// 1 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 1 component1
+// 1 component2
+// 1 reversed

compiler/testData/codegen/bytecodeText/forLoop/forInProgressionWithIndex/forInWithIndexWithIndex.kt

@@ -0,0 +1,18 @@
+fun box(): String {
+    for ((outer, iv) in (4..7).withIndex().withIndex()) {
+    }
+
+    return "OK"
+}
+
+// We optimize the outer `withIndex()` and treat the inner one as an Iterable
+
+// 1 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 0 component1
+// 0 component2
+
+// The ICONST_0 is for initializing the index in the lowered for-loop.
+// 1 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInSequenceWithIndex/forInEmptySequenceWithIndex.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf<Any>().asSequence()
 
 fun box(): String {
@@ -15,3 +14,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInSequenceWithIndex/forInSequenceWithIndex.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d").asSequence()
 
 fun box(): String {
@@ -18,3 +17,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInSequenceWithIndex/forInSequenceWithIndexNoElementVar.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d").asSequence()
 
 fun box(): String {
@@ -18,3 +17,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInSequenceWithIndex/forInSequenceWithIndexNoIndexVar.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d").asSequence()
 
 fun box(): String {
@@ -18,3 +17,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInSequenceWithIndex/forInSequenceWithIndexThrowsCME.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 // FULL_JDK
 
 val xsl = arrayListOf("a", "b", "c", "d")
@@ -29,3 +28,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for cmeThrown. 3rd is for initializing the index in the lowered for-loop.
+// 3 ICONST_0

compiler/testData/codegen/bytecodeText/forLoop/forInSequenceWithIndex/forInSequenceWithIndexWithExplicitlyTypedIndexVariable.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val xs = listOf("a", "b", "c", "d").asSequence()
 
 fun useAny(x: Any) {}
@@ -21,3 +20,6 @@ fun box(): String {
 // 1 next
 // 0 component1
 // 0 component2
+
+// The 1st ICONST_0 is for initializing the list. 2nd is for initializing the index in the lowered for-loop.
+// 2 ICONST_0