Provide optimized code generation for for-in-withIndex for iterables

#KT-5177 In Progress

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

@@ -0,0 +1,18 @@
+// WITH_RUNTIME
+
+val xs = listOf<Any>()
+
+fun box(): String {
+    val s = StringBuilder()
+    for ((index, x) in xs.withIndex()) {
+        return "Loop over empty array should not be executed"
+    }
+    return "OK"
+}
+
+// 0 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 0 component1
+// 0 component2

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

@@ -0,0 +1,21 @@
+// WITH_RUNTIME
+
+val xs = listOf("a", "b", "c", "d")
+
+fun box(): String {
+    val s = StringBuilder()
+
+    for ((index, x) in xs.withIndex()) {
+        s.append("$index:$x;")
+    }
+
+    val ss = s.toString()
+    return if (ss == "0:a;1:b;2:c;3:d;") "OK" else "fail: '$ss'"
+}
+
+// 0 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 0 component1
+// 0 component2

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

@@ -0,0 +1,21 @@
+// WITH_RUNTIME
+
+val xs = listOf("a", "b", "c", "d")
+
+fun box(): String {
+    val s = StringBuilder()
+
+    for ((i, _) in xs.withIndex()) {
+        s.append("$i;")
+    }
+
+    val ss = s.toString()
+    return if (ss == "0;1;2;3;") "OK" else "fail: '$ss'"
+}
+
+// 0 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 0 component1
+// 0 component2

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

@@ -0,0 +1,21 @@
+// WITH_RUNTIME
+
+val xs = listOf("a", "b", "c", "d")
+
+fun box(): String {
+    val s = StringBuilder()
+
+    for ((_, x) in xs.withIndex()) {
+        s.append("$x;")
+    }
+
+    val ss = s.toString()
+    return if (ss == "a;b;c;d;") "OK" else "fail: '$ss'"
+}
+
+// 0 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 0 component1
+// 0 component2

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

@@ -0,0 +1,24 @@
+// WITH_RUNTIME
+
+val xs = listOf("a", "b", "c", "d")
+
+fun useAny(x: Any) {}
+
+fun box(): String {
+    val s = StringBuilder()
+
+    for ((index: Any, x) in xs.withIndex()) {
+        useAny(index)
+        s.append("$index:$x;")
+    }
+
+    val ss = s.toString()
+    return if (ss == "0:a;1:b;2:c;3:d;") "OK" else "fail: '$ss'"
+}
+
+// 0 withIndex
+// 1 iterator
+// 1 hasNext
+// 1 next
+// 0 component1
+// 0 component2