Support const-bound counter loop generation for 'downTo'

compiler/testData/codegen/box/ranges/forInDownTo/forIntInDownToWithNonConstBounds.kt

@@ -0,0 +1,16 @@
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+fun low() = 4
+fun high() = 1
+
+fun box(): String {
+    var sum = 0
+    for (i in low() downTo high()) {
+        sum = sum * 10 + i
+    }
+    assertEquals(4321, sum)
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forWithPossibleOverflow/forInDownToCharMinValue.kt

@@ -0,0 +1,15 @@
+// WITH_RUNTIME
+
+const val M = 0.toChar()
+
+fun box(): String {
+    var count = 0
+    for (i in M downTo M) {
+        ++count
+        if (count > 1) {
+            throw AssertionError("Loop should be executed once")
+        }
+    }
+    if (count != 1) throw AssertionError("Should be executed once")
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forWithPossibleOverflow/forInDownToIntMinValue.kt

@@ -0,0 +1,15 @@
+// WITH_RUNTIME
+
+const val M = Int.MIN_VALUE
+
+fun box(): String {
+    var count = 0
+    for (i in M downTo M) {
+        ++count
+        if (count > 1) {
+            throw AssertionError("Loop should be executed once")
+        }
+    }
+    if (count != 1) throw AssertionError("Should be executed once")
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forWithPossibleOverflow/forInDownToLongMinValue.kt

@@ -0,0 +1,15 @@
+// WITH_RUNTIME
+
+const val M = Long.MIN_VALUE
+
+fun box(): String {
+    var count = 0
+    for (i in M downTo M) {
+        ++count
+        if (count > 1) {
+            throw AssertionError("Loop should be executed once")
+        }
+    }
+    if (count != 1) throw AssertionError("Should be executed once")
+    return "OK"
+}

compiler/testData/codegen/bytecodeText/forLoop/forInReversed/forInReversedRangeLiteral.kt

@@ -29,4 +29,7 @@ fun box(): String {
 // 0 getFirst
 // 0 getLast
 // 0 getStep
-// 0 IF_ICMPEQ
+// 0 IFEQ
+// 0 IF_ICMPEQ
+// 2 IF_ICMPLT
+// 1 LCMP

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

@@ -12,4 +12,6 @@ fun test(): Int {
 // 0 getStart
 // 0 getEnd
 // 0 getFirst
-// 0 getLast
+// 0 getLast
+// 0 IF_ICMPEQ
+// 1 IF_ICMPLT