Generate for-in-indices as a precondition loop

Precondition loops are better optimized by HotSpot
(and, quite likely, by ART).
Also, we generate more compact bytecode that way.

KT-17903 Generate 'for-in-indices' as a precondition loop

compiler/backend/src/org/jetbrains/kotlin/codegen/forLoop/ForInOptimizedIndicesLoopGenerator.kt

@@ -28,21 +28,18 @@ abstract class ForInOptimizedIndicesLoopGenerator(
         codegen: ExpressionCodegen,
         forExpression: KtForExpression,
         loopRangeCall: ResolvedCall<*>
-) : AbstractForInRangeLoopGenerator(codegen, forExpression) {
+) : AbstractForInExclusiveRangeLoopGenerator(codegen, forExpression) {
     protected val receiverValue: ReceiverValue = loopRangeCall.extensionReceiver!!
     protected val expectedReceiverType: KotlinType = ExpressionCodegen.getExpectedReceiverType(loopRangeCall)
 
-    override fun storeRangeStartAndEnd() {
+    override fun generateFrom(): StackValue =
-        loopParameter().store(StackValue.constant(0, asmElementType), codegen.v)
+            StackValue.constant(0, asmElementType)
 
-        val receiver = codegen.generateReceiverValue(receiverValue, false)
+    override fun generateTo(): StackValue =
-        val receiverType = codegen.asmType(expectedReceiverType)
+            StackValue.operation(Type.INT_TYPE) { v ->
-        receiver.put(receiverType, codegen.v)
+                codegen.generateReceiverValue(receiverValue, false).put(codegen.asmType(expectedReceiverType), v)
-        getReceiverSizeAsInt()
+                getReceiverSizeAsInt()
-        codegen.v.iconst(1)
+            }
-        codegen.v.sub(Type.INT_TYPE)
-        StackValue.local(endVar, asmElementType).store(StackValue.onStack(Type.INT_TYPE), codegen.v)
-    }
 
     /**
      * `(receiver -> size:I)`

compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCharSequenceIndices.kt

@@ -12,4 +12,8 @@ fun test(s: CharSequence): Int {
 // 0 getStart
 // 0 getEnd
 // 0 getFirst
-// 0 getLast
+// 0 getLast
+
+// 0 IF_ICMPGT
+// 0 IF_ICMPEQ
+// 1 IF_ICMPGE

compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCollectionImplicitReceiverIndices.kt

@@ -12,4 +12,8 @@ fun Collection<Int>.sumIndices(): Int {
 // 0 getStart
 // 0 getEnd
 // 0 getFirst
-// 0 getLast
+// 0 getLast
+
+// 0 IF_ICMPGT
+// 0 IF_ICMPEQ
+// 1 IF_ICMPGE

compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCollectionIndices.kt

@@ -11,4 +11,8 @@ fun test() {
 // 0 getStart
 // 0 getEnd
 // 0 getFirst
-// 0 getLast
+// 0 getLast
+
+// 0 IF_ICMPGT
+// 0 IF_ICMPEQ
+// 1 IF_ICMPGE

compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInObjectArrayIndices.kt

@@ -11,4 +11,8 @@ fun test() {
 // 0 getStart
 // 0 getEnd
 // 0 getFirst
-// 0 getLast
+// 0 getLast
+
+// 0 IF_ICMPGT
+// 0 IF_ICMPEQ
+// 1 IF_ICMPGE

compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInPrimitiveArrayIndices.kt

@@ -11,4 +11,8 @@ fun test() {
 // 0 getStart
 // 0 getEnd
 // 0 getFirst
-// 0 getLast
+// 0 getLast
+
+// 0 IF_ICMPGT
+// 0 IF_ICMPEQ
+// 1 IF_ICMPGE