[IR] Fix issue getting the length property from CharSequence bounded type parameter

Use the class of the subtype of CharSequence when available. When
it is not (for type parameters bounded by CharSequence) call the
CharSequence getter and 'get' method. Using the most specific type
posible fixes the forInStringSpecialized test that expects the
use of INVOKEVIRTUAL and not INVOKEINTERFACE.

Add tests for the type parameter use.

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/ProgressionHandlers.kt

@@ -17,7 +17,6 @@ import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.declarations.IrVariable
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
-import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
@@ -220,7 +219,7 @@ internal class UntilHandler(private val context: CommonBackendContext, private v
 }
 
 /** Builds a [HeaderInfo] for progressions built using the `indices` extension property. */
-internal abstract class IndicesHandler(private val context: CommonBackendContext) : ProgressionHandler {
+internal abstract class IndicesHandler(protected val context: CommonBackendContext) : ProgressionHandler {
 
     // TODO: Handle Collection<*>.indices
 
@@ -228,8 +227,7 @@ internal abstract class IndicesHandler(private val context: CommonBackendContext
         with(context.createIrBuilder(scopeOwner, expression.startOffset, expression.endOffset)) {
             // `last = array.size - 1` (last is inclusive) for the loop `for (i in array.indices)`.
             val receiver = expression.extensionReceiver!!
-            val sizeProperty = receiver.type.getClass()!!.properties.first { it.name.asString() == sizePropertyName() }
-            val last = irCall(sizeProperty.getter!!).apply {
+            val last = irCall(receiver.type.sizePropertyGetter).apply {
                 dispatchReceiver = receiver
             }.decrement()
 
@@ -243,7 +241,7 @@ internal abstract class IndicesHandler(private val context: CommonBackendContext
             )
         }
 
-    internal abstract fun sizePropertyName() : String
+    abstract val IrType.sizePropertyGetter: IrSimpleFunction
 }
 
 internal class ArrayIndicesHandler(context: CommonBackendContext) : IndicesHandler(context) {
@@ -253,7 +251,8 @@ internal class ArrayIndicesHandler(context: CommonBackendContext) : IndicesHandl
         parameterCount { it == 0 }
     }
 
-    override fun sizePropertyName(): String = "size"
+    override val IrType.sizePropertyGetter
+        get() = getClass()!!.properties.first { it.name.asString() == "size" }.getter!!
 }
 
 internal class CharSequenceIndicesHandler(context: CommonBackendContext) : IndicesHandler(context) {
@@ -264,7 +263,13 @@ internal class CharSequenceIndicesHandler(context: CommonBackendContext) : Indic
         parameterCount { it == 0 }
     }
 
-    override fun sizePropertyName(): String = "length"
+    // The lowering operates on subtypes of CharSequence. Therefore, the IrType could be
+    // a type parameter bounded by CharSequence. When that is the case, we cannot get
+    // the class from the type and instead uses the CharSequence getter.
+    override val IrType.sizePropertyGetter
+        get() = getClass()?.properties?.first { it.name.asString() == "length" }?.let {
+            it.getter!!
+        } ?: context.ir.symbols.charSequence.getPropertyGetter("length")!!.owner
 }
 
 /** Builds a [HeaderInfo] for calls to reverse an iterable. */
@@ -372,7 +377,7 @@ internal class ArrayIterationHandler(context: CommonBackendContext) : IndexedGet
     override fun match(expression: IrExpression) = expression.type.run { isArray() || isPrimitiveArray() }
 
     override val IrType.sizePropertyGetter
-        get() = getClass()!!.properties.first { it.name == Name.identifier("size") }.getter!!
+        get() = getClass()!!.properties.first { it.name.asString() == "size" }.getter!!
 
     override val IrType.getFunction
         get() = getClass()!!.functions.first { it.name.asString() == "get" }
@@ -382,9 +387,15 @@ internal class ArrayIterationHandler(context: CommonBackendContext) : IndexedGet
 internal class CharSequenceIterationHandler(context: CommonBackendContext) : IndexedGetIterationHandler(context) {
     override fun match(expression: IrExpression) = expression.type.isSubtypeOfClass(context.ir.symbols.charSequence)
 
+    // The lowering operates on subtypes of CharSequence. Therefore, the IrType could be
+    // a type parameter bounded by CharSequence. When that is the case, we cannot get
+    // the class from the type and instead uses the CharSequence getter and function.
     override val IrType.sizePropertyGetter
-        get() = context.ir.symbols.charSequence.getPropertyGetter("length")!!.owner
+        get() = getClass()?.properties?.first { it.name.asString() == "length" }?.let {
+            it.getter!!
+        } ?: context.ir.symbols.charSequence.getPropertyGetter("length")!!.owner
 
     override val IrType.getFunction
-        get() = context.ir.symbols.charSequence.getSimpleFunction("get")!!.owner
-}
+        get() = getClass()?.functions?.first { it.name.asString() == "get" }
+            ?: context.ir.symbols.charSequence.getSimpleFunction("get")!!.owner
+}

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

@@ -0,0 +1,10 @@
+fun <T: CharSequence> test(sequence: T) {
+    var s = ""
+    for (c in sequence) {
+        s += c
+    }
+}
+
+// 0 iterator
+// 0 hasNext
+// 0 nextChar

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

@@ -0,0 +1,27 @@
+fun <T: CharSequence> test(s: T): Int {
+    var result = 0
+    for (i in s.indices) {
+        result = result * 10 + (i + 1)
+    }
+    return result
+}
+
+// JVM non-IR uses while.
+// JVM IR uses if + do-while.
+
+// 0 iterator
+// 0 getStart
+// 0 getEnd
+// 0 getFirst
+// 0 getLast
+
+// JVM_TEMPLATES
+// 0 IF_ICMPGT
+// 0 IF_ICMPEQ
+// 1 IF_ICMPGE
+// 1 IF
+
+// JVM_IR_TEMPLATES
+// 1 IF_ICMPGT
+// 1 IF_ICMPLE
+// 2 IF

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java

@@ -1677,6 +1677,11 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             runTest("compiler/testData/codegen/bytecodeText/forLoop/forInCharSequence.kt");
         }
 
+        @TestMetadata("forInCharSequenceTypeParameter.kt")
+        public void testForInCharSequenceTypeParameter() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/forLoop/forInCharSequenceTypeParameter.kt");
+        }
+
         @TestMetadata("forInDownToCharMinValue.kt")
         public void testForInDownToCharMinValue() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/forLoop/forInDownToCharMinValue.kt");
@@ -1890,6 +1895,11 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
                 runTest("compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCharSequenceIndices.kt");
             }
 
+            @TestMetadata("forInCharSequenceTypeParameterIndices.kt")
+            public void testForInCharSequenceTypeParameterIndices() throws Exception {
+                runTest("compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCharSequenceTypeParameterIndices.kt");
+            }
+
             @TestMetadata("forInCollectionImplicitReceiverIndices.kt")
             public void testForInCollectionImplicitReceiverIndices() throws Exception {
                 runTest("compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCollectionImplicitReceiverIndices.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBytecodeTextTestGenerated.java

@@ -1632,6 +1632,11 @@ public class IrBytecodeTextTestGenerated extends AbstractIrBytecodeTextTest {
             runTest("compiler/testData/codegen/bytecodeText/forLoop/forInCharSequence.kt");
         }
 
+        @TestMetadata("forInCharSequenceTypeParameter.kt")
+        public void testForInCharSequenceTypeParameter() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/forLoop/forInCharSequenceTypeParameter.kt");
+        }
+
         @TestMetadata("forInDownToCharMinValue.kt")
         public void testForInDownToCharMinValue() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/forLoop/forInDownToCharMinValue.kt");
@@ -1845,6 +1850,11 @@ public class IrBytecodeTextTestGenerated extends AbstractIrBytecodeTextTest {
                 runTest("compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCharSequenceIndices.kt");
             }
 
+            @TestMetadata("forInCharSequenceTypeParameterIndices.kt")
+            public void testForInCharSequenceTypeParameterIndices() throws Exception {
+                runTest("compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCharSequenceTypeParameterIndices.kt");
+            }
+
             @TestMetadata("forInCollectionImplicitReceiverIndices.kt")
             public void testForInCollectionImplicitReceiverIndices() throws Exception {
                 runTest("compiler/testData/codegen/bytecodeText/forLoop/forInIndices/forInCollectionImplicitReceiverIndices.kt");