JVM_IR: Generate counter loop for reversed array (KT-22429)

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -1234,6 +1234,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/codegen/box/arrays/forInReversed"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);
             }
 
+            @Test
+            @TestMetadata("reversedArray.kt")
+            public void testReversedArray() throws Exception {
+                runTest("compiler/testData/codegen/box/arrays/forInReversed/reversedArray.kt");
+            }
+
             @Test
             @TestMetadata("reversedArrayOriginalUpdatedInLoopBody.kt")
             public void testReversedArrayOriginalUpdatedInLoopBody() throws Exception {

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

@@ -10,12 +10,15 @@ import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.loops.ExpressionHandler
 import org.jetbrains.kotlin.backend.common.lower.loops.HeaderInfo
 import org.jetbrains.kotlin.backend.common.lower.loops.IndexedGetHeaderInfo
+import org.jetbrains.kotlin.backend.common.lower.matchers.Quantifier
 import org.jetbrains.kotlin.backend.common.lower.matchers.SimpleCalleeMatcher
+import org.jetbrains.kotlin.backend.common.lower.matchers.createIrCallMatcher
 import org.jetbrains.kotlin.ir.builders.createTmpVariable
 import org.jetbrains.kotlin.ir.builders.irCall
 import org.jetbrains.kotlin.ir.builders.irGet
 import org.jetbrains.kotlin.ir.builders.irInt
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
+import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.types.*
@@ -75,7 +78,21 @@ internal class ArrayIterationHandler(context: CommonBackendContext) : IndexedGet
     private val supportsUnsignedArrays = context.optimizeLoopsOverUnsignedArrays
 
     override fun matchIterable(expression: IrExpression) =
-        expression.type.run { isArray() || isPrimitiveArray() || (supportsUnsignedArrays && isUnsignedArray()) }
+        expression.type.run { isArray() || isPrimitiveArray() || (supportsUnsignedArrays && isUnsignedArray()) } ||
+                expression.run {
+                    this is IrCall && reversedArrayMatcher(this)
+                }
+
+    private val reversedArrayMatcher =
+        createIrCallMatcher(Quantifier.ANY) {
+            callee {
+                fqName { it == FqName("kotlin.collections.reversed") }
+                extensionReceiver {
+                    it != null && it.type.run { isArray() || isPrimitiveArray() }
+                }
+                parameterCount { it == 0 }
+            }
+        }
 
     override val IrType.sizePropertyGetter
         get() = getClass()!!.getPropertyGetter("size")!!.owner

compiler/testData/codegen/box/arrays/forInReversed/reversedArray.kt

@@ -0,0 +1,33 @@
+// TARGET_BACKEND: JVM_IR
+// WITH_STDLIB
+import kotlin.test.*
+
+fun box(): String {
+    testReversed()
+    testReversedArray()
+    return "OK"
+}
+
+fun testReversed() {
+    val arr = intArrayOf(6, 7, 8, 9)
+    var result = ""
+    for (i in arr.reversed()) {
+        arr[0] = 0
+        result += i
+    }
+    assertEquals("9876", result)
+}
+
+fun testReversedArray() {
+    val arr = intArrayOf(6, 7, 8, 9)
+    var result = ""
+    for (i in arr.reversedArray()) {
+        arr[0] = 0
+        result += i
+    }
+    assertEquals("9876", result)
+}
+
+// CHECK_BYTECODE_TEXT
+// 0 java/util/List.iterator
+// 2 IINC

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -1234,6 +1234,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/codegen/box/arrays/forInReversed"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);
             }
 
+            @Test
+            @TestMetadata("reversedArray.kt")
+            public void testReversedArray() throws Exception {
+                runTest("compiler/testData/codegen/box/arrays/forInReversed/reversedArray.kt");
+            }
+
             @Test
             @TestMetadata("reversedArrayOriginalUpdatedInLoopBody.kt")
             public void testReversedArrayOriginalUpdatedInLoopBody() throws Exception {