JVM_IR KT-47398 handle @EnhancedNullability String subject as in 1.0

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

@@ -42767,12 +42767,24 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/when/stringOptimization/duplicatingItemsSameHashCode3.kt");
             }
 
+            @Test
+            @TestMetadata("enhancedNullability.kt")
+            public void testEnhancedNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/enhancedNullability.kt");
+            }
+
             @Test
             @TestMetadata("expression.kt")
             public void testExpression() throws Exception {
                 runTest("compiler/testData/codegen/box/when/stringOptimization/expression.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleNullability.kt")
+            public void testFlexibleNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/flexibleNullability.kt");
+            }
+
             @Test
             @TestMetadata("nullability.kt")
             public void testNullability() throws Exception {

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/SwitchGenerator.kt

@@ -9,10 +9,11 @@ import org.jetbrains.kotlin.codegen.`when`.SwitchCodegen.Companion.preferLookupO
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.dump
+import org.jetbrains.kotlin.ir.util.hasAnnotation
 import org.jetbrains.kotlin.ir.util.isTrueConst
+import org.jetbrains.kotlin.load.java.JvmAnnotationNames
 import org.jetbrains.org.objectweb.asm.Label
 import org.jetbrains.org.objectweb.asm.Type
-import java.util.*
 
 // TODO: eliminate the temporary variable
 class SwitchGenerator(private val expression: IrWhen, private val data: BlockInfo, private val codegen: ExpressionCodegen) {
@@ -446,9 +447,19 @@ class SwitchGenerator(private val expression: IrWhen, private val data: BlockInf
                 hashAndSwitchLabels.add(ValueToLabel(key, Label()))
         }
 
-        // Using a switch, the subject string has to be traversed at least twice (hash + comparison * N, where N is #strings hashed into the
+        // Using a switch, the subject string has to be traversed at least twice
-        // same bucket). The optimization isn't better than an IF cascade when #switch-targets <= 2.
+        // (hash + comparison * N, where N is #strings hashed into the same bucket).
-        override fun shouldOptimize() = hashAndSwitchLabels.size > 2
+        // The optimization isn't better than an IF cascade when #switch-targets <= 2.
+        //
+        // Generate "optimized" version for @EnhancedNullability subject type
+        // to model 1.0 behavior causing NPE in case of null value.
+        // TODO make 'when' with String subject behavior consistent.
+        // see:
+        //  box/when/stringOptimization/enhancedNullability.kt
+        //  box/when/stringOptimization/flexibleNullability.kt
+        override fun shouldOptimize() =
+            hashAndSwitchLabels.size > 2 ||
+                    subject.type.hasAnnotation(JvmAnnotationNames.ENHANCED_NULLABILITY_ANNOTATION) && hashAndSwitchLabels.isNotEmpty()
 
         override fun genSwitch() {
             with(codegen) {

compiler/testData/codegen/box/when/kt47365.kt

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// IGNORE_BACKEND: WASM
 
 enum class EType {
     A

compiler/testData/codegen/box/when/stringOptimization/enhancedNullability.kt

@@ -0,0 +1,75 @@
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+
+// FILE: enhancedNullability.kt
+fun testEmpty() {
+    when (J.nullString()) {
+    }
+}
+
+fun testSingle() {
+    try {
+        var q = "other"
+        when (J.nullString()) {
+            "a" -> q = "A"
+        }
+        throw Exception("Should throw NPE, got '$q'")
+    } catch (e: NullPointerException) {
+    }
+}
+
+fun testElseOnly() {
+    var q = "other"
+    when (J.nullString()) {
+        else -> q = "A"
+    }
+    if (q != "A") {
+        throw Exception("Expected: 'A', got '$q'")
+    }
+}
+
+fun testSmall() {
+    try {
+        val q = when (J.nullString()) {
+            "a" -> "A"
+            else -> "other"
+        }
+        throw Exception("Should throw NPE, got '$q'")
+    } catch (e: NullPointerException) {
+    }
+}
+
+fun testBigger() {
+    try {
+        val q = when (J.nullString()) {
+            "a" -> "A"
+            "b" -> "B"
+            "c" -> "C"
+            "d" -> "D"
+            "e" -> "E"
+            "f" -> "F"
+            "g" -> "G"
+            "h" -> "H"
+            else -> "other"
+        }
+        throw Exception("Should throw NPE, got '$q'")
+    } catch (e: NullPointerException) {
+    }
+}
+
+
+fun box(): String {
+    testEmpty()
+    testSingle()
+    testElseOnly()
+    testSmall()
+    testBigger()
+    return "OK"
+}
+
+// FILE: J.java
+import org.jetbrains.annotations.NotNull;
+
+public class J {
+    public static @NotNull String nullString() { return null; }
+}

compiler/testData/codegen/box/when/stringOptimization/flexibleNullability.kt

@@ -0,0 +1,71 @@
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+
+// FILE: flexibleNullability.kt
+fun testEmpty() {
+    when (J.nullString()) {
+    }
+}
+
+fun testSingle() {
+    var q = "other"
+    when (J.nullString()) {
+        "a" -> q = "A"
+    }
+    if (q != "other") {
+        throw Exception("Expected 'other', got '$q'")
+    }
+
+}
+
+fun testElseOnly() {
+    var q = "other"
+    when (J.nullString()) {
+        else -> q = "A"
+    }
+    if (q != "A") {
+        throw Exception("Expected: 'A', got '$q'")
+    }
+}
+
+fun testSmall() {
+    val q = when (J.nullString()) {
+        "a" -> "A"
+        else -> "other"
+    }
+    if (q != "other") {
+        throw Exception("Expected 'other', got '$q'")
+    }
+}
+
+fun testBigger() {
+    val q = when (J.nullString()) {
+        "a" -> "A"
+        "b" -> "B"
+        "c" -> "C"
+        "d" -> "D"
+        "e" -> "E"
+        "f" -> "F"
+        "g" -> "G"
+        "h" -> "H"
+        else -> "other"
+    }
+    if (q != "other") {
+        throw Exception("Expected 'other', got '$q'")
+    }
+}
+
+
+fun box(): String {
+    testEmpty()
+    testSingle()
+    testElseOnly()
+    testSmall()
+    testBigger()
+    return "OK"
+}
+
+// FILE: J.java
+public class J {
+    public static String nullString() { return null; }
+}

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

@@ -42725,12 +42725,24 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/when/stringOptimization/duplicatingItemsSameHashCode3.kt");
             }
 
+            @Test
+            @TestMetadata("enhancedNullability.kt")
+            public void testEnhancedNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/enhancedNullability.kt");
+            }
+
             @Test
             @TestMetadata("expression.kt")
             public void testExpression() throws Exception {
                 runTest("compiler/testData/codegen/box/when/stringOptimization/expression.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleNullability.kt")
+            public void testFlexibleNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/flexibleNullability.kt");
+            }
+
             @Test
             @TestMetadata("nullability.kt")
             public void testNullability() throws Exception {

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

@@ -42767,12 +42767,24 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/when/stringOptimization/duplicatingItemsSameHashCode3.kt");
             }
 
+            @Test
+            @TestMetadata("enhancedNullability.kt")
+            public void testEnhancedNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/enhancedNullability.kt");
+            }
+
             @Test
             @TestMetadata("expression.kt")
             public void testExpression() throws Exception {
                 runTest("compiler/testData/codegen/box/when/stringOptimization/expression.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleNullability.kt")
+            public void testFlexibleNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/flexibleNullability.kt");
+            }
+
             @Test
             @TestMetadata("nullability.kt")
             public void testNullability() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -34445,11 +34445,21 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/when/stringOptimization/duplicatingItemsSameHashCode3.kt");
             }
 
+            @TestMetadata("enhancedNullability.kt")
+            public void testEnhancedNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/enhancedNullability.kt");
+            }
+
             @TestMetadata("expression.kt")
             public void testExpression() throws Exception {
                 runTest("compiler/testData/codegen/box/when/stringOptimization/expression.kt");
             }
 
+            @TestMetadata("flexibleNullability.kt")
+            public void testFlexibleNullability() throws Exception {
+                runTest("compiler/testData/codegen/box/when/stringOptimization/flexibleNullability.kt");
+            }
+
             @TestMetadata("nullability.kt")
             public void testNullability() throws Exception {
                 runTest("compiler/testData/codegen/box/when/stringOptimization/nullability.kt");