[IR] Support function references

Signed-off-by: Evgeniy.Zhelenskiy <Evgeniy.Zhelenskiy@jetbrains.com>

#KT-1179

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

@@ -50459,6 +50459,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/valueClasses/forStatement.kt", TransformersFunctions.getReplaceOptionalJvmInlineAnnotationWithReal());
         }
 
+        @Test
+        @TestMetadata("functionReferences.kt")
+        public void testFunctionReferences() throws Exception {
+            runTest("compiler/testData/codegen/box/valueClasses/functionReferences.kt", TransformersFunctions.getReplaceOptionalJvmInlineAnnotationWithReal());
+        }
+
         @Test
         @TestMetadata("mfvcFieldInitializationOrder.kt")
         public void testMfvcFieldInitializationOrder() throws Exception {

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmMultiFieldValueClassLowering.kt

@@ -24,6 +24,8 @@ import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.builders.declarations.buildFun
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.impl.IrConstructorCallImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrFunctionReferenceImpl
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
 import org.jetbrains.kotlin.ir.symbols.impl.IrAnonymousInitializerSymbolImpl
@@ -680,8 +682,34 @@ private class JvmMultiFieldValueClassLowering(context: JvmBackendContext) : JvmV
     }
 
     override fun visitFunctionReference(expression: IrFunctionReference): IrExpression {
-        // todo implement
-        return super.visitFunctionReference(expression)
+        val function = expression.symbol.owner
+        val replacement = function.let {
+            replacements.run {
+                getReplacementFunction(it) ?: if (it is IrConstructor) getReplacementForRegularClassConstructor(it) else null
+            }
+        } ?: return super.visitFunctionReference(expression)
+        return if (function is IrConstructor && function.isPrimary && function.constructedClass.isMultiFieldValueClass) {
+            expression.run {
+                IrConstructorCallImpl(
+                    startOffset, endOffset, type, function.symbol, typeArgumentsCount, typeArgumentsCount, valueArgumentsCount, origin
+                )
+            }.transform(this, null)
+        } else {
+            context.createJvmIrBuilder(getCurrentScopeSymbol()).irBlock {
+                expression.run {
+                    IrFunctionReferenceImpl(
+                        startOffset,
+                        endOffset,
+                        type,
+                        replacement.symbol,
+                        function.typeParameters.size,
+                        replacement.valueParameters.size,
+                        reflectionTarget,
+                        origin
+                    )
+                }.apply { buildReplacement(function, expression, replacement) }.copyAttributes(expression)
+            }.unwrapBlock()
+        }
     }
 
     override fun visitFunctionAccess(expression: IrFunctionAccessExpression): IrExpression {
@@ -1057,7 +1085,12 @@ private class JvmMultiFieldValueClassLowering(context: JvmBackendContext) : JvmV
         }
         if (expression is IrTry) {
             expression.tryResult = irBlock { flattenExpressionTo(expression.tryResult, instance) }.unwrapBlock()
-            expression.catches.replaceAll { irCatch(it.catchParameter, irBlock { flattenExpressionTo(it.result, instance) }.unwrapBlock()) }
+            expression.catches.replaceAll {
+                irCatch(
+                    it.catchParameter,
+                    irBlock { flattenExpressionTo(it.result, instance) }.unwrapBlock()
+                )
+            }
             expression.finallyExpression = expression.finallyExpression?.transform(lowering, null)
             +expression
             return

compiler/testData/codegen/box/valueClasses/functionReferences.kt

@@ -0,0 +1,33 @@
+// CHECK_BYTECODE_LISTING
+// WITH_STDLIB
+// TARGET_BACKEND: JVM_IR
+// WORKS_WHEN_VALUE_CLASS
+// LANGUAGE: +ValueClasses
+
+@JvmInline
+value class DPoint(val x: Double, val y: Double) {
+    fun f(z: Double) = x + y + z
+}
+
+fun g(point: DPoint, z: Double) = point.f(z)
+
+class A(val point: DPoint) {
+    fun f(otherDPoint: DPoint, z: Double) = point.f(z) * otherDPoint.f(z)
+}
+
+fun box(): String {
+    val dPoint = DPoint(1.0, 2.0)
+    val a = A(dPoint)
+    
+    require((::DPoint)(1.0, 2.0) == dPoint)
+    require((dPoint::f)(3.0) == 6.0)
+    require((::g)(dPoint, 3.0) == 6.0)
+    require((a::f)(dPoint, 3.0) == 36.0)
+    
+    require((::DPoint)(1.0, DPoint(1.0, 2.0).y) == dPoint)
+    require((dPoint::f)(DPoint(1.0, 3.0).y) == 6.0)
+    require((::g)(dPoint, DPoint(1.0, 3.0).y) == 6.0)
+    require((a::f)(dPoint, DPoint(1.0, 3.0).y) == 36.0)
+    
+    return "OK"
+}

compiler/testData/codegen/box/valueClasses/functionReferences.txt

@@ -0,0 +1,39 @@
+@kotlin.Metadata
+public final class A {
+    // source: 'functionReferences.kt'
+    private final field point-0: double
+    private final field point-1: double
+    public method <init>(p0: double, p1: double): void
+    public final method f-GPBa7dw(p0: double, p1: double, p2: double): double
+    public final @org.jetbrains.annotations.NotNull method getPoint(): DPoint
+    public synthetic final method getPoint-0(): double
+    public synthetic final method getPoint-1(): double
+}
+
+@kotlin.jvm.JvmInline
+@kotlin.Metadata
+public final class DPoint {
+    // source: 'functionReferences.kt'
+    private final field field-0: double
+    private final field field-1: double
+    private synthetic method <init>(p0: double, p1: double): void
+    public synthetic final static method box-impl(p0: double, p1: double): DPoint
+    public final static method constructor-impl(p0: double, p1: double): void
+    public method equals(@org.jetbrains.annotations.Nullable p0: java.lang.Object): boolean
+    public static method equals-impl(p0: double, p1: double, p2: java.lang.Object): boolean
+    public final static method equals-impl0(p0: double, p1: double, p2: double, p3: double): boolean
+    public final static method f-impl(p0: double, p1: double, p2: double): double
+    public method hashCode(): int
+    public static method hashCode-impl(p0: double, p1: double): int
+    public @org.jetbrains.annotations.NotNull method toString(): java.lang.String
+    public static method toString-impl(p0: double, p1: double): java.lang.String
+    public synthetic final method unbox-impl-0(): double
+    public synthetic final method unbox-impl-1(): double
+}
+
+@kotlin.Metadata
+public final class FunctionReferencesKt {
+    // source: 'functionReferences.kt'
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+    public final static method g-GPBa7dw(p0: double, p1: double, p2: double): double
+}

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

@@ -50459,6 +50459,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/valueClasses/forStatement.kt", TransformersFunctions.getReplaceOptionalJvmInlineAnnotationWithReal());
         }
 
+        @Test
+        @TestMetadata("functionReferences.kt")
+        public void testFunctionReferences() throws Exception {
+            runTest("compiler/testData/codegen/box/valueClasses/functionReferences.kt", TransformersFunctions.getReplaceOptionalJvmInlineAnnotationWithReal());
+        }
+
         @Test
         @TestMetadata("mfvcFieldInitializationOrder.kt")
         public void testMfvcFieldInitializationOrder() throws Exception {