JVM_IR: further refine synthetic accessor generation

References to protected members from crossinline lambdas in the same
package do not need accessors.

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/IrInlineReferenceLocator.kt

@@ -12,16 +12,11 @@ import org.jetbrains.kotlin.backend.jvm.codegen.isInlineIrExpression
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.declarations.IrValueParameter
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 
 internal open class IrInlineReferenceLocator(private val context: JvmBackendContext) : IrElementVisitorVoidWithContext() {
-    val inlineReferences = mutableSetOf<IrCallableReference>()
-
-    // For crossinline lambdas, the call site is null as it's probably in a separate class somewhere.
-    // All other lambdas are guaranteed to be inlined into the scope they are declared in.
-    val lambdaToCallSite = mutableMapOf<IrFunction, IrDeclaration?>()
-
     override fun visitElement(element: IrElement) = element.acceptChildrenVoid(this)
 
     override fun visitFunctionAccess(expression: IrFunctionAccessExpression) {
@@ -35,37 +30,30 @@ internal open class IrInlineReferenceLocator(private val context: JvmBackendCont
                 if (!isInlineIrExpression(valueArgument))
                     continue
 
-                if (valueArgument is IrPropertyReference) {
-                    handleInlineFunctionCallableReferenceParam(valueArgument)
-                    continue
-                }
-
-                val reference = when (valueArgument) {
-                    is IrFunctionReference -> valueArgument
-                    is IrBlock -> valueArgument.statements.filterIsInstance<IrFunctionReference>().singleOrNull()
-                    else -> null
-                } ?: continue
-
-                handleInlineFunctionCallableReferenceParam(reference)
                 if (valueArgument is IrBlock && valueArgument.origin.isLambda) {
-                    val declaration = if (parameter.isCrossinline) null else currentScope!!.irElement as IrDeclaration
-                    handleInlineFunctionLambdaParam(reference, function, declaration)
+                    val reference = valueArgument.statements.last() as IrFunctionReference
+                    visitInlineLambda(reference, function, parameter, currentScope!!.irElement as IrDeclaration)
+                } else if (valueArgument is IrCallableReference) {
+                    visitInlineReference(valueArgument)
                 }
             }
         }
         return super.visitFunctionAccess(expression)
     }
 
-    open fun handleInlineFunctionCallableReferenceParam(valueArgument: IrCallableReference) {
-        inlineReferences.add(valueArgument)
-    }
+    open fun visitInlineReference(argument: IrCallableReference) {}
 
-    open fun handleInlineFunctionLambdaParam(lambdaReference: IrFunctionReference, callee: IrFunction, callSite: IrDeclaration?) {
-        lambdaToCallSite[lambdaReference.symbol.owner] = callSite
-    }
+    open fun visitInlineLambda(argument: IrFunctionReference, callee: IrFunction, parameter: IrValueParameter, scope: IrDeclaration) =
+        visitInlineReference(argument)
 
     companion object {
-        fun scan(context: JvmBackendContext, element: IrElement) =
-            IrInlineReferenceLocator(context).apply { element.accept(this, null) }
+        fun scan(context: JvmBackendContext, element: IrElement): Set<IrCallableReference> =
+            mutableSetOf<IrCallableReference>().apply {
+                element.accept(object : IrInlineReferenceLocator(context) {
+                    override fun visitInlineReference(argument: IrCallableReference) {
+                        add(argument)
+                    }
+                }, null)
+            }
     }
 }

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

@@ -641,17 +641,18 @@ private class AddContinuationLowering(private val context: JvmBackendContext) :
     private fun markSuspendLambdas(irElement: IrElement): Pair<List<SuspendLambdaInfo>, List<IrFunction>> {
         val suspendLambdas = arrayListOf<SuspendLambdaInfo>()
         val capturesCrossinline = mutableSetOf<IrCallableReference>()
-        val visitor = object : IrInlineReferenceLocator(context) {
+        val inlineReferences = mutableSetOf<IrCallableReference>()
+        irElement.acceptChildrenVoid(object : IrInlineReferenceLocator(context) {
             override fun visitElement(element: IrElement) {
                 element.acceptChildrenVoid(this)
             }
 
-            override fun handleInlineFunctionCallableReferenceParam(valueArgument: IrCallableReference) {
-                super.handleInlineFunctionCallableReferenceParam(valueArgument)
-                val getValue = (valueArgument as? IrGetValue) ?: return
+            override fun visitInlineReference(argument: IrCallableReference) {
+                inlineReferences.add(argument)
+                val getValue = (argument as? IrGetValue) ?: return
                 val parameter = getValue.symbol.owner as? IrValueParameter ?: return
                 if (parameter.isCrossinline) {
-                    capturesCrossinline += valueArgument
+                    capturesCrossinline += argument
                 }
             }
 
@@ -676,9 +677,8 @@ private class AddContinuationLowering(private val context: JvmBackendContext) :
                     )
                 }
             }
-        }
-        irElement.acceptChildrenVoid(visitor)
-        return suspendLambdas to visitor.inlineReferences.map { it.symbol.owner as IrFunction }
+        })
+        return suspendLambdas to inlineReferences.map { it.symbol.owner as IrFunction }
     }
 
     private class SuspendLambdaInfo(

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

@@ -56,7 +56,7 @@ internal class CallableReferenceLowering(private val context: JvmBackendContext)
     private fun IrFunctionReference.isSuspendCallableReference(): Boolean = isSuspend && origin == null
 
     override fun lower(irFile: IrFile) {
-        ignoredFunctionReferences.addAll(IrInlineReferenceLocator.scan(context, irFile).inlineReferences)
+        ignoredFunctionReferences.addAll(IrInlineReferenceLocator.scan(context, irFile))
         irFile.transformChildrenVoid(this)
     }
 

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

@@ -14,12 +14,8 @@ import org.jetbrains.kotlin.ir.builders.createTmpVariable
 import org.jetbrains.kotlin.ir.builders.irBlockBody
 import org.jetbrains.kotlin.ir.builders.irInt
 import org.jetbrains.kotlin.ir.builders.irReturn
-import org.jetbrains.kotlin.ir.declarations.IrDeclaration
-import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
-import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrBlockBody
-import org.jetbrains.kotlin.ir.expressions.IrCallableReference
 import org.jetbrains.kotlin.ir.expressions.IrExpressionBody
 import org.jetbrains.kotlin.ir.expressions.IrFunctionReference
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
@@ -44,16 +40,11 @@ internal class FakeInliningLocalVariablesLowering(val context: JvmBackendContext
         }
     }
 
-    override fun handleInlineFunctionCallableReferenceParam(valueArgument: IrCallableReference) {
-        // Do not record inline function callable reference parameters. They will not be used.
-    }
-
-    override fun handleInlineFunctionLambdaParam(lambdaReference: IrFunctionReference, callee: IrFunction, callSite: IrDeclaration?) {
-        // Do not record lambda parameters. Instead deal with them now.
-        val lambda = lambdaReference.symbol.owner
+    override fun visitInlineLambda(argument: IrFunctionReference, callee: IrFunction, parameter: IrValueParameter, scope: IrDeclaration) {
+        val lambda = argument.symbol.owner
         if (lambda.origin == IrDeclarationOrigin.LOCAL_FUNCTION_FOR_LAMBDA) {
             val argumentToFunctionName = context.methodSignatureMapper.mapFunctionName(callee)
-            val lambdaReferenceName = context.getLocalClassType(lambdaReference)!!.internalName.substringAfterLast("/")
+            val lambdaReferenceName = context.getLocalClassType(argument)!!.internalName.substringAfterLast("/")
             val localName = "${JvmAbi.LOCAL_VARIABLE_NAME_PREFIX_INLINE_ARGUMENT}-$argumentToFunctionName-$lambdaReferenceName"
             lambda.addFakeLocalVariable(localName)
         }

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

@@ -50,9 +50,7 @@ internal class InlineCallableReferenceToLambdaPhase(val context: JvmBackendConte
     private var inlinableReferences = mutableSetOf<IrCallableReference>()
 
     override fun lower(irFile: IrFile) {
-        IrInlineReferenceLocator.scan(context, irFile).let {
-            inlinableReferences.addAll(it.inlineReferences)
-        }
+        inlinableReferences.addAll(IrInlineReferenceLocator.scan(context, irFile))
         irFile.transformChildrenVoid(this)
     }
 

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

@@ -41,11 +41,18 @@ import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 internal class SyntheticAccessorLowering(val context: JvmBackendContext) : IrElementTransformerVoidWithContext(), FileLoweringPass {
+    data class LambdaCallSite(val scope: IrDeclaration, val crossinline: Boolean)
+
     private val pendingAccessorsToAdd = mutableListOf<IrFunction>()
-    private val inlineLambdaToCallSite = mutableMapOf<IrFunction, IrDeclaration?>()
+    private val inlineLambdaToCallSite = mutableMapOf<IrFunction, LambdaCallSite>()
 
     override fun lower(irFile: IrFile) {
-        inlineLambdaToCallSite.putAll(IrInlineReferenceLocator.scan(context, irFile).lambdaToCallSite)
+        irFile.accept(object : IrInlineReferenceLocator(context) {
+            override fun visitInlineLambda(argument: IrFunctionReference, callee: IrFunction, parameter: IrValueParameter, scope: IrDeclaration) {
+                inlineLambdaToCallSite[argument.symbol.owner] = LambdaCallSite(scope, parameter.isCrossinline)
+            }
+        }, null)
+
         irFile.transformChildrenVoid(this)
 
         for (accessor in pendingAccessorsToAdd) {
@@ -509,16 +516,18 @@ internal class SyntheticAccessorLowering(val context: JvmBackendContext) : IrEle
                 this == JavaVisibilities.PROTECTED_AND_PACKAGE ||
                 this == JavaVisibilities.PROTECTED_STATIC_VISIBILITY
 
-    private fun IrDeclaration.getAccessContext(withSuper: Boolean): IrDeclarationContainer? = when {
+    private fun IrDeclaration.getAccessContext(allowSamePackage: Boolean): IrDeclarationContainer? = when {
         this is IrDeclarationContainer -> this
-        // For inline lambdas, we can navigate to the only call site directly.
-        this in inlineLambdaToCallSite -> inlineLambdaToCallSite[this]?.getAccessContext(withSuper)
+        // For inline lambdas, we can navigate to the only call site directly. Crossinline lambdas might be inlined
+        // into other classes in the same package, so private/super require accessors anyway.
+        this in inlineLambdaToCallSite ->
+            inlineLambdaToCallSite[this]!!.takeIf { allowSamePackage || !it.crossinline }?.scope?.getAccessContext(allowSamePackage)
         // Accesses from inline functions can actually be anywhere; even private inline functions can be
         // inlined into a different class, e.g. a callable reference. For protected inline functions
         // calling methods on `super` we also need an accessor to satisfy INVOKESPECIAL constraints.
         // TODO scan nested classes for calls to private inline functions?
         this is IrFunction && isInline -> null
-        else -> (parent as? IrDeclaration)?.getAccessContext(withSuper)
+        else -> (parent as? IrDeclaration)?.getAccessContext(allowSamePackage)
     }
 
     private fun IrSymbol.isAccessible(withSuper: Boolean, thisObjReference: IrClassSymbol?): Boolean {
@@ -547,7 +556,8 @@ internal class SyntheticAccessorLowering(val context: JvmBackendContext) : IrEle
 
         // If local variables are accessible by Kotlin rules, they also are by Java rules.
         val symbolDeclarationContainer = (declaration.parent as? IrDeclarationContainer) as? IrElement ?: return true
-        val contextDeclarationContainer = (currentScope!!.irElement as IrDeclaration).getAccessContext(withSuper) ?: return false
+        val contextDeclarationContainer =
+            (currentScope!!.irElement as IrDeclaration).getAccessContext(declaration.visibility.isProtected && !withSuper) ?: return false
 
         val samePackage = declaration.getPackageFragment()?.fqName == contextDeclarationContainer.getPackageFragment()?.fqName
         val fromSubclassOfReceiversClass = contextDeclarationContainer is IrClass && symbolDeclarationContainer is IrClass &&

compiler/testData/codegen/boxAgainstJava/visibility/protectedAndPackage/protectedPropertyInPackageFromCrossinline.kt

@@ -0,0 +1,19 @@
+// FILE: protectedPack/J.java
+
+package protectedPack;
+
+public class J {
+    protected String foo = "OK";
+}
+
+// FILE: 1.kt
+
+package protectedPack
+
+inline fun foo(crossinline bar: () -> String) = object {
+    fun baz() = bar()
+}.baz()
+
+fun box(): String {
+    return foo { J().foo!! }
+}

compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/protectedMembersFromSuper.kt

@@ -0,0 +1,31 @@
+// !LANGUAGE: -ProhibitProtectedCallFromInline
+// IGNORE_BACKEND: JVM
+// IGNORE_BACKEND_MULTI_MODULE: JVM
+// FILE: 1.kt
+
+package test
+
+inline fun runCrossinline(crossinline f: () -> String) = f()
+
+open class Base {
+    protected open val FOO = "O"
+
+    protected open fun test() = "K"
+}
+
+open class P : Base() {
+    inline fun protectedProp(crossinline f: (String) -> String): String =
+        runCrossinline { f(FOO) }
+
+    inline fun protectedFun(crossinline f: (String) -> String): String =
+        runCrossinline { f(test()) }
+}
+
+// FILE: 2.kt
+
+import test.*
+
+fun box() : String {
+    val p = P()
+    return p.protectedProp { it } + p.protectedFun { it }
+}

compiler/testData/codegen/bytecodeText/noAccessorForProtectedInSamePackageCrossinline.kt

@@ -0,0 +1,17 @@
+package a
+
+open class A {
+    protected fun protectedFun(): String = "OK"
+}
+
+inline fun foo(crossinline bar: () -> String) = object {
+    fun baz() = bar()
+}.baz()
+
+class BSamePackage: A() {
+    fun test(): String = foo {
+        protectedFun()
+    }
+}
+
+// 0 INVOKESTATIC a/BSamePackage.access

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

@@ -1147,6 +1147,11 @@ public class BlackBoxAgainstJavaCodegenTestGenerated extends AbstractBlackBoxAga
                 runTest("compiler/testData/codegen/boxAgainstJava/visibility/protectedAndPackage/protectedPropertyInPackage.kt");
             }
 
+            @TestMetadata("protectedPropertyInPackageFromCrossinline.kt")
+            public void testProtectedPropertyInPackageFromCrossinline() throws Exception {
+                runTest("compiler/testData/codegen/boxAgainstJava/visibility/protectedAndPackage/protectedPropertyInPackageFromCrossinline.kt");
+            }
+
             @TestMetadata("protectedStaticClass.kt")
             public void testProtectedStaticClass() throws Exception {
                 runTest("compiler/testData/codegen/boxAgainstJava/visibility/protectedAndPackage/protectedStaticClass.kt");

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

@@ -4320,6 +4320,11 @@ public class BlackBoxInlineCodegenTestGenerated extends AbstractBlackBoxInlineCo
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/privateInCrossInline.kt");
             }
 
+            @TestMetadata("protectedMembersFromSuper.kt")
+            public void testProtectedMembersFromSuper() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/protectedMembersFromSuper.kt");
+            }
+
             @TestMetadata("superCall.kt")
             public void testSuperCall() throws Exception {
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/superCall.kt");

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

@@ -254,6 +254,11 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
         runTest("compiler/testData/codegen/bytecodeText/maxStackAfterOptimizations.kt");
     }
 
+    @TestMetadata("noAccessorForProtectedInSamePackageCrossinline.kt")
+    public void testNoAccessorForProtectedInSamePackageCrossinline() throws Exception {
+        runTest("compiler/testData/codegen/bytecodeText/noAccessorForProtectedInSamePackageCrossinline.kt");
+    }
+
     @TestMetadata("noFlagAnnotations.kt")
     public void testNoFlagAnnotations() throws Exception {
         runTest("compiler/testData/codegen/bytecodeText/noFlagAnnotations.kt");

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

@@ -4320,6 +4320,11 @@ public class CompileKotlinAgainstInlineKotlinTestGenerated extends AbstractCompi
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/privateInCrossInline.kt");
             }
 
+            @TestMetadata("protectedMembersFromSuper.kt")
+            public void testProtectedMembersFromSuper() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/protectedMembersFromSuper.kt");
+            }
+
             @TestMetadata("superCall.kt")
             public void testSuperCall() throws Exception {
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/superCall.kt");

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

@@ -1148,6 +1148,11 @@ public class IrBlackBoxAgainstJavaCodegenTestGenerated extends AbstractIrBlackBo
                 runTest("compiler/testData/codegen/boxAgainstJava/visibility/protectedAndPackage/protectedPropertyInPackage.kt");
             }
 
+            @TestMetadata("protectedPropertyInPackageFromCrossinline.kt")
+            public void testProtectedPropertyInPackageFromCrossinline() throws Exception {
+                runTest("compiler/testData/codegen/boxAgainstJava/visibility/protectedAndPackage/protectedPropertyInPackageFromCrossinline.kt");
+            }
+
             @TestMetadata("protectedStaticClass.kt")
             public void testProtectedStaticClass() throws Exception {
                 runTest("compiler/testData/codegen/boxAgainstJava/visibility/protectedAndPackage/protectedStaticClass.kt");

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

@@ -4070,6 +4070,11 @@ public class IrBlackBoxInlineCodegenTestGenerated extends AbstractIrBlackBoxInli
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/privateInCrossInline.kt");
             }
 
+            @TestMetadata("protectedMembersFromSuper.kt")
+            public void testProtectedMembersFromSuper() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/protectedMembersFromSuper.kt");
+            }
+
             @TestMetadata("superCall.kt")
             public void testSuperCall() throws Exception {
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/superCall.kt");

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

@@ -254,6 +254,11 @@ public class IrBytecodeTextTestGenerated extends AbstractIrBytecodeTextTest {
         runTest("compiler/testData/codegen/bytecodeText/maxStackAfterOptimizations.kt");
     }
 
+    @TestMetadata("noAccessorForProtectedInSamePackageCrossinline.kt")
+    public void testNoAccessorForProtectedInSamePackageCrossinline() throws Exception {
+        runTest("compiler/testData/codegen/bytecodeText/noAccessorForProtectedInSamePackageCrossinline.kt");
+    }
+
     @TestMetadata("noFlagAnnotations.kt")
     public void testNoFlagAnnotations() throws Exception {
         runTest("compiler/testData/codegen/bytecodeText/noFlagAnnotations.kt");

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

@@ -4070,6 +4070,11 @@ public class IrCompileKotlinAgainstInlineKotlinTestGenerated extends AbstractIrC
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/privateInCrossInline.kt");
             }
 
+            @TestMetadata("protectedMembersFromSuper.kt")
+            public void testProtectedMembersFromSuper() throws Exception {
+                runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/protectedMembersFromSuper.kt");
+            }
+
             @TestMetadata("superCall.kt")
             public void testSuperCall() throws Exception {
                 runTest("compiler/testData/codegen/boxInline/syntheticAccessors/withinInlineLambda/superCall.kt");