[K/N] Safer handling of bridges function in dce

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/BitcodePhases.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.backend.common.phaser.PhaserState
 import org.jetbrains.kotlin.backend.common.phaser.namedUnitPhase
 import org.jetbrains.kotlin.backend.konan.*
 import org.jetbrains.kotlin.backend.konan.descriptors.GlobalHierarchyAnalysis
+import org.jetbrains.kotlin.backend.konan.lower.DECLARATION_ORIGIN_BRIDGE_METHOD
 import org.jetbrains.kotlin.backend.konan.lower.RedundantCoercionsCleaner
 import org.jetbrains.kotlin.backend.konan.lower.ReturnsInsertionLowering
 import org.jetbrains.kotlin.backend.konan.optimizations.*
@@ -25,6 +26,7 @@ import org.jetbrains.kotlin.ir.util.parentAsClass
 import org.jetbrains.kotlin.ir.visitors.*
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.utils.addToStdlib.cast
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 internal val contextLLVMSetupPhase = makeKonanModuleOpPhase(
         name = "ContextLLVMSetup",
@@ -199,6 +201,11 @@ internal val dcePhase = makeKonanModuleOpPhase(
                 }
             })
 
+            // TODO: Bridge function normally calls it's target, but it could be optimized out by Autoboxing and InlinePropertyAccessor
+            //       lowerings. But Devirtualization doesn't handle this correctly, and can replace bridge call with call of it's target.
+            //       So it's safer not to remove target if bridge is preserved, even if target itself is not called directly
+            referencedFunctions.addAll(referencedFunctions.mapNotNull { it.origin.safeAs<DECLARATION_ORIGIN_BRIDGE_METHOD>()?.bridgeTarget })
+
             context.irModule!!.transformChildrenVoid(object: IrElementTransformerVoid() {
                 override fun visitFile(declaration: IrFile): IrFile {
                     declaration.declarations.removeAll {

kotlin-native/backend.native/tests/build.gradle

@@ -2955,6 +2955,14 @@ standaloneTest("devirtualization_getter_looking_as_box_function") {
     source = "codegen/devirtualization/getter_looking_as_box_function.kt"
 }
 
+standaloneTest("devirtualization_inline_getter") {
+    disabled = (cacheTesting != null) // Cache is not compatible with -opt.
+    useGoldenData = true
+    flags = ["-opt"]
+    source = "codegen/devirtualization/inline_getter.kt"
+}
+
+
 standaloneTest("devirtualization_anonymousObject") {
     disabled = (cacheTesting != null) // Cache is not compatible with -opt.
     useGoldenData = true

kotlin-native/backend.native/tests/codegen/devirtualization/inline_getter.kt

@@ -0,0 +1,13 @@
+interface Base { val id: Int }
+
+inline class Child(override val id: Int = 1) : Base
+
+interface Base2 { val prop: Base }
+class Child2(override val prop: Child) : Base2
+
+fun main() {
+    val x : Base = Child(5)
+    println(x.id)
+    val y : Base2 = Child2(Child(5))
+    println(y.prop)
+}

kotlin-native/backend.native/tests/codegen/devirtualization/inline_getter.out

@@ -0,0 +1,2 @@
+5
+Child(id=5)