[K/N] Add trivial test for llvm.objc.clang.arc.use lowering

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

@@ -4862,6 +4862,19 @@ if (PlatformInfo.isAppleTarget(project)) {
             }
         }
     }
+
+    standaloneTest("objc_arc_contract") {
+        doBeforeBuild {
+            mkdir(buildDir)
+            ExecLlvmKt.execLlvmUtility(project, "llvm-as") {
+                args "$projectDir/interop/objc_arc_contract/main.ll"
+                args "-o", "$buildDir/objc_arc_contract.bc"
+            }
+        }
+        source = "interop/objc_arc_contract/main.kt"
+        goldValue = "ok\n"
+        flags = ["-native-library", "$buildDir/objc_arc_contract.bc"]
+    }
 }
 
 standaloneTest("jsinterop_math") {

kotlin-native/backend.native/tests/interop/objc_arc_contract/main.kt

@@ -0,0 +1,10 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+// We don't do anything meaningful here, because the test is actually checks
+// how compiler handles external bitcode (see main.ll). So this file is needed only for compiler invocation.
+fun main() {
+    println("ok")
+}

kotlin-native/backend.native/tests/interop/objc_arc_contract/main.ll

@@ -0,0 +1,9 @@
+; Prevent function from DCE
+@llvm.compiler.used = appending global [1 x i8*] [ i8* bitcast (void (i8*, i8*)* @test to i8*) ], section "llvm.metadata"
+
+declare void @llvm.objc.clang.arc.use(...) nounwind
+
+define void @test(i8* %a, i8* %b) {
+  call void (...) @llvm.objc.clang.arc.use(i8* %a, i8* %b) nounwind
+  ret void
+}

kotlin-native/build-tools/src/main/kotlin/org/jetbrains/kotlin/ExecLlvm.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin
+
+import groovy.lang.Closure
+import org.gradle.api.Action
+import org.gradle.api.Project
+import org.gradle.process.ExecResult
+import org.gradle.process.ExecSpec
+import org.gradle.util.ConfigureUtil
+import org.jetbrains.kotlin.konan.util.DependencyProcessor
+
+fun execLlvmUtility(project: Project, utility: String, action: Action<in ExecSpec>): ExecResult {
+    val llvmBinDirectory = "${project.platformManager.hostPlatform.absoluteLlvmHome}/bin"
+    return project.exec(Action<ExecSpec> {
+        action.execute(this)
+        executable = "$llvmBinDirectory/$utility"
+    })
+}
+
+fun execLlvmUtility(project: Project, utility: String, closure: Closure<in ExecSpec>): ExecResult {
+    return execLlvmUtility(project, utility, ConfigureUtil.configureUsing(closure))
+}