[cinterop] Allow compiling auxiliary c/c++ files

Add `-Xcompile-source` and `-Xsource-compile-options` flags to cinterop tools.
These flags allow to compile C and C++ files into klib.

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/jvm/CommandLine.kt

@@ -27,6 +27,7 @@ const val NOENDORSEDLIBS = "no-endorsed-libs"
 const val PURGE_USER_LIBS = "Xpurge-user-libs"
 const val TEMP_DIR = "Xtemporary-files-dir"
 const val NOPACK = "nopack"
+const val COMPILE_SOURCES = "Xcompile-source"
 
 // TODO: unify camel and snake cases.
 // Possible solution is to accept both cases
@@ -103,6 +104,16 @@ class CInteropArguments(argParser: ArgParser =
     val linkerOption = argParser.option(ArgType.String, "linker-option",
             description = "additional linker option").multiple()
     val linker by argParser.option(ArgType.String, description = "use specified linker")
+
+    val compileSource by argParser.option(ArgType.String,
+            fullName = COMPILE_SOURCES,
+            description = "additional C/C++ sources to be compiled into resulting library"
+    ).multiple()
+
+    val sourceCompileOptions by argParser.option(ArgType.String,
+            fullName = "Xsource-compiler-option",
+            description = "compiler options for sources provided via -$COMPILE_SOURCES"
+    ).multiple()
 }
 
 class JSInteropArguments(argParser: ArgParser = ArgParser("jsinterop",

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/jvm/ToolConfig.kt

@@ -34,6 +34,8 @@ class ToolConfig(userProvidedTargetName: String?, flavor: KotlinPlatform) {
 
     private val platform = platformManager.platform(target)
 
+    val clang = platform.clang
+
     val substitutions = defaultTargetSubstitutions(target)
 
     fun downloadDependencies() = platform.downloadDependencies()

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/jvm/main.kt

@@ -329,14 +329,17 @@ private fun processCLib(args: Array<String>, additionalArgs: Map<String, Any> =
         }
     }
 
+    val compiledFiles = compileSources(nativeLibsDir, tool, cinteropArguments)
+
     return when (stubIrOutput) {
         is StubIrDriver.Result.SourceCode -> {
-            argsToCompiler(staticLibraries, libraryPaths)
+            val bitcodePaths = compiledFiles.map {  listOf("-native-library", it) }.flatten()
+            argsToCompiler(staticLibraries, libraryPaths) + bitcodePaths
         }
         is StubIrDriver.Result.Metadata -> {
             createInteropLibrary(
                     metadata = stubIrOutput.metadata,
-                    nativeBitcodeFiles = listOf(nativeOutputPath),
+                    nativeBitcodeFiles = compiledFiles + nativeOutputPath,
                     target = tool.target,
                     moduleName = moduleName,
                     outputPath = cinteropArguments.output,
@@ -349,6 +352,20 @@ private fun processCLib(args: Array<String>, additionalArgs: Map<String, Any> =
     }
 }
 
+private fun compileSources(
+        nativeLibsDir: String,
+        toolConfig: ToolConfig,
+        cinteropArguments: CInteropArguments
+): List<String> = cinteropArguments.compileSource.mapIndexed { index, source ->
+    // Mangle file name to avoid collisions.
+    val mangledFileName = "${index}_${File(source).nameWithoutExtension}"
+    val outputFileName = "$nativeLibsDir/${mangledFileName}.bc"
+    val compilerArgs = cinteropArguments.sourceCompileOptions.toTypedArray()
+    val compilerCmd = toolConfig.clang.clangCXX(*compilerArgs, source, "-emit-llvm", "-c", "-o", outputFileName)
+    runCmd(compilerCmd.toTypedArray(), verbose = cinteropArguments.verbose)
+    outputFileName
+}
+
 private fun resolveDependencies(
         cinteropArguments: CInteropArguments, target: KonanTarget
 ): List<KotlinLibrary> {