[JS IR] add a flag which prepends a custom prefix to the per-module .js files

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JSCompilerArguments.kt

@@ -157,6 +157,9 @@ class K2JSCompilerArguments : CommonCompilerArguments() {
     @Argument(value = "-Xir-per-module", description = "Splits generated .js per-module")
     var irPerModule: Boolean by FreezableVar(false)
 
+    @Argument(value = "-Xir-per-module-prefix", description = "Adds a custom prefix to the splitted js files")
+    var irPerModulePrefix: String? by NullableStringFreezableVar(null)
+
     @Argument(
         value = "-Xinclude",
         valueDescription = "<path>",

compiler/cli/cli-js/src/org/jetbrains/kotlin/cli/js/K2JsIrCompiler.kt

@@ -274,6 +274,7 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                 relativeRequirePath = true,
                 propertyLazyInitialization = arguments.irPropertyLazyInitialization,
                 legacyPropertyAccess = arguments.irLegacyPropertyAccess,
+                irPerModulePrefix = arguments.irPerModulePrefix
             )
 
             val jsCode = if (arguments.irDce && !arguments.irDceDriven) compiledModule.dceJsCode!! else compiledModule.jsCode!!

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/compiler.kt

@@ -53,6 +53,7 @@ fun compile(
     relativeRequirePath: Boolean = false,
     propertyLazyInitialization: Boolean,
     legacyPropertyAccess: Boolean = false,
+    irPerModulePrefix: String? = null,
 ): CompilerResult {
     val (moduleFragment: IrModuleFragment, dependencyModules, irBuiltIns, symbolTable, deserializer, moduleToName) =
         loadIr(project, mainModule, analyzer, configuration, allDependencies, friendDependencies, irFactory)
@@ -111,6 +112,7 @@ fun compile(
             multiModule = multiModule,
             relativeRequirePath = relativeRequirePath,
             moduleToName = moduleToName,
+            irPerModulePrefix = irPerModulePrefix,
         )
         return transformer.generateModule(allModules)
     } else {
@@ -123,6 +125,7 @@ fun compile(
             multiModule = multiModule,
             relativeRequirePath = relativeRequirePath,
             moduleToName = moduleToName,
+            irPerModulePrefix = irPerModulePrefix,
         )
         return transformer.generateModule(allModules)
     }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrModuleToJsTransformer.kt

@@ -32,7 +32,8 @@ class IrModuleToJsTransformer(
     private val dceJs: Boolean = false,
     private val multiModule: Boolean = false,
     private val relativeRequirePath: Boolean = false,
-    private val moduleToName: Map<IrModuleFragment, String> = emptyMap()
+    private val moduleToName: Map<IrModuleFragment, String> = emptyMap(),
+    private val irPerModulePrefix: String? = null,
 ) {
     private val generateRegionComments = backendContext.configuration.getBoolean(JSConfigurationKeys.GENERATE_REGION_COMMENTS)
 
@@ -92,7 +93,7 @@ class IrModuleToJsTransformer(
             )
 
             val dependencies = others.mapIndexed { index, module ->
-                val moduleName = moduleToName[module] ?: sanitizeName(module.safeName)
+                val moduleName = module.externalModuleName()
 
                 val exportedDeclarations = ExportModelGenerator(backendContext).let { module.files.flatMap { file -> it.generateExport(file) } }
 
@@ -191,6 +192,10 @@ class IrModuleToJsTransformer(
         return program.toString()
     }
 
+    private fun IrModuleFragment.externalModuleName(): String {
+        return (irPerModulePrefix ?: "") + (moduleToName[this] ?: sanitizeName(safeName))
+    }
+
     private fun generateCrossModuleImports(
         namerWithImports: IrNamerWithImports,
         currentModules: Iterable<IrModuleFragment>,
@@ -207,7 +212,7 @@ class IrModuleToJsTransformer(
             }
 
             val moduleName = declareFreshGlobal(module.safeName)
-            modules += JsImportedModule(moduleToName[module] ?: moduleName.ident, moduleName, moduleName.makeRef(), relativeRequirePath)
+            modules += JsImportedModule(module.externalModuleName(), moduleName, moduleName.makeRef(), relativeRequirePath)
 
             names.forEach {
                 imports += JsVars(JsVars.JsVar(JsName(it), JsNameRef(it, JsNameRef("\$crossModule\$", moduleName.makeRef()))))