Introduce -Xuse-ir flag for cli compiler

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -72,6 +72,9 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
 
     // Advanced options
 
+    @Argument(value = "-Xuse-ir", description = "Use the IR backend")
+    var useIR: Boolean by FreezableVar(false)
+
     @Argument(value = "-Xmodule-path", valueDescription = "<path>", description = "Paths where to find Java 9+ modules")
     var javaModulePath: String? by FreezableVar(null)
 

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/K2JVMCompiler.kt

@@ -342,6 +342,7 @@ class K2JVMCompiler : CLICompiler<K2JVMCompilerArguments>() {
         }
 
         private fun putAdvancedOptions(configuration: CompilerConfiguration, arguments: K2JVMCompilerArguments) {
+            configuration.put(JVMConfigurationKeys.IR, arguments.useIR)
             configuration.put(JVMConfigurationKeys.DISABLE_CALL_ASSERTIONS, arguments.noCallAssertions)
             configuration.put(JVMConfigurationKeys.DISABLE_RECEIVER_ASSERTIONS, arguments.noReceiverAssertions)
             configuration.put(JVMConfigurationKeys.DISABLE_PARAM_ASSERTIONS, arguments.noParamAssertions)

compiler/testData/cli/jvm/extraHelp.out

@@ -54,6 +54,7 @@ where advanced options include:
   -Xsupport-compatqual-checker-framework-annotations=enable|disable
                              Specify behavior for Checker Framework compatqual annotations (NullableDecl/NonNullDecl).
                              Default value is 'enable'
+  -Xuse-ir                   Use the IR backend
   -Xuse-javac                Use javac for Java source and class files analysis
   -Xuse-old-class-files-reading Use old class files reading implementation (may slow down the build and should be used in case of problems with the new implementation)
   -Xuse-type-table           Use type table in metadata serialization