[codegen][debug info] Introduce -Xdebug-info-version flag

- emit DW_LANG_Kotlin in debug info
- change Dwarf version to 4.

backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2Native.kt

@@ -189,6 +189,7 @@ class K2Native : CLICompiler<K2NativeCompilerArguments>() {
                     put(FRIEND_MODULES, arguments.friendModules!!.split(File.pathSeparator).filterNot(String::isEmpty))
 
                 put(BITCODE_EMBEDDING_MODE, selectBitcodeEmbeddingMode(this, arguments, outputKind))
+                put(DEBUG_INFO_VERSION, arguments.debugInfoFormatVersion.toInt())
             }
         }
     }

backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2NativeCompilerArguments.kt

@@ -152,6 +152,9 @@ class K2NativeCompilerArguments : CommonCompilerArguments() {
     )
     var friendModules: String? = null
 
+    @Argument(value = "-Xdebug-info-version", description = "generate debug info of given version (1, 2)")
+    var debugInfoFormatVersion: String = "1" /* command line parser doesn't accept kotlin.Int type */
+
     override fun configureAnalysisFlags(collector: MessageCollector): MutableMap<AnalysisFlag<*>, Any> =
             super.configureAnalysisFlags(collector).also {
                 val useExperimental = it[AnalysisFlags.useExperimental] as List<*>

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/KonanConfigurationKeys.kt

@@ -100,6 +100,9 @@ class KonanConfigKeys {
                 = CompilerConfigurationKey.create("verify ir")
         val VERBOSE_PHASES: CompilerConfigurationKey<List<String>> 
                 = CompilerConfigurationKey.create("verbose backend phases")
+        val DEBUG_INFO_VERSION: CompilerConfigurationKey<Int>
+                = CompilerConfigurationKey.create("debug info format version")
+
     }
 }
 

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

@@ -9,12 +9,13 @@ import kotlinx.cinterop.allocArrayOf
 import kotlinx.cinterop.memScoped
 import llvm.*
 import org.jetbrains.kotlin.backend.konan.Context
-import org.jetbrains.kotlin.konan.KonanVersion
+import org.jetbrains.kotlin.backend.konan.KonanConfig
+import org.jetbrains.kotlin.backend.konan.KonanConfigKeys
 import org.jetbrains.kotlin.backend.konan.irasdescriptors.FunctionDescriptor
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.ir.SourceManager.FileEntry
-import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.js.descriptorUtils.getJetTypeFqName
+import org.jetbrains.kotlin.konan.KonanVersion
 import org.jetbrains.kotlin.konan.file.File
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeUtils
@@ -23,18 +24,39 @@ import org.jetbrains.kotlin.types.TypeUtils
 internal object DWARF {
     val producer                       = "konanc ${KonanVersion.CURRENT} / kotlin-compiler: ${KotlinVersion.CURRENT}"
     /* TODO: from LLVM sources is unclear what runtimeVersion corresponds to term in terms of dwarf specification. */
-    val runtimeVersion                 = 2
     val dwarfVersionMetaDataNodeName   = "Dwarf Version".mdString()
     val dwarfDebugInfoMetaDataNodeName = "Debug Info Version".mdString()
-    val dwarfVersion = 2 /* TODO: configurable? like gcc/clang -gdwarf-2 and so on. */
-    val debugInfoVersion = 3 /* TODO: configurable? */
+    const val debugInfoVersion = 3 /* TODO: configurable? */
     /**
      * This is  the value taken from [DIFlags.FlagFwdDecl], to mark type declaration as
      * forward one.
      */
-    val flagsForwardDeclaration = 4
+    const val flagsForwardDeclaration = 4
+
+    fun runtimeVersion(config: KonanConfig) = when (config.debugInfoVersion()) {
+        2 -> 0
+        1 -> 2 /* legacy :/ */
+        else -> TODO("unsupported debug info format version")
+    }
+
+    /**
+     * Note: Kotlin language constant appears in DWARF v6, while modern linker fails to links DWARF other then [2;4],
+     * that why we emit version 4 actually.
+     */
+    fun dwarfVersion(config : KonanConfig) = when (config.debugInfoVersion()) {
+        1 -> 2
+        2 -> 4 /* likely the most of the future kotlin native debug info format versions will emit DWARF v4 */
+        else -> TODO("unsupported debug info format version")
+    }
+
+    fun language(config: KonanConfig) = when (config.debugInfoVersion()) {
+        1 -> DwarfLanguage.DW_LANG_C89.value
+        else -> DwarfLanguage.DW_LANG_Kotlin.value
+    }
 }
 
+fun KonanConfig.debugInfoVersion():Int = configuration[KonanConfigKeys.DEBUG_INFO_VERSION] ?: 1
+
 internal class DebugInfo internal constructor(override val context: Context):ContextUtils {
     val files = mutableMapOf<String, DIFileRef>()
     val subprograms = mutableMapOf<LLVMValueRef, DISubprogramRef>()
@@ -119,7 +141,7 @@ internal fun generateDebugInfoHeader(context: Context) {
          * !6 = !{!"Apple LLVM version 8.0.0 (clang-800.0.38)"}
          */
         val llvmTwo = Int32(2).llvm
-        val dwarfVersion = node(llvmTwo, DWARF.dwarfVersionMetaDataNodeName, Int32(DWARF.dwarfVersion).llvm)
+        val dwarfVersion = node(llvmTwo, DWARF.dwarfVersionMetaDataNodeName, Int32(DWARF.dwarfVersion(context.config)).llvm)
         val nodeDebugInfoVersion = node(llvmTwo, DWARF.dwarfDebugInfoMetaDataNodeName, Int32(DWARF.debugInfoVersion).llvm)
         val llvmModuleFlags = "llvm.module.flags"
         LLVMAddNamedMetadataOperand(context.llvmModule, llvmModuleFlags, dwarfVersion)

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

@@ -305,5 +305,5 @@ internal enum class DwarfLanguage(val value:Int) {
   DW_LANG_Mips_Assembler(0x8001),
   DW_LANG_GOOGLE_RenderScript(0x8e57),
   DW_LANG_BORLAND_Delphi(0xb000),
-  DW_LANG_Kotlin(0x0001) /* manually added, should be changed someday. */
+  DW_LANG_Kotlin(0x0026)
 }

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

@@ -1907,13 +1907,13 @@ internal class CodeGeneratorVisitor(val context: Context, val lifetimes: Map<IrE
             val path = this.fileEntry.name.toFileAndFolder()
             DICreateCompilationUnit(
                     builder     = context.debugInfo.builder,
-                    lang        = DwarfLanguage.DW_LANG_Kotlin.value,
+                    lang        = DWARF.language(context.config),
                     File        = path.file,
                     dir         = path.folder,
                     producer    = DWARF.producer,
                     isOptimized = 0,
                     flags       = "",
-                    rv          = DWARF.runtimeVersion)
+                    rv          = DWARF.runtimeVersion(context.config))
             DICreateFile(context.debugInfo.builder, path.file, path.folder)!!
         }
     }