CODEGEN: Support for "Throw" implemented

for code
--------8<--------
fun main(args : Array<String>) {
    val cond = 1
    if (cond == 2) throw RuntimeException()
    if (cond == 3) throw NoSuchElementException("no such element")
    if (cond == 4) throw Error("error happens")

    println("Done")
}
--------8<--------
translator generates following: code
--------8<--------
; ModuleID = 'backend.native/tests/runtime/basic/throw0.kt.bc'
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.12.0"

...

define void @"kfun:main(Array<String>)"(i8*) {
entry:
  %args = alloca i8*
  store i8* %0, i8** %args
  %cond = alloca i32
  store i32 1, i32* %cond
  %tmp_1 = load i32, i32* %cond
  %tmp_0 = icmp eq i32 %tmp_1, 2
  br i1 %tmp_0, label %label_1, label %label_0

label_0:                                          ; preds = %label_1, %entry
  %tmp_7 = load i32, i32* %cond
  %tmp_6 = icmp eq i32 %tmp_7, 3
  br i1 %tmp_6, label %label_3, label %label_2

label_1:                                          ; preds = %entry
  %tmp_4 = call i8* @AllocInstance(%struct.TypeInfo* @"ktype:kotlin.RuntimeException", i32 1)
  %tmp_41 = call i8* @"kfun:kotlin.RuntimeException.<init>()"(i8* %tmp_4)
  %tmp_5 = bitcast i8* %tmp_41 to %struct.ObjHeader*
  call void @ThrowException(%struct.ObjHeader* %tmp_5) ; <------- throwing RuntimeException
  br label %label_0

label_2:                                          ; preds = %label_3, %label_0
  %tmp_14 = load i32, i32* %cond
  %tmp_13 = icmp eq i32 %tmp_14, 4
  br i1 %tmp_13, label %label_5, label %label_4

label_3:                                          ; preds = %label_0
  %tmp_10 = call i8* @AllocInstance(%struct.TypeInfo* @"ktype:kotlin.NoSuchElementException", i32 1)
  %tmp_102 = call i8* @"kfun:kotlin.NoSuchElementException.<init>(String)"(i8* %tmp_10, i8* @"kstr:2E869yDM+y/5vqQYAKDPRI+j44w=")
  %tmp_12 = bitcast i8* %tmp_102 to %struct.ObjHeader*
  call void @ThrowException(%struct.ObjHeader* %tmp_12)
  br label %label_2

label_4:                                          ; preds = %label_5, %label_2
  call void @Kotlin_io_Console_println(i8* @"kstr:6bRQ0UvCNj0pLITxfPrVz71YpFg=")
  ret void

label_5:                                          ; preds = %label_2
  %tmp_17 = call i8* @AllocInstance(%struct.TypeInfo* @"ktype:kotlin.Error", i32 1)
  %tmp_173 = call i8* @"kfun:kotlin.Error.<init>(String)"(i8* %tmp_17, i8* @"kstr:7YdnBMJy09naL/RsuOEV6Im2kOg=")
  %tmp_19 = bitcast i8* %tmp_173 to %struct.ObjHeader*
  call void @ThrowException(%struct.ObjHeader* %tmp_19)
  br label %label_4
}
--------8<--------

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

@@ -164,6 +164,7 @@ internal class CodeGenerator(override val context:Context) : ContextUtils {
         = LLVMPositionBuilderAtEnd(context.llvmBuilder, bbLabel)
 
     fun ret(value: LLVMOpaqueValue?) = LLVMBuildRet(context.llvmBuilder, value)
+    fun  unreachable(): LLVMOpaqueValue? = LLVMBuildUnreachable(context.llvmBuilder)
 }
 
 

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

@@ -30,6 +30,7 @@ internal class Context(val irModule: IrModuleFragment, val runtime: Runtime, val
     val lookupOpenMethodFunction = importRtFunction("LookupOpenMethod")
     val isInstanceFunction = importRtFunction("IsInstance")
     val checkInstanceFunction = importRtFunction("CheckInstance")
+    val throwExceptionFunction = importRtFunction("ThrowException")
 
     fun dispose() {
         LLVMDisposeBuilder(llvmBuilder)

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

@@ -201,6 +201,13 @@ internal class CodeGeneratorVisitor(val context: Context) : IrElementVisitorVoid
 
     //-------------------------------------------------------------------------//
 
+    override fun visitThrow(expression: IrThrow) {
+        logger.log("visitThrow                 : ${ir2string(expression)}")
+        evaluateExpression("", expression)
+    }
+
+    //-------------------------------------------------------------------------//
+
     override fun visitFunction(declaration: IrFunction) {
         logger.log("visitFunction                  : ${ir2string(declaration)}")
         codegen.function(declaration)
@@ -328,6 +335,7 @@ internal class CodeGeneratorVisitor(val context: Context) : IrElementVisitorVoid
             is IrBlock           -> return evaluateBlock       (                 value)
             is IrExpressionBody  -> return evaluateExpression  (tmpVariableName, value.expression)
             is IrWhen            -> return evaluateWhen        (tmpVariableName, value)
+            is IrThrow           -> return evaluateThrow       (tmpVariableName, value)
             null                 -> return null
             else                 -> {
                 TODO()
@@ -337,6 +345,15 @@ internal class CodeGeneratorVisitor(val context: Context) : IrElementVisitorVoid
 
     //-------------------------------------------------------------------------//
 
+    private fun evaluateThrow(tmpVariableName: String, expression: IrThrow): LLVMOpaqueValue? {
+        val objPointer = evaluateExpression(codegen.newVar(), expression.value)
+        val objHeaderPtr = codegen.bitcast(kObjHeaderPtr, objPointer!!, codegen.newVar())
+        val args = listOf(objHeaderPtr)                         // Create arg list.
+        return codegen.call(context.throwExceptionFunction, args, "")
+    }
+
+    //-------------------------------------------------------------------------//
+
     private fun evaluateWhen(tmpVariableName:String, expression: IrWhen): LLVMOpaqueValue? {
         logger.log("evaluateWhen               : ${ir2string(expression)}")
         var bbExit:LLVMOpaqueBasicBlock? = null             // By default "when" does not have "exit".