Generate trap before each unreachable instruction in debug mode

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

@@ -424,6 +424,9 @@ internal class FunctionGenerationContext(val function: LLVMValueRef,
             call(context.llvm.allocArrayFunction, listOf(typeInfo, count), lifetime, exceptionHandler)
 
     fun unreachable(): LLVMValueRef? {
+        if (context.config.debug) {
+            call(context.llvm.llvmTrap, emptyList())
+        }
         val res = LLVMBuildUnreachable(builder)
         currentPositionHolder.setAfterTerminator()
         return res

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

@@ -296,6 +296,16 @@ internal class Llvm(val context: Context, val llvmModule: LLVMModuleRef) {
         return LLVMAddFunction(llvmModule, "llvm.memcpy.p0i8.p0i8.i32", functionType)!!
     }
 
+    private fun llvmIntrinsic(name: String, type: LLVMTypeRef, vararg attributes: String): LLVMValueRef {
+        val result = LLVMAddFunction(llvmModule, name, type)!!
+        attributes.forEach {
+            val kindId = getLlvmAttributeKindId(it)
+            val attribute = LLVMCreateEnumAttribute(LLVMGetTypeContext(type), kindId, 0)!!
+            LLVMAddAttributeAtIndex(result, LLVMAttributeFunctionIndex, attribute)
+        }
+        return result
+    }
+
     internal fun externalFunction(
             name: String,
             type: LLVMTypeRef,
@@ -474,6 +484,12 @@ internal class Llvm(val context: Context, val llvmModule: LLVMModuleRef) {
     val memsetFunction = importMemset()
     //val memcpyFunction = importMemcpy()
 
+    val llvmTrap = llvmIntrinsic(
+            "llvm.trap",
+            functionType(voidType, false),
+            "cold", "noreturn", "nounwind"
+    )
+
     val usedFunctions = mutableListOf<LLVMValueRef>()
     val usedGlobals = mutableListOf<LLVMValueRef>()
     val compilerUsedGlobals = mutableListOf<LLVMValueRef>()

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

@@ -277,15 +277,15 @@ fun parseBitcodeFile(path: String): LLVMModuleRef = memScoped {
 }
 
 private val nounwindAttrKindId by lazy {
-    getAttributeKindId("nounwind")
+    getLlvmAttributeKindId("nounwind")
 }
 
 private val noreturnAttrKindId by lazy {
-    getAttributeKindId("noreturn")
+    getLlvmAttributeKindId("noreturn")
 }
 
 private val signextAttrKindId by lazy {
-    getAttributeKindId("signext")
+    getLlvmAttributeKindId("signext")
 }
 
 
@@ -294,12 +294,12 @@ fun isFunctionNoUnwind(function: LLVMValueRef): Boolean {
     return attribute != null
 }
 
-private fun getAttributeKindId(attributeName: String): Int {
-    val nounwindAttrKindId = LLVMGetEnumAttributeKindForName(attributeName, attributeName.length.signExtend())
-    if (nounwindAttrKindId == 0) {
+internal fun getLlvmAttributeKindId(attributeName: String): Int {
+    val attrKindId = LLVMGetEnumAttributeKindForName(attributeName, attributeName.length.signExtend())
+    if (attrKindId == 0) {
         throw Error("Unable to find '$attributeName' attribute kind id")
     }
-    return nounwindAttrKindId
+    return attrKindId
 }
 
 fun setFunctionNoUnwind(function: LLVMValueRef) {