Annotation used

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

@@ -43,6 +43,10 @@ internal class CodeGenerator(override val context: Context) : ContextUtils {
 
             currentFunction!!.registerVariable(name, v)
         }
+
+        if (descriptor.usedAnnotation) {
+            context.usedFunctions.add(fn!!)
+        }
     }
 
 

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

@@ -29,4 +29,6 @@ internal class Context(val irModule: IrModuleFragment, val runtime: Runtime, val
     val isInstanceFunction = importRtFunction("IsInstance")
     val checkInstanceFunction = importRtFunction("CheckInstance")
     val throwExceptionFunction = importRtFunction("ThrowException")
+
+    val usedFunctions = mutableListOf<LLVMValueRef>()
 }

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

@@ -165,6 +165,9 @@ internal class CodeGeneratorVisitor(val context: Context) : IrElementVisitorVoid
     override fun visitModuleFragment(module: IrModuleFragment) {
         logger.log("visitModule                  : ${ir2string(module)}")
         module.acceptChildrenVoid(this)
+
+        appendLlvmUsed(context.usedFunctions) 
+
         metadator.endModule(module)
     }
 
@@ -1436,4 +1439,20 @@ internal class CodeGeneratorVisitor(val context: Context) : IrElementVisitorVoid
         })
         return skipBody
     }
+
+    //-------------------------------------------------------------------------//
+
+    fun appendLlvmUsed(args: List<LLVMValueRef>) {
+        if (args.isEmpty()) return
+
+        memScoped {
+            val arrayLength = args.size
+            val argsCasted = args.map{it -> constPointer(LLVMConstBitCast(it, int8TypePtr)) }
+            val llvmUsedGlobal = 
+                context.staticData.placeGlobalArray("llvm.used", int8TypePtr, argsCasted)
+
+            LLVMSetLinkage(llvmUsedGlobal.llvmGlobal, LLVMLinkage.LLVMAppendingLinkage);
+            LLVMSetSection(llvmUsedGlobal.llvmGlobal, "llvm.metadata");
+        }
+    }
 }

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

@@ -0,0 +1,12 @@
+package org.jetbrains.kotlin.backend.konan.llvm
+
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.descriptors.annotations.*
+import org.jetbrains.kotlin.name.FqName
+
+private val annotationName = FqName("kotlin.Used")
+
+internal val FunctionDescriptor.usedAnnotation: Boolean 
+    get() {
+        return (this.annotations.findAnnotation(annotationName) != null)
+    }

backend.native/tests/main.c

@@ -12,10 +12,16 @@
 extern int run_test();
 
 void * resolve_symbol(char *name) {
-  /* here we can add here some magic to resolve symbols in kotlin native*/
-  return dlsym(RTLD_DEFAULT, name);
+    /* here we can add here some magic to resolve symbols in kotlin native*/
+    void* symbol = dlsym(RTLD_DEFAULT, name);
+
+    if (!symbol) {
+        printf("Could not find kotlin symbol '%s': %s\n", name, dlerror());
+        exit(1);
+    }
+
+    return symbol;
 }
-    
 
 int
 kotlinNativeMain() {
@@ -28,20 +34,3 @@ kotlinNativeMain() {
 #endif
 }
 
-int ktype_kotlin_any asm("_ktype:kotlin.Any");
-
-#define DEFINE(name, symbol) int name() asm(#symbol);
-#define DECLARE(name) \
-int \
-name() { \
-  abort(); \
-  return 1; \
-}
-
-#define DEFINE_AND_DECLARE(name, sym) \
-  DEFINE(name, sym) \
-  DECLARE(name)
-
-DEFINE_AND_DECLARE(kfun_kotlin_any_to_string,_kfun:kotlin.Any.toString)
-DEFINE_AND_DECLARE(kfun_kotlin_any_hash_code,_kfun:kotlin.Any.hashCode)
-DEFINE_AND_DECLARE(kfun_kotlin_any_equals,_kfun:kotlin.Any.equals)

runtime/src/main/kotlin/kotlin/Annotations.kt

@@ -34,4 +34,10 @@ public annotation class Suppress(vararg val names: String)
 @Target(AnnotationTarget.TYPE)
 //@Retention(SOURCE)
 //@MustBeDocumented
-public annotation class UnsafeVariance
+public annotation class UnsafeVariance
+
+/**
+ * Preserve the function entry point during global optimizations
+ */
+public annotation class Used
+