Now we can add metadata nodes to bitcode module.

We just put in the names of functions for now.

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

@@ -71,6 +71,7 @@ internal class CodeGeneratorVisitor(val context: Context) : IrElementVisitorVoid
 
     val generator = CodeGenerator(context)
     val logger = Logger(generator, context)
+    val metadator = MetadataGenerator(context)
 
     //-------------------------------------------------------------------------//
 
@@ -140,6 +141,7 @@ internal class CodeGeneratorVisitor(val context: Context) : IrElementVisitorVoid
 
     override fun visitFunction(declaration: IrFunction) {
         generator.function(declaration)
+        metadator.function(declaration)
         declaration.acceptChildrenVoid(this)
     }
 

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

@@ -3,6 +3,7 @@ package org.jetbrains.kotlin.backend.native.llvm
 import kotlin_native.interop.asCString
 import llvm.LLVMPrintModuleToString
 import llvm.LLVMPrintValueToString
+import llvm.LLVMOpaqueValue
 import org.jetbrains.kotlin.backend.native.llvm.Context
 import org.jetbrains.kotlin.backend.native.llvm.ContextUtils
 import org.jetbrains.kotlin.ir.IrElement
@@ -36,3 +37,8 @@ fun ir2string(ir: IrElement?): String {
   ir?.accept(DumpIrTreeVisitor(strWriter), "")
   return strWriter.toString().takeWhile { it != '\n' }
 }
+
+fun llvm2string(value: LLVMOpaqueValue?): String {
+  return LLVMPrintValueToString(value)!!.asCString().toString()
+}
+

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

@@ -0,0 +1,66 @@
+package org.jetbrains.kotlin.backend.native.llvm
+
+
+import kotlin_native.interop.*
+import llvm.*
+import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.backend.BinaryMetadata
+import org.jetbrains.kotlin.backend.BinaryMetadata.FunMetadata
+
+internal class MetadataGenerator(override val context: Context): ContextUtils {
+
+    private fun metadata_string(str: String): LLVMOpaqueValue? {
+        return LLVMMDString(str, str.length)
+    }
+
+    private fun metadata_node(args: MutableList<LLVMOpaqueValue?>): LLVMOpaqueValue? {
+        memScoped {
+            val rargs = alloc(array[args.size](Ref to LLVMOpaqueValue))
+                args.forEachIndexed { i, llvmOpaqueValue ->  rargs[i].value = args[i]}
+            return LLVMMDNode(rargs[0], args.size);
+        }
+    }
+
+    private fun metadata_fun(fn: LLVMOpaqueValue?, info: String): LLVMOpaqueValue? {
+        val args: MutableList<LLVMOpaqueValue?> = mutableListOf()
+            args += fn
+            args += metadata_string(info);
+
+        val md = metadata_node(args)
+        return md
+    }
+
+    private fun emit_module_metadata(name: String, md: LLVMOpaqueValue?) {
+        LLVMAddNamedMetadataOperand(context.llvmModule, name, md)
+    }
+
+    private fun serialize_fun_signature(declaration:IrFunction): String {
+        val builder = FunMetadata.newBuilder()
+
+        val hash = "0x123456 some hash"
+        val name = declaration.descriptor.name.asString()
+
+        val proto = builder
+            .setHash(hash)
+            .setName(name)
+            .build()
+
+        // Convert it to ProtoBuf's TextFormat representation.
+        // Use TextFormat.merge(str, builder) to parse it back
+        val str = proto.toString()
+
+        return  str
+    }
+
+    internal fun function(declaration: IrFunction) {
+
+        val fn = declaration.descriptor.llvmFunction.getLlvmValue()
+
+        val proto = serialize_fun_signature(declaration)
+
+        val md = metadata_fun(fn, proto)
+        emit_module_metadata("kfun", md);
+    }
+}
+
+