Add debug info to some ObjCExport bridges (#3237)

to fix inlined frames decoding.

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

@@ -155,6 +155,11 @@ private inline fun <R> generateFunctionBody(
     functionGenerationContext.resetDebugLocation()
 }
 
+internal fun FunctionGenerationContext.initBridgeDebugInfo() {
+    val location = setupBridgeDebugInfo(context, function) ?: return
+    debugLocation(location, location)
+}
+
 /**
  * There're cases when we don't need end position or it is meaningless.
  */

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

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.backend.konan.llvm
 
 import kotlinx.cinterop.allocArrayOf
 import kotlinx.cinterop.memScoped
+import kotlinx.cinterop.reinterpret
 import llvm.*
 import org.jetbrains.kotlin.backend.konan.*
 import org.jetbrains.kotlin.ir.SourceManager.FileEntry
@@ -81,6 +82,10 @@ internal class DebugInfo internal constructor(override val context: Context):Con
     val otherLlvmType = LLVMPointerType(LLVMInt64Type(), 0)!!
     val otherTypeSize = LLVMSizeOfTypeInBits(llvmTargetData, otherLlvmType)
     val otherTypeAlignment = LLVMPreferredAlignmentOfType(llvmTargetData, otherLlvmType)
+
+    val compilerGeneratedFile by lazy {
+        DICreateFile(builder, "<compiler-generated>", "")!!
+    }
 }
 
 /**
@@ -250,3 +255,29 @@ internal fun subroutineType(context: Context, llvmTargetData: LLVMTargetDataRef,
 @Suppress("UNCHECKED_CAST")
 private fun dwarfPointerType(context: Context, type: DITypeOpaqueRef) =
         DICreatePointerType(context.debugInfo.builder, type) as DITypeOpaqueRef
+
+internal fun setupBridgeDebugInfo(context: Context, function: LLVMValueRef): LocationInfo? {
+    if (!context.shouldContainLocationDebugInfo()) {
+        return null
+    }
+
+    val file = context.debugInfo.compilerGeneratedFile
+
+    // TODO: can we share the scope among all bridges?
+    val scope: DIScopeOpaqueRef = DICreateFunction(
+            builder = context.debugInfo.builder,
+            scope = file.reinterpret(),
+            name = function.name,
+            linkageName = function.name,
+            file = file,
+            lineNo = 0,
+            type = subroutineType(context, context.llvm.runtime.targetData, emptyList()), // TODO: use proper type.
+            isLocal = 0,
+            isDefinition = 1,
+            scopeLine = 0
+    )!!.also {
+        DIFunctionAddSubprogram(function, it)
+    }.reinterpret()
+
+    return LocationInfo(scope, 1, 0)
+}

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

@@ -535,7 +535,7 @@ private inline fun ObjCExportCodeGenerator.generateObjCImpBy(
         genBody()
     }
 
-    LLVMSetLinkage(result, LLVMLinkage.LLVMPrivateLinkage)
+    LLVMSetLinkage(result, LLVMLinkage.LLVMInternalLinkage)
     return result
 }
 
@@ -555,7 +555,7 @@ private fun ObjCExportCodeGenerator.generateObjCImp(
 ) = if (target == null) {
     generateAbstractObjCImp(methodBridge)
 } else {
-    generateObjCImp(methodBridge) { args, resultLifetime, exceptionHandler ->
+    generateObjCImp(methodBridge, isDirect = !isVirtual) { args, resultLifetime, exceptionHandler ->
         val llvmTarget = if (!isVirtual) {
             codegen.llvmFunction(target)
         } else {
@@ -568,12 +568,19 @@ private fun ObjCExportCodeGenerator.generateObjCImp(
 
 private fun ObjCExportCodeGenerator.generateObjCImp(
         methodBridge: MethodBridge,
+        isDirect: Boolean,
         callKotlin: FunctionGenerationContext.(
                 args: List<LLVMValueRef>,
                 resultLifetime: Lifetime,
                 exceptionHandler: ExceptionHandler
         ) -> LLVMValueRef?
 ): LLVMValueRef = generateObjCImpBy(methodBridge) {
+    if (isDirect) {
+        // Consider this call inlinable. If it is inlined into a bridge with no debug information,
+        // lldb will not decode the inlined frame even if the callee has debug information.
+        initBridgeDebugInfo()
+        // TODO: consider adding debug info to other bridges.
+    }
 
     val returnType = methodBridge.returnBridge
 
@@ -674,7 +681,7 @@ private fun ObjCExportCodeGenerator.generateObjCImp(
 private fun ObjCExportCodeGenerator.generateObjCImpForArrayConstructor(
         target: IrConstructor,
         methodBridge: MethodBridge
-): LLVMValueRef = generateObjCImp(methodBridge) { args, resultLifetime, exceptionHandler ->
+): LLVMValueRef = generateObjCImp(methodBridge, isDirect = true) { args, resultLifetime, exceptionHandler ->
     val arrayInstance = callFromBridge(
             context.llvm.allocArrayFunction,
             listOf(target.constructedClass.llvmTypeInfoPtr, args.first()),