[K/N] Avoid string copying when setting up bridge debug info.

The name of the function was copied at least 4 times. This reduces
a 56 seconds codegen phase in a non-optimized build by 2 seconds.

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

@@ -275,20 +275,17 @@ internal fun setupBridgeDebugInfo(generationState: NativeGenerationState, functi
     val file = debugInfo.compilerGeneratedFile
 
     // TODO: can we share the scope among all bridges?
-    val scope: DIScopeOpaqueRef = DICreateFunction(
+    val scope: DIScopeOpaqueRef = DICreateBridgeFunction(
             builder = debugInfo.builder,
             scope = file.reinterpret(),
-            name = function.name,
+            function = function,
-            linkageName = function.name,
             file = file,
             lineNo = 0,
             type = debugInfo.subroutineType(generationState.runtime.targetData, emptyList()), // TODO: use proper type.
             isLocal = 0,
             isDefinition = 1,
             scopeLine = 0
-    )!!.also {
+    )!!.reinterpret()
-        DIFunctionAddSubprogram(function, it)
-    }.reinterpret()
 
     return LocationInfo(scope, 1, 0)
 }

kotlin-native/llvmDebugInfoC/src/main/cpp/DebugInfoC.cpp

@@ -81,11 +81,11 @@ DIModuleRef DICreateModule(DIBuilderRef builder, DIScopeOpaqueRef scope,
   return llvm::wrap(llvm::unwrap(builder)->createModule(llvm::unwrap(scope), name, configurationMacro, includePath, iSysRoot));
 }
 
-DISubprogramRef DICreateFunction(DIBuilderRef builderRef, DIScopeOpaqueRef scope,
+static DISubprogramRef DICreateFunctionShared(DIBuilderRef builderRef, DIScopeOpaqueRef scope,
-                                 const char* name, const char *linkageName,
+                                              llvm::StringRef name, llvm::StringRef linkageName,
-                                 DIFileRef file, unsigned lineNo,
+                                              DIFileRef file, unsigned lineNo,
-                                 DISubroutineTypeRef type, int isLocal,
+                                              DISubroutineTypeRef type, int isLocal,
-                                 int isDefinition, unsigned scopeLine) {
+                                              int isDefinition, unsigned scopeLine) {
   auto builder = llvm::unwrap(builderRef);
   auto subprogram = builder->createFunction(llvm::unwrap(scope),
                                             name,
@@ -102,6 +102,26 @@ DISubprogramRef DICreateFunction(DIBuilderRef builderRef, DIScopeOpaqueRef scope
   return llvm::wrap(subprogram);
 }
 
+DISubprogramRef DICreateFunction(DIBuilderRef builderRef, DIScopeOpaqueRef scope,
+                                 const char* name, const char *linkageName,
+                                 DIFileRef file, unsigned lineNo,
+                                 DISubroutineTypeRef type, int isLocal,
+                                 int isDefinition, unsigned scopeLine) {
+  return DICreateFunctionShared(builderRef, scope, name, linkageName, file, lineNo, type, isLocal, isDefinition, scopeLine);
+}
+
+DISubprogramRef DICreateBridgeFunction(DIBuilderRef builderRef, DIScopeOpaqueRef scope,
+                                       LLVMValueRef function,
+                                       DIFileRef file, unsigned lineNo,
+                                       DISubroutineTypeRef type, int isLocal,
+                                       int isDefinition, unsigned scopeLine) {
+  auto fn = llvm::cast<llvm::Function>(llvm::unwrap(function));
+  auto name = fn->getName();
+  auto subprogram = DICreateFunctionShared(builderRef, scope, name, name, file, lineNo, type, isLocal, isDefinition, scopeLine);
+  fn->setSubprogram(llvm::unwrap(subprogram));
+  return subprogram;
+}
+
 DIScopeOpaqueRef DICreateLexicalBlockFile(DIBuilderRef builderRef, DIScopeOpaqueRef scopeRef, DIFileRef fileRef) {
   return llvm::wrap(llvm::unwrap(builderRef)->createLexicalBlockFile(llvm::unwrap(scopeRef), llvm::unwrap(fileRef)));
 }

kotlin-native/llvmDebugInfoC/src/main/include/DebugInfoC.h

@@ -93,6 +93,12 @@ DISubprogramRef DICreateFunction(DIBuilderRef builder, DIScopeOpaqueRef scope,
                                  DISubroutineTypeRef type, int isLocal,
                                  int isDefinition, unsigned scopeLine);
 
+DISubprogramRef DICreateBridgeFunction(DIBuilderRef builder, DIScopeOpaqueRef scope,
+                                       LLVMValueRef function,
+                                       DIFileRef file, unsigned lineNo,
+                                       DISubroutineTypeRef type, int isLocal,
+                                       int isDefinition, unsigned scopeLine);
+
 DISubroutineTypeRef DICreateSubroutineType(DIBuilderRef builder,
                                            DITypeOpaqueRef* types,
                                            unsigned typesCount);