[lldb] Add support for calling objc_direct methods from LLDB's expression evaluator.

[teemperor]

Summary

D69991 introduced __attribute__((objc_direct)) that allows directly calling methods without message passing.
This patch adds support for calling methods with this attribute to LLDB's expression evaluator.

The patch can be summarised in that LLDB just adds the same attribute to our module AST when we find a
method with __attribute__((objc_direct)) in our debug information.

[shafik]

LGTM

lldb/include/lldb/Symbol/ClangASTContext.h

static bool AddObjCClassProperty(const CompilerType &type,
                                    ClangASTMetadata *metadata);
 
   static clang::ObjCMethodDecl *AddMethodToObjCObjectType(
       const CompilerType &type,
       const char *name, // the full symbol name as seen in the symbol table
                         // (lldb::opaque_compiler_type_t type, "-[NString
                         // stringWithCString:]")
       const CompilerType &method_compiler_type, lldb::AccessType access,
-      bool is_artificial, bool is_variadic);
+      bool is_artificial, bool is_variadic, bool is_objc_direct_call);
 
   static bool SetHasExternalStorage(lldb::opaque_compiler_type_t type,
                                     bool has_extern);
 
   // Tag Declarations
   static bool StartTagDeclarationDefinition(const CompilerType &type);
 
   static bool CompleteTagDeclarationDefinition(const CompilerType &type);

lldb/packages/Python/lldbsuite/test/lang/objc/objc_direct-methods/Makefile

+OBJC_SOURCES := main.m
+LD_EXTRAS := -lobjc -framework Foundation
+
+include Makefile.rules

lldb/packages/Python/lldbsuite/test/lang/objc/objc_direct-methods/TestObjCDirectMethods.py

+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(
+    __file__, globals(), [decorators.skipUnlessDarwin])

lldb/packages/Python/lldbsuite/test/lang/objc/objc_direct-methods/main.m

+#import <Foundation/Foundation.h>
+
+int side_effect = 0;
+
+NSString *str = @"some string";
+
+const char *directCallConflictingName() {
+  return "wrong function";
+}
+
+@interface Foo : NSObject {
+  int instance_var;
+}
+-(int) entryPoint;
+@end
+
+@implementation Foo
+-(int) entryPoint
+{
+  // Try calling directly with self. Same as in the main method otherwise.
+  return 0; //%self.expect("expr [self directCallNoArgs]", substrs=["called directCallNoArgs"])
+            //%self.expect("expr [self directCallArgs: 1111]", substrs=["= 2345"])
+            //%self.expect("expr side_effect = 0; [self directCallVoidReturn]; side_effect", substrs=["= 4321"])
+            //%self.expect("expr [self directCallNSStringArg: str]", substrs=['@"some string"'])
+            //%self.expect("expr [self directCallIdArg: (id)str]", substrs=['@"some string appendix"'])
+            //%self.expect("expr [self directCallConflictingName]", substrs=["correct function"])
+}
+
+// Declare several objc_direct functions we can test.
+-(const char *) directCallNoArgs __attribute__((objc_direct))
+{
+  return "called directCallNoArgs";
+}
+
+-(void) directCallVoidReturn __attribute__((objc_direct))
+{
+  side_effect = 4321;
+}
+
+-(int) directCallArgs:(int)i __attribute__((objc_direct))
+{
+  // Use the arg in some way to make sure that gets passed correctly.
+  return i + 1234;
+}
+
+-(NSString *) directCallNSStringArg:(NSString *)str __attribute__((objc_direct))
+{
+  return str;
+}
+
+-(NSString *) directCallIdArg:(id)param __attribute__((objc_direct))
+{
+  return [param stringByAppendingString:@" appendix"];
+}
+
+// We have another function with the same name above. Make sure this doesn't influence
+// what we call.
+-(const char *) directCallConflictingName  __attribute__((objc_direct))
+{
+  return "correct function";
+}
+@end
+
+int main()
+{
+  Foo *foo = [[Foo alloc] init];
+  [foo directCallNoArgs];
+  [foo directCallArgs: 1];
+  [foo directCallVoidReturn];
+  [foo directCallNSStringArg: str];
+  [foo directCallIdArg: (id)str];
+  [foo entryPoint];  //%self.expect("expr [foo directCallNoArgs]", substrs=["called directCallNoArgs"])
+                     //%self.expect("expr [foo directCallArgs: 1111]", substrs=["= 2345"])
+                     //%self.expect("expr side_effect = 0; [foo directCallVoidReturn]; side_effect", substrs=["= 4321"])
+                     //%self.expect("expr [foo directCallNSStringArg: str]", substrs=['@"some string"'])
+                     //%self.expect("expr [foo directCallIdArg: (id)str]", substrs=['@"some string appendix"'])
+                     //%self.expect("expr [foo directCallConflictingName]", substrs=["correct function"])
+  return 0;
+}

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h

struct ParsedDWARFTypeAttributes {
   bool is_artificial = false;
   bool is_complete_objc_class = false;
   bool is_explicit = false;
   bool is_forward_declaration = false;
   bool is_inline = false;
   bool is_scoped_enum = false;
   bool is_vector = false;
   bool is_virtual = false;
+  bool is_objc_direct_call = false;
   bool exports_symbols = false;
   clang::StorageClass storage = clang::SC_None;
   const char *mangled_name = nullptr;
   lldb_private::ConstString name;
   lldb_private::Declaration decl;
   DWARFDIE object_pointer;
   DWARFFormValue abstract_origin;
   DWARFFormValue containing_type;

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

for (size_t i = 0; i < num_attributes; ++i) {
     case DW_AT_virtuality:
       is_virtual = form_value.Boolean();
       break;
 
     case DW_AT_APPLE_objc_complete_type:
       is_complete_objc_class = form_value.Signed();
       break;
 
+    case DW_AT_APPLE_objc_direct:
+      is_objc_direct_call = true;
+      break;
+
     case DW_AT_APPLE_runtime_class:
       class_language = (LanguageType)form_value.Signed();
       break;
 
     case DW_AT_GNU_vector:
       is_vector = form_value.Boolean();
       break;
     case DW_AT_export_symbols:
if (tag == DW_TAG_subprogram || tag == DW_TAG_inlined_subroutine) {
           // If accessibility isn't set to anything valid, assume public
           // for now...
           if (attrs.accessibility == eAccessNone)
             attrs.accessibility = eAccessPublic;
 
           clang::ObjCMethodDecl *objc_method_decl =
               m_ast.AddMethodToObjCObjectType(
                   class_opaque_type, attrs.name.GetCString(), clang_type,
-                  attrs.accessibility, attrs.is_artificial, is_variadic);
+                  attrs.accessibility, attrs.is_artificial, is_variadic,
+                  attrs.is_objc_direct_call);
           type_handled = objc_method_decl != NULL;
           if (type_handled) {
             LinkDeclContextToDIE(objc_method_decl, die);
             m_ast.SetMetadataAsUserID(objc_method_decl, die.GetID());
           } else {
             dwarf->GetObjectFile()->GetModule()->ReportError(
                 "{0x%8.8x}: invalid Objective-C method 0x%4.4x (%s), "
                 "please file a bug and attach the file at the start of "

lldb/source/Symbol/ClangASTContext.cpp

 }
 
 clang::ObjCMethodDecl *ClangASTContext::AddMethodToObjCObjectType(
     const CompilerType &type,
     const char *name, // the full symbol name as seen in the symbol table
                       // (lldb::opaque_compiler_type_t type, "-[NString
                       // stringWithCString:]")
     const CompilerType &method_clang_type, lldb::AccessType access,
-    bool is_artificial, bool is_variadic) {
+    bool is_artificial, bool is_variadic, bool is_objc_direct_call) {
   if (!type || !method_clang_type.IsValid())
     return nullptr;
 
   clang::ObjCInterfaceDecl *class_interface_decl = GetAsObjCInterfaceDecl(type);
 
   if (class_interface_decl == nullptr)
     return nullptr;
   ClangASTContext *lldb_ast =
for (unsigned param_index = 0; param_index < num_args; ++param_index) {
           clang::SC_Auto, nullptr));
     }
 
     objc_method_decl->setMethodParams(
         *ast, llvm::ArrayRef<clang::ParmVarDecl *>(params),
         llvm::ArrayRef<clang::SourceLocation>());
   }
 
+  if (is_objc_direct_call) {
+    // Add a the objc_direct attribute to the declaration we generate that
+    // we generate a direct method call for this ObjCMethodDecl.
+    objc_method_decl->addAttr(
+        clang::ObjCDirectAttr::CreateImplicit(*ast, SourceLocation()));
+    // Usually Sema is creating implicit parameters (e.g., self) when it
+    // parses the method. We don't have a parsing Sema when we build our own
+    // AST here so we manually need to create these implicit parameters to
+    // make the direct call code generation happy.
+    objc_method_decl->createImplicitParams(*ast, class_interface_decl);
+  }
+
   class_interface_decl->addDecl(objc_method_decl);
 
 #ifdef LLDB_CONFIGURATION_DEBUG
   VerifyDecl(objc_method_decl);
 #endif
 
   return objc_method_decl;
 }