[lldb] Add parent address to Task synthetic provider

lldb/source/Plugins/Language/Swift/SwiftFormatters.cpp

@@ -734,6 +734,11 @@ namespace lldb_private {
 namespace formatters {
 namespace swift {
 
+/// The size of Swift Tasks. Fragments are tail allocated.
+static constexpr size_t AsyncTaskSize = sizeof(::swift::AsyncTask);
+/// The offset of ChildFragment, which is the first fragment of an AsyncTask.
+static constexpr offset_t ChildFragmentOffset = AsyncTaskSize;
+
 class EnumSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
 public:
   EnumSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
@@ -806,6 +811,7 @@ class TaskSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
       "address",
       "id",
       "enqueuePriority",
+      "parent",
       "children",
 
       // Children below this point are hidden.
@@ -823,8 +829,9 @@ class TaskSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
   };
 
   llvm::Expected<uint32_t> CalculateNumChildren() override {
-    // Show only the first four children address/id/enqueuePriority/children.
-    return 4;
+    // Show only the first five children
+    // address/id/enqueuePriority/parent/children.
+    return 5;
   }
 
   lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override {
@@ -873,6 +880,36 @@ class TaskSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
       RETURN_CHILD(m_enqueue_priority_sp, enqueuePriority, priority_type);
     }
     case 3: {
+      if (!m_parent_task_sp) {
+        auto process_sp = m_backend.GetProcessSP();
+        if (!process_sp)
+          return {};
+
+        // TypeMangling for "Swift.Optional<Swift.UnsafeRawPointer>"
+        CompilerType raw_pointer_type =
+            m_ts->GetTypeFromMangledTypename(ConstString("$sSVSgD"));
+
+        addr_t parent_addr = 0;
+        if (m_task_info.isChildTask) {
+          // Read ChildFragment::Parent, the first field of the ChildFragment.
+          Status status;
+          parent_addr = process_sp->ReadPointerFromMemory(
+              m_task_ptr + ChildFragmentOffset, status);
+          if (status.Fail() || parent_addr == LLDB_INVALID_ADDRESS)
+            parent_addr = 0;
+        }
+
+        addr_t value = parent_addr;
+        DataExtractor data{reinterpret_cast<const void *>(&value),
+                           sizeof(value), endian::InlHostByteOrder(),
+                           sizeof(void *)};
+        m_parent_task_sp = ValueObject::CreateValueObjectFromData(
+            "parent", data, m_backend.GetExecutionContextRef(),
+            raw_pointer_type);
+      }
+      return m_parent_task_sp;
+    }
+    case 4: {
       if (!m_child_tasks_sp) {
         using task_type = decltype(m_task_info.childTasks)::value_type;
         std::vector<task_type> tasks = m_task_info.childTasks;
@@ -901,26 +938,26 @@ class TaskSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
       }
       return m_child_tasks_sp;
     }
-    case 4:
-      RETURN_CHILD(m_is_child_task_sp, isChildTask, bool_type);
     case 5:
-      RETURN_CHILD(m_is_future_sp, isFuture, bool_type);
+      RETURN_CHILD(m_is_child_task_sp, isChildTask, bool_type);
     case 6:
-      RETURN_CHILD(m_is_group_child_task_sp, isGroupChildTask, bool_type);
+      RETURN_CHILD(m_is_future_sp, isFuture, bool_type);
     case 7:
-      RETURN_CHILD(m_is_async_let_task_sp, isAsyncLetTask, bool_type);
+      RETURN_CHILD(m_is_group_child_task_sp, isGroupChildTask, bool_type);
     case 8:
-      RETURN_CHILD(m_is_cancelled_sp, isCancelled, bool_type);
+      RETURN_CHILD(m_is_async_let_task_sp, isAsyncLetTask, bool_type);
     case 9:
+      RETURN_CHILD(m_is_cancelled_sp, isCancelled, bool_type);
+    case 10:
       RETURN_CHILD(m_is_status_record_locked_sp, isStatusRecordLocked,
                    bool_type);
-    case 10:
-      RETURN_CHILD(m_is_escalated_sp, isEscalated, bool_type);
     case 11:
-      RETURN_CHILD(m_is_enqueued_sp, isEnqueued, bool_type);
+      RETURN_CHILD(m_is_escalated_sp, isEscalated, bool_type);
     case 12:
+      RETURN_CHILD(m_is_enqueued_sp, isEnqueued, bool_type);
+    case 13:
       RETURN_CHILD(m_is_complete_sp, isComplete, bool_type);
-    case 13: {
+    case 14: {
       if (m_task_info.hasIsRunning)
         RETURN_CHILD(m_is_running_sp, isRunning, bool_type);
       return {};
@@ -953,8 +990,8 @@ class TaskSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
                 m_is_child_task_sp, m_is_future_sp, m_is_group_child_task_sp,
                 m_is_async_let_task_sp, m_is_cancelled_sp,
                 m_is_status_record_locked_sp, m_is_escalated_sp,
-                m_is_enqueued_sp, m_is_complete_sp, m_child_tasks_sp,
-                m_is_running_sp})
+                m_is_enqueued_sp, m_is_complete_sp, m_parent_task_sp,
+                m_child_tasks_sp, m_is_running_sp})
             child.reset();
         }
       }
@@ -990,6 +1027,7 @@ class TaskSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
   ValueObjectSP m_is_escalated_sp;
   ValueObjectSP m_is_enqueued_sp;
   ValueObjectSP m_is_complete_sp;
+  ValueObjectSP m_parent_task_sp;
   ValueObjectSP m_child_tasks_sp;
   ValueObjectSP m_is_running_sp;
 };
@@ -1280,8 +1318,6 @@ class TaskGroupSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
     bool operator==(const Task &other) const { return addr == other.addr; }
     bool operator!=(const Task &other) const { return !(*this == other); }
 
-    static constexpr offset_t AsyncTaskSize = sizeof(::swift::AsyncTask);
-    static constexpr offset_t ChildFragmentOffset = AsyncTaskSize;
     static constexpr offset_t NextChildOffset = ChildFragmentOffset + 0x8;
 
     Task getNextChild(Status &status) {

lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.cpp

@@ -2857,6 +2857,13 @@ TypeSystemSwiftTypeRef::RemangleAsType(swift::Demangle::Demangler &dem,
   if (!node)
     return {};
 
+  // Guard against an empty opaque type. This can happen when demangling an
+  // OpaqueTypeRef (ex `$sBpD`). An empty opaque will assert when mangled.
+  if (auto *opaque_type =
+          swift_demangle::ChildAtPath(node, {Node::Kind::OpaqueType}))
+    if (!opaque_type->hasChildren())
+      return {};
+
   using namespace swift::Demangle;
   if (node->getKind() != Node::Kind::Global) {
     auto global = dem.createNode(Node::Kind::Global);

lldb/test/API/lang/swift/async/continuations/TestSwiftContinuationSynthetic.py

@@ -24,6 +24,7 @@ def test_unsafe_continuation_printing(self):
                         address = 0x[0-9a-f]+
                         id = \1
                         enqueuePriority = 0
+                        parent = nil
                         children = \{\}
                       \}
                     \}
@@ -49,6 +50,7 @@ def test_checked_continuation_printing(self):
                         address = 0x[0-9a-f]+
                         id = \1
                         enqueuePriority = 0
+                        parent = nil
                         children = \{\}
                       \}
                     \}

lldb/test/API/lang/swift/async/formatters/task/TestSwiftTaskSyntheticProvider.py

@@ -25,6 +25,7 @@ def test_top_level_task(self):
                       address = 0x[0-9a-f]+
                       id = \1
                       enqueuePriority = \.medium
+                      parent = nil
                       children = \{\}
                     }
                     """
@@ -49,6 +50,7 @@ def test_current_task(self):
                       address = 0x[0-9a-f]+
                       id = \1
                       enqueuePriority = \.medium
+                      parent = 0x[0-9a-f]+ \{\}
                       children = \{\}
                     \}
                     """

lldb/test/API/lang/swift/async/formatters/task/children/TestSwiftSyntheticTaskChildren.py

@@ -21,14 +21,16 @@ def test(self):
                 textwrap.dedent(
                     r"""
                     \(UnsafeCurrentTask\) current_task = id:1 flags:(?:running|enqueued) \{
-                      address = 0x[0-9a-f]+
+                      address = (0x[0-9a-f]+)
                       id = 1
                       enqueuePriority = 0
+                      parent = nil
                       children = \{
                         0 = id:2 flags:(?:running\|)?(?:enqueued\|)?asyncLetTask \{
                           address = 0x[0-9a-f]+
                           id = 2
                           enqueuePriority = \.medium
+                          parent = \1 \{\}
                           children = \{\}
                         \}
                       \}

lldb/test/API/lang/swift/async/formatters/task/parent/Makefile

@@ -0,0 +1,3 @@
+SWIFT_SOURCES := main.swift
+SWIFTFLAGS_EXTRAS := -parse-as-library
+include Makefile.rules

lldb/test/API/lang/swift/async/formatters/task/parent/TestSwiftSyntheticTaskParent.py

@@ -0,0 +1,35 @@
+import re
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+ADDR_PATTERN = "(0x[0-9a-f]{6,})"
+
+class TestCase(TestBase):
+
+    @skipUnlessDarwin
+    @swiftTest
+    def test(self):
+        self.build()
+        _, process, _, _ = lldbutil.run_to_name_breakpoint(self, "breakHere")
+
+        # First breakpoint hit occurrs in a root task, with no parent.
+        self.expect("task info", substrs=["parent = nil"])
+        root_task = self._extract("task info", f"address = {ADDR_PATTERN}")
+
+        # Continue to the next hit of the same breakpoint, which is called from
+        # an async let child task.
+        process.Continue()
+        parent_of_child_task = self._extract("task info", f"parent = {ADDR_PATTERN}")
+
+        # Ensure the parent of the child is the same as the root task.
+        self.assertEqual(root_task, parent_of_child_task)
+
+    def _extract(self, command: str, pattern: str) -> str:
+        ret = lldb.SBCommandReturnObject()
+        self.ci.HandleCommand(command, ret)
+        match = re.search(pattern, ret.GetOutput(), flags=re.I)
+        self.assertTrue(match)
+        return match.group(1) if match else ""

lldb/test/API/lang/swift/async/formatters/task/parent/main.swift

@@ -0,0 +1,9 @@
+func breakHere() {}
+
+@main struct Main {
+    static func main() async {
+        await breakHere()
+        async let x = breakHere()
+        await x
+    }
+}

lldb/test/API/lang/swift/async/taskgroups/TestSwiftTaskGroupSynthetic.py

@@ -36,18 +36,21 @@ def do_test_print(self):
                         address = 0x[0-9a-f]+
                         id = \1
                         enqueuePriority = \.medium
+                        parent = (.+)
                         children = \{\}
                       \}
                       \[1\] = id:([1-9]\d*) flags:(?:running\|)?(?:enqueued\|)?groupChildTask \{
                         address = 0x[0-9a-f]+
-                        id = \2
+                        id = \3
                         enqueuePriority = \.medium
+                        parent = \2
                         children = \{\}
                       \}
                       \[2\] = id:([1-9]\d*) flags:(?:running\|)?(?:enqueued\|)?groupChildTask \{
                         address = 0x[0-9a-f]+
-                        id = \3
+                        id = \4
                         enqueuePriority = \.medium
+                        parent = \2
                         children = \{\}
                       \}
                     \}