This revision was automatically updated to reflect the committed changes.
Closed by commit rG51d8c598331b: [lldb] Don't model std::atomic as a 
transparent data structure in the data… (authored by teemperor).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D74310/new/

https://reviews.llvm.org/D74310

Files:
  lldb/source/Plugins/Language/CPlusPlus/LibCxxAtomic.cpp
  
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/TestLibCxxAtomic.py
  
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/main.cpp

Index: lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/main.cpp
===================================================================
--- lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/main.cpp
+++ lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/main.cpp
@@ -8,6 +8,18 @@
 
 #include <atomic>
 
+// Define a Parent and Child struct that can point to each other.
+class Parent;
+struct Child {
+  // This should point to the parent which in turn owns this
+  // child instance. This cycle should not cause LLDB to infinite loop
+  // during printing.
+  std::atomic<Parent*> parent{nullptr};
+};
+struct Parent {
+  Child child;
+};
+
 struct S {
     int x = 1;
     int y = 2;
@@ -19,7 +31,11 @@
     s.store(S());
     std::atomic<int> i;
     i.store(5);
-    
+
+    Parent p;
+    // Let the child node know what its parent is.
+    p.child.parent = &p;
+
     return 0; // Set break point at this line.
 }
 
Index: lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/TestLibCxxAtomic.py
===================================================================
--- lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/TestLibCxxAtomic.py
+++ lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/TestLibCxxAtomic.py
@@ -42,13 +42,19 @@
                     substrs=['stopped',
                              'stop reason = breakpoint'])
 
-        s = self.get_variable('s')
-        i = self.get_variable('i')
+        s_atomic = self.get_variable('s')
+        i_atomic = self.get_variable('i')
 
         if self.TraceOn():
-            print(s)
+            print(s_atomic)
         if self.TraceOn():
-            print(i)
+            print(i_atomic)
+
+        # Extract the content of the std::atomic wrappers.
+        self.assertEqual(s_atomic.GetNumChildren(), 1)
+        s = s_atomic.GetChildAtIndex(0)
+        self.assertEqual(i_atomic.GetNumChildren(), 1)
+        i = i_atomic.GetChildAtIndex(0)
 
         self.assertTrue(i.GetValueAsUnsigned(0) == 5, "i == 5")
         self.assertTrue(s.GetNumChildren() == 2, "s has two children")
@@ -58,3 +64,9 @@
         self.assertTrue(
             s.GetChildAtIndex(1).GetValueAsUnsigned(0) == 2,
             "s.y == 2")
+
+        # Try printing the child that points to its own parent object.
+        # This should just treat the atomic pointer as a normal pointer.
+        self.expect("frame var p.child", substrs=["Value = 0x"])
+        self.expect("frame var p", substrs=["parent = {", "Value = 0x", "}"])
+        self.expect("frame var p.child.parent", substrs=["p.child.parent = {\n  Value = 0x"])
Index: lldb/source/Plugins/Language/CPlusPlus/LibCxxAtomic.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibCxxAtomic.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibCxxAtomic.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "LibCxxAtomic.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
 
 using namespace lldb;
 using namespace lldb_private;
@@ -100,8 +101,6 @@
 
   size_t GetIndexOfChildWithName(ConstString name) override;
 
-  lldb::ValueObjectSP GetSyntheticValue() override;
-
 private:
   ValueObject *m_real_child;
 };
@@ -127,26 +126,20 @@
 
 size_t lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
     CalculateNumChildren() {
-  return m_real_child ? m_real_child->GetNumChildren() : 0;
+  return m_real_child ? 1 : 0;
 }
 
 lldb::ValueObjectSP
 lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::GetChildAtIndex(
     size_t idx) {
-  return m_real_child ? m_real_child->GetChildAtIndex(idx, true) : nullptr;
+  if (idx == 0)
+    return m_real_child->GetSP()->Clone(ConstString("Value"));
+  return nullptr;
 }
 
 size_t lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
     GetIndexOfChildWithName(ConstString name) {
-  return m_real_child ? m_real_child->GetIndexOfChildWithName(name)
-                      : UINT32_MAX;
-}
-
-lldb::ValueObjectSP lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
-    GetSyntheticValue() {
-  if (m_real_child && m_real_child->CanProvideValue())
-    return m_real_child->GetSP();
-  return nullptr;
+  return formatters::ExtractIndexFromString(name.GetCString());
 }
 
 SyntheticChildrenFrontEnd *
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