Because of our lifetime rules w.r.t. ValueObjects and ClusterManagers, synthetic children caching is a tricky area:

- if a synthetic child comes from the same hierarchy as its parent object, then it can't be cached by SharedPointer inside the synthetic provider, or it will cause a reference loop;
- but, if a synthetic child is made from whole cloth (e.g. from an expression, a memory region, ...), then it better be cached by SharedPointer, or it will be cleared out and cause an assert() to fail if used at a later point

For most cases of self-rooted synthetic children, we have a flag we set "IsSyntheticChildrenGenerated", but we were not using it to track caching. So, what ended up happening is each provider would set up its own cache, and if it got it wrong, a hard to diagnose crash would ensue

This patch fixes that by centralizing caching in ValueObjectSynthetic - if a provider returns a self-rooted child (as per the flag), then it gets cached centrally by the ValueObject itself
This cache is used only for lifetime management and not later retrieval of child values - a different cache handles that (because we might have a mix of self-rooted and properly nested child values for the same parent, we can't trivially use this lifetime cache for retrieval)

Fixes rdar://26480007

llvm-svn: 274683

16 files changed, 199 insertions, 82 deletions

diff --git a/lldb/include/lldb/API/SBValue.h b/lldb/include/lldb/API/SBValue.h
index a7e015064f9..b9f1e6f5c93 100644
--- a/lldb/include/lldb/API/SBValue.h
+++ b/lldb/include/lldb/API/SBValue.h
@@ -125,6 +125,12 @@ public:
     
     bool
     IsSynthetic ();
+    
+    bool
+    IsSyntheticChildrenGenerated ();
+    
+    void
+    SetSyntheticChildrenGenerated (bool);
 
     const char *
     GetLocation ();
diff --git a/lldb/include/lldb/Core/ThreadSafeSTLVector.h b/lldb/include/lldb/Core/ThreadSafeSTLVector.h
new file mode 100644
index 00000000000..dd90d49afcb
--- /dev/null
+++ b/lldb/include/lldb/Core/ThreadSafeSTLVector.h
@@ -0,0 +1,99 @@
+//===-- ThreadSafeSTLVector.h ------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_ThreadSafeSTLVector_h_
+#define liblldb_ThreadSafeSTLVector_h_
+
+// C Includes
+// C++ Includes
+#include <vector>
+#include <mutex>
+
+// Other libraries and framework includes
+// Project includes
+#include "lldb/lldb-defines.h"
+
+namespace lldb_private {
+    
+    template <typename _Object>
+    class ThreadSafeSTLVector
+    {
+    public:
+        typedef std::vector<_Object> collection;
+        typedef typename collection::iterator iterator;
+        typedef typename collection::const_iterator const_iterator;
+        //------------------------------------------------------------------
+        // Constructors and Destructors
+        //------------------------------------------------------------------
+        ThreadSafeSTLVector() : m_collection(), m_mutex() {}
+        
+        ~ThreadSafeSTLVector() = default;
+        
+        bool
+        IsEmpty() const
+        {
+            std::lock_guard<std::recursive_mutex> guard(m_mutex);
+            return m_collection.empty();
+        }
+        
+        void
+        Clear()
+        {
+            std::lock_guard<std::recursive_mutex> guard(m_mutex);
+            return m_collection.clear();
+        }
+        
+        size_t
+        GetCount()
+        {
+            std::lock_guard<std::recursive_mutex> guard(m_mutex);
+            return m_collection.size();
+        }
+        
+        void
+        AppendObject (_Object& object)
+        {
+            std::lock_guard<std::recursive_mutex> guard(m_mutex);
+            m_collection.push_back(object);
+        }
+        
+        _Object
+        GetObject (size_t index)
+        {
+            std::lock_guard<std::recursive_mutex> guard(m_mutex);
+            return m_collection.at(index);
+        }
+        
+        void
+        SetObject (size_t index, const _Object& object)
+        {
+            std::lock_guard<std::recursive_mutex> guard(m_mutex);
+            m_collection.at(index) = object;
+        }
+        
+        std::recursive_mutex &
+        GetMutex()
+        {
+            return m_mutex;
+        }
+        
+    private:
+        collection m_collection;
+        mutable std::recursive_mutex m_mutex;
+        
+        //------------------------------------------------------------------
+        // For ThreadSafeSTLVector only
+        //------------------------------------------------------------------
+        DISALLOW_COPY_AND_ASSIGN (ThreadSafeSTLVector);
+    };
+    
+    
+} // namespace lldb_private
+
+#endif  // liblldb_ThreadSafeSTLVector_h_
diff --git a/lldb/include/lldb/Core/ValueObjectSyntheticFilter.h b/lldb/include/lldb/Core/ValueObjectSyntheticFilter.h
index 05bc3781a3c..3a8068298e2 100644
--- a/lldb/include/lldb/Core/ValueObjectSyntheticFilter.h
+++ b/lldb/include/lldb/Core/ValueObjectSyntheticFilter.h
@@ -17,6 +17,7 @@
 // Other libraries and framework includes
 // Project includes
 #include "lldb/Core/ThreadSafeSTLMap.h"
+#include "lldb/Core/ThreadSafeSTLVector.h"
 #include "lldb/Core/ValueObject.h"
 
 namespace lldb_private {
@@ -177,6 +178,7 @@ protected:
     
     typedef ThreadSafeSTLMap<uint32_t, ValueObject*> ByIndexMap;
     typedef ThreadSafeSTLMap<const char*, uint32_t> NameToIndexMap;
+    typedef ThreadSafeSTLVector<lldb::ValueObjectSP> SyntheticChildrenCache;
     
     typedef ByIndexMap::iterator ByIndexIterator;
     typedef NameToIndexMap::iterator NameToIndexIterator;
@@ -184,6 +186,7 @@ protected:
     ByIndexMap      m_children_byindex;
     NameToIndexMap  m_name_toindex;
     uint32_t        m_synthetic_children_count; // FIXME use the ValueObject's ChildrenManager instead of a special purpose solution
+    SyntheticChildrenCache m_synthetic_children_cache;
     
     ConstString     m_parent_type_name;
 
diff --git a/lldb/include/lldb/Utility/SharedCluster.h b/lldb/include/lldb/Utility/SharedCluster.h
index 0057844549f..dfcc119e14b 100644
--- a/lldb/include/lldb/Utility/SharedCluster.h
+++ b/lldb/include/lldb/Utility/SharedCluster.h
@@ -10,6 +10,7 @@
 #ifndef utility_SharedCluster_h_
 #define utility_SharedCluster_h_
 
+#include "lldb/Utility/LLDBAssert.h"
 #include "lldb/Utility/SharingPtr.h"
 
 #include "llvm/ADT/SmallPtrSet.h"
@@ -75,7 +76,11 @@ public:
         {
             std::lock_guard<std::mutex> guard(m_mutex);
             m_external_ref++;
-            assert(m_objects.count(desired_object));
+            if (0 == m_objects.count(desired_object))
+            {
+                lldbassert(false && "object not found in shared cluster when expected");
+                desired_object = nullptr;
+            }
         }
         return typename lldb_private::SharingPtr<T>(desired_object, new imp::shared_ptr_refcount<ClusterManager>(this));
     }
diff --git a/lldb/lldb.xcodeproj/project.pbxproj b/lldb/lldb.xcodeproj/project.pbxproj
index 4e63c2a3e40..6b54194fece 100644
--- a/lldb/lldb.xcodeproj/project.pbxproj
+++ b/lldb/lldb.xcodeproj/project.pbxproj
@@ -2532,6 +2532,7 @@
 		940495791BEC497E00926025 /* NSException.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = NSException.cpp; path = Language/ObjC/NSException.cpp; sourceTree = "<group>"; };
 		94094C68163B6CCC0083A547 /* ValueObjectCast.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = ValueObjectCast.h; path = include/lldb/Core/ValueObjectCast.h; sourceTree = "<group>"; };
 		94094C69163B6CD90083A547 /* ValueObjectCast.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = ValueObjectCast.cpp; path = source/Core/ValueObjectCast.cpp; sourceTree = "<group>"; };
+		940B01FE1D2D82220058795E /* ThreadSafeSTLVector.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = ThreadSafeSTLVector.h; path = include/lldb/Core/ThreadSafeSTLVector.h; sourceTree = "<group>"; };
 		940B02F419DC96CB00AD0F52 /* SBExecutionContext.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = SBExecutionContext.h; path = include/lldb/API/SBExecutionContext.h; sourceTree = "<group>"; };
 		940B02F519DC96E700AD0F52 /* SBExecutionContext.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = SBExecutionContext.cpp; path = source/API/SBExecutionContext.cpp; sourceTree = "<group>"; };
 		940B02F719DC970900AD0F52 /* SBExecutionContext.i */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.c.preprocessed; path = SBExecutionContext.i; sourceTree = "<group>"; };
@@ -4422,6 +4423,7 @@
 				AFEC3361194A8ABA00FF05C6 /* StructuredData.cpp */,
 				26B167A41123BF5500DC7B4F /* ThreadSafeValue.h */,
 				263FEDA5112CC1DA00E4C208 /* ThreadSafeSTLMap.h */,
+				940B01FE1D2D82220058795E /* ThreadSafeSTLVector.h */,
 				26BC7D7E10F1B77400F91463 /* Timer.h */,
 				26BC7E9610F1B85900F91463 /* Timer.cpp */,
 				94ED54A119C8A822007BE2EA /* ThreadSafeDenseMap.h */,
diff --git a/lldb/scripts/interface/SBValue.i b/lldb/scripts/interface/SBValue.i
index 5049fd05794..ef9fe3c7485 100644
--- a/lldb/scripts/interface/SBValue.i
+++ b/lldb/scripts/interface/SBValue.i
@@ -157,6 +157,12 @@ public:
     
     bool
     IsSynthetic ();
+    
+    bool
+    IsSyntheticChildrenGenerated ();
+    
+    void
+    SetSyntheticChildrenGenerated (bool);
 
     const char *
     GetLocation ();
@@ -533,6 +539,23 @@ public:
         
         __swig_getmethods__["path"] = get_expr_path
         if _newclass: path = property(get_expr_path, None, doc='''A read only property that returns the expression path that one can use to reach this value in an expression.''')
+        
+        def synthetic_child_from_expression(self, name, expr, options=None):
+            if options is None: options = lldb.SBExpressionOptions()
+            child = self.CreateValueFromExpression(name, expr, options)
+            child.SetSyntheticChildrenGenerated(True)
+            return child
+        
+        def synthetic_child_from_data(self, name, data, type):
+            child = self.CreateValueFromData(name, data, type)
+            child.SetSyntheticChildrenGenerated(True)
+            return child
+                
+        def synthetic_child_from_address(self, name, addr, type):
+            child = self.CreateValueFromAddress(name, addr, type)
+            child.SetSyntheticChildrenGenerated(True)
+            return child
+
     %}
 
 };
diff --git a/lldb/source/API/SBValue.cpp b/lldb/source/API/SBValue.cpp
index d08073306cc..4fdcb0d5ecb 100644
--- a/lldb/source/API/SBValue.cpp
+++ b/lldb/source/API/SBValue.cpp
@@ -1145,6 +1145,25 @@ SBValue::IsSynthetic ()
     return false;
 }
 
+bool
+SBValue::IsSyntheticChildrenGenerated ()
+{
+    ValueLocker locker;
+    lldb::ValueObjectSP value_sp(GetSP(locker));
+    if (value_sp)
+        return value_sp->IsSyntheticChildrenGenerated();
+    return false;
+}
+
+void
+SBValue::SetSyntheticChildrenGenerated (bool is)
+{
+    ValueLocker locker;
+    lldb::ValueObjectSP value_sp(GetSP(locker));
+    if (value_sp)
+        return value_sp->SetSyntheticChildrenGenerated(is);
+}
+
 lldb::SBValue
 SBValue::GetValueForExpressionPath(const char* expr_path)
 {
diff --git a/lldb/source/Core/ValueObjectSyntheticFilter.cpp b/lldb/source/Core/ValueObjectSyntheticFilter.cpp
index 888933416d4..53e38ecd3fe 100644
--- a/lldb/source/Core/ValueObjectSyntheticFilter.cpp
+++ b/lldb/source/Core/ValueObjectSyntheticFilter.cpp
@@ -63,6 +63,7 @@ ValueObjectSynthetic::ValueObjectSynthetic (ValueObject &parent, lldb::Synthetic
     m_children_byindex(),
     m_name_toindex(),
     m_synthetic_children_count(UINT32_MAX),
+    m_synthetic_children_cache(),
     m_parent_type_name(parent.GetTypeName()),
     m_might_have_children(eLazyBoolCalculate),
     m_provides_value(eLazyBoolCalculate)
@@ -212,6 +213,7 @@ ValueObjectSynthetic::UpdateValue ()
         // for a synthetic VO that might indeed happen, so we need to tell the upper echelons
         // that they need to come back to us asking for children
         m_children_count_valid = false;
+        m_synthetic_children_cache.Clear();
         m_synthetic_children_count = UINT32_MAX;
         m_might_have_children = eLazyBoolCalculate;
     }
@@ -271,13 +273,17 @@ ValueObjectSynthetic::GetChildAtIndex (size_t idx, bool can_create)
             lldb::ValueObjectSP synth_guy = m_synth_filter_ap->GetChildAtIndex (idx);
             
             if (log)
-                log->Printf("[ValueObjectSynthetic::GetChildAtIndex] name=%s, child at index %zu created as %p",
+                log->Printf("[ValueObjectSynthetic::GetChildAtIndex] name=%s, child at index %zu created as %p (is synthetic: %s)",
                             GetName().AsCString(),
                             idx,
-                            synth_guy.get());
+                            synth_guy.get(),
+                            synth_guy.get() ? (synth_guy->IsSyntheticChildrenGenerated() ? "yes" : "no") : "no");
 
             if (!synth_guy)
                 return synth_guy;
+            
+            if (synth_guy->IsSyntheticChildrenGenerated())
+                m_synthetic_children_cache.AppendObject(synth_guy);
             m_children_byindex.SetValueForKey(idx, synth_guy.get());
             synth_guy->SetPreferredDisplayLanguageIfNeeded(GetPreferredDisplayLanguage());
             return synth_guy;
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxInitializerList.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxInitializerList.cpp
index 71a94b798c0..54fddd15dd0 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxInitializerList.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxInitializerList.cpp
@@ -50,7 +50,6 @@ namespace lldb_private {
             CompilerType m_element_type;
             uint32_t m_element_size;
             size_t m_num_elements;
-            std::map<size_t,lldb::ValueObjectSP> m_children;
         };
     } // namespace formatters
 } // namespace lldb_private
@@ -60,8 +59,7 @@ lldb_private::formatters::LibcxxInitializerListSyntheticFrontEnd::LibcxxInitiali
     m_start(nullptr),
     m_element_type(),
     m_element_size(0),
-    m_num_elements(0),
-    m_children()
+    m_num_elements(0)
 {
     if (valobj_sp)
         Update();
@@ -90,17 +88,11 @@ lldb_private::formatters::LibcxxInitializerListSyntheticFrontEnd::GetChildAtInde
     if (!m_start)
         return lldb::ValueObjectSP();
     
-    auto cached = m_children.find(idx);
-    if (cached != m_children.end())
-        return cached->second;
-    
     uint64_t offset = idx * m_element_size;
     offset = offset + m_start->GetValueAsUnsigned(0);
     StreamString name;
     name.Printf("[%" PRIu64 "]", (uint64_t)idx);
-    ValueObjectSP child_sp = CreateValueObjectFromAddress(name.GetData(), offset, m_backend.GetExecutionContextRef(), m_element_type);
-    m_children[idx] = child_sp;
-    return child_sp;
+    return CreateValueObjectFromAddress(name.GetData(), offset, m_backend.GetExecutionContextRef(), m_element_type);
 }
 
 bool
@@ -110,7 +102,6 @@ lldb_private::formatters::LibcxxInitializerListSyntheticFrontEnd::Update()
 
     m_start = nullptr;
     m_num_elements = 0;
-    m_children.clear();
     lldb::TemplateArgumentKind kind;
     m_element_type = m_backend.GetCompilerType().GetTemplateArgument(0, kind);
     if (kind != lldb::eTemplateArgumentKindType || !m_element_type.IsValid())
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp
index 8e089ae91ca..35cee566a77 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp
@@ -200,7 +200,6 @@ namespace lldb_private {
             ValueObject* m_tail;
             CompilerType m_element_type;
             size_t m_count;
-            std::map<size_t,lldb::ValueObjectSP> m_children;
             std::map<size_t, ListIterator> m_iterators;
         };
     } // namespace formatters
@@ -215,7 +214,6 @@ lldb_private::formatters::LibcxxStdListSyntheticFrontEnd::LibcxxStdListSynthetic
     m_tail(nullptr),
     m_element_type(),
     m_count(UINT32_MAX),
-    m_children(),
     m_iterators()
 {
     if (valobj_sp)
@@ -312,10 +310,6 @@ lldb_private::formatters::LibcxxStdListSyntheticFrontEnd::GetChildAtIndex (size_
     if (!m_head || !m_tail || m_node_address == 0)
         return lldb::ValueObjectSP();
     
-    auto cached = m_children.find(idx);
-    if (cached != m_children.end())
-        return cached->second;
-    
     if (HasLoop(idx+1))
         return lldb::ValueObjectSP();
     
@@ -350,13 +344,15 @@ lldb_private::formatters::LibcxxStdListSyntheticFrontEnd::GetChildAtIndex (size_
     
     StreamString name;
     name.Printf("[%" PRIu64 "]", (uint64_t)idx);
-    return (m_children[idx] = CreateValueObjectFromData(name.GetData(), data, m_backend.GetExecutionContextRef(), m_element_type));
+    return CreateValueObjectFromData(name.GetData(),
+                                     data,
+                                     m_backend.GetExecutionContextRef(),
+                                     m_element_type);
 }
 
 bool
 lldb_private::formatters::LibcxxStdListSyntheticFrontEnd::Update()
 {
-    m_children.clear();
     m_iterators.clear();
     m_head = m_tail = nullptr;
     m_node_address = 0;
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp
index 7e50c213647..d89869283cd 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxMap.cpp
@@ -246,7 +246,6 @@ namespace lldb_private {
             CompilerType m_element_type;
             uint32_t m_skip_size;
             size_t m_count;
-            std::map<size_t, lldb::ValueObjectSP> m_children;
             std::map<size_t, MapIterator> m_iterators;
         };
     } // namespace formatters
@@ -259,7 +258,6 @@ lldb_private::formatters::LibcxxStdMapSyntheticFrontEnd::LibcxxStdMapSyntheticFr
     m_element_type(),
     m_skip_size(UINT32_MAX),
     m_count(UINT32_MAX),
-    m_children(),
     m_iterators()
 {
     if (valobj_sp)
@@ -332,10 +330,6 @@ lldb_private::formatters::LibcxxStdMapSyntheticFrontEnd::GetChildAtIndex (size_t
     if (m_tree == nullptr || m_root_node == nullptr)
         return lldb::ValueObjectSP();
     
-    auto cached = m_children.find(idx);
-    if (cached != m_children.end())
-        return cached->second;
-
     MapIterator iterator(m_root_node, CalculateNumChildren());
     
     const bool need_to_skip = (idx > 0);
@@ -437,7 +431,7 @@ lldb_private::formatters::LibcxxStdMapSyntheticFrontEnd::GetChildAtIndex (size_t
         potential_child_sp->SetName(ConstString(name.GetData()));
     }
     m_iterators[idx] = iterator;
-    return (m_children[idx] = potential_child_sp);
+    return potential_child_sp;
 }
 
 bool
@@ -447,7 +441,6 @@ lldb_private::formatters::LibcxxStdMapSyntheticFrontEnd::Update()
     static ConstString g___begin_node_("__begin_node_");
     m_count = UINT32_MAX;
     m_tree = m_root_node = nullptr;
-    m_children.clear();
     m_iterators.clear();
     m_tree = m_backend.GetChildMemberWithName(g___tree_, true).get();
     if (!m_tree)
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp
index 5424776950a..a547695448c 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxUnorderedMap.cpp
@@ -55,7 +55,6 @@ namespace lldb_private {
             ValueObject* m_tree;
             size_t m_num_elements;
             ValueObject* m_next_element;
-            std::map<size_t,lldb::ValueObjectSP> m_children;
             std::vector<std::pair<ValueObject*, uint64_t> > m_elements_cache;
         };
     } // namespace formatters
@@ -66,7 +65,6 @@ lldb_private::formatters::LibcxxStdUnorderedMapSyntheticFrontEnd::LibcxxStdUnord
     m_tree(nullptr),
     m_num_elements(0),
     m_next_element(nullptr),
-    m_children(),
     m_elements_cache()
 {
     if (valobj_sp)
@@ -89,10 +87,6 @@ lldb_private::formatters::LibcxxStdUnorderedMapSyntheticFrontEnd::GetChildAtInde
     if (m_tree == nullptr)
         return lldb::ValueObjectSP();
     
-    auto cached = m_children.find(idx);
-    if (cached != m_children.end())
-        return cached->second;
-    
     while (idx >= m_elements_cache.size())
     {
         if (m_next_element == nullptr)
@@ -125,13 +119,10 @@ lldb_private::formatters::LibcxxStdUnorderedMapSyntheticFrontEnd::GetChildAtInde
         return lldb::ValueObjectSP();
     const bool thread_and_frame_only_if_stopped = true;
     ExecutionContext exe_ctx = val_hash.first->GetExecutionContextRef().Lock(thread_and_frame_only_if_stopped);
-    ValueObjectSP child_sp(val_hash.first->CreateValueObjectFromData(stream.GetData(),
-                                                                     data,
-                                                                     exe_ctx,
-                                                                     val_hash.first->GetCompilerType()));
-    if (child_sp)
-        m_children.emplace(idx, child_sp);
-    return child_sp;
+    return CreateValueObjectFromData(stream.GetData(),
+                                     data,
+                                     exe_ctx,
+                                     val_hash.first->GetCompilerType());
 }
 
 bool
@@ -140,7 +131,6 @@ lldb_private::formatters::LibcxxStdUnorderedMapSyntheticFrontEnd::Update()
     m_num_elements = UINT32_MAX;
     m_next_element = nullptr;
     m_elements_cache.clear();
-    m_children.clear();
     ValueObjectSP table_sp = m_backend.GetChildMemberWithName(ConstString("__table_"), true);
     if (!table_sp)
         return false;
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
index b39ea51d193..ed26eaea121 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
@@ -50,7 +50,6 @@ namespace lldb_private {
             ValueObject* m_finish;
             CompilerType m_element_type;
             uint32_t m_element_size;
-            std::map<size_t,lldb::ValueObjectSP> m_children;
         };
     } // namespace formatters
 } // namespace lldb_private
@@ -60,8 +59,7 @@ lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::LibcxxStdVectorSynth
     m_start(nullptr),
     m_finish(nullptr),
     m_element_type(),
-    m_element_size(0),
-    m_children()
+    m_element_size(0)
 {
     if (valobj_sp)
         Update();
@@ -100,24 +98,20 @@ lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::GetChildAtIndex (siz
     if (!m_start || !m_finish)
         return lldb::ValueObjectSP();
     
-    auto cached = m_children.find(idx);
-    if (cached != m_children.end())
-        return cached->second;
-    
     uint64_t offset = idx * m_element_size;
     offset = offset + m_start->GetValueAsUnsigned(0);
     StreamString name;
     name.Printf("[%" PRIu64 "]", (uint64_t)idx);
-    ValueObjectSP child_sp = CreateValueObjectFromAddress(name.GetData(), offset, m_backend.GetExecutionContextRef(), m_element_type);
-    m_children[idx] = child_sp;
-    return child_sp;
+    return CreateValueObjectFromAddress(name.GetData(),
+                                        offset,
+                                        m_backend.GetExecutionContextRef(),
+                                        m_element_type);
 }
 
 bool
 lldb_private::formatters::LibcxxStdVectorSyntheticFrontEnd::Update()
 {
     m_start = m_finish = nullptr;
-    m_children.clear();
     ValueObjectSP data_type_finder_sp(m_backend.GetChildMemberWithName(ConstString("__end_cap_"),true));
     if (!data_type_finder_sp)
         return false;
diff --git a/lldb/source/Plugins/Language/ObjC/NSArray.cpp b/lldb/source/Plugins/Language/ObjC/NSArray.cpp
index 7f29c190e27..5de97b6f025 100644
--- a/lldb/source/Plugins/Language/ObjC/NSArray.cpp
+++ b/lldb/source/Plugins/Language/ObjC/NSArray.cpp
@@ -87,7 +87,6 @@ namespace  lldb_private {
             ExecutionContextRef m_exe_ctx_ref;
             uint8_t m_ptr_size;
             CompilerType m_id_type;
-            std::vector<lldb::ValueObjectSP> m_children;
         };
         
         class NSArrayMSyntheticFrontEnd_109 : public NSArrayMSyntheticFrontEnd
@@ -216,7 +215,6 @@ namespace  lldb_private {
             uint64_t m_items;
             lldb::addr_t m_data_ptr;
             CompilerType m_id_type;
-            std::vector<lldb::ValueObjectSP> m_children;
         };
         
         class NSArray0SyntheticFrontEnd : public SyntheticChildrenFrontEnd
@@ -368,8 +366,7 @@ lldb_private::formatters::NSArrayMSyntheticFrontEnd::NSArrayMSyntheticFrontEnd (
 SyntheticChildrenFrontEnd(*valobj_sp),
 m_exe_ctx_ref(),
 m_ptr_size(8),
-m_id_type(),
-m_children()
+m_id_type()
 {
     if (valobj_sp)
     {
@@ -414,18 +411,15 @@ lldb_private::formatters::NSArrayMSyntheticFrontEnd::GetChildAtIndex (size_t idx
     object_at_idx += (pyhs_idx * m_ptr_size);
     StreamString idx_name;
     idx_name.Printf("[%" PRIu64 "]", (uint64_t)idx);
-    lldb::ValueObjectSP retval_sp = CreateValueObjectFromAddress(idx_name.GetData(),
-                                                                 object_at_idx,
-                                                                 m_exe_ctx_ref,
-                                                                 m_id_type);
-    m_children.push_back(retval_sp);
-    return retval_sp;
+    return CreateValueObjectFromAddress(idx_name.GetData(),
+                                        object_at_idx,
+                                        m_exe_ctx_ref,
+                                        m_id_type);
 }
 
 bool
 lldb_private::formatters::NSArrayMSyntheticFrontEnd_109::Update()
 {
-    m_children.clear();
     ValueObjectSP valobj_sp = m_backend.GetSP();
     m_ptr_size = 0;
     delete m_data_32;
@@ -460,7 +454,6 @@ lldb_private::formatters::NSArrayMSyntheticFrontEnd_109::Update()
 bool
 lldb_private::formatters::NSArrayMSyntheticFrontEnd_1010::Update()
 {
-    m_children.clear();
     ValueObjectSP valobj_sp = m_backend.GetSP();
     m_ptr_size = 0;
     delete m_data_32;
@@ -637,7 +630,6 @@ lldb_private::formatters::NSArrayISyntheticFrontEnd::Update()
     m_ptr_size = 0;
     m_items = 0;
     m_data_ptr = 0;
-    m_children.clear();
     ValueObjectSP valobj_sp = m_backend.GetSP();
     if (!valobj_sp)
         return false;
@@ -677,12 +669,10 @@ lldb_private::formatters::NSArrayISyntheticFrontEnd::GetChildAtIndex (size_t idx
         return lldb::ValueObjectSP();
     StreamString idx_name;
     idx_name.Printf("[%" PRIu64 "]", (uint64_t)idx);
-    lldb::ValueObjectSP retval_sp = CreateValueObjectFromAddress(idx_name.GetData(),
-                                                                 object_at_idx,
-                                                                 m_exe_ctx_ref,
-                                                                 m_id_type);
-    m_children.push_back(retval_sp);
-    return retval_sp;
+    return CreateValueObjectFromAddress(idx_name.GetData(),
+                                        object_at_idx,
+                                        m_exe_ctx_ref,
+                                        m_id_type);
 }
 
 lldb_private::formatters::NSArray0SyntheticFrontEnd::NSArray0SyntheticFrontEnd (lldb::ValueObjectSP valobj_sp) :
diff --git a/lldb/source/Plugins/Language/ObjC/NSError.cpp b/lldb/source/Plugins/Language/ObjC/NSError.cpp
index 0fb7db1b582..4bfb024206d 100644
--- a/lldb/source/Plugins/Language/ObjC/NSError.cpp
+++ b/lldb/source/Plugins/Language/ObjC/NSError.cpp
@@ -169,10 +169,10 @@ public:
         if (userinfo == LLDB_INVALID_ADDRESS || error.Fail())
             return false;
         InferiorSizedWord isw(userinfo,*process_sp);
-        m_child_sp = ValueObject::CreateValueObjectFromData("_userInfo",
-                                                            isw.GetAsData(process_sp->GetByteOrder()),
-                                                            m_backend.GetExecutionContextRef(),
-                                                            process_sp->GetTarget().GetScratchClangASTContext()->GetBasicType(lldb::eBasicTypeObjCID));
+        m_child_sp = CreateValueObjectFromData("_userInfo",
+                                               isw.GetAsData(process_sp->GetByteOrder()),
+                                               m_backend.GetExecutionContextRef(),
+                                               process_sp->GetTarget().GetScratchClangASTContext()->GetBasicType(lldb::eBasicTypeObjCID));
         return false;
     }
     
diff --git a/lldb/source/Plugins/Language/ObjC/NSException.cpp b/lldb/source/Plugins/Language/ObjC/NSException.cpp
index e58223a4d46..f70e7c7356e 100644
--- a/lldb/source/Plugins/Language/ObjC/NSException.cpp
+++ b/lldb/source/Plugins/Language/ObjC/NSException.cpp
@@ -157,10 +157,10 @@ public:
         if (userinfo == LLDB_INVALID_ADDRESS || error.Fail())
             return false;
         InferiorSizedWord isw(userinfo,*process_sp);
-        m_child_sp = ValueObject::CreateValueObjectFromData("userInfo",
-                                                            isw.GetAsData(process_sp->GetByteOrder()),
-                                                            m_backend.GetExecutionContextRef(),
-                                                            process_sp->GetTarget().GetScratchClangASTContext()->GetBasicType(lldb::eBasicTypeObjCID));
+        m_child_sp = CreateValueObjectFromData("userInfo",
+                                               isw.GetAsData(process_sp->GetByteOrder()),
+                                               m_backend.GetExecutionContextRef(),
+                                               process_sp->GetTarget().GetScratchClangASTContext()->GetBasicType(lldb::eBasicTypeObjCID));
         return false;
     }