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

3 files changed, 17 insertions, 27 deletions

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;
     }