yinghuitan created this revision.
yinghuitan added reviewers: clayborg, labath, jingham, jdoerfert, JDevlieghere,
kusmour, GeorgeHuyubo.
Herald added a project: All.
yinghuitan requested review of this revision.
Herald added subscribers: lldb-commits, wangpc.
Herald added a project: LLDB.
We noticed some performance issue while in lldb-vscode for grabing the name of
the SBValue.
Profiling shows SBValue::GetName() can cause synthetic children provider of
shared/unique_ptr
to deference underlying object and complete it type.
This patch lazily moves the dereference from synthetic child provider's
Update() method to
GetChildAtIndex() so that SBValue::GetName() won't trigger the slow code path.
Here is the culprit slow code path:
...
frame #59: 0x00007ff4102e0660
liblldb.so.15`SymbolFileDWARF::CompleteType(this=<unavailable>,
compiler_type=0x00007ffdd9829450) at SymbolFileDWARF.cpp:1567:25 [opt]
...
frame #67: 0x00007ff40fdf9bd4
liblldb.so.15`lldb_private::ValueObject::Dereference(this=0x0000022bb5dfe980,
error=0x00007ffdd9829970) at ValueObject.cpp:2672:41 [opt]
frame #68: 0x00007ff41011bb0a liblldb.so.15`(anonymous
namespace)::LibStdcppSharedPtrSyntheticFrontEnd::Update(this=0x000002298fb94380)
at LibStdcpp.cpp:403:40 [opt]
frame #69: 0x00007ff41011af9a
liblldb.so.15`lldb_private::formatters::LibStdcppSharedPtrSyntheticFrontEndCreator(lldb_private::CXXSyntheticChildren*,
std::shared_ptr<lldb_private::ValueObject>) [inlined] (anonymous
namespace)::LibStdcppSharedPtrSyntheticFrontEnd::LibStdcppSharedPtrSyntheticFrontEnd(this=0x000002298fb94380,
valobj_sp=<unavailable>) at LibStdcpp.cpp:371:5 [opt]
...
frame #78: 0x00007ff40fdf6e42
liblldb.so.15`lldb_private::ValueObject::CalculateSyntheticValue(this=0x000002296c66a500)
at ValueObject.cpp:1836:27 [opt]
frame #79: 0x00007ff40fdf1939
liblldb.so.15`lldb_private::ValueObject::GetSyntheticValue(this=<unavailable>)
at ValueObject.cpp:1867:3 [opt]
frame #80: 0x00007ff40fc89008
liblldb.so.15`ValueImpl::GetSP(this=0x0000022c71b90de0,
stop_locker=0x00007ffdd9829d00, lock=0x00007ffdd9829d08,
error=0x00007ffdd9829d18) at SBValue.cpp:141:46 [opt]
frame #81: 0x00007ff40fc7d82a
liblldb.so.15`lldb::SBValue::GetSP(ValueLocker&) const [inlined]
ValueLocker::GetLockedSP(this=0x00007ffdd9829d00, in_value=<unavailable>) at
SBValue.cpp:208:21 [opt]
frame #82: 0x00007ff40fc7d817
liblldb.so.15`lldb::SBValue::GetSP(this=0x00007ffdd9829d90,
locker=0x00007ffdd9829d00) const at SBValue.cpp:1047:17 [opt]
frame #83: 0x00007ff40fc7da6f
liblldb.so.15`lldb::SBValue::GetName(this=0x00007ffdd9829d90) at
SBValue.cpp:294:32 [opt]
...
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D159542
Files:
lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
Index: lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
@@ -108,14 +108,7 @@
if (del_obj)
m_del_obj = del_obj->Clone(ConstString("deleter")).get();
}
-
- if (m_ptr_obj) {
- Status error;
- ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
- if (error.Success()) {
- m_obj_obj = obj_obj->Clone(ConstString("object")).get();
- }
- }
+ m_obj_obj = nullptr;
return false;
}
@@ -128,8 +121,17 @@
return m_ptr_obj->GetSP();
if (idx == 1 && m_del_obj)
return m_del_obj->GetSP();
- if (idx == 2 && m_obj_obj)
- return m_obj_obj->GetSP();
+ if (idx == 2) {
+ if (m_ptr_obj && !m_obj_obj) {
+ Status error;
+ ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
+ if (error.Success()) {
+ m_obj_obj = obj_obj->Clone(ConstString("object")).get();
+ }
+ }
+ if (m_obj_obj)
+ return m_obj_obj->GetSP();
+ }
return lldb::ValueObjectSP();
}
Index: lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
@@ -377,9 +377,16 @@
LibStdcppSharedPtrSyntheticFrontEnd::GetChildAtIndex(size_t idx) {
if (idx == 0)
return m_ptr_obj->GetSP();
- if (idx == 1)
- return m_obj_obj->GetSP();
-
+ if (idx == 1) {
+ if (m_ptr_obj && !m_obj_obj) {
+ Status error;
+ ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
+ if (error.Success())
+ m_obj_obj = obj_obj->Clone(ConstString("object")).get();
+ }
+ if (m_obj_obj)
+ return m_obj_obj->GetSP();
+ }
return lldb::ValueObjectSP();
}
@@ -397,14 +404,7 @@
return false;
m_ptr_obj = ptr_obj_sp->Clone(ConstString("pointer")).get();
-
- if (m_ptr_obj) {
- Status error;
- ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
- if (error.Success()) {
- m_obj_obj = obj_obj->Clone(ConstString("object")).get();
- }
- }
+ m_obj_obj = nullptr;
return false;
}
Index: lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
@@ -108,14 +108,7 @@
if (del_obj)
m_del_obj = del_obj->Clone(ConstString("deleter")).get();
}
-
- if (m_ptr_obj) {
- Status error;
- ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
- if (error.Success()) {
- m_obj_obj = obj_obj->Clone(ConstString("object")).get();
- }
- }
+ m_obj_obj = nullptr;
return false;
}
@@ -128,8 +121,17 @@
return m_ptr_obj->GetSP();
if (idx == 1 && m_del_obj)
return m_del_obj->GetSP();
- if (idx == 2 && m_obj_obj)
- return m_obj_obj->GetSP();
+ if (idx == 2) {
+ if (m_ptr_obj && !m_obj_obj) {
+ Status error;
+ ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
+ if (error.Success()) {
+ m_obj_obj = obj_obj->Clone(ConstString("object")).get();
+ }
+ }
+ if (m_obj_obj)
+ return m_obj_obj->GetSP();
+ }
return lldb::ValueObjectSP();
}
Index: lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
@@ -377,9 +377,16 @@
LibStdcppSharedPtrSyntheticFrontEnd::GetChildAtIndex(size_t idx) {
if (idx == 0)
return m_ptr_obj->GetSP();
- if (idx == 1)
- return m_obj_obj->GetSP();
-
+ if (idx == 1) {
+ if (m_ptr_obj && !m_obj_obj) {
+ Status error;
+ ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
+ if (error.Success())
+ m_obj_obj = obj_obj->Clone(ConstString("object")).get();
+ }
+ if (m_obj_obj)
+ return m_obj_obj->GetSP();
+ }
return lldb::ValueObjectSP();
}
@@ -397,14 +404,7 @@
return false;
m_ptr_obj = ptr_obj_sp->Clone(ConstString("pointer")).get();
-
- if (m_ptr_obj) {
- Status error;
- ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
- if (error.Success()) {
- m_obj_obj = obj_obj->Clone(ConstString("object")).get();
- }
- }
+ m_obj_obj = nullptr;
return false;
}
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