Improve the libstdc++ smart pointer formatters
* Display the strong/weak count in the summary
* Display the pointed object as a synthetic member
* Create synthetic children for weak/strong count
Differential revision: https://reviews.llvm.org/D25726
llvm-svn: 284828
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibStdcppSmartPointer.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibStdcppSmartPointer.cpp
new file mode 100644
index 0000000..4edeaab
--- /dev/null
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibStdcppSmartPointer.cpp
@@ -0,0 +1,200 @@
+//===-- LibStdcppSmartPointer.cpp -------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "LibStdcpp.h"
+
+#include "lldb/Core/ConstString.h"
+#include "lldb/Core/ValueObject.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include "lldb/DataFormatters/TypeSynthetic.h"
+#include "lldb/Target/Target.h"
+
+#include <memory>
+#include <vector>
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::formatters;
+
+namespace {
+
+class SharedPtrFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+ explicit SharedPtrFrontEnd(lldb::ValueObjectSP valobj_sp);
+
+ size_t CalculateNumChildren() override;
+
+ lldb::ValueObjectSP GetChildAtIndex(size_t idx) override;
+
+ bool Update() override;
+
+ bool MightHaveChildren() override;
+
+ size_t GetIndexOfChildWithName(const ConstString &name) override;
+
+ bool GetSummary(Stream &stream, const TypeSummaryOptions &options);
+
+private:
+ ValueObjectSP m_ptr_obj;
+ ValueObjectSP m_obj_obj;
+ ValueObjectSP m_use_obj;
+ ValueObjectSP m_weak_obj;
+
+ uint8_t m_ptr_size = 0;
+ lldb::ByteOrder m_byte_order = lldb::eByteOrderInvalid;
+
+ bool IsEmpty();
+ bool IsValid();
+};
+
+} // end of anonymous namespace
+
+SharedPtrFrontEnd::SharedPtrFrontEnd(lldb::ValueObjectSP valobj_sp)
+ : SyntheticChildrenFrontEnd(*valobj_sp) {
+ Update();
+}
+
+bool SharedPtrFrontEnd::Update() {
+ ValueObjectSP valobj_backend_sp = m_backend.GetSP();
+ if (!valobj_backend_sp)
+ return false;
+
+ ValueObjectSP valobj_sp = valobj_backend_sp->GetNonSyntheticValue();
+ if (!valobj_sp)
+ return false;
+
+ TargetSP target_sp(valobj_sp->GetTargetSP());
+ if (!target_sp)
+ return false;
+
+ m_byte_order = target_sp->GetArchitecture().GetByteOrder();
+ m_ptr_size = target_sp->GetArchitecture().GetAddressByteSize();
+
+ m_ptr_obj = valobj_sp->GetChildMemberWithName(ConstString("_M_ptr"), true);
+
+ m_use_obj = valobj_sp->GetChildAtNamePath({ConstString("_M_refcount"),
+ ConstString("_M_pi"),
+ ConstString("_M_use_count")});
+
+ m_weak_obj = valobj_sp->GetChildAtNamePath({ConstString("_M_refcount"),
+ ConstString("_M_pi"),
+ ConstString("_M_weak_count")});
+
+ // libstdc++ implements the weak usage count in a way that it is offset by 1
+ // if the strong count is not 0 (as part of a preformance optimization). We
+ // want to undo this before showing the weak count to the user as an offseted
+ // weak count would be very confusing.
+ if (m_use_obj && m_weak_obj && m_use_obj->GetValueAsUnsigned(0) > 0) {
+ bool success = false;
+ uint64_t count = m_weak_obj->GetValueAsUnsigned(0, &success) - 1;
+ if (success) {
+ auto data = std::make_shared<DataBufferHeap>(&count, sizeof(count));
+ m_weak_obj = CreateValueObjectFromData(
+ "weak_count", DataExtractor(data, m_byte_order, m_ptr_size),
+ m_weak_obj->GetExecutionContextRef(), m_weak_obj->GetCompilerType());
+ }
+ }
+
+ if (m_ptr_obj && !IsEmpty()) {
+ Error error;
+ m_obj_obj = m_ptr_obj->Dereference(error);
+ if (error.Success()) {
+ m_obj_obj->SetName(ConstString("object"));
+ }
+ }
+
+ return false;
+}
+
+bool SharedPtrFrontEnd::MightHaveChildren() { return true; }
+
+lldb::ValueObjectSP SharedPtrFrontEnd::GetChildAtIndex(size_t idx) {
+ if (idx == 0)
+ return m_obj_obj;
+ if (idx == 1)
+ return m_ptr_obj;
+ if (idx == 2)
+ return m_use_obj;
+ if (idx == 3)
+ return m_weak_obj;
+ return lldb::ValueObjectSP();
+}
+
+size_t SharedPtrFrontEnd::CalculateNumChildren() {
+ if (IsEmpty())
+ return 0;
+ return 1;
+}
+
+size_t SharedPtrFrontEnd::GetIndexOfChildWithName(const ConstString &name) {
+ if (name == ConstString("obj") || name == ConstString("object"))
+ return 0;
+ if (name == ConstString("ptr") || name == ConstString("pointer") ||
+ name == ConstString("_M_ptr"))
+ return 1;
+ if (name == ConstString("cnt") || name == ConstString("count") ||
+ name == ConstString("use_count") || name == ConstString("strong") ||
+ name == ConstString("_M_use_count"))
+ return 2;
+ if (name == ConstString("weak") || name == ConstString("weak_count") ||
+ name == ConstString("_M_weak_count"))
+ return 3;
+ return UINT32_MAX;
+}
+
+bool SharedPtrFrontEnd::GetSummary(Stream &stream,
+ const TypeSummaryOptions &options) {
+ if (!IsValid())
+ return false;
+
+ if (IsEmpty()) {
+ stream.Printf("nullptr");
+ } else {
+ Error error;
+ bool print_pointee = false;
+ if (m_obj_obj) {
+ if (m_obj_obj->DumpPrintableRepresentation(
+ stream, ValueObject::eValueObjectRepresentationStyleSummary,
+ lldb::eFormatInvalid,
+ ValueObject::ePrintableRepresentationSpecialCasesDisable,
+ false)) {
+ print_pointee = true;
+ }
+ }
+ if (!print_pointee)
+ stream.Printf("ptr = 0x%" PRIx64, m_ptr_obj->GetValueAsUnsigned(0));
+ }
+
+ if (m_use_obj && m_use_obj->GetError().Success())
+ stream.Printf(" strong=%" PRIu64, m_use_obj->GetValueAsUnsigned(0));
+
+ if (m_weak_obj && m_weak_obj->GetError().Success())
+ stream.Printf(" weak=%" PRIu64, m_weak_obj->GetValueAsUnsigned(0));
+
+ return true;
+}
+
+bool SharedPtrFrontEnd::IsValid() { return m_ptr_obj != nullptr; }
+
+bool SharedPtrFrontEnd::IsEmpty() {
+ return !IsValid() || m_ptr_obj->GetValueAsUnsigned(0) == 0 ||
+ (m_use_obj && m_use_obj->GetValueAsUnsigned(0) == 0);
+}
+
+SyntheticChildrenFrontEnd *
+lldb_private::formatters::LibStdcppSharedPtrSyntheticFrontEndCreator(
+ CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+ return valobj_sp ? new SharedPtrFrontEnd(valobj_sp) : nullptr;
+}
+
+bool lldb_private::formatters::LibStdcppSmartPointerSummaryProvider(
+ ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
+ SharedPtrFrontEnd formatter(valobj.GetSP());
+ return formatter.GetSummary(stream, options);
+}