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[lldb][DataFormatter] Format libstdc++ unique_ptr like we do libc++ #146909

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Merged
merged 5 commits into from
Jul 4, 2025
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[lldb][DataFormatter] Format libstdc++ unique_ptr like we do libc++ #146909

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[lldb][DataFormatter] Format libstdc++ unique_ptr like we do libc++
Michael137 Jul 3, 2025
63066cc
fixup! python format
Michael137 Jul 3, 2025
84de12d
fixup! remove early-return for empty shared_ptrs; refactor weak/stron…
Michael137 Jul 3, 2025
bd20056
fixup! uncomment subobject constructor test
Michael137 Jul 3, 2025
3117231
fixup! python format
Michael137 Jul 3, 2025
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5 changes: 5 additions & 0 deletions lldb/include/lldb/DataFormatters/FormattersHelpers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,11 @@ void AddFilter(TypeCategoryImpl::SharedPointer category_sp,

std::optional<size_t> ExtractIndexFromString(const char *item_name);

/// Prints the summary for the pointer value of a C++
/// std::unique_ptr/std::shared_ptr/std::weak_ptr.
void DumpCxxSmartPtrPointerSummary(Stream &stream, ValueObject &ptr,
const TypeSummaryOptions &options);
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The return value is a bit awkward. Happy to consider alternatives.

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@labath labath Jul 3, 2025 •
edited
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Is it actually needed though? In my experiments, a normally constructed empty shared pointer will have the __ctrl_ field as null anyway.

I was able to construct a nullptr shared_ptr with a non-empty control field using the subobject constructor (std::shared_ptr<int> si(new int(47)); std::shared_ptr<int> sie(si, nullptr);), but in that case, maybe we actually should show the weak and shared counts?

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Good point, don't think the early return is necessary. Let me add that subobject constructor test too

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Applied your suggestion (and refactored the weak/strong count logic in the latest commit). Happy to split that up into a separate PR if this is becoming too noisy.


Address GetArrayAddressOrPointerValue(ValueObject &valobj);

time_t GetOSXEpoch();
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19 changes: 19 additions & 0 deletions lldb/source/DataFormatters/FormattersHelpers.cpp
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Expand Up @@ -126,3 +126,22 @@ lldb_private::formatters::GetArrayAddressOrPointerValue(ValueObject &valobj) {

return data_addr.address;
}

void lldb_private::formatters::DumpCxxSmartPtrPointerSummary(
Stream &stream, ValueObject &ptr, const TypeSummaryOptions &options) {
if (ptr.GetValueAsUnsigned(0) == 0) {
stream.Printf("nullptr");
return;
}

Status error;
ValueObjectSP pointee_sp = ptr.Dereference(error);
if (!pointee_sp || !error.Success())
return;

if (!pointee_sp->DumpPrintableRepresentation(
stream, ValueObject::eValueObjectRepresentationStyleSummary,
lldb::eFormatInvalid,
ValueObject::PrintableRepresentationSpecialCases::eDisable, false))
stream.Printf("ptr = 0x%" PRIx64, ptr.GetValueAsUnsigned(0));
}
70 changes: 26 additions & 44 deletions lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
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Expand Up @@ -157,39 +157,38 @@ bool lldb_private::formatters::LibcxxSmartPointerSummaryProvider(
ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
if (!valobj_sp)
return false;
ValueObjectSP ptr_sp(valobj_sp->GetChildMemberWithName("__ptr_"));
ValueObjectSP count_sp(
valobj_sp->GetChildAtNamePath({"__cntrl_", "__shared_owners_"}));
ValueObjectSP weakcount_sp(
valobj_sp->GetChildAtNamePath({"__cntrl_", "__shared_weak_owners_"}));

if (!ptr_sp)
ValueObjectSP ptr_sp(valobj_sp->GetChildMemberWithName("__ptr_"));
ValueObjectSP ctrl_sp(valobj_sp->GetChildMemberWithName("__cntrl_"));
if (!ctrl_sp || !ptr_sp)
return false;

if (ptr_sp->GetValueAsUnsigned(0) == 0) {
stream.Printf("nullptr");
DumpCxxSmartPtrPointerSummary(stream, *ptr_sp, options);

bool success;
uint64_t ctrl_addr = ctrl_sp->GetValueAsUnsigned(0, &success);
// Empty control field. We're done.
if (!success || ctrl_addr == 0)
return true;
} else {
bool print_pointee = false;
Status error;
ValueObjectSP pointee_sp = ptr_sp->Dereference(error);
if (pointee_sp && error.Success()) {
if (pointee_sp->DumpPrintableRepresentation(
stream, ValueObject::eValueObjectRepresentationStyleSummary,
lldb::eFormatInvalid,
ValueObject::PrintableRepresentationSpecialCases::eDisable,
false))
print_pointee = true;
}
if (!print_pointee)
stream.Printf("ptr = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0));

if (auto count_sp = ctrl_sp->GetChildMemberWithName("__shared_owners_")) {
bool success;
uint64_t count = count_sp->GetValueAsUnsigned(0, &success);
if (!success)
return false;

stream.Printf(" strong=%" PRIu64, count + 1);
}

if (count_sp)
stream.Printf(" strong=%" PRIu64, 1 + count_sp->GetValueAsUnsigned(0));
if (auto weak_count_sp =
ctrl_sp->GetChildMemberWithName("__shared_weak_owners_")) {
bool success;
uint64_t count = weak_count_sp->GetValueAsUnsigned(0, &success);
if (!success)
return false;

if (weakcount_sp)
stream.Printf(" weak=%" PRIu64, 1 + weakcount_sp->GetValueAsUnsigned(0));
stream.Printf(" weak=%" PRIu64, count + 1);
}

return true;
}
Expand All @@ -210,24 +209,7 @@ bool lldb_private::formatters::LibcxxUniquePointerSummaryProvider(
if (!ptr_sp)
return false;

if (ptr_sp->GetValueAsUnsigned(0) == 0) {
stream.Printf("nullptr");
return true;
} else {
bool print_pointee = false;
Status error;
ValueObjectSP pointee_sp = ptr_sp->Dereference(error);
if (pointee_sp && error.Success()) {
if (pointee_sp->DumpPrintableRepresentation(
stream, ValueObject::eValueObjectRepresentationStyleSummary,
lldb::eFormatInvalid,
ValueObject::PrintableRepresentationSpecialCases::eDisable,
false))
print_pointee = true;
}
if (!print_pointee)
stream.Printf("ptr = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0));
}
DumpCxxSmartPtrPointerSummary(stream, *ptr_sp, options);

return true;
}
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10 changes: 2 additions & 8 deletions lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
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Expand Up @@ -156,14 +156,8 @@ bool LibStdcppUniquePtrSyntheticFrontEnd::GetSummary(
if (!m_ptr_obj)
return false;

bool success;
uint64_t ptr_value = m_ptr_obj->GetValueAsUnsigned(0, &success);
if (!success)
return false;
if (ptr_value == 0)
stream.Printf("nullptr");
else
stream.Printf("0x%" PRIx64, ptr_value);
DumpCxxSmartPtrPointerSummary(stream, *m_ptr_obj, options);

return true;
}

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9 changes: 8 additions & 1 deletion ...s/data-formatter/data-formatter-stl/libcxx/shared_ptr/TestDataFormatterLibcxxSharedPtr.py
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Expand Up @@ -2,7 +2,6 @@
Test lldb data formatter for libc++ std::shared_ptr.
"""


import lldb
from lldbsuite.test.decorators import *
from lldbsuite.test.lldbtest import *
Expand Down Expand Up @@ -91,6 +90,14 @@ def test_shared_ptr_variables(self):
self.expect_var_path("sp_user->id", type="int", value="30")
self.expect_var_path("sp_user->name", type="std::string", summary='"steph"')

valobj = self.expect_var_path(
"si", type="std::shared_ptr<int>", summary="47 strong=2 weak=1"
)

valobj = self.expect_var_path(
"sie", type="std::shared_ptr<int>", summary="nullptr strong=2 weak=1"
)

self.runCmd("settings set target.experimental.use-DIL true")
self.expect_var_path("ptr_node->value", value="1")
self.expect_var_path("ptr_node->next->value", value="2")
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4 changes: 4 additions & 0 deletions lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/shared_ptr/main.cpp
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Expand Up @@ -22,5 +22,9 @@ int main() {
std::shared_ptr<NodeS>(new NodeS{nullptr, 2});
ptr_node = std::shared_ptr<NodeS>(new NodeS{std::move(ptr_node), 1});

// Construct empty shared_ptr with non-null control field.
std::shared_ptr<int> si(new int(47));
std::shared_ptr<int> sie(si, nullptr);

return 0; // break here
}
16 changes: 8 additions & 8 deletions ...s/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py
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Expand Up @@ -2,7 +2,6 @@
Test lldb data formatter subsystem.
"""


import lldb
from lldbsuite.test.decorators import *
from lldbsuite.test.lldbtest import *
Expand Down Expand Up @@ -31,15 +30,16 @@ def test_with_run_command(self):
self.assertTrue(frame.IsValid())

self.expect("frame variable nup", substrs=["nup = nullptr"])
self.expect("frame variable iup", substrs=["iup = 0x"])
self.expect("frame variable sup", substrs=["sup = 0x"])
self.expect("frame variable iup", substrs=["iup = 123"])
self.expect("frame variable sup", substrs=['sup = "foobar"'])

self.expect("frame variable ndp", substrs=["ndp = nullptr"])
self.expect(
"frame variable idp", substrs=["idp = 0x", "deleter = ", "a = 1", "b = 2"]
"frame variable idp", substrs=["idp = 456", "deleter = ", "a = 1", "b = 2"]
)
self.expect(
"frame variable sdp", substrs=["sdp = 0x", "deleter = ", "a = 3", "b = 4"]
"frame variable sdp",
substrs=['sdp = "baz"', "deleter = ", "a = 3", "b = 4"],
)

self.assertEqual(
Expand Down Expand Up @@ -106,13 +106,13 @@ def test_recursive_unique_ptr(self):
substrs=["stopped", "stop reason = breakpoint"],
)

self.expect("frame variable f1->fp", substrs=["fp = 0x"])
self.expect("frame variable f1->fp", substrs=["fp = Foo @ 0x"])
self.expect(
"frame variable --ptr-depth=1 f1->fp", substrs=["data = 2", "fp = 0x"]
"frame variable --ptr-depth=1 f1->fp", substrs=["data = 2", "fp = Foo @ 0x"]
)
self.expect(
"frame variable --ptr-depth=2 f1->fp",
substrs=["data = 2", "fp = 0x", "data = 1"],
substrs=["data = 2", "fp = Foo @ 0x", "data = 1"],
)

frame = self.frame()
Expand Down
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