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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
Merged

[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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6 changes: 6 additions & 0 deletions lldb/include/lldb/DataFormatters/FormattersHelpers.h
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Expand Up @@ -55,6 +55,12 @@ void AddFilter(TypeCategoryImpl::SharedPointer category_sp,

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

/// Returns \c false if the smart pointer formatters shouldn't continue
/// formatting the rest of the object. Currently this is the case when the
/// pointer is a nullptr.
bool DumpCxxSmartPtrPointerSummary(Stream &stream, ValueObject &ptr,
const TypeSummaryOptions &options);
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@Michael137 Michael137 Jul 3, 2025

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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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@Michael137 Michael137 Jul 3, 2025

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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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@Michael137 Michael137 Jul 3, 2025

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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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22 changes: 22 additions & 0 deletions lldb/source/DataFormatters/FormattersHelpers.cpp
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Expand Up @@ -126,3 +126,25 @@ lldb_private::formatters::GetArrayAddressOrPointerValue(ValueObject &valobj) {

return data_addr.address;
}

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

Status error;
ValueObjectSP pointee_sp = ptr.Dereference(error);
// FIXME: should we be handling this as an error?
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@labath labath Jul 3, 2025

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I think it's reasonable to not print anything in this case.

if (!pointee_sp || !error.Success())
return false;

if (!pointee_sp->DumpPrintableRepresentation(
stream, ValueObject::eValueObjectRepresentationStyleSummary,
lldb::eFormatInvalid,
ValueObject::PrintableRepresentationSpecialCases::eDisable, false))
stream.Printf("ptr = 0x%" PRIx64, ptr.GetValueAsUnsigned(0));

return false;
}
37 changes: 2 additions & 35 deletions lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
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Expand Up @@ -166,24 +166,8 @@ bool lldb_private::formatters::LibcxxSmartPointerSummaryProvider(
if (!ptr_sp)
return false;

if (ptr_sp->GetValueAsUnsigned(0) == 0) {
stream.Printf("nullptr");
if (!DumpCxxSmartPtrPointerSummary(stream, *ptr_sp, options))
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 (count_sp)
stream.Printf(" strong=%" PRIu64, 1 + count_sp->GetValueAsUnsigned(0));
Expand All @@ -210,24 +194,7 @@ 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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14 changes: 7 additions & 7 deletions ...s/data-formatter/data-formatter-stl/libstdcpp/unique_ptr/TestDataFormatterStdUniquePtr.py
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Expand Up @@ -31,15 +31,15 @@ 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()
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