[Lldb-commits] [lldb] d366da9 - [lldb] Make the libcxx unique_ptr prettyprinter support custom deleters.

Jorge Gorbe Moya via lldb-commits lldb-commits at lists.llvm.org
Mon May 1 13:08:20 PDT 2023


Author: Jorge Gorbe Moya
Date: 2023-05-01T13:08:04-07:00
New Revision: d366da97bd24ddfb91c9f260fa0aaf105d947652

URL: https://github.com/llvm/llvm-project/commit/d366da97bd24ddfb91c9f260fa0aaf105d947652
DIFF: https://github.com/llvm/llvm-project/commit/d366da97bd24ddfb91c9f260fa0aaf105d947652.diff

LOG: [lldb] Make the libcxx unique_ptr prettyprinter support custom deleters.

The unique_ptr prettyprinter calls `GetValueOfLibCXXCompressedPair`,
which looks for a `__value_` child. However, when the second value in
the compressed pair is not an empty class, there are two `__value_`
children because `__compressed_pair` derives twice from
`__compressed_pair_elem`, one for each member of the pair. And then the
lookup fails because it's ambiguous.

This patch makes the following changes:

- Rename `GetValueOfLibCXXCompressedPair` to
  `GetFirstValueOfLibCXXCompressedPair`, and add a similar function to
  get the second value. Put both functions in
  Plugin/Language/CPlusPlus/LibCxx.cpp because it seems inappropriate to
  have libcxx-specific helpers separate from all the libcxx-dependent
  code.

- Read the second value of the `__ptr_` pair and display a "deleter"
  child in the unique_ptr synthetic child provider, when available.

- Add a test case for the non-empty deleter case.

Differential Revision: https://reviews.llvm.org/D148662

Added: 
    

Modified: 
    lldb/include/lldb/DataFormatters/FormattersHelpers.h
    lldb/source/DataFormatters/FormattersHelpers.cpp
    lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
    lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
    lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp
    lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/TestDataFormatterLibcxxUniquePtr.py
    lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/main.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/include/lldb/DataFormatters/FormattersHelpers.h b/lldb/include/lldb/DataFormatters/FormattersHelpers.h
index e9af6656e3d7d..a2e8521d96651 100644
--- a/lldb/include/lldb/DataFormatters/FormattersHelpers.h
+++ b/lldb/include/lldb/DataFormatters/FormattersHelpers.h
@@ -58,8 +58,6 @@ size_t ExtractIndexFromString(const char *item_name);
 
 Address GetArrayAddressOrPointerValue(ValueObject &valobj);
 
-lldb::ValueObjectSP GetValueOfLibCXXCompressedPair(ValueObject &pair);
-
 time_t GetOSXEpoch();
 
 struct InferiorSizedWord {

diff  --git a/lldb/source/DataFormatters/FormattersHelpers.cpp b/lldb/source/DataFormatters/FormattersHelpers.cpp
index 87da31769ff12..085ed3d0a2f29 100644
--- a/lldb/source/DataFormatters/FormattersHelpers.cpp
+++ b/lldb/source/DataFormatters/FormattersHelpers.cpp
@@ -126,14 +126,3 @@ lldb_private::formatters::GetArrayAddressOrPointerValue(ValueObject &valobj) {
 
   return data_addr;
 }
-
-lldb::ValueObjectSP
-lldb_private::formatters::GetValueOfLibCXXCompressedPair(ValueObject &pair) {
-  ValueObjectSP value =
-      pair.GetChildMemberWithName(ConstString("__value_"), true);
-  if (!value) {
-    // pre-r300140 member name
-    value = pair.GetChildMemberWithName(ConstString("__first_"), true);
-  }
-  return value;
-}

diff  --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
index faa33ecefc2d0..236a8129eeb34 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
@@ -46,6 +46,38 @@ lldb::ValueObjectSP lldb_private::formatters::GetChildMemberWithName(
   return {};
 }
 
+lldb::ValueObjectSP
+lldb_private::formatters::GetFirstValueOfLibCXXCompressedPair(
+    ValueObject &pair) {
+  ValueObjectSP value;
+  ValueObjectSP first_child = pair.GetChildAtIndex(0, true);
+  if (first_child)
+    value = first_child->GetChildMemberWithName(ConstString("__value_"), true);
+  if (!value) {
+    // pre-r300140 member name
+    value = pair.GetChildMemberWithName(ConstString("__first_"), true);
+  }
+  return value;
+}
+
+lldb::ValueObjectSP
+lldb_private::formatters::GetSecondValueOfLibCXXCompressedPair(
+    ValueObject &pair) {
+  ValueObjectSP value;
+  if (pair.GetNumChildren() > 1) {
+    ValueObjectSP second_child = pair.GetChildAtIndex(1, true);
+    if (second_child) {
+      value =
+          second_child->GetChildMemberWithName(ConstString("__value_"), true);
+    }
+  }
+  if (!value) {
+    // pre-r300140 member name
+    value = pair.GetChildMemberWithName(ConstString("__second_"), true);
+  }
+  return value;
+}
+
 bool lldb_private::formatters::LibcxxOptionalSummaryProvider(
     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
@@ -170,7 +202,7 @@ bool lldb_private::formatters::LibcxxUniquePointerSummaryProvider(
   if (!ptr_sp)
     return false;
 
-  ptr_sp = GetValueOfLibCXXCompressedPair(*ptr_sp);
+  ptr_sp = GetFirstValueOfLibCXXCompressedPair(*ptr_sp);
   if (!ptr_sp)
     return false;
 
@@ -658,7 +690,9 @@ lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEndCreator(
 
 size_t lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
     CalculateNumChildren() {
-  return (m_value_ptr_sp ? 1 : 0);
+  if (m_value_ptr_sp)
+    return m_deleter_sp ? 2 : 1;
+  return 0;
 }
 
 lldb::ValueObjectSP
@@ -670,7 +704,10 @@ lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::GetChildAtIndex(
   if (idx == 0)
     return m_value_ptr_sp;
 
-  if (idx == 1) {
+  if (idx == 1)
+    return m_deleter_sp;
+
+  if (idx == 2) {
     Status status;
     auto value_sp = m_value_ptr_sp->Dereference(status);
     if (status.Success()) {
@@ -691,7 +728,15 @@ bool lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::Update() {
   if (!ptr_sp)
     return false;
 
-  m_value_ptr_sp = GetValueOfLibCXXCompressedPair(*ptr_sp);
+  // Retrieve the actual pointer and the deleter, and clone them to give them
+  // user-friendly names.
+  ValueObjectSP value_pointer_sp = GetFirstValueOfLibCXXCompressedPair(*ptr_sp);
+  if (value_pointer_sp)
+    m_value_ptr_sp = value_pointer_sp->Clone(ConstString("pointer"));
+
+  ValueObjectSP deleter_sp = GetSecondValueOfLibCXXCompressedPair(*ptr_sp);
+  if (deleter_sp)
+    m_deleter_sp = deleter_sp->Clone(ConstString("deleter"));
 
   return false;
 }
@@ -703,10 +748,12 @@ bool lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
 
 size_t lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
     GetIndexOfChildWithName(ConstString name) {
-  if (name == "__value_")
+  if (name == "pointer")
     return 0;
-  if (name == "$$dereference$$")
+  if (name == "deleter")
     return 1;
+  if (name == "$$dereference$$")
+    return 2;
   return UINT32_MAX;
 }
 

diff  --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
index 9ab22153a92a8..2dae71b24419d 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
@@ -23,6 +23,10 @@ lldb::ValueObjectSP
 GetChildMemberWithName(ValueObject &obj,
                        llvm::ArrayRef<ConstString> alternative_names);
 
+lldb::ValueObjectSP GetFirstValueOfLibCXXCompressedPair(ValueObject &pair);
+lldb::ValueObjectSP GetSecondValueOfLibCXXCompressedPair(ValueObject &pair);
+
+
 bool LibcxxStringSummaryProviderASCII(
     ValueObject &valobj, Stream &stream,
     const TypeSummaryOptions &summary_options); // libc++ std::string
@@ -200,6 +204,7 @@ class LibcxxUniquePtrSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
 
 private:
   lldb::ValueObjectSP m_value_ptr_sp;
+  lldb::ValueObjectSP m_deleter_sp;
 };
 
 SyntheticChildrenFrontEnd *

diff  --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp
index a1953a1c7a227..3ae26a3012ac8 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxList.cpp
@@ -300,7 +300,7 @@ bool ForwardListFrontEnd::Update() {
       m_backend.GetChildMemberWithName(ConstString("__before_begin_"), true));
   if (!impl_sp)
     return false;
-  impl_sp = GetValueOfLibCXXCompressedPair(*impl_sp);
+  impl_sp = GetFirstValueOfLibCXXCompressedPair(*impl_sp);
   if (!impl_sp)
     return false;
   m_head = impl_sp->GetChildMemberWithName(ConstString("__next_"), true).get();
@@ -321,7 +321,7 @@ size_t ListFrontEnd::CalculateNumChildren() {
   ValueObjectSP size_alloc(
       m_backend.GetChildMemberWithName(ConstString("__size_alloc_"), true));
   if (size_alloc) {
-    ValueObjectSP value = GetValueOfLibCXXCompressedPair(*size_alloc);
+    ValueObjectSP value = GetFirstValueOfLibCXXCompressedPair(*size_alloc);
     if (value) {
       m_count = value->GetValueAsUnsigned(UINT32_MAX);
     }

diff  --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/TestDataFormatterLibcxxUniquePtr.py b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/TestDataFormatterLibcxxUniquePtr.py
index cc147de4ff481..a2d16375f1b86 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/TestDataFormatterLibcxxUniquePtr.py
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/TestDataFormatterLibcxxUniquePtr.py
@@ -40,7 +40,7 @@ def test_unique_ptr_variables(self):
             "up_empty",
             type=self.make_expected_type("int"),
             summary="nullptr",
-            children=[ValueCheck(name="__value_")],
+            children=[ValueCheck(name="pointer")],
         )
         self.assertEqual(
             valobj.child[0].GetValueAsUnsigned(lldb.LLDB_INVALID_ADDRESS), 0
@@ -54,7 +54,7 @@ def test_unique_ptr_variables(self):
             "up_int",
             type=self.make_expected_type("int"),
             summary="10",
-            children=[ValueCheck(name="__value_")],
+            children=[ValueCheck(name="pointer")],
         )
         self.assertNotEqual(valobj.child[0].unsigned, 0)
 
@@ -62,7 +62,7 @@ def test_unique_ptr_variables(self):
             "up_int_ref",
             type=self.make_expected_type("int", qualifiers="&"),
             summary="10",
-            children=[ValueCheck(name="__value_")],
+            children=[ValueCheck(name="pointer")],
         )
         self.assertNotEqual(valobj.child[0].unsigned, 0)
 
@@ -70,7 +70,7 @@ def test_unique_ptr_variables(self):
             "up_int_ref_ref",
             type=self.make_expected_type("int", qualifiers="&&"),
             summary="10",
-            children=[ValueCheck(name="__value_")],
+            children=[ValueCheck(name="pointer")],
         )
         self.assertNotEqual(valobj.child[0].unsigned, 0)
 
@@ -78,7 +78,7 @@ def test_unique_ptr_variables(self):
             "up_str",
             type=self.make_expected_basic_string_ptr(),
             summary='"hello"',
-            children=[ValueCheck(name="__value_", summary='"hello"')],
+            children=[ValueCheck(name="pointer", summary='"hello"')],
         )
 
         valobj = self.expect_var_path(
@@ -95,7 +95,20 @@ def test_unique_ptr_variables(self):
                 ValueCheck(name="name", summary='"steph"'),
             ],
         )
-        self.assertEqual(str(valobj), '(User) *__value_ = (id = 30, name = "steph")')
+        self.assertEqual(str(valobj), '(User) *pointer = (id = 30, name = "steph")')
+
+        valobj = self.expect_var_path(
+            "up_non_empty_deleter",
+            type="std::unique_ptr<int, NonEmptyIntDeleter>",
+            summary="1234",
+            children=[
+                ValueCheck(name="pointer"),
+                ValueCheck(name="deleter", children=[
+                    ValueCheck(name="dummy_", value="9999")
+                ]),
+            ],
+        )
+        self.assertNotEqual(valobj.child[0].unsigned, 0)
 
         self.expect_var_path("up_user->id", type="int", value="30")
         self.expect_var_path("up_user->name", type="std::string", summary='"steph"')

diff  --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/main.cpp b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/main.cpp
index 5201b2a6e9cb3..ab65d95b248ef 100644
--- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/main.cpp
+++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/unique_ptr/main.cpp
@@ -6,6 +6,15 @@ struct User {
   std::string name = "steph";
 };
 
+// libc++ stores unique_ptr data in a compressed pair, which has a specialized
+// representation when the type of the second element is an empty class. So
+// we need a deleter class with a dummy data member to trigger the other path.
+struct NonEmptyIntDeleter {
+  void operator()(int* ptr) { delete ptr; }
+
+  int dummy_ = 9999;
+};
+
 int main() {
   std::unique_ptr<int> up_empty;
   std::unique_ptr<int> up_int = std::make_unique<int>(10);
@@ -13,6 +22,8 @@ int main() {
   std::unique_ptr<int> &up_int_ref = up_int;
   std::unique_ptr<int> &&up_int_ref_ref = std::make_unique<int>(10);
   std::unique_ptr<User> up_user = std::make_unique<User>();
+  auto up_non_empty_deleter =
+      std::unique_ptr<int, NonEmptyIntDeleter>(new int(1234));
 
   return 0; // break here
 }


        


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