[Lldb-commits] [PATCH] D77153: [lldb/DataFormatters] Display null C++ pointers as nullptr

[Frederic Riss via Phabricator via lldb-commits]

friss updated this revision to Diff 255571.
friss added a comment.

Implement null C++ printing at the ValueObjectPrinter level


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D77153/new/

https://reviews.llvm.org/D77153

Files:
  lldb/include/lldb/Target/Language.h
  lldb/source/DataFormatters/TypeSummary.cpp
  lldb/source/DataFormatters/ValueObjectPrinter.cpp
  lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
  lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
  lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
  
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/TestDataFormatterLibcxxString.py
  
lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/main.cpp


Index: lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/main.cpp
===================================================================
--- lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/main.cpp
+++ lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/main.cpp
@@ -71,6 +71,7 @@
     std::u32string u32_string(U"🍄🍅🍆🍌");
     std::u32string u32_empty(U"");
     std::basic_string<unsigned char> uchar(5, 'a');
+    std::string *null_str = nullptr;
 
 #if _LIBCPP_ABI_VERSION == 1
     std::string garbage1, garbage2, garbage3, garbage4, garbage5;
Index: lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/TestDataFormatterLibcxxString.py
===================================================================
--- lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/TestDataFormatterLibcxxString.py
+++ lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx/string/TestDataFormatterLibcxxString.py
@@ -77,6 +77,7 @@
                 '(%s::u32string) u32_empty = ""'%ns,
                 '(%s::basic_string<unsigned char, %s::char_traits<unsigned char>, '
                 '%s::allocator<unsigned char> >) uchar = "aaaaa"'%(ns,ns,ns),
+                '(%s::string *) null_str = nullptr'%ns,
         ])
 
         self.runCmd("n")
@@ -114,6 +115,7 @@
                 '(%s::u32string) u32_empty = ""'%ns,
                 '(%s::basic_string<unsigned char, %s::char_traits<unsigned char>, '
                 '%s::allocator<unsigned char> >) uchar = "aaaaa"'%(ns,ns,ns),
+                '(%s::string *) null_str = nullptr'%ns,
         ])
 
         # The test assumes that std::string is in its cap-size-data layout.
Index: lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
===================================================================
--- lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
+++ lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
@@ -119,6 +119,8 @@
 
   bool IsNilReference(ValueObject &valobj) override;
 
+  llvm::StringRef NilReferenceSummaryString() override { return "nil"; }
+
   bool IsSourceFile(llvm::StringRef file_path) const override;
 
   const Highlighter *GetHighlighter() const override { return &m_highlighter; }
Index: lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
+++ lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
@@ -88,6 +88,10 @@
   HardcodedFormatters::HardcodedSyntheticFinder
   GetHardcodedSynthetics() override;
 
+  bool IsNilReference(ValueObject &valobj) override;
+
+  llvm::StringRef NilReferenceSummaryString() override { return "nullptr"; }
+
   bool IsSourceFile(llvm::StringRef file_path) const override;
 
   const Highlighter *GetHighlighter() const override { return &m_highlighter; }
Index: lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
@@ -1133,6 +1133,17 @@
   return g_formatters;
 }
 
+bool CPlusPlusLanguage::IsNilReference(ValueObject &valobj) {
+  const uint32_t mask = eTypeIsCPlusPlus | eTypeIsPointer;
+  bool isCPPpointer =
+      (((valobj.GetCompilerType().GetTypeInfo(nullptr)) & mask) == mask);
+  if (!isCPPpointer)
+    return false;
+  bool canReadValue = true;
+  bool isZero = valobj.GetValueAsUnsigned(0, &canReadValue) == 0;
+  return canReadValue && isZero;
+}
+
 bool CPlusPlusLanguage::IsSourceFile(llvm::StringRef file_path) const {
   const auto suffixes = {".cpp", ".cxx", ".c++", ".cc",  ".c",
                          ".h",   ".hh",  ".hpp", ".hxx", ".h++"};
Index: lldb/source/DataFormatters/ValueObjectPrinter.cpp
===================================================================
--- lldb/source/DataFormatters/ValueObjectPrinter.cpp
+++ lldb/source/DataFormatters/ValueObjectPrinter.cpp
@@ -361,9 +361,11 @@
     error.assign(err_cstr);
 
   if (ShouldPrintValueObject()) {
-    if (IsNil())
-      summary.assign("nil");
-    else if (IsUninitialized())
+    if (IsNil()) {
+      Language *lang_plugin =
+          Language::FindPlugin(m_valobj->GetObjectRuntimeLanguage());
+      summary.assign(lang_plugin->NilReferenceSummaryString().str());
+    } else if (IsUninitialized())
       summary.assign("<uninitialized>");
     else if (m_options.m_omit_summary_depth == 0) {
       TypeSummaryImpl *entry = GetSummaryFormatter();
Index: lldb/source/DataFormatters/TypeSummary.cpp
===================================================================
--- lldb/source/DataFormatters/TypeSummary.cpp
+++ lldb/source/DataFormatters/TypeSummary.cpp
@@ -123,6 +123,17 @@
                                             std::string &dest,
                                             const TypeSummaryOptions &options) {
   dest.clear();
+
+  if (valobj && valobj->IsPointerType()) {
+    bool success = true;
+    if (!valobj->GetValueAsUnsigned(0, &success)) {
+      if (!success)
+        return false;
+      dest = "nullptr";
+      return true;
+    }
+  }
+
   StreamString stream;
   if (!m_impl || !m_impl(*valobj, stream, options))
     return false;
Index: lldb/include/lldb/Target/Language.h
===================================================================
--- lldb/include/lldb/Target/Language.h
+++ lldb/include/lldb/Target/Language.h
@@ -215,6 +215,8 @@
   // nil/null object, this method returns true
   virtual bool IsNilReference(ValueObject &valobj);
 
+  virtual llvm::StringRef NilReferenceSummaryString() { return {}; }
+
   // for a ValueObject of some "reference type", if the language provides a
   // technique to decide whether the reference has ever been assigned to some
   // object, this method will return true if such detection is possible, and if

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