[lldb] Implement a formatter bytecode interpreter in C++

Compared to the python version, this also does type checking and error
handling, so it's slightly longer, however, it's still comfortably
under 500 lines.

Author: adrian-prantl

lldb/include/lldb/DataFormatters/TypeSummary.h

@@ -22,6 +22,10 @@
 #include "lldb/Utility/Status.h"
 #include "lldb/Utility/StructuredData.h"
 
+namespace llvm {
+class MemoryBuffer;
+}
+
 namespace lldb_private {
 class TypeSummaryOptions {
 public:
@@ -44,7 +48,7 @@ class TypeSummaryOptions {
 
 class TypeSummaryImpl {
 public:
-  enum class Kind { eSummaryString, eScript, eCallback, eInternal };
+  enum class Kind { eSummaryString, eScript, eBytecode, eCallback, eInternal };
 
   virtual ~TypeSummaryImpl() = default;
 
@@ -409,6 +413,22 @@ struct ScriptSummaryFormat : public TypeSummaryImpl {
   ScriptSummaryFormat(const ScriptSummaryFormat &) = delete;
   const ScriptSummaryFormat &operator=(const ScriptSummaryFormat &) = delete;
 };
+
+/// A summary formatter that is defined in LLDB formmater bytecode.
+class BytecodeSummaryFormat : public TypeSummaryImpl {
+  std::unique_ptr<llvm::MemoryBuffer> m_bytecode;
+public:
+  BytecodeSummaryFormat(const TypeSummaryImpl::Flags &flags,
+                        std::unique_ptr<llvm::MemoryBuffer> bytecode);
+  bool FormatObject(ValueObject *valobj, std::string &dest,
+                    const TypeSummaryOptions &options) override;
+  std::string GetDescription() override;
+  std::string GetName() override;
+  static bool classof(const TypeSummaryImpl *S) {
+    return S->GetKind() == Kind::eBytecode;
+  }
+};
+
 } // namespace lldb_private
 
 #endif // LLDB_DATAFORMATTERS_TYPESUMMARY_H

lldb/include/lldb/lldb-enumerations.h

@@ -762,6 +762,7 @@ enum SectionType {
   eSectionTypeDWARFDebugTuIndex,
   eSectionTypeCTF,
   eSectionTypeLLDBTypeSummaries,
+  eSectionTypeLLDBFormatters,
   eSectionTypeSwiftModules,
 };
 

lldb/source/Core/Section.cpp

@@ -460,6 +460,7 @@ bool Section::ContainsOnlyDebugInfo() const {
   case eSectionTypeDWARFGNUDebugAltLink:
   case eSectionTypeCTF:
   case eSectionTypeLLDBTypeSummaries:
+  case eSectionTypeLLDBFormatters:
   case eSectionTypeSwiftModules:
     return true;
   }

lldb/source/DataFormatters/CMakeLists.txt

@@ -5,6 +5,7 @@ add_lldb_library(lldbDataFormatters NO_PLUGIN_DEPENDENCIES
   FormatCache.cpp
   FormatClasses.cpp
   FormatManager.cpp
+  FormatterBytecode.cpp
   FormattersHelpers.cpp
   LanguageCategory.cpp
   StringPrinter.cpp