[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/FormatterSection.h

@@ -0,0 +1,26 @@
+//===-- FormattersSection.h -------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_DATAFORMATTERS_FORMATTERSECTION_H
+#define LLDB_DATAFORMATTERS_FORMATTERSECTION_H
+
+#include "lldb/lldb-enumerations.h"
+#include "lldb/lldb-forward.h"
+
+namespace lldb_private {
+/// Load type summaries embedded in the binary. These are type summaries
+/// provided by the authors of the code.
+void LoadTypeSummariesForModule(lldb::ModuleSP module_sp);
+
+/// Load data formatters embedded in the binary. These are formatters provided
+/// by the authors of the code using LLDB formatter bytecode.
+void LoadFormattersForModule(lldb::ModuleSP module_sp);
+
+} // namespace lldb_private
+
+#endif // LLDB_DATAFORMATTERS_FORMATTERSECTION_H

lldb/include/lldb/DataFormatters/FormattersHelpers.h

@@ -1,5 +1,4 @@
-//===-- FormattersHelpers.h --------------------------------------*- C++
-//-*-===//
+//===-- FormattersHelpers.h -------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.

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 +413,23 @@ 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

@@ -764,6 +764,7 @@ enum SectionType {
   eSectionTypeDWARFDebugTuIndex,
   eSectionTypeCTF,
   eSectionTypeLLDBTypeSummaries,
+  eSectionTypeLLDBFormatters,
   eSectionTypeSwiftModules,
 };
 

lldb/source/API/SBTypeSummary.cpp

@@ -343,6 +343,7 @@ bool SBTypeSummary::IsEqualTo(lldb::SBTypeSummary &rhs) {
   case TypeSummaryImpl::Kind::eCallback:
     return llvm::dyn_cast<CXXFunctionSummaryFormat>(m_opaque_sp.get()) ==
            llvm::dyn_cast<CXXFunctionSummaryFormat>(rhs.m_opaque_sp.get());
+  case TypeSummaryImpl::Kind::eBytecode:
   case TypeSummaryImpl::Kind::eScript:
     if (IsFunctionCode() != rhs.IsFunctionCode())
       return false;

lldb/source/Core/Section.cpp

@@ -149,10 +149,12 @@ const char *Section::GetTypeAsCString() const {
     return "ctf";
   case eSectionTypeLLDBTypeSummaries:
     return "lldb-type-summaries";
-  case eSectionTypeOther:
-    return "regular";
+  case eSectionTypeLLDBFormatters:
+    return "lldb-formatters";
   case eSectionTypeSwiftModules:
     return "swift-modules";
+  case eSectionTypeOther:
+    return "regular";
   }
   return "unknown";
 }
@@ -460,6 +462,7 @@ bool Section::ContainsOnlyDebugInfo() const {
   case eSectionTypeDWARFGNUDebugAltLink:
   case eSectionTypeCTF:
   case eSectionTypeLLDBTypeSummaries:
+  case eSectionTypeLLDBFormatters:
   case eSectionTypeSwiftModules:
     return true;
   }

lldb/source/DataFormatters/CMakeLists.txt

@@ -5,7 +5,9 @@ add_lldb_library(lldbDataFormatters NO_PLUGIN_DEPENDENCIES
   FormatCache.cpp
   FormatClasses.cpp
   FormatManager.cpp
+  FormatterBytecode.cpp
   FormattersHelpers.cpp
+  FormatterSection.cpp
   LanguageCategory.cpp
   StringPrinter.cpp
   TypeCategory.cpp