Reland: [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.

Relanding with more explicit type conversions.

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