TypeGraph: Add "--tree-builder-v2" flag

oi/CodeGen.cpp

@@ -778,7 +778,7 @@ void CodeGen::transform(type_graph::TypeGraph& typeGraph) {
         type_graph::TypeIdentifier::createPass(config_.passThroughTypes));
   }
   pm.addPass(type_graph::RemoveIgnored::createPass(config_.membersToStub));
-  pm.addPass(type_graph::AddPadding::createPass());
+  pm.addPass(type_graph::AddPadding::createPass(config_.features));
   pm.addPass(type_graph::NameGen::createPass());
   pm.addPass(type_graph::AlignmentCalc::createPass());
   pm.addPass(type_graph::RemoveTopLevelPointer::createPass());

oi/Features.cpp

@@ -33,9 +33,11 @@ std::string_view featureHelp(Feature f) {
     case Feature::CaptureThriftIsset:
       return "Capture isset data for Thrift object.";
     case Feature::TypeGraph:
-      return "Use Type Graph for code generation (CodeGen V2).";
+      return "Use Type Graph for code generation (CodeGen v2).";
     case Feature::TypedDataSegment:
       return "Use Typed Data Segment in generated code.";
+    case Feature::TreeBuilderV2:
+      return "Use Tree Builder v2 for reading the data segment";
     case Feature::GenJitDebug:
       return "Generate debug information for the JIT object.";
     case Feature::JitLogging:

oi/Features.h

@@ -28,6 +28,7 @@
   X(CaptureThriftIsset, "capture-thrift-isset") \
   X(TypeGraph, "type-graph")                    \
   X(TypedDataSegment, "typed-data-segment")     \
+  X(TreeBuilderV2, "tree-builder-v2")           \
   X(GenJitDebug, "gen-jit-debug")               \
   X(JitLogging, "jit-logging")                  \
   X(JitTiming, "jit-timing")                    \

oi/type_graph/AddPadding.cpp

@@ -17,16 +17,20 @@
 
 #include <cassert>
 
+#include "Flattener.h"
 #include "TypeGraph.h"
 
 template <typename T>
 using ref = std::reference_wrapper<T>;
 
+using ObjectIntrospection::Feature;
+using ObjectIntrospection::FeatureSet;
+
 namespace type_graph {
 
-Pass AddPadding::createPass() {
-  auto fn = [](TypeGraph& typeGraph) {
-    AddPadding pass(typeGraph);
+Pass AddPadding::createPass(FeatureSet features) {
+  auto fn = [features](TypeGraph& typeGraph) {
+    AddPadding pass(typeGraph, features);
     for (auto& type : typeGraph.rootTypes()) {
       pass.visit(type);
     }
@@ -67,6 +71,19 @@ void AddPadding::visit(Class& c) {
     if (i >= 1) {
       addPadding(c.members[i - 1], c.members[i].bitOffset, paddedMembers);
     }
+
+    if (!features_[Feature::TreeBuilderV2] &&
+        c.members[i].name.starts_with(Flattener::ParentPrefix)) {
+      // CodeGen v1 can't handle parent containers. It replaces them with
+      // padding.
+      auto& primitive = typeGraph_.makeType<Primitive>(Primitive::Kind::Int8);
+      auto& paddingArray =
+          typeGraph_.makeType<Array>(primitive, c.members[i].type().size());
+      paddedMembers.emplace_back(paddingArray, MemberPrefix,
+                                 c.members[i].bitOffset);
+      continue;
+    }
+
     paddedMembers.push_back(c.members[i]);
   }
 

oi/type_graph/AddPadding.h

@@ -15,12 +15,13 @@
  */
 #pragma once
 
-#include <functional>
+#include <string>
 #include <unordered_set>
 
 #include "PassManager.h"
 #include "Types.h"
 #include "Visitor.h"
+#include "oi/Features.h"
 
 namespace type_graph {
 
@@ -35,9 +36,11 @@ class TypeGraph;
  */
 class AddPadding final : public RecursiveVisitor {
  public:
-  static Pass createPass();
+  static Pass createPass(ObjectIntrospection::FeatureSet features);
 
-  explicit AddPadding(TypeGraph& typeGraph) : typeGraph_(typeGraph) {
+  explicit AddPadding(TypeGraph& typeGraph,
+                      ObjectIntrospection::FeatureSet features)
+      : typeGraph_(typeGraph), features_(features) {
   }
 
   using RecursiveVisitor::visit;
@@ -50,6 +53,7 @@ class AddPadding final : public RecursiveVisitor {
  private:
   std::unordered_set<Type*> visited_;
   TypeGraph& typeGraph_;
+  ObjectIntrospection::FeatureSet features_;
 
   void addPadding(const Member& prevMember,
                   uint64_t paddingEndBits,

oi/type_graph/Flattener.cpp

@@ -71,7 +71,7 @@ void flattenParent(const Parent& parent,
   } else if (Container* parentContainer =
                  dynamic_cast<Container*>(&parentType)) {
     // Create a new member to represent this parent container
-    flattenedMembers.emplace_back(*parentContainer, "__parent",
+    flattenedMembers.emplace_back(*parentContainer, Flattener::ParentPrefix,
                                   parent.bitOffset);
   } else {
     throw std::runtime_error("Invalid type for parent");

oi/type_graph/Flattener.h

@@ -15,6 +15,7 @@
  */
 #pragma once
 
+#include <string>
 #include <unordered_set>
 #include <vector>
 
@@ -42,6 +43,8 @@ class Flattener : public RecursiveVisitor {
   void visit(Class& c) override;
   void visit(Container& c) override;
 
+  static const inline std::string ParentPrefix = "__oi_parent";
+
  private:
   std::unordered_set<Type*> visited_;
   std::vector<Member> flattened_members_;

test/test_add_padding.cpp

@@ -5,6 +5,17 @@
 #include "test/type_graph_utils.h"
 
 using namespace type_graph;
+using ObjectIntrospection::Feature;
+using ObjectIntrospection::FeatureSet;
+
+namespace {
+void test(std::vector<std::reference_wrapper<type_graph::Type>> rootTypes,
+          std::string_view expectedAfter) {
+  FeatureSet features;
+  features[Feature::TreeBuilderV2] = true;
+  ::test(AddPadding::createPass({}), rootTypes, expectedAfter);
+}
+}  // namespace
 
 TEST(AddPaddingTest, BetweenMembers) {
   auto myclass = Class{0, Class::Kind::Class, "MyClass", 16};
@@ -13,7 +24,7 @@ TEST(AddPaddingTest, BetweenMembers) {
   myclass.members.push_back(Member{myint8, "n1", 0});
   myclass.members.push_back(Member{myint64, "n2", 8 * 8});
 
-  test(AddPadding::createPass(), {myclass}, R"(
+  test({myclass}, R"(
 [0] Class: MyClass (size: 16)
       Member: n1 (offset: 0)
         Primitive: int8_t
@@ -32,7 +43,7 @@ TEST(AddPaddingTest, AtEnd) {
   myclass.members.push_back(Member{myint64, "n1", 0});
   myclass.members.push_back(Member{myint8, "n2", 8 * 8});
 
-  test(AddPadding::createPass(), {myclass}, R"(
+  test({myclass}, R"(
 [0] Struct: MyStruct (size: 16)
       Member: n1 (offset: 0)
         Primitive: int64_t
@@ -51,7 +62,7 @@ TEST(AddPaddingTest, UnionNotPadded) {
   myclass.members.push_back(Member{myint64, "n1", 0});
   myclass.members.push_back(Member{myint8, "n2", 0});
 
-  test(AddPadding::createPass(), {myclass}, R"(
+  test({myclass}, R"(
 [0] Union: MyUnion (size: 8)
       Member: n1 (offset: 0)
         Primitive: int64_t
@@ -86,7 +97,7 @@ TEST(AddPaddingTest, Bitfields) {
   myclass.members.push_back(b4);
   myclass.members.push_back(n);
 
-  test(AddPadding::createPass(), {myclass}, R"(
+  test({myclass}, R"(
 [0] Class: MyClass (size: 16)
       Member: b1 (offset: 0, bitsize: 3)
         Primitive: int64_t
@@ -111,4 +122,29 @@ TEST(AddPaddingTest, Bitfields) {
 )");
 }
 
+TEST(AddPaddingTest, CodeGenCompatibility) {
+  auto myint = Primitive{Primitive::Kind::Int32};
+  auto vector = getVector(1);
+  vector.templateParams.push_back(TemplateParam{myint});
+
+  auto myclass = Class{0, Class::Kind::Class, "MyClass", 24};
+  myclass.members.push_back(Member{vector, "__oi_parent", 0});
+
+  FeatureSet features;
+  features[Feature::TreeBuilderV2] = false;
+  test(AddPadding::createPass(features), {myclass}, R"(
+[0] Class: MyClass (size: 24)
+      Member: __oi_parent (offset: 0)
+[1]     Container: std::vector (size: 24)
+          Param
+            Primitive: int32_t
+)",
+       R"(
+[0] Class: MyClass (size: 24)
+      Member: __oi_padding (offset: 0)
+[1]     Array: (length: 24)
+          Primitive: int8_t
+)");
+}
+
 // TODO test we follow class members, templates, children

test/test_flattener.cpp

@@ -705,7 +705,7 @@ TEST(FlattenerTest, ParentContainer) {
 )",
        R"(
 [0] Class: ClassA (size: 32)
-      Member: __parent (offset: 0)
+      Member: __oi_parent (offset: 0)
 [1]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t
@@ -735,11 +735,11 @@ TEST(FlattenerTest, ParentTwoContainers) {
 )",
        R"(
 [0] Class: ClassA (size: 48)
-      Member: __parent (offset: 0)
+      Member: __oi_parent (offset: 0)
 [1]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t
-      Member: __parent (offset: 24)
+      Member: __oi_parent (offset: 24)
         [1]
 )");
 }
@@ -772,7 +772,7 @@ TEST(FlattenerTest, ParentClassAndContainer) {
 [0] Class: ClassA (size: 32)
       Member: b (offset: 0)
         Primitive: int32_t
-      Member: __parent (offset: 8)
+      Member: __oi_parent (offset: 8)
 [1]     Container: std::vector (size: 24)
           Param
             Primitive: int32_t