TypeGraph: Fix multi dimensional arrays

Multi dimensional arrays are not flattened into 1-D arrays when using
TypeGraph. Update TreeBuilder to account for this.

By not flattening arrays, we are able to produce more descriptive
results.

The disadvantage is that we must now recurse inside arrays
containing only primitives. A better solution to requiring flattening
would be the planned work to not recurse into any static types (not just
primitives). This would also apply to multi-dimensional arrays of
primtivies.

oi/CodeGen.cpp

@@ -81,6 +81,9 @@ struct OIArray {
 }
 
 void addIncludes(const TypeGraph& typeGraph, std::string& code) {
+  // Required for the offsetof() macro
+  code += "#include <cstddef>\n";
+
   // TODO deduplicate containers
   for (const Type& t : typeGraph.finalTypes) {
     if (const auto* c = dynamic_cast<const Container*>(&t)) {

oi/TreeBuilder.cpp

@@ -571,8 +571,13 @@ void TreeBuilder::processContainer(const Variable& variable, Node& node) {
     kind = ARRAY_TYPE;
     struct drgn_type* arrayElementType = nullptr;
     size_t numElems = 0;
-    drgn_utils::getDrgnArrayElementType(variable.type, &arrayElementType,
-                                        numElems);
+    if (config.features[Feature::TypeGraph]) {
+      arrayElementType = drgn_type_type(variable.type).type;
+      numElems = drgn_type_length(variable.type);
+    } else {
+      drgn_utils::getDrgnArrayElementType(variable.type, &arrayElementType,
+                                          numElems);
+    }
     assert(numElems > 0);
     elementTypes.push_back(
         drgn_qualified_type{arrayElementType, (enum drgn_qualifiers)(0)});

test/integration/arrays.toml

@@ -43,7 +43,8 @@ definitions = '''
         "staticSize":0,
         "dynamicSize":0
       }]}]'''
-  [cases.multidim]
+  [cases.multidim_legacy] # Test for legacy behaviour. Remove with OICodeGen
+    cli_options = ["-Ftype-graph"]
     param_types = ["const MultiDim&"]
     setup = "return {};"
     expect_json = '''[{
@@ -56,6 +57,16 @@ definitions = '''
         "capacity":6,
         "elementStaticSize":4
       }]}]'''
+  [cases.multidim]
+    cli_options = ["-ftype-graph"]
+    param_types = ["const MultiDim&"]
+    setup = "return {};"
+    expect_json = '''[
+      {"staticSize":24, "dynamicSize":0, "exclusiveSize":0, "members":[
+        {"staticSize":24, "dynamicSize":0, "exclusiveSize":0, "length":2, "capacity":2, "elementStaticSize":12, "members":[
+          {"staticSize":12, "dynamicSize":0, "exclusiveSize":12, "length":3, "capacity":3, "elementStaticSize":4},
+          {"staticSize":12, "dynamicSize":0, "exclusiveSize":12, "length":3, "capacity":3, "elementStaticSize":4}]
+      }]}]'''
   [cases.direct_int10]
     skip = "Direct array arguments don't work"
     param_types = ["int[10]"]