Enable generation of pointer variables by eBPF CodeGenInspector

backends/ebpf/codeGen.cpp

@@ -200,7 +200,12 @@ bool CodeGenInspector::preorder(const IR::Member* expression) {
     auto ei = P4::EnumInstance::resolve(expression, typeMap);
     if (ei == nullptr) {
         visit(expression->expr);
-        builder->append(".");
+        auto pe = expression->expr->to<IR::PathExpression>();
+        if (pe != nullptr && isPointerVariable(pe->path->name.name)) {
+            builder->append("->");
+        } else {
+            builder->append(".");
+        }
     }
     builder->append(expression->member);
     expressionPrecedence = prec;

backends/ebpf/codeGen.h

@@ -44,6 +44,9 @@ class CodeGenInspector : public Inspector {
     P4::ReferenceMap* refMap;
     P4::TypeMap* typeMap;
     std::map<const IR::Parameter*, const IR::Parameter*> substitution;
+    // asPointerVariables stores the list of string expressions that
+    // should be emitted as pointer variables.
+    std::set<cstring> asPointerVariables;
 
  public:
     int expressionPrecedence;  /// precedence of current IR::Operation
@@ -65,6 +68,18 @@ class CodeGenInspector : public Inspector {
             substitute(s.first, s.second);
     }
 
+    void useAsPointerVariable(cstring name) {
+        this->asPointerVariables.insert(name);
+    }
+    void copyPointerVariables(CodeGenInspector *other) {
+        for (auto s : other->asPointerVariables) {
+            this->asPointerVariables.insert(s);
+        }
+    }
+    bool isPointerVariable(cstring name) {
+        return asPointerVariables.count(name) > 0;
+    }
+
     bool notSupported(const IR::Expression* expression)
     { ::error(ErrorType::ERR_UNSUPPORTED,
               "%1%: not yet implemented", expression); return false; }

backends/ebpf/ebpfControl.cpp

@@ -537,7 +537,8 @@ void EBPFControl::emitDeclaration(CodeBuilder* builder, const IR::Declaration* d
         auto vd = decl->to<IR::Declaration_Variable>();
         auto etype = EBPFTypeFactory::instance->create(vd->type);
         builder->emitIndent();
-        etype->declareInit(builder, vd->name, false);
+        bool isPointer = codeGen->isPointerVariable(decl->name.name);
+        etype->declareInit(builder, vd->name, isPointer);
         builder->endOfStatement(true);
         BUG_CHECK(vd->initializer == nullptr,
                   "%1%: declarations with initializers not supported", decl);