tracking of optimization information associated with expressions

src/Expr.cc

@@ -19,6 +19,7 @@
 #include "zeek/module_util.h"
 #include "zeek/DebugLogger.h"
 #include "zeek/Hash.h"
+#include "zeek/script_opt/ExprOptInfo.h"
 
 #include "zeek/broker/Data.h"
 
@@ -79,6 +80,12 @@ const char* expr_name(BroExprTag t)
 Expr::Expr(BroExprTag arg_tag) : tag(arg_tag), paren(false), type(nullptr)
 	{
 	SetLocationInfo(&start_location, &end_location);
+	opt_info = new ExprOptInfo();
+	}
+
+Expr::~Expr()
+	{
+	delete opt_info;
 	}
 
 const ListExpr* Expr::AsListExpr() const

src/Expr.h

@@ -117,6 +117,8 @@ using RefExprPtr = IntrusivePtr<RefExpr>;
 class Stmt;
 using StmtPtr = IntrusivePtr<Stmt>;
 
+class ExprOptInfo;
+
 class Expr : public Obj {
 public:
 	const TypePtr& GetType() const
@@ -389,6 +391,12 @@ public:
 			return Obj::GetLocationInfo();
 		}
 
+	// Access script optimization information associated with
+	// this statement.
+	ExprOptInfo* GetOptInfo() const		{ return opt_info; }
+
+	~Expr() override;
+
 protected:
 	Expr() = default;
 	explicit Expr(BroExprTag arg_tag);
@@ -418,6 +426,10 @@ protected:
 	// derived, if any.  Used as an aid for generating meaningful
 	// and correctly-localized error messages.
 	ExprPtr original = nullptr;
+
+	// Information associated with the Expr for purposes of
+	// script optimization.
+	ExprOptInfo* opt_info;
 };
 
 class NameExpr final : public Expr {

src/script_opt/ExprOptInfo.h

@@ -0,0 +1,17 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+// Auxiliary information associated with expressions to aid script
+// optimization.
+
+#pragma once
+
+namespace zeek::detail {
+
+class ExprOptInfo {
+public:
+	// The AST number of the statement in which this expression
+	// appears.
+	int stmt_num = -1;	// -1 = not assigned yet
+};
+
+} // namespace zeek::detail