Speed up exception propagation

Avoid catch (...) with re-throw as it turns that this is very slow because it
throws a new exception and the unwinder starts from scratch. Instead use stack
allocated objects and cleaning destructors to restore state before continuing
with the propagation of exceptions.

Change-Id: I6d95026bcd60b58cb6258a9dae28623a46739532
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/src/qml/jsruntime/qv4engine_p.h b/src/qml/jsruntime/qv4engine_p.h
index 5da556452e..e49b6a4ebf 100644
--- a/src/qml/jsruntime/qv4engine_p.h
+++ b/src/qml/jsruntime/qv4engine_p.h
@@ -326,11 +326,9 @@ struct Q_QML_EXPORT ExecutionEngine
     StackTrace exceptionStackTrace;
 
     void Q_NORETURN throwException(const ValueRef value);
-    void Q_NORETURN rethrowException(ExecutionContext *intermediateCatchingContext);
     ReturnedValue catchException(ExecutionContext *catchingContext, StackTrace *trace);
 
     void Q_NORETURN throwInternal();
-    void Q_NORETURN rethrowInternal();
     // ----
 
 
@@ -351,6 +349,23 @@ inline ExecutionContext *ExecutionEngine::popContext()
     return current;
 }
 
+struct ExecutionContextSaver
+{
+    ExecutionEngine *engine;
+    ExecutionContext *savedContext;
+
+    ExecutionContextSaver(ExecutionContext *context)
+        : engine(context->engine)
+        , savedContext(context)
+    {
+    }
+    ~ExecutionContextSaver()
+    {
+        while (engine->current != savedContext)
+            engine->popContext();
+    }
+};
+
 } // namespace QV4
 
 QT_END_NAMESPACE