ES7: Detect Tail Position Calls and pass that to the runtime

Doing the tail call in the runtime will come in a follow-up patch

Change-Id: I8224aac0edbdc765ee9b97703948edd52fd33f3e
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 26 insertions, 0 deletions

diff --git a/src/qml/compiler/qv4codegen_p.h b/src/qml/compiler/qv4codegen_p.h
index ae3e074e07..aaf8baef34 100644
--- a/src/qml/compiler/qv4codegen_p.h
+++ b/src/qml/compiler/qv4codegen_p.h
@@ -733,12 +733,38 @@ protected:
     bool insideSwitch = false;
     bool inFormalParameterList = false;
     bool functionEndsWithReturn = false;
+    bool _tailCallsAreAllowed = true;
+
     ControlFlow *controlFlow = nullptr;
 
     bool _fileNameIsUrl;
     bool hasError;
     QList<QQmlJS::DiagnosticMessage> _errors;
 
+    class TailCallBlocker
+    {
+    public:
+        TailCallBlocker(Codegen *cg, bool onoff = false)
+            : _cg(cg)
+            , _saved(_cg->_tailCallsAreAllowed)
+            , _onoff(onoff)
+        { _cg->_tailCallsAreAllowed = onoff; }
+
+        ~TailCallBlocker()
+        { _cg->_tailCallsAreAllowed = _saved; }
+
+        void unblock() const
+        { _cg->_tailCallsAreAllowed = _saved; }
+
+        void reblock() const
+        { _cg->_tailCallsAreAllowed = _onoff; }
+
+    private:
+        Codegen *_cg;
+        bool _saved;
+        bool _onoff;
+    };
+
 private:
     VolatileMemoryLocations scanVolatileMemoryLocations(AST::Node *ast) const;
     void handleConstruct(const Reference &base, AST::ArgumentList *args);