Ensure we have a lexical scope for global code

This requires a bit more work than simply pushing a
new BlockContext for the lexically declared variables,
as eval() and the Function constructor operate on the
global scope (including the lexically declared names).

To fix this introduce Push/PopScriptContext instructions,
that create a BlockContext for the lexically declared
vars and pushes that one as a global script context that
eval and friends use.

Change-Id: I0fd0b0f682f82e250545e874fe93978449fe5e46
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 36 insertions, 0 deletions

diff --git a/src/qml/jit/qv4jit.cpp b/src/qml/jit/qv4jit.cpp
index 16b6b5fb94..f659ddfb00 100644
--- a/src/qml/jit/qv4jit.cpp
+++ b/src/qml/jit/qv4jit.cpp
@@ -659,6 +659,34 @@ void BaselineJIT::generate_PushBlockContext(int reg, int index)
     JIT_GENERATE_RUNTIME_CALL(pushBlockContextHelper, Assembler::IgnoreResult);
 }
 
+static void pushScriptContextHelper(QV4::Value *stack, ExecutionEngine *engine, int index)
+{
+    stack[CallData::Context] = Runtime::method_createScriptContext(engine, index);
+}
+
+void BaselineJIT::generate_PushScriptContext(int index)
+{
+    as->saveAccumulatorInFrame();
+    as->prepareCallWithArgCount(3);
+    as->passInt32AsArg(index, 2);
+    as->passEngineAsArg(1);
+    as->passRegAsArg(0, 0);
+    JIT_GENERATE_RUNTIME_CALL(pushScriptContextHelper, Assembler::IgnoreResult);
+}
+
+static void popScriptContextHelper(QV4::Value *stack, ExecutionEngine *engine)
+{
+    stack[CallData::Context] = Runtime::method_popScriptContext(engine);
+}
+
+void BaselineJIT::generate_PopScriptContext()
+{
+    as->saveAccumulatorInFrame();
+    as->prepareCallWithArgCount(2);
+    as->passEngineAsArg(1);
+    as->passRegAsArg(0, 0);
+    JIT_GENERATE_RUNTIME_CALL(popScriptContextHelper, Assembler::IgnoreResult);
+}
 
 void BaselineJIT::generate_PopContext(int reg) { as->popContext(reg); }
 
@@ -1208,6 +1236,12 @@ void BaselineJIT::collectLabelsInBytecode()
         MOTH_BEGIN_INSTR(PushBlockContext)
         MOTH_END_INSTR(PushBlockContext)
 
+        MOTH_BEGIN_INSTR(PushScriptContext)
+        MOTH_END_INSTR(PushScriptContext)
+
+        MOTH_BEGIN_INSTR(PopScriptContext)
+        MOTH_END_INSTR(PopScriptContext)
+
         MOTH_BEGIN_INSTR(PopContext)
         MOTH_END_INSTR(PopContext)
 
diff --git a/src/qml/jit/qv4jit_p.h b/src/qml/jit/qv4jit_p.h
index 157fbffeb1..97dd2ef2a5 100644
--- a/src/qml/jit/qv4jit_p.h
+++ b/src/qml/jit/qv4jit_p.h
@@ -181,6 +181,8 @@ public:
     void generate_PushCatchContext(int reg, int index, int name) override;
     void generate_PushWithContext(int reg) override;
     void generate_PushBlockContext(int reg, int index) override;
+    void generate_PushScriptContext(int index) override;
+    void generate_PopScriptContext() override;
     void generate_PopContext(int reg) override;
     void generate_GetIterator(int iterator) override;
     void generate_DeleteMember(int member, int base) override;