Unify JSStackFrame and CallData

Change-Id: I4494dae8166026074c9efc74bac62de9d3fa2342
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

6 files changed, 37 insertions, 46 deletions

diff --git a/src/qml/jsruntime/qv4context_p.h b/src/qml/jsruntime/qv4context_p.h
index 8bcf89c1a4..ec027c9fd3 100644
--- a/src/qml/jsruntime/qv4context_p.h
+++ b/src/qml/jsruntime/qv4context_p.h
@@ -72,10 +72,21 @@ struct CatchContext;
 struct QmlContext;
 struct QQmlContextWrapper;
 
-// Attention: Make sure that this structure is the same size on 32-bit and 64-bit
-// architecture or you'll have to change the JIT code.
 struct CallData
 {
+    enum Offsets {
+        Function = 0,
+        Context = 1,
+        Accumulator = 2,
+        This = 3,
+        Argc = 4
+    };
+
+    Value function;
+    Value context;
+    Value accumulator;
+    Value thisObject;
+
     // below is to be compatible with Value. Initialize tag to 0
 #if Q_BYTE_ORDER != Q_LITTLE_ENDIAN
     uint tag;
@@ -88,17 +99,14 @@ struct CallData
         return i < argc ? args[i].asReturnedValue() : Primitive::undefinedValue().asReturnedValue();
     }
 
-    Value function;
-    Value context;
-    Value thisObject;
     Value args[1];
 
     static Q_DECL_CONSTEXPR int HeaderSize() { return offsetof(CallData, args) / sizeof(QV4::Value); }
 };
 
 Q_STATIC_ASSERT(std::is_standard_layout<CallData>::value);
-Q_STATIC_ASSERT(offsetof(CallData, thisObject) == 3*sizeof(Value));
-Q_STATIC_ASSERT(offsetof(CallData, args) == 4*sizeof(Value));
+Q_STATIC_ASSERT(offsetof(CallData, thisObject) == CallData::This*sizeof(Value));
+Q_STATIC_ASSERT(offsetof(CallData, args) == 5*sizeof(Value));
 
 namespace Heap {
 
diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 618565a806..531bfa3737 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -809,7 +809,7 @@ int CppStackFrame::lineNumber() const
 }
 
 ReturnedValue CppStackFrame::thisObject() const {
-    return jsFrame->stack[-(int)v4Function->nFormals - 1].asReturnedValue();
+    return jsFrame->thisObject.asReturnedValue();
 }
 
 StackTrace ExecutionEngine::stackTrace(int frameLimit) const
diff --git a/src/qml/jsruntime/qv4engine_p.h b/src/qml/jsruntime/qv4engine_p.h
index 4cee69ed33..fcadf57508 100644
--- a/src/qml/jsruntime/qv4engine_p.h
+++ b/src/qml/jsruntime/qv4engine_p.h
@@ -87,26 +87,10 @@ struct CompilationUnit;
 struct InternalClass;
 struct InternalClassPool;
 
-struct JSStackFrame {
-    enum Offsets {
-        JSFunction = 0,
-        Context = 1,
-        Accumulator = 2
-    };
-    // callData is directly before this
-    union {
-        Value jsFunction;
-        Value stack[1];
-    };
-    Value context;
-    Value accumulator; // ###
-    // registers follow
-};
-
 struct Q_QML_EXPORT CppStackFrame {
     CppStackFrame *parent;
     Function *v4Function;
-    JSStackFrame *jsFrame;
+    CallData *jsFrame;
     const uchar *instructionPointer;
 
     QString source() const;
diff --git a/src/qml/jsruntime/qv4functionobject.cpp b/src/qml/jsruntime/qv4functionobject.cpp
index 724d41be82..08963f18b4 100644
--- a/src/qml/jsruntime/qv4functionobject.cpp
+++ b/src/qml/jsruntime/qv4functionobject.cpp
@@ -369,7 +369,7 @@ ReturnedValue ScriptFunction::construct(const Managed *that, CallData *callData)
     Q_ASSERT(v4Function);
 
     callData->context = f->scope();
-ReturnedValue result = v4Function->call(callData);
+    ReturnedValue result = v4Function->call(callData);
 
     if (Q_UNLIKELY(v4->hasException))
         return Encode::undefined();
diff --git a/src/qml/jsruntime/qv4scopedvalue_p.h b/src/qml/jsruntime/qv4scopedvalue_p.h
index b21f23c34e..9522e919bd 100644
--- a/src/qml/jsruntime/qv4scopedvalue_p.h
+++ b/src/qml/jsruntime/qv4scopedvalue_p.h
@@ -381,7 +381,7 @@ struct ScopedStackFrame {
         frame.parent = scope.engine->currentStackFrame;
         if (!context)
             return;
-        frame.jsFrame = reinterpret_cast<JSStackFrame *>(scope.alloc(sizeof(JSStackFrame)/sizeof(Value)));
+        frame.jsFrame = reinterpret_cast<CallData *>(scope.alloc(sizeof(CallData)/sizeof(Value)));
         frame.jsFrame->context = context;
         frame.v4Function = frame.parent ? frame.parent->v4Function : 0;
         scope.engine->currentStackFrame = &frame;
diff --git a/src/qml/jsruntime/qv4vme_moth.cpp b/src/qml/jsruntime/qv4vme_moth.cpp
index ad3fd0bce1..da0b06dac7 100644
--- a/src/qml/jsruntime/qv4vme_moth.cpp
+++ b/src/qml/jsruntime/qv4vme_moth.cpp
@@ -336,7 +336,7 @@ static struct InstrCount {
 
 static inline Heap::CallContext *getScope(Value *stack, int level)
 {
-    Heap::ExecutionContext *scope = static_cast<ExecutionContext &>(stack[JSStackFrame::Context]).d();
+    Heap::ExecutionContext *scope = static_cast<ExecutionContext &>(stack[CallData::Context]).d();
     while (level > 0) {
         --level;
         scope = scope->outer;
@@ -499,22 +499,21 @@ QV4::ReturnedValue VME::exec(CallData *callData, QV4::Function *function)
     Profiling::FunctionCallProfiler(engine, function);
 
     Value *jsStackTop = engine->jsStackTop;
-    engine->jsStackTop = reinterpret_cast<QV4::Value *>(callData) + sizeof(CallData)/sizeof(Value) - 1 + (int)function->nFormals;
-    for (int i = callData->argc; i < (int)function->nFormals; ++i)
-        callData->args[i] = Encode::undefined();
 
     CppStackFrame frame;
     frame.parent = engine->currentStackFrame;
     frame.v4Function = function;
     frame.instructionPointer = function->codeData;
+    frame.jsFrame = callData;
     engine->currentStackFrame = &frame;
 
-    QV4::Value *stack = nullptr;
-    const uchar *exceptionHandler = 0;
+    engine->jsStackTop = reinterpret_cast<QV4::Value *>(callData) + function->compiledFunction->nRegisters + 1;
+    // clear out remaining arguments and local registers
+    for (Value *v = callData->args + callData->argc; v < jsStackTop; ++v)
+        *v = Encode::undefined();
 
-    stack = engine->jsAlloca(function->compiledFunction->nRegisters + sizeof(JSStackFrame)/sizeof(QV4::Value));
-    frame.jsFrame = reinterpret_cast<JSStackFrame *>(stack);
-    frame.jsFrame->context = callData->context;
+    QV4::Value *stack = reinterpret_cast<QV4::Value *>(callData);
+    const uchar *exceptionHandler = 0;
 
     QV4::Value &accumulator = frame.jsFrame->accumulator;
     QV4::ReturnedValue acc = Encode::undefined();
@@ -572,13 +571,13 @@ QV4::ReturnedValue VME::exec(CallData *callData, QV4::Function *function)
     MOTH_END_INSTR(MoveReg)
 
     MOTH_BEGIN_INSTR(LoadLocal)
-        auto cc = static_cast<Heap::CallContext *>(stack[JSStackFrame::Context].m());
+        auto cc = static_cast<Heap::CallContext *>(stack[CallData::Context].m());
         acc = cc->locals[index].asReturnedValue();
     MOTH_END_INSTR(LoadLocal)
 
     MOTH_BEGIN_INSTR(StoreLocal)
         CHECK_EXCEPTION;
-        auto cc = static_cast<Heap::CallContext *>(stack[JSStackFrame::Context].m());
+        auto cc = static_cast<Heap::CallContext *>(stack[CallData::Context].m());
         QV4::WriteBarrier::write(engine, cc, cc->locals.values + index, ACC);
     MOTH_END_INSTR(StoreLocal)
 
@@ -803,9 +802,9 @@ QV4::ReturnedValue VME::exec(CallData *callData, QV4::Function *function)
     MOTH_END_INSTR(SetException)
 
     MOTH_BEGIN_INSTR(PushCatchContext)
-        STACK_VALUE(reg) = STACK_VALUE(JSStackFrame::Context);
-        ExecutionContext *c = static_cast<ExecutionContext *>(stack + JSStackFrame::Context);
-        STACK_VALUE(JSStackFrame::Context) = Runtime::method_createCatchContext(c, name);
+        STACK_VALUE(reg) = STACK_VALUE(CallData::Context);
+        ExecutionContext *c = static_cast<ExecutionContext *>(stack + CallData::Context);
+        STACK_VALUE(CallData::Context) = Runtime::method_createCatchContext(c, name);
     MOTH_END_INSTR(PushCatchContext)
 
     MOTH_BEGIN_INSTR(PushWithContext)
@@ -813,13 +812,13 @@ QV4::ReturnedValue VME::exec(CallData *callData, QV4::Function *function)
         STORE_ACC();
         accumulator = accumulator.toObject(engine);
         CHECK_EXCEPTION;
-        STACK_VALUE(reg) = STACK_VALUE(JSStackFrame::Context);
-        ExecutionContext *c = static_cast<ExecutionContext *>(stack + JSStackFrame::Context);
-        STACK_VALUE(JSStackFrame::Context) = Runtime::method_createWithContext(c, accumulator);
+        STACK_VALUE(reg) = STACK_VALUE(CallData::Context);
+        ExecutionContext *c = static_cast<ExecutionContext *>(stack + CallData::Context);
+        STACK_VALUE(CallData::Context) = Runtime::method_createWithContext(c, accumulator);
     MOTH_END_INSTR(PushWithContext)
 
     MOTH_BEGIN_INSTR(PopContext)
-        STACK_VALUE(JSStackFrame::Context) = STACK_VALUE(reg);
+        STACK_VALUE(CallData::Context) = STACK_VALUE(reg);
     MOTH_END_INSTR(PopContext)
 
     MOTH_BEGIN_INSTR(ForeachIteratorObject)
@@ -906,7 +905,7 @@ QV4::ReturnedValue VME::exec(CallData *callData, QV4::Function *function)
     MOTH_END_INSTR(CreateUnmappedArgumentsObject)
 
     MOTH_BEGIN_INSTR(ConvertThisToObject)
-        Value *t = &stack[-(int)function->nFormals - 1];
+        Value *t = &stack[CallData::This];
         if (!t->isObject()) {
             if (t->isNullOrUndefined()) {
                 *t = engine->globalObject->asReturnedValue();