Rework catch context handling

Remove the need for a specialized catch context, instead
use a regular block context, that also captures the
catched variable.

This also removes the need to do lookups by name inside
a catch expression.

Change-Id: I8b037add7f423922e2a76b4c0da646ca7e25813a
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

7 files changed, 17 insertions, 75 deletions

diff --git a/src/qml/jsruntime/qv4context.cpp b/src/qml/jsruntime/qv4context.cpp
index 39fdcf0227..bd2e0faebf 100644
--- a/src/qml/jsruntime/qv4context.cpp
+++ b/src/qml/jsruntime/qv4context.cpp
@@ -53,7 +53,6 @@ using namespace QV4;
 
 DEFINE_MANAGED_VTABLE(ExecutionContext);
 DEFINE_MANAGED_VTABLE(CallContext);
-DEFINE_MANAGED_VTABLE(CatchContext);
 
 Heap::CallContext *ExecutionContext::newBlockContext(CppStackFrame *frame, int blockIndex)
 {
@@ -119,11 +118,14 @@ Heap::ExecutionContext *ExecutionContext::newWithContext(Heap::Object *with)
     return c;
 }
 
-Heap::CatchContext *ExecutionContext::newCatchContext(Heap::String *exceptionVarName, ReturnedValue exceptionValue)
+Heap::ExecutionContext *ExecutionContext::newCatchContext(CppStackFrame *frame, int blockIndex, Heap::String *exceptionVarName)
 {
-    Scope scope(this);
-    ScopedValue e(scope, exceptionValue);
-    return engine()->memoryManager->alloc<CatchContext>(d(), exceptionVarName, e);
+    Scope scope(frame->context());
+    ScopedString name(scope, exceptionVarName);
+    ScopedValue val(scope, scope.engine->catchException(nullptr));
+    ScopedContext ctx(scope, newBlockContext(frame, blockIndex));
+    ctx->setProperty(name, val);
+    return ctx->d();
 }
 
 void ExecutionContext::createMutableBinding(String *name, bool deletable)
@@ -170,16 +172,6 @@ void ExecutionContext::createMutableBinding(String *name, bool deletable)
     activation->__defineOwnProperty__(scope.engine, name, desc, attrs);
 }
 
-void Heap::CatchContext::init(ExecutionContext *outerContext, String *exceptionVarName,
-                              const Value &exceptionValue)
-{
-    Heap::ExecutionContext::init(Heap::ExecutionContext::Type_CatchContext);
-    outer.set(internalClass->engine, outerContext);
-
-    this->exceptionVarName.set(internalClass->engine, exceptionVarName);
-    this->exceptionValue.set(internalClass->engine, exceptionValue);
-}
-
 bool ExecutionContext::deleteProperty(String *name)
 {
     name->makeIdentifier();
@@ -188,12 +180,6 @@ bool ExecutionContext::deleteProperty(String *name)
     Heap::ExecutionContext *ctx = d();
     for (; ctx; ctx = ctx->outer) {
         switch (ctx->type) {
-        case Heap::ExecutionContext::Type_CatchContext: {
-            Heap::CatchContext *c = static_cast<Heap::CatchContext *>(ctx);
-            if (c->exceptionVarName->isEqualTo(name->d()))
-                return false;
-            break;
-        }
         case Heap::ExecutionContext::Type_BlockContext:
         case Heap::ExecutionContext::Type_CallContext: {
             Heap::CallContext *c = static_cast<Heap::CallContext *>(ctx);
@@ -232,14 +218,6 @@ ExecutionContext::Error ExecutionContext::setProperty(String *name, const Value
 
     for (; ctx; ctx = ctx->outer) {
         switch (ctx->type) {
-        case Heap::ExecutionContext::Type_CatchContext: {
-            Heap::CatchContext *c = static_cast<Heap::CatchContext *>(ctx);
-            if (c->exceptionVarName->isEqualTo(name->d())) {
-                    c->exceptionValue.set(v4, value);
-                    return NoError;
-            }
-            break;
-        }
         case Heap::ExecutionContext::Type_WithContext: {
             Scope scope(v4);
             ScopedObject w(scope, ctx->activation);
@@ -293,12 +271,6 @@ ReturnedValue ExecutionContext::getProperty(String *name)
     Heap::ExecutionContext *ctx = d();
     for (; ctx; ctx = ctx->outer) {
         switch (ctx->type) {
-        case Heap::ExecutionContext::Type_CatchContext: {
-            Heap::CatchContext *c = static_cast<Heap::CatchContext *>(ctx);
-            if (c->exceptionVarName->isEqualTo(name->d()))
-                return c->exceptionValue.asReturnedValue();
-            break;
-        }
         case Heap::ExecutionContext::Type_BlockContext:
         case Heap::ExecutionContext::Type_CallContext: {
             Heap::CallContext *c = static_cast<Heap::CallContext *>(ctx);
@@ -335,12 +307,6 @@ ReturnedValue ExecutionContext::getPropertyAndBase(String *name, Value *base)
     Heap::ExecutionContext *ctx = d();
     for (; ctx; ctx = ctx->outer) {
         switch (ctx->type) {
-        case Heap::ExecutionContext::Type_CatchContext: {
-            Heap::CatchContext *c = static_cast<Heap::CatchContext *>(ctx);
-            if (c->exceptionVarName->isEqualTo(name->d()))
-                return c->exceptionValue.asReturnedValue();
-            break;
-        }
         case Heap::ExecutionContext::Type_BlockContext:
         case Heap::ExecutionContext::Type_CallContext: {
             Heap::CallContext *c = static_cast<Heap::CallContext *>(ctx);
diff --git a/src/qml/jsruntime/qv4context_p.h b/src/qml/jsruntime/qv4context_p.h
index 5a9c85c941..cd99f162d2 100644
--- a/src/qml/jsruntime/qv4context_p.h
+++ b/src/qml/jsruntime/qv4context_p.h
@@ -107,11 +107,10 @@ DECLARE_HEAP_OBJECT(ExecutionContext, Base) {
 
     enum ContextType {
         Type_GlobalContext = 0x1,
-        Type_CatchContext = 0x2,
-        Type_WithContext = 0x3,
-        Type_QmlContext = 0x4,
-        Type_BlockContext = 0x5,
-        Type_CallContext = 0x6
+        Type_WithContext = 0x2,
+        Type_QmlContext = 0x3,
+        Type_BlockContext = 0x4,
+        Type_CallContext = 0x5
     };
 
     void init(ContextType t)
@@ -169,16 +168,6 @@ Q_STATIC_ASSERT(offsetof(CallContextData, function) == 0);
 //Q_STATIC_ASSERT(sizeof(CallContext) == sizeof(ExecutionContext) + sizeof(CallContextData));
 //#endif
 
-#define CatchContextMembers(class, Member) \
-    Member(class, Pointer, String *, exceptionVarName) \
-    Member(class, HeapValue, HeapValue, exceptionValue)
-
-DECLARE_HEAP_OBJECT(CatchContext, ExecutionContext) {
-    DECLARE_MARKOBJECTS(CatchContext);
-
-    void init(ExecutionContext *outerContext, String *exceptionVarName, const Value &exceptionValue);
-};
-Q_STATIC_ASSERT(std::is_trivial< CatchContext >::value);
 
 }
 
@@ -195,7 +184,7 @@ struct Q_QML_EXPORT ExecutionContext : public Managed
     static Heap::CallContext *newBlockContext(QV4::CppStackFrame *frame, int blockIndex);
     static Heap::CallContext *newCallContext(QV4::CppStackFrame *frame);
     Heap::ExecutionContext *newWithContext(Heap::Object *with);
-    Heap::CatchContext *newCatchContext(Heap::String *exceptionVarName, ReturnedValue exceptionValue);
+    static Heap::ExecutionContext *newCatchContext(CppStackFrame *frame, int blockIndex, Heap::String *exceptionVarName);
 
     void createMutableBinding(String *name, bool deletable);
 
@@ -228,12 +217,6 @@ struct Q_QML_EXPORT CallContext : public ExecutionContext
     }
 };
 
-struct CatchContext : public ExecutionContext
-{
-    V4_MANAGED(CatchContext, ExecutionContext)
-    V4_INTERNALCLASS(CatchContext)
-};
-
 inline CallContext *ExecutionContext::asCallContext()
 {
     return d()->type == Heap::ExecutionContext::Type_CallContext ? static_cast<CallContext *>(this) : nullptr;
diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 10030a14e4..3660ab3855 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -209,7 +209,6 @@ ExecutionEngine::ExecutionEngine(QJSEngine *jsEngine)
     classes[Class_SparseArrayData] = classes[Class_Empty]->changeVTable(QV4::SparseArrayData::staticVTable());
     classes[Class_ExecutionContext] = classes[Class_Empty]->changeVTable(QV4::ExecutionContext::staticVTable());
     classes[Class_CallContext] = classes[Class_Empty]->changeVTable(QV4::CallContext::staticVTable());
-    classes[Class_CatchContext] = classes[Class_Empty]->changeVTable(QV4::CatchContext::staticVTable());
     classes[Class_QmlContext] = classes[Class_Empty]->changeVTable(QV4::QmlContext::staticVTable());
 
     jsStrings[String_Empty] = newIdentifier(QString());
diff --git a/src/qml/jsruntime/qv4enginebase_p.h b/src/qml/jsruntime/qv4enginebase_p.h
index b7f6b8d3cd..c01b9b1842 100644
--- a/src/qml/jsruntime/qv4enginebase_p.h
+++ b/src/qml/jsruntime/qv4enginebase_p.h
@@ -96,7 +96,6 @@ struct Q_QML_EXPORT EngineBase {
         Class_SparseArrayData,
         Class_ExecutionContext,
         Class_CallContext,
-        Class_CatchContext,
         Class_QmlContext,
         Class_Object,
         Class_ArrayObject,
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index 95e4017344..40e08ededb 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -1183,11 +1183,6 @@ QV4::ReturnedValue Runtime::method_typeofName(ExecutionEngine *engine, int nameI
     return method_typeofValue(engine, prop);
 }
 
-/* The next three methods are a bit tricky. They can't open up a Scope, as that
- * would mess up the pushing of the context.
- *
- * Instead the push/pop pair acts as a non local scope.
- */
 ReturnedValue Runtime::method_createWithContext(ExecutionContext *parent, const Value &o)
 {
     Q_ASSERT(o.isObject());
@@ -1195,11 +1190,11 @@ ReturnedValue Runtime::method_createWithContext(ExecutionContext *parent, const
     return parent->newWithContext(obj.d())->asReturnedValue();
 }
 
-ReturnedValue Runtime::method_createCatchContext(ExecutionContext *parent, int exceptionVarNameIndex)
+ReturnedValue Runtime::method_createCatchContext(ExecutionContext *parent, int blockIndex, int exceptionVarNameIndex)
 {
     ExecutionEngine *e = parent->engine();
-    return parent->newCatchContext(e->currentStackFrame->v4Function->compilationUnit->runtimeStrings[exceptionVarNameIndex],
-                                   e->catchException(nullptr))->asReturnedValue();
+    return parent->newCatchContext(e->currentStackFrame, blockIndex,
+                                   e->currentStackFrame->v4Function->compilationUnit->runtimeStrings[exceptionVarNameIndex])->asReturnedValue();
 }
 
 ReturnedValue Runtime::method_createBlockContext(ExecutionContext *parent, int index)
diff --git a/src/qml/jsruntime/qv4runtimeapi_p.h b/src/qml/jsruntime/qv4runtimeapi_p.h
index 24bab70327..a1a7bd9ed0 100644
--- a/src/qml/jsruntime/qv4runtimeapi_p.h
+++ b/src/qml/jsruntime/qv4runtimeapi_p.h
@@ -125,7 +125,7 @@ struct ExceptionCheck<void (*)(QV4::NoThrowEngine *, A, B, C)> {
     /* exceptions & scopes */ \
     F(void, throwException, (ExecutionEngine *engine, const Value &value)) \
     F(ReturnedValue, createWithContext, (ExecutionContext *parent, const Value &o)) \
-    F(ReturnedValue, createCatchContext, (ExecutionContext *parent, int exceptionVarNameIndex)) \
+    F(ReturnedValue, createCatchContext, (ExecutionContext *parent, int blockIndex, int exceptionVarNameIndex)) \
     F(ReturnedValue, createBlockContext, (ExecutionContext *parent, int index)) \
     \
     /* closures */ \
diff --git a/src/qml/jsruntime/qv4vme_moth.cpp b/src/qml/jsruntime/qv4vme_moth.cpp
index a515abd9de..4a7339ca3a 100644
--- a/src/qml/jsruntime/qv4vme_moth.cpp
+++ b/src/qml/jsruntime/qv4vme_moth.cpp
@@ -877,7 +877,7 @@ QV4::ReturnedValue VME::exec(const FunctionObject *fo, const QV4::Value *thisObj
     MOTH_BEGIN_INSTR(PushCatchContext)
         STACK_VALUE(reg) = STACK_VALUE(CallData::Context);
         ExecutionContext *c = static_cast<ExecutionContext *>(stack + CallData::Context);
-        STACK_VALUE(CallData::Context) = Runtime::method_createCatchContext(c, name);
+        STACK_VALUE(CallData::Context) = Runtime::method_createCatchContext(c, index, name);
     MOTH_END_INSTR(PushCatchContext)
 
     MOTH_BEGIN_INSTR(CreateCallContext)