Move conversion of this object into generated code

When a non strict mode function uses the this object, we
need to make sure it's being correctly converted into a
object before being accessed. So far this was being done
by ScriptFunction::call. Move this into the generated code to
avoid overhead for methods not using 'this', and simplify our
ScriptFunction::call() implementation.

Change-Id: I739f4a89d29ed8082ce59e48d1523776224fc29d
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

17 files changed, 64 insertions, 19 deletions

diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 58c9fc59bb..4810e4dace 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -355,6 +355,12 @@ bool Codegen::ScanFunctions::visit(LocalForEachStatement *ast) {
     return false;
 }
 
+bool Codegen::ScanFunctions::visit(ThisExpression *)
+{
+    _env->usesThis = true;
+    return false;
+}
+
 bool Codegen::ScanFunctions::visit(Block *ast) {
     TemporaryBoolAssignment allowFuncDecls(_allowFuncDecls, _env->isStrict ? false : _allowFuncDecls);
     Node::accept(ast->statements, this);
@@ -1953,6 +1959,7 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
     V4IR::BasicBlock *exitBlock = function->newBasicBlock(groupStartBlock(), 0, V4IR::Function::DontInsertBlock);
     function->hasDirectEval = _env->hasDirectEval;
     function->usesArgumentsObject = _env->parent && (_env->usesArgumentsObject == Environment::ArgumentsObjectUsed);
+    function->usesThis = _env->usesThis;
     function->maxNumberOfArguments = qMax(_env->maxNumberOfArguments, (int)QV4::Global::ReservedArgumentCount);
     function->isStrict = _env->isStrict;
     function->isNamedExpression = _env->isNamedFunctionExpression;
@@ -2036,6 +2043,11 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
              _block->CALL(_block->NAME(V4IR::Name::builtin_setup_argument_object,
                      ast->firstSourceLocation().startLine, ast->firstSourceLocation().startColumn), 0));
     }
+    if (_function->usesThis && !_function->isStrict) {
+        // make sure we convert this to an object
+        _block->EXP(_block->CALL(_block->NAME(V4IR::Name::builtin_convert_this_to_object,
+                ast->firstSourceLocation().startLine, ast->firstSourceLocation().startColumn), 0));
+    }
 
     sourceElements(body);
 
diff --git a/src/qml/compiler/qv4codegen_p.h b/src/qml/compiler/qv4codegen_p.h
index 490e469dc7..b20db26467 100644
--- a/src/qml/compiler/qv4codegen_p.h
+++ b/src/qml/compiler/qv4codegen_p.h
@@ -148,6 +148,7 @@ protected:
         bool hasNestedFunctions;
         bool isStrict;
         bool isNamedFunctionExpression;
+        bool usesThis;
         enum UsesArgumentsObject {
             ArgumentsObjectUnknown,
             ArgumentsObjectNotUsed,
@@ -166,6 +167,7 @@ protected:
             , hasNestedFunctions(false)
             , isStrict(false)
             , isNamedFunctionExpression(false)
+            , usesThis(false)
             , usesArgumentsObject(ArgumentsObjectUnknown)
             , compilationMode(mode)
         {
@@ -513,6 +515,7 @@ protected:
         virtual bool visit(AST::LocalForStatement *ast);
         virtual bool visit(AST::ForEachStatement *ast);
         virtual bool visit(AST::LocalForEachStatement *ast);
+        virtual bool visit(AST::ThisExpression *ast);
 
         virtual bool visit(AST::Block *ast);
 
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index 854b9a3a8d..9aaab2f105 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -95,6 +95,7 @@ QT_BEGIN_NAMESPACE
     F(CallBuiltinDefineArray, callBuiltinDefineArray) \
     F(CallBuiltinDefineObjectLiteral, callBuiltinDefineObjectLiteral) \
     F(CallBuiltinSetupArgumentsObject, callBuiltinSetupArgumentsObject) \
+    F(CallBuiltinConvertThisToObject, callBuiltinConvertThisToObject) \
     F(CreateValue, createValue) \
     F(CreateProperty, createProperty) \
     F(CreateActivationProperty, createActivationProperty) \
@@ -471,6 +472,9 @@ union Instr
         MOTH_INSTR_HEADER
         Param result;
     };
+    struct instr_callBuiltinConvertThisToObject {
+        MOTH_INSTR_HEADER
+    };
     struct instr_createValue {
         MOTH_INSTR_HEADER
         quint32 argc;
@@ -704,6 +708,7 @@ union Instr
     instr_callBuiltinDefineArray callBuiltinDefineArray;
     instr_callBuiltinDefineObjectLiteral callBuiltinDefineObjectLiteral;
     instr_callBuiltinSetupArgumentsObject callBuiltinSetupArgumentsObject;
+    instr_callBuiltinConvertThisToObject callBuiltinConvertThisToObject;
     instr_createValue createValue;
     instr_createProperty createProperty;
     instr_createActivationProperty createActivationProperty;
diff --git a/src/qml/compiler/qv4isel_masm.cpp b/src/qml/compiler/qv4isel_masm.cpp
index ff6fed2f30..cddaac08bd 100644
--- a/src/qml/compiler/qv4isel_masm.cpp
+++ b/src/qml/compiler/qv4isel_masm.cpp
@@ -936,6 +936,11 @@ void InstructionSelection::callBuiltinSetupArgumentObject(V4IR::Temp *result)
     generateFunctionCall(result, __qmljs_builtin_setup_arguments_object, Assembler::ContextRegister);
 }
 
+void InstructionSelection::callBuiltinConvertThisToObject()
+{
+    generateFunctionCall(Assembler::Void, __qmljs_builtin_convert_this_to_object, Assembler::ContextRegister);
+}
+
 void InstructionSelection::callValue(V4IR::Temp *value, V4IR::ExprList *args, V4IR::Temp *result)
 {
     Q_ASSERT(value);
diff --git a/src/qml/compiler/qv4isel_masm_p.h b/src/qml/compiler/qv4isel_masm_p.h
index bf01d0429d..72251f44d7 100644
--- a/src/qml/compiler/qv4isel_masm_p.h
+++ b/src/qml/compiler/qv4isel_masm_p.h
@@ -1477,6 +1477,7 @@ protected:
     virtual void callBuiltinDefineArray(V4IR::Temp *result, V4IR::ExprList *args);
     virtual void callBuiltinDefineObjectLiteral(V4IR::Temp *result, V4IR::ExprList *args);
     virtual void callBuiltinSetupArgumentObject(V4IR::Temp *result);
+    virtual void callBuiltinConvertThisToObject();
     virtual void callValue(V4IR::Temp *value, V4IR::ExprList *args, V4IR::Temp *result);
     virtual void callProperty(V4IR::Expr *base, const QString &name, V4IR::ExprList *args, V4IR::Temp *result);
     virtual void callSubscript(V4IR::Expr *base, V4IR::Expr *index, V4IR::ExprList *args, V4IR::Temp *result);
diff --git a/src/qml/compiler/qv4isel_moth.cpp b/src/qml/compiler/qv4isel_moth.cpp
index df206d7890..44b4d666ef 100644
--- a/src/qml/compiler/qv4isel_moth.cpp
+++ b/src/qml/compiler/qv4isel_moth.cpp
@@ -1174,6 +1174,13 @@ void InstructionSelection::callBuiltinSetupArgumentObject(V4IR::Temp *result)
     addInstruction(call);
 }
 
+
+void QQmlJS::Moth::InstructionSelection::callBuiltinConvertThisToObject()
+{
+    Instruction::CallBuiltinConvertThisToObject call;
+    addInstruction(call);
+}
+
 ptrdiff_t InstructionSelection::addInstructionHelper(Instr::Type type, Instr &instr)
 {
 #ifdef MOTH_THREADED_INTERPRETER
diff --git a/src/qml/compiler/qv4isel_moth_p.h b/src/qml/compiler/qv4isel_moth_p.h
index c5ef1e44ba..0bf7444329 100644
--- a/src/qml/compiler/qv4isel_moth_p.h
+++ b/src/qml/compiler/qv4isel_moth_p.h
@@ -106,6 +106,7 @@ protected:
     virtual void callBuiltinDefineArray(V4IR::Temp *result, V4IR::ExprList *args);
     virtual void callBuiltinDefineObjectLiteral(V4IR::Temp *result, V4IR::ExprList *args);
     virtual void callBuiltinSetupArgumentObject(V4IR::Temp *result);
+    virtual void callBuiltinConvertThisToObject();
     virtual void callValue(V4IR::Temp *value, V4IR::ExprList *args, V4IR::Temp *result);
     virtual void callProperty(V4IR::Expr *base, const QString &name, V4IR::ExprList *args, V4IR::Temp *result);
     virtual void callSubscript(V4IR::Expr *base, V4IR::Expr *index, V4IR::ExprList *args, V4IR::Temp *result);
diff --git a/src/qml/compiler/qv4isel_p.cpp b/src/qml/compiler/qv4isel_p.cpp
index 0afd25315e..3f9e666c98 100644
--- a/src/qml/compiler/qv4isel_p.cpp
+++ b/src/qml/compiler/qv4isel_p.cpp
@@ -383,6 +383,10 @@ void IRDecoder::callBuiltin(V4IR::Call *call, V4IR::Temp *result)
         callBuiltinSetupArgumentObject(result);
         return;
 
+    case V4IR::Name::builtin_convert_this_to_object:
+        callBuiltinConvertThisToObject();
+        return;
+
     default:
         break;
     }
diff --git a/src/qml/compiler/qv4isel_p.h b/src/qml/compiler/qv4isel_p.h
index fafe741fd5..5fba560d27 100644
--- a/src/qml/compiler/qv4isel_p.h
+++ b/src/qml/compiler/qv4isel_p.h
@@ -132,6 +132,7 @@ public: // to implement by subclasses:
     virtual void callBuiltinDefineArray(V4IR::Temp *result, V4IR::ExprList *args) = 0;
     virtual void callBuiltinDefineObjectLiteral(V4IR::Temp *result, V4IR::ExprList *args) = 0;
     virtual void callBuiltinSetupArgumentObject(V4IR::Temp *result) = 0;
+    virtual void callBuiltinConvertThisToObject() = 0;
     virtual void callValue(V4IR::Temp *value, V4IR::ExprList *args, V4IR::Temp *result) = 0;
     virtual void callProperty(V4IR::Expr *base, const QString &name, V4IR::ExprList *args, V4IR::Temp *result) = 0;
     virtual void callSubscript(V4IR::Expr *base, V4IR::Expr *index, V4IR::ExprList *args, V4IR::Temp *result) = 0;
diff --git a/src/qml/compiler/qv4jsir.cpp b/src/qml/compiler/qv4jsir.cpp
index b4630793ef..f8189b673d 100644
--- a/src/qml/compiler/qv4jsir.cpp
+++ b/src/qml/compiler/qv4jsir.cpp
@@ -422,6 +422,8 @@ static const char *builtin_to_string(Name::Builtin b)
         return "builtin_define_object_literal";
     case V4IR::Name::builtin_setup_argument_object:
         return "builtin_setup_argument_object";
+    case V4IR::Name::builtin_convert_this_to_object:
+        return "builtin_convert_this_to_object";
     case V4IR::Name::builtin_qml_id_scope:
         return "builtin_qml_id_scope";
     case V4IR::Name::builtin_qml_imported_scripts_object:
diff --git a/src/qml/compiler/qv4jsir_p.h b/src/qml/compiler/qv4jsir_p.h
index 933ba1321d..a7bed6419b 100644
--- a/src/qml/compiler/qv4jsir_p.h
+++ b/src/qml/compiler/qv4jsir_p.h
@@ -324,6 +324,7 @@ struct Name: Expr {
         builtin_define_getter_setter,
         builtin_define_object_literal,
         builtin_setup_argument_object,
+        builtin_convert_this_to_object,
         builtin_qml_id_scope,
         builtin_qml_imported_scripts_object,
         builtin_qml_context_object,
@@ -733,12 +734,13 @@ struct Function {
 
     uint hasDirectEval: 1;
     uint usesArgumentsObject : 1;
+    uint usesThis : 1;
     uint isStrict: 1;
     uint isNamedExpression : 1;
     uint hasTry: 1;
     uint hasWith: 1;
     uint hasQmlDependencies : 1;
-    uint unused : 25;
+    uint unused : 24;
 
     // Location of declaration in source code (-1 if not specified)
     int line;
diff --git a/src/qml/compiler/qv4regalloc.cpp b/src/qml/compiler/qv4regalloc.cpp
index 9a1897d494..f746902814 100644
--- a/src/qml/compiler/qv4regalloc.cpp
+++ b/src/qml/compiler/qv4regalloc.cpp
@@ -207,6 +207,7 @@ protected: // IRDecoder
     virtual void callBuiltinDefineArray(V4IR::Temp *, V4IR::ExprList *) {}
     virtual void callBuiltinDefineObjectLiteral(V4IR::Temp *, V4IR::ExprList *) {}
     virtual void callBuiltinSetupArgumentObject(V4IR::Temp *) {}
+    virtual void callBuiltinConvertThisToObject() {}
 
     virtual void callValue(V4IR::Temp *value, V4IR::ExprList *args, V4IR::Temp *result)
     {
diff --git a/src/qml/jsruntime/qv4engine_p.h b/src/qml/jsruntime/qv4engine_p.h
index c585714dd0..3413238f3d 100644
--- a/src/qml/jsruntime/qv4engine_p.h
+++ b/src/qml/jsruntime/qv4engine_p.h
@@ -369,8 +369,7 @@ struct ExecutionContextSaver
     }
     ~ExecutionContextSaver()
     {
-        while (engine->current != savedContext)
-            engine->popContext();
+        engine->current = savedContext;
     }
 };
 
diff --git a/src/qml/jsruntime/qv4functionobject.cpp b/src/qml/jsruntime/qv4functionobject.cpp
index a270689b43..35e4202790 100644
--- a/src/qml/jsruntime/qv4functionobject.cpp
+++ b/src/qml/jsruntime/qv4functionobject.cpp
@@ -471,14 +471,6 @@ ReturnedValue ScriptFunction::call(Managed *that, CallData *callData)
 
     CallContext *ctx = context->newCallContext(f, callData);
 
-    if (!f->strictMode && !callData->thisObject.isObject()) {
-        if (callData->thisObject.isNullOrUndefined()) {
-            ctx->callData->thisObject = v4->globalObject->asReturnedValue();
-        } else {
-            ctx->callData->thisObject = callData->thisObject.toObject(context)->asReturnedValue();
-        }
-    }
-
     if (f->function->compiledFunction->hasQmlDependencies())
         QmlContextWrapper::registerQmlDependencies(ctx->engine, f->function->compiledFunction);
 
@@ -568,14 +560,6 @@ ReturnedValue SimpleScriptFunction::call(Managed *that, CallData *callData)
     ExecutionContext *context = v4->current;
     ExecutionContext *ctx = context->newCallContext(stackSpace, scope.alloc(f->varCount), f.getPointer(), callData);
 
-    if (!f->strictMode && !callData->thisObject.isObject()) {
-        if (callData->thisObject.isNullOrUndefined()) {
-            ctx->callData->thisObject = v4->globalObject->asReturnedValue();
-        } else {
-            ctx->callData->thisObject = callData->thisObject.toObject(context)->asReturnedValue();
-        }
-    }
-
     if (f->function->compiledFunction->hasQmlDependencies())
         QmlContextWrapper::registerQmlDependencies(v4, f->function->compiledFunction);
 
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index d8ebe635bd..22af24e527 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -1277,6 +1277,18 @@ ReturnedValue __qmljs_get_imported_scripts(NoThrowContext *ctx)
     return context->importedScripts.value();
 }
 
+void __qmljs_builtin_convert_this_to_object(ExecutionContext *ctx)
+{
+    SafeValue *t = &ctx->callData->thisObject;
+    if (t->isObject())
+        return;
+    if (t->isNullOrUndefined()) {
+        *t = ctx->engine->globalObject->asReturnedValue();
+    } else {
+        *t = t->toObject(ctx)->asReturnedValue();
+    }
+}
+
 } // namespace QV4
 
 QT_END_NAMESPACE
diff --git a/src/qml/jsruntime/qv4runtime_p.h b/src/qml/jsruntime/qv4runtime_p.h
index 4f6f3a33d4..b2d2d211eb 100644
--- a/src/qml/jsruntime/qv4runtime_p.h
+++ b/src/qml/jsruntime/qv4runtime_p.h
@@ -144,6 +144,7 @@ QV4::ReturnedValue __qmljs_builtin_define_array(QV4::ExecutionContext *ctx, QV4:
 void __qmljs_builtin_define_getter_setter(QV4::ExecutionContext *ctx, const QV4::ValueRef object, const QV4::StringRef name, const QV4::ValueRef getter, const QV4::ValueRef setter);
 QV4::ReturnedValue __qmljs_builtin_define_object_literal(QV4::ExecutionContext *ctx, const QV4::Value *args, int classId);
 QV4::ReturnedValue __qmljs_builtin_setup_arguments_object(ExecutionContext *ctx);
+void __qmljs_builtin_convert_this_to_object(ExecutionContext *ctx);
 
 QV4::ReturnedValue __qmljs_value_from_string(QV4::String *string);
 QV4::ReturnedValue __qmljs_lookup_runtime_regexp(QV4::ExecutionContext *ctx, int id);
diff --git a/src/qml/jsruntime/qv4vme_moth.cpp b/src/qml/jsruntime/qv4vme_moth.cpp
index 82d9599582..74a42b6f2f 100644
--- a/src/qml/jsruntime/qv4vme_moth.cpp
+++ b/src/qml/jsruntime/qv4vme_moth.cpp
@@ -478,6 +478,11 @@ QV4::ReturnedValue VME::run(QV4::ExecutionContext *context, const uchar *code,
         STOREVALUE(instr.result, __qmljs_builtin_setup_arguments_object(context));
     MOTH_END_INSTR(CallBuiltinSetupArgumentsObject)
 
+    MOTH_BEGIN_INSTR(CallBuiltinConvertThisToObject)
+        __qmljs_builtin_convert_this_to_object(context);
+        CHECK_EXCEPTION;
+    MOTH_END_INSTR(CallBuiltinConvertThisToObject)
+
     MOTH_BEGIN_INSTR(CreateValue)
         Q_ASSERT(instr.callData + instr.argc + qOffsetOf(QV4::CallData, args)/sizeof(QV4::SafeValue) <= stackSize);
         QV4::CallData *callData = reinterpret_cast<QV4::CallData *>(stack + instr.callData);