Switch over to new JS call setup

Differences:
- push parameters on the stack, including space for CallData members
- call instructions calculate the argument start
- use temp space above the calldata to evaluate arguments
- fewer temporaries are needed when a call is done while generating the
  arguments of another call
- when calling the function, the js stack space above the callData is
  not used, allowing for optimizations in the future
- Array and ObjectLiteral use the same mechanism

Change-Id: Id100fa06f12cc9d941b0f90b0b81b8270a8e4f5d
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

8 files changed, 88 insertions, 113 deletions

diff --git a/src/qml/compiler/qv4bytecodegenerator.cpp b/src/qml/compiler/qv4bytecodegenerator.cpp
index 8f9b062af6..3a023c9989 100644
--- a/src/qml/compiler/qv4bytecodegenerator.cpp
+++ b/src/qml/compiler/qv4bytecodegenerator.cpp
@@ -63,6 +63,15 @@ unsigned BytecodeGenerator::newTemp()
     return t;
 }
 
+unsigned BytecodeGenerator::newTempArray(int n)
+{
+    int t = function->currentTemp;
+    function->currentTemp += n;
+    if (function->tempCount < function->currentTemp)
+        function->tempCount = function->currentTemp;
+    return t;
+}
+
 QByteArray BytecodeGenerator::finalize()
 {
     QByteArray code;
diff --git a/src/qml/compiler/qv4bytecodegenerator_p.h b/src/qml/compiler/qv4bytecodegenerator_p.h
index a9e2bce159..c7a27727e8 100644
--- a/src/qml/compiler/qv4bytecodegenerator_p.h
+++ b/src/qml/compiler/qv4bytecodegenerator_p.h
@@ -193,7 +193,7 @@ public:
     }
 
     unsigned newTemp();
-
+    unsigned newTempArray(int n);
 
     QByteArray finalize();
 
diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 7f4a72c2fc..5ade244bd9 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -1328,43 +1328,44 @@ bool Codegen::visit(ArrayLiteral *ast)
     TempScope scope(this);
 
     int argc = 0;
-    Reference _args[16];
-    Reference *args = _args;
-    if (_variableEnvironment->maxNumberOfArguments > 16)
-        args = new Reference[_variableEnvironment->maxNumberOfArguments];
-    auto empty = [this](){ return Reference::fromConst(this, Primitive::emptyValue().asReturnedValue()); };
-    auto push = [this, &argc, args](const Reference &arg) {
-        args[argc] = arg;
-        if (arg.type != Reference::Const)
-            args[argc].asRValue();
-        argc += 1;
+    int args = -1;
+    auto push = [this, &argc, &args](AST::ExpressionNode *arg) {
+        int temp = bytecodeGenerator->newTemp();
+        if (args == -1)
+            args = temp;
+        if (!arg) {
+            Reference::fromTemp(this, temp).store(Reference::fromConst(this, Primitive::emptyValue().asReturnedValue()));
+        } else {
+            TempScope scope(this);
+            Reference::fromTemp(this, temp).store(expression(arg));
+        }
+        ++argc;
     };
 
     for (ElementList *it = ast->elements; it; it = it->next) {
+
         for (Elision *elision = it->elision; elision; elision = elision->next)
-            push(empty());
+            push(0);
 
-        Reference expr = expression(it->expression);
+        push(it->expression);
         if (hasError)
             return false;
-
-        push(expr);
     }
     for (Elision *elision = ast->elision; elision; elision = elision->next)
-        push(empty());
+        push(0);
 
-    for (int i = 0; i < argc; ++i)
-        Reference::fromTemp(this, i).store(args[i]);
+    if (args == -1) {
+        Q_ASSERT(argc == 0);
+        args = 0;
+    }
 
     Instruction::CallBuiltinDefineArray call;
     call.argc = argc;
-    call.args = 0;
+    call.args = args;
     call.result = result.asLValue();
     bytecodeGenerator->addInstruction(call);
     _expr.result = result;
 
-    if (args != _args)
-        delete [] args;
     return false;
 }
 
@@ -1731,7 +1732,7 @@ bool Codegen::visit(CallExpression *ast)
     if (hasError)
         return false;
 
-    auto argc = pushArgs(ast->arguments);
+    auto calldata = pushArgs(ast->arguments);
     if (hasError)
         return false;
 
@@ -1739,39 +1740,34 @@ bool Codegen::visit(CallExpression *ast)
         Instruction::CallProperty call;
         call.base = base.base;
         call.name = base.nameIndex;
-        call.argc = argc;
-        call.callData = 0;
+        call.callData = calldata;
         call.result = r.asLValue();
         bytecodeGenerator->addInstruction(call);
     } else if (base.type == Reference::Subscript) {
         Instruction::CallElement call;
         call.base = base.base;
         call.index = base.subscript;
-        call.argc = argc;
-        call.callData = 0;
+        call.callData = calldata;
         call.result = r.asLValue();
         bytecodeGenerator->addInstruction(call);
     } else if (base.type == Reference::Name) {
         if (useFastLookups && base.global) {
             Instruction::CallGlobalLookup call;
             call.index = registerGlobalGetterLookup(base.nameIndex);
-            call.argc = argc;
-            call.callData = 0;
+            call.callData = calldata;
             call.result = r.asLValue();
             bytecodeGenerator->addInstruction(call);
         } else {
             Instruction::CallActivationProperty call;
             call.name = base.nameIndex;
-            call.argc = argc;
-            call.callData = 0;
+            call.callData = calldata;
             call.result = r.asLValue();
             bytecodeGenerator->addInstruction(call);
         }
     } else {
         Instruction::CallValue call;
         call.dest = base.asRValue();
-        call.argc = argc;
-        call.callData = 0;
+        call.callData = calldata;
         call.result = r.asLValue();
         bytecodeGenerator->addInstruction(call);
     }
@@ -1781,26 +1777,22 @@ bool Codegen::visit(CallExpression *ast)
 
 int Codegen::pushArgs(ArgumentList *args)
 {
-    int minNrOfStackEntries = offsetof(QV4::CallData, args)/sizeof(QV4::Value);
     int argc = 0;
-    Reference _rargs[16];
-    Reference *rargs = _rargs;
-    if (_variableEnvironment->maxNumberOfArguments > 16)
-        rargs = new Reference[_variableEnvironment->maxNumberOfArguments];
+    for (ArgumentList *it = args; it; it = it->next)
+        ++argc;
+    int calldata = bytecodeGenerator->newTempArray(argc + 2); // 2 additional values for CallData
+
+    Reference::fromTemp(this, calldata).store(Reference::fromConst(this, QV4::Encode(argc)));
+    Reference::fromTemp(this, calldata + 1).store(Reference::fromConst(this, QV4::Encode::undefined()));
+
+    argc = 0;
     for (ArgumentList *it = args; it; it = it->next) {
-        rargs[argc] = expression(it->expression);
-        rargs[argc].asRValue();
-        if (hasError)
-            return -1;
-        argc += 1;
+        TempScope scope(this);
+        Reference::fromTemp(this, calldata + 2 + argc).store(expression(it->expression));
+        ++argc;
     }
 
-    for (int i = 0; i < argc; ++i)
-        Reference::fromTemp(this, minNrOfStackEntries + i).store(rargs[i]);
-
-    if (rargs != _rargs)
-        delete [] rargs;
-    return argc;
+    return calldata;
 }
 
 bool Codegen::visit(ConditionalExpression *ast)
@@ -2012,7 +2004,6 @@ bool Codegen::visit(NewExpression *ast)
 
     Instruction::CreateValue create;
     create.func = base.asRValue();
-    create.argc = 0;
     create.callData = 0;
     create.result = r.asLValue();
     bytecodeGenerator->addInstruction(create);
@@ -2032,14 +2023,13 @@ bool Codegen::visit(NewMemberExpression *ast)
     if (hasError)
         return false;
 
-    auto argc = pushArgs(ast->arguments);
+    auto calldata = pushArgs(ast->arguments);
     if (hasError)
         return false;
 
     Instruction::CreateValue create;
     create.func = base.asRValue();
-    create.argc = argc;
-    create.callData = 0;
+    create.callData = calldata;
     create.result = r.asRValue();
     bytecodeGenerator->addInstruction(create);
     _expr.result = r;
@@ -2143,10 +2133,12 @@ bool Codegen::visit(ObjectLiteral *ast)
         }
     }
 
-    int argc = 0;
-    auto push = [this, &argc](const Reference &arg) {
-        Reference::fromTemp(this, argc).store(arg);
-        argc += 1;
+    int args = -1;
+    auto push = [this, &args](const Reference &arg) {
+        int temp = bytecodeGenerator->newTemp();
+        if (args == -1)
+            args = temp;
+        Reference::fromTemp(this, temp).store(arg);
     };
 
     auto undefined = [this](){ return Reference::fromConst(this, Encode::undefined()); };
@@ -2190,11 +2182,14 @@ bool Codegen::visit(ObjectLiteral *ast)
     uint arrayGetterSetterCountAndFlags = arrayKeyWithGetterSetter.size();
     arrayGetterSetterCountAndFlags |= needSparseArray << 30;
 
+    if (args == -1)
+        args = 0;
+
     Instruction::CallBuiltinDefineObjectLiteral call;
     call.internalClassId = classId;
     call.arrayValueCount = arrayKeyWithValue.size();
     call.arrayGetterSetterCountAndFlags = arrayGetterSetterCountAndFlags;
-    call.args = 0;
+    call.args = args;
     call.result = result.asLValue();
     bytecodeGenerator->addInstruction(call);
 
@@ -2440,13 +2435,6 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
     savedBytecodeGenerator = bytecodeGenerator;
     bytecodeGenerator = &bytecode;
 
-    { // reserve space for outgoing call arguments
-        Q_ASSERT(function->tempCount == 0);
-        int minNrOfStackEntries = offsetof(QV4::CallData, args)/sizeof(QV4::Value);
-        function->tempCount = minNrOfStackEntries + _variableEnvironment->maxNumberOfArguments;
-        function->currentTemp = function->tempCount;
-    }
-
     unsigned returnAddress = bytecodeGenerator->newTemp();
     if (function->usesArgumentsObject)
         _variableEnvironment->enter(QStringLiteral("arguments"), Environment::VariableDeclaration, AST::VariableDeclaration::FunctionScope);
@@ -3405,6 +3393,13 @@ void Codegen::Reference::store(const Reference &r) const
         codegen->bytecodeGenerator->addInstruction(move);
         return;
     }
+    if (r.type == Closure) {
+        Instruction::LoadClosure load;
+        load.value = r.closureId;
+        load.result = b;
+        codegen->bytecodeGenerator->addInstruction(load);
+        return;
+    }
     Moth::Param x = r.asRValue();
     Q_ASSERT(b != x);
     Instruction::Move move;
diff --git a/src/qml/compiler/qv4instr_moth.cpp b/src/qml/compiler/qv4instr_moth.cpp
index 4b0865a7ca..72a0ccc2ac 100644
--- a/src/qml/compiler/qv4instr_moth.cpp
+++ b/src/qml/compiler/qv4instr_moth.cpp
@@ -242,8 +242,7 @@ void dumpBytecode(const char *code, int len)
         MOTH_END_INSTR(CallValue)
 
         MOTH_BEGIN_INSTR(CallProperty)
-            d << instr.result << ", " << instr.base<<"."<<instr.name << "(" << instr.callData
-              << ", " << instr.argc << ")";
+            d << instr.result << ", " << instr.base<<"."<<instr.name << "(" << instr.callData << ")";
         MOTH_END_INSTR(CallProperty)
 
         MOTH_BEGIN_INSTR(CallPropertyLookup)
@@ -263,7 +262,7 @@ void dumpBytecode(const char *code, int len)
         MOTH_END_INSTR(CallElement)
 
         MOTH_BEGIN_INSTR(CallActivationProperty)
-            d << instr.result << ", " << instr.name << "(" << instr.callData << ", " << instr.argc << ")";
+            d << instr.result << ", " << instr.name << "(" << instr.callData << ")";
         MOTH_END_INSTR(CallActivationProperty)
 
         MOTH_BEGIN_INSTR(CallGlobalLookup)
@@ -368,7 +367,7 @@ void dumpBytecode(const char *code, int len)
         MOTH_END_INSTR(CallBuiltinConvertThisToObject)
 
         MOTH_BEGIN_INSTR(CreateValue)
-            d << instr.result << ", new" << instr.func << "(" << instr.callData << instr.argc << ")";
+            d << instr.result << ", new" << instr.func << "(" << instr.callData << ")";
         MOTH_END_INSTR(CreateValue)
 
         MOTH_BEGIN_INSTR(CreateProperty)
@@ -535,8 +534,10 @@ void dumpBytecode(const char *code, int len)
         MOTH_BEGIN_INSTR(LoadQmlSingleton)
                 d << instr.result << instr.name;
         MOTH_END_INSTR(LoadQmlSingleton)
-        }
 
+        default:
+            Q_UNREACHABLE();
+        }
     }
 }
 
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index fe6fee5e2d..0daca9bb9d 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -430,7 +430,6 @@ union Instr
     };
     struct instr_callValue {
         MOTH_INSTR_HEADER
-        quint32 argc;
         quint32 callData;
         Param dest;
         Param result;
@@ -438,7 +437,6 @@ union Instr
     struct instr_callProperty {
         MOTH_INSTR_HEADER
         int name;
-        quint32 argc;
         quint32 callData;
         Param base;
         Param result;
@@ -471,21 +469,18 @@ union Instr
         MOTH_INSTR_HEADER
         Param base;
         Param index;
-        quint32 argc;
         quint32 callData;
         Param result;
     };
     struct instr_callActivationProperty {
         MOTH_INSTR_HEADER
         int name;
-        quint32 argc;
         quint32 callData;
         Param result;
     };
     struct instr_callGlobalLookup {
         MOTH_INSTR_HEADER
         int index;
-        quint32 argc;
         quint32 callData;
         Param result;
     };
@@ -609,7 +604,6 @@ union Instr
     };
     struct instr_createValue {
         MOTH_INSTR_HEADER
-        quint32 argc;
         quint32 callData;
         Param func;
         Param result;
diff --git a/src/qml/compiler/qv4isel_moth.cpp b/src/qml/compiler/qv4isel_moth.cpp
index 89140a1a5e..8f11253cca 100644
--- a/src/qml/compiler/qv4isel_moth.cpp
+++ b/src/qml/compiler/qv4isel_moth.cpp
@@ -314,7 +314,7 @@ void InstructionSelection::callValue(IR::Expr *value, IR::ExprList *args, IR::Ex
 {
     Instruction::CallValue call;
     prepareCallArgs(args, call.argc);
-    call.callData = callDataStart();
+//    call.callData = callDataStart();
     call.dest = getParam(value);
     call.result = getResultParam(result);
     addInstruction(call);
@@ -360,7 +360,7 @@ void InstructionSelection::callProperty(IR::Expr *base, const QString &name, IR:
         call.base = getParam(base);
         call.name = registerString(name);
         prepareCallArgs(args, call.argc);
-        call.callData = callDataStart();
+//        call.callData = callDataStart();
         call.result = getResultParam(result);
         addInstruction(call);
     }
@@ -374,7 +374,7 @@ void InstructionSelection::callSubscript(IR::Expr *base, IR::Expr *index, IR::Ex
     call.base = getParam(base);
     call.index = getParam(index);
     prepareCallArgs(args, call.argc);
-    call.callData = callDataStart();
+//    call.callData = callDataStart();
     call.result = getResultParam(result);
     addInstruction(call);
 }
@@ -434,7 +434,7 @@ void InstructionSelection::constructValue(IR::Expr *value, IR::ExprList *args, I
 {
     Instruction::CreateValue create;
     create.func = getParam(value);
-    prepareCallArgs(args, create.argc);
+//    prepareCallArgs(args, create.argc);
     create.callData = callDataStart();
     create.result = getResultParam(target);
     addInstruction(create);
@@ -1028,7 +1028,7 @@ void InstructionSelection::callBuiltinInvalid(IR::Name *func, IR::ExprList *args
         Instruction::CallGlobalLookup call;
         call.index = registerGlobalGetterLookup(*func->id);
         prepareCallArgs(args, call.argc);
-        call.callData = callDataStart();
+//        call.callData = callDataStart();
         call.result = getResultParam(result);
         addInstruction(call);
         return;
@@ -1036,7 +1036,7 @@ void InstructionSelection::callBuiltinInvalid(IR::Name *func, IR::ExprList *args
     Instruction::CallActivationProperty call;
     call.name = registerString(*func->id);
     prepareCallArgs(args, call.argc);
-    call.callData = callDataStart();
+//    call.callData = callDataStart();
     call.result = getResultParam(result);
     addInstruction(call);
 }
diff --git a/src/qml/jsruntime/qv4context_p.h b/src/qml/jsruntime/qv4context_p.h
index a854c324d0..5cf134bc70 100644
--- a/src/qml/jsruntime/qv4context_p.h
+++ b/src/qml/jsruntime/qv4context_p.h
@@ -92,6 +92,8 @@ struct CallData
 
     Value thisObject;
     Value args[1];
+
+    static constexpr int HeaderSize() { return offsetof(CallData, args)/sizeof(QV4::Value); }
 };
 
 Q_STATIC_ASSERT(std::is_standard_layout<CallData>::value);
diff --git a/src/qml/jsruntime/qv4vme_moth.cpp b/src/qml/jsruntime/qv4vme_moth.cpp
index 23a76a15bf..14aef11e7f 100644
--- a/src/qml/jsruntime/qv4vme_moth.cpp
+++ b/src/qml/jsruntime/qv4vme_moth.cpp
@@ -563,32 +563,17 @@ QV4::ReturnedValue VME::run(ExecutionEngine *engine, const uchar *code)
     MOTH_END_INSTR(InitStackFrame)
 
     MOTH_BEGIN_INSTR(CallValue)
-#if 0 //def DO_TRACE_INSTR
-        if (Debugging::Debugger *debugger = context->engine()->debugger) {
-            if (QV4::FunctionObject *o = (VALUE(instr.dest)).asFunctionObject()) {
-                if (Debugging::FunctionDebugInfo *info = debugger->debugInfo(o)) {
-                    QString n = debugger->name(o);
-                    std::cerr << "*** Call to \"" << (n.isNull() ? "<no name>" : qPrintable(n)) << "\" defined @" << info->startLine << ":" << info->startColumn << std::endl;
-                }
-            }
-        }
-#endif // DO_TRACE_INSTR
-        Q_ASSERT(instr.callData + instr.argc + offsetof(QV4::CallData, args)/sizeof(QV4::Value) <= stackSize);
         QV4::CallData *callData = reinterpret_cast<QV4::CallData *>(stack + instr.callData);
-        callData->tag = quint32(Value::ValueTypeInternal::Integer);
-        callData->argc = instr.argc;
-        callData->thisObject = QV4::Primitive::undefinedValue();
         STOREVALUE(instr.result, Runtime::method_callValue(engine, VALUE(instr.dest), callData));
+        //### write barrier?
     MOTH_END_INSTR(CallValue)
 
     MOTH_BEGIN_INSTR(CallProperty)
         TRACE(property name, "%s, args=%u, argc=%u, this=%s", qPrintable(runtimeStrings[instr.name]->toQString()), instr.callData, instr.argc, (VALUE(instr.base)).toString(engine)->toQString().toUtf8().constData());
-        Q_ASSERT(instr.callData + instr.argc + offsetof(QV4::CallData, args)/sizeof(QV4::Value) <= stackSize);
         QV4::CallData *callData = reinterpret_cast<QV4::CallData *>(stack + instr.callData);
-        callData->tag = quint32(Value::ValueTypeInternal::Integer);
-        callData->argc = instr.argc;
         callData->thisObject = VALUE(instr.base);
         STOREVALUE(instr.result, Runtime::method_callProperty(engine, instr.name, callData));
+        //### write barrier?
     MOTH_END_INSTR(CallProperty)
 
     MOTH_BEGIN_INSTR(CallPropertyLookup)
@@ -621,30 +606,22 @@ QV4::ReturnedValue VME::run(ExecutionEngine *engine, const uchar *code)
     MOTH_END_INSTR(CallContextObjectProperty)
 
     MOTH_BEGIN_INSTR(CallElement)
-        Q_ASSERT(instr.callData + instr.argc + offsetof(QV4::CallData, args)/sizeof(QV4::Value) <= stackSize);
         QV4::CallData *callData = reinterpret_cast<QV4::CallData *>(stack + instr.callData);
-        callData->tag = quint32(Value::ValueTypeInternal::Integer);
-        callData->argc = instr.argc;
         callData->thisObject = VALUE(instr.base);
         STOREVALUE(instr.result, Runtime::method_callElement(engine, VALUE(instr.index), callData));
+        //### write barrier?
     MOTH_END_INSTR(CallElement)
 
     MOTH_BEGIN_INSTR(CallActivationProperty)
-        Q_ASSERT(instr.callData + instr.argc + offsetof(QV4::CallData, args)/sizeof(QV4::Value) <= stackSize);
         QV4::CallData *callData = reinterpret_cast<QV4::CallData *>(stack + instr.callData);
-        callData->tag = quint32(Value::ValueTypeInternal::Integer);
-        callData->argc = instr.argc;
-        callData->thisObject = QV4::Primitive::undefinedValue();
         STOREVALUE(instr.result, Runtime::method_callActivationProperty(engine, instr.name, callData));
+        //### write barrier?
     MOTH_END_INSTR(CallActivationProperty)
 
     MOTH_BEGIN_INSTR(CallGlobalLookup)
-        Q_ASSERT(instr.callData + instr.argc + offsetof(QV4::CallData, args)/sizeof(QV4::Value) <= stackSize);
         QV4::CallData *callData = reinterpret_cast<QV4::CallData *>(stack + instr.callData);
-        callData->tag = quint32(Value::ValueTypeInternal::Integer);
-        callData->argc = instr.argc;
-        callData->thisObject = QV4::Primitive::undefinedValue();
         STOREVALUE(instr.result, Runtime::method_callGlobalLookup(engine, instr.index, callData));
+        //### write barrier?
     MOTH_END_INSTR(CallGlobalLookup)
 
     MOTH_BEGIN_INSTR(SetExceptionHandler)
@@ -752,12 +729,9 @@ QV4::ReturnedValue VME::run(ExecutionEngine *engine, const uchar *code)
     MOTH_END_INSTR(CallBuiltinConvertThisToObject)
 
     MOTH_BEGIN_INSTR(CreateValue)
-        Q_ASSERT(instr.callData + instr.argc + offsetof(QV4::CallData, args)/sizeof(QV4::Value) <= stackSize);
         QV4::CallData *callData = reinterpret_cast<QV4::CallData *>(stack + instr.callData);
-        callData->tag = quint32(Value::ValueTypeInternal::Integer);
-        callData->argc = instr.argc;
-        callData->thisObject = QV4::Primitive::undefinedValue();
         STOREVALUE(instr.result, Runtime::method_constructValue(engine, VALUE(instr.func), callData));
+        //### write barrier?
     MOTH_END_INSTR(CreateValue)
 
     MOTH_BEGIN_INSTR(CreateProperty)