20 files changed, 159 insertions, 129 deletions

diff --git a/src/qml/compiler/qv4bytecodegenerator_p.h b/src/qml/compiler/qv4bytecodegenerator_p.h
index 35e539fb5e..fa14754f85 100644
--- a/src/qml/compiler/qv4bytecodegenerator_p.h
+++ b/src/qml/compiler/qv4bytecodegenerator_p.h
@@ -58,7 +58,7 @@ public:
                 link();
         }
 
-        void link() {
+        void link() const {
             Q_ASSERT(index >= 0);
             Q_ASSERT(generator->labels[index] == -1);
             generator->labels[index] = generator->instructions.size();
diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index aba071580b..1fca7bd75a 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -713,9 +713,8 @@ void Codegen::destructureElementList(const Codegen::Reference &array, PatternEle
     RegisterScope scope(this);
 
     Reference iterator = Reference::fromStackSlot(this);
-    Reference iteratorValue = Reference::fromStackSlot(this);
-    Reference iteratorDone = Reference::fromStackSlot(this);
-    Reference::storeConstOnStack(this, Encode(false), iteratorDone.stackSlot());
+    QVarLengthArray<Reference> iteratorValues;
+    Reference ignored;
 
     array.loadInAccumulator();
     Instruction::GetIterator iteratorObjInstr;
@@ -723,45 +722,76 @@ void Codegen::destructureElementList(const Codegen::Reference &array, PatternEle
     bytecodeGenerator->addInstruction(iteratorObjInstr);
     iterator.storeConsumeAccumulator();
 
+    BytecodeGenerator::Label done = bytecodeGenerator->newLabel();
+    Reference needsClose = Reference::storeConstOnStack(this, Encode(false));
+
+    for (PatternElementList *p = bindingList; p; p = p->next) {
+        PatternElement *e = p->element;
+        for (Elision *elision = p->elision; elision; elision = elision->next) {
+            iterator.loadInAccumulator();
+            Instruction::IteratorNext next;
+            if (!ignored.isValid())
+                ignored = Reference::fromStackSlot(this);
+            next.value = ignored.stackSlot();
+            bytecodeGenerator->addJumpInstruction(next).link(done);
+        }
+
+        if (!e)
+            continue;
+
+        if (e->type != PatternElement::RestElement) {
+            iterator.loadInAccumulator();
+            Instruction::IteratorNext next;
+            iteratorValues.push_back(Reference::fromStackSlot(this));
+            next.value = iteratorValues.back().stackSlot();
+            bytecodeGenerator->addJumpInstruction(next).link(done);
+        }
+    }
+
+    // If we've iterated through all the patterns without exhausing the iterator, it needs
+    // to be closed. But we don't close it here because:
+    // a, closing might throw an exception and we want to assign the values before we handle that
+    // b, there might be a rest element that could still continue iterating
+    Reference::fromConst(this, Encode(true)).storeOnStack(needsClose.stackSlot());
+
+    done.link();
+    bytecodeGenerator->checkException();
+
     {
-        auto cleanup = [this, iterator, iteratorDone]() {
+        ControlFlowUnwindCleanup flow(this, [&]() {
+            BytecodeGenerator::Label skipClose = bytecodeGenerator->newLabel();
+            needsClose.loadInAccumulator();
+            bytecodeGenerator->jumpFalse().link(skipClose);
             iterator.loadInAccumulator();
             Instruction::IteratorClose close;
-            close.done = iteratorDone.stackSlot();
             bytecodeGenerator->addInstruction(close);
-        };
-
-        ControlFlowUnwindCleanup flow(this, cleanup);
+            skipClose.link();
+        });
 
+        auto it = iteratorValues.constBegin();
         for (PatternElementList *p = bindingList; p; p = p->next) {
             PatternElement *e = p->element;
-            for (Elision *elision = p->elision; elision; elision = elision->next) {
-                iterator.loadInAccumulator();
-                Instruction::IteratorNext next;
-                next.value = iteratorValue.stackSlot();
-                next.done = iteratorDone.stackSlot();
-                bytecodeGenerator->addInstruction(next);
-            }
 
             if (!e)
                 continue;
 
-            RegisterScope scope(this);
-            iterator.loadInAccumulator();
-
             if (e->type == PatternElement::RestElement) {
-                Reference::fromConst(this, Encode(true)).storeOnStack(iteratorDone.stackSlot());
+                Q_ASSERT(it == iteratorValues.constEnd());
+
+                // The rest element is guaranteed to exhaust the iterator
+                Reference::fromConst(this, Encode(false)).storeOnStack(needsClose.stackSlot());
+
+                iterator.loadInAccumulator();
                 bytecodeGenerator->addInstruction(Instruction::DestructureRestElement());
-                initializeAndDestructureBindingElement(e, Reference::fromAccumulator(this), isDefinition);
+                initializeAndDestructureBindingElement(
+                        e, Reference::fromAccumulator(this), isDefinition);
             } else {
-                Instruction::IteratorNext next;
-                next.value = iteratorValue.stackSlot();
-                next.done = iteratorDone.stackSlot();
-                bytecodeGenerator->addInstruction(next);
-                initializeAndDestructureBindingElement(e, iteratorValue, isDefinition);
-                if (hasError())
-                    return;
+                Q_ASSERT(it != iteratorValues.constEnd());
+                initializeAndDestructureBindingElement(e, *it++, isDefinition);
             }
+
+            if (hasError())
+                return;
         }
     }
 }
@@ -1167,7 +1197,6 @@ bool Codegen::visit(ArrayPattern *ast)
             RegisterScope scope(this);
 
             Reference iterator = Reference::fromStackSlot(this);
-            Reference iteratorDone = Reference::fromConst(this, Encode(false)).storeOnStack();
             Reference lhsValue = Reference::fromStackSlot(this);
 
             // There should be a temporal block, so that variables declared in lhs shadow outside vars.
@@ -1187,24 +1216,23 @@ bool Codegen::visit(ArrayPattern *ast)
 
             BytecodeGenerator::Label in = bytecodeGenerator->newLabel();
             BytecodeGenerator::Label end = bytecodeGenerator->newLabel();
+            BytecodeGenerator::Label done = bytecodeGenerator->newLabel();
 
             {
-                auto cleanup = [this, iterator, iteratorDone]() {
+                auto cleanup = [this, iterator, done]() {
                     iterator.loadInAccumulator();
                     Instruction::IteratorClose close;
-                    close.done = iteratorDone.stackSlot();
                     bytecodeGenerator->addInstruction(close);
+                    done.link();
                 };
-                ControlFlowLoop flow(this, &end, &in, cleanup);
+                ControlFlowLoop flow(this, &end, &in, std::move(cleanup));
 
                 in.link();
                 bytecodeGenerator->addLoopStart(in);
                 iterator.loadInAccumulator();
                 Instruction::IteratorNext next;
                 next.value = lhsValue.stackSlot();
-                next.done = iteratorDone.stackSlot();
-                bytecodeGenerator->addInstruction(next);
-                bytecodeGenerator->addJumpInstruction(Instruction::JumpTrue()).link(end);
+                bytecodeGenerator->addJumpInstruction(next).link(done);
 
                 lhsValue.loadInAccumulator();
                 pushAccumulator();
@@ -3220,15 +3248,15 @@ bool Codegen::visit(YieldExpression *ast)
         Instruction::IteratorNextForYieldStar next;
         next.object = lhsValue.stackSlot();
         next.iterator = iterator.stackSlot();
-        bytecodeGenerator->addInstruction(next);
-
-        BytecodeGenerator::Jump done = bytecodeGenerator->jumpTrue();
+        BytecodeGenerator::Jump done = bytecodeGenerator->addJumpInstruction(next);
         bytecodeGenerator->jumpNotUndefined().link(loop);
+
         lhsValue.loadInAccumulator();
         emitReturn(acc);
 
 
         done.link();
+        bytecodeGenerator->checkException();
 
         lhsValue.loadInAccumulator();
         setExprResult(acc);
@@ -3572,7 +3600,6 @@ bool Codegen::visit(ForEachStatement *ast)
     TailCallBlocker blockTailCalls(this);
 
     Reference iterator = Reference::fromStackSlot(this);
-    Reference iteratorDone = Reference::fromConst(this, Encode(false)).storeOnStack();
     Reference lhsValue = Reference::fromStackSlot(this);
 
     // There should be a temporal block, so that variables declared in lhs shadow outside vars.
@@ -3593,16 +3620,20 @@ bool Codegen::visit(ForEachStatement *ast)
 
     BytecodeGenerator::Label in = bytecodeGenerator->newLabel();
     BytecodeGenerator::Label end = bytecodeGenerator->newLabel();
+    BytecodeGenerator::Label done;
 
     {
         std::function<void()> cleanup;
         if (ast->type == ForEachType::Of) {
-            cleanup = [iterator, iteratorDone, this]() {
+            done = bytecodeGenerator->newLabel();
+            cleanup = [iterator, this, done]() {
                 iterator.loadInAccumulator();
                 Instruction::IteratorClose close;
-                close.done = iteratorDone.stackSlot();
                 bytecodeGenerator->addInstruction(close);
+                done.link();
             };
+        } else {
+            done = end;
         }
         ControlFlowLoop flow(this, &end, &in, std::move(cleanup));
         bytecodeGenerator->addLoopStart(in);
@@ -3610,9 +3641,7 @@ bool Codegen::visit(ForEachStatement *ast)
         iterator.loadInAccumulator();
         Instruction::IteratorNext next;
         next.value = lhsValue.stackSlot();
-        next.done = iteratorDone.stackSlot();
-        bytecodeGenerator->addInstruction(next);
-        bytecodeGenerator->addJumpInstruction(Instruction::JumpTrue()).link(end);
+        bytecodeGenerator->addJumpInstruction(next).link(done);
 
         // each iteration gets it's own context, as per spec
         {
diff --git a/src/qml/compiler/qv4compilercontrolflow_p.h b/src/qml/compiler/qv4compilercontrolflow_p.h
index 070a1390ce..b190b77410 100644
--- a/src/qml/compiler/qv4compilercontrolflow_p.h
+++ b/src/qml/compiler/qv4compilercontrolflow_p.h
@@ -167,8 +167,8 @@ struct ControlFlowUnwindCleanup : public ControlFlowUnwind
     ~ControlFlowUnwindCleanup() {
         if (cleanup) {
             unwindLabel.link();
-            generator()->setUnwindHandler(parentUnwindHandler());
             cleanup();
+            generator()->setUnwindHandler(parentUnwindHandler());
             emitUnwindHandler();
         }
     }
diff --git a/src/qml/compiler/qv4instr_moth.cpp b/src/qml/compiler/qv4instr_moth.cpp
index 4fda5b1b19..2f6f12437d 100644
--- a/src/qml/compiler/qv4instr_moth.cpp
+++ b/src/qml/compiler/qv4instr_moth.cpp
@@ -405,15 +405,15 @@ QString dumpBytecode(
         MOTH_END_INSTR(GetIterator)
 
         MOTH_BEGIN_INSTR(IteratorNext)
-            s << dumpRegister(value, nFormals) << ", " << dumpRegister(done, nFormals);
+            s << dumpRegister(value, nFormals) << ", " << ABSOLUTE_OFFSET();
         MOTH_END_INSTR(IteratorNext)
 
         MOTH_BEGIN_INSTR(IteratorNextForYieldStar)
-            s << dumpRegister(iterator, nFormals) << ", " << dumpRegister(object, nFormals);
+            s << dumpRegister(iterator, nFormals) << ", " << dumpRegister(object, nFormals)
+              << ABSOLUTE_OFFSET();
         MOTH_END_INSTR(IteratorNextForYieldStar)
 
         MOTH_BEGIN_INSTR(IteratorClose)
-            s << dumpRegister(done, nFormals);
         MOTH_END_INSTR(IteratorClose)
 
         MOTH_BEGIN_INSTR(DestructureRestElement)
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index 7ebf849f3e..70e9f9e7a2 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -60,7 +60,7 @@ QT_BEGIN_NAMESPACE
 #define INSTR_Yield(op) INSTRUCTION(op, Yield, 0)
 #define INSTR_YieldStar(op) INSTRUCTION(op, YieldStar, 0)
 #define INSTR_Resume(op) INSTRUCTION(op, Resume, 1, offset)
-#define INSTR_IteratorNextForYieldStar(op) INSTRUCTION(op, IteratorNextForYieldStar, 2, iterator, object)
+#define INSTR_IteratorNextForYieldStar(op) INSTRUCTION(op, IteratorNextForYieldStar, 3, iterator, object, offset)
 #define INSTR_StoreProperty(op) INSTRUCTION(op, StoreProperty, 2, name, base)
 #define INSTR_SetLookup(op) INSTRUCTION(op, SetLookup, 2, index, base)
 #define INSTR_LoadSuperProperty(op) INSTRUCTION(op, LoadSuperProperty, 1, property)
@@ -94,8 +94,8 @@ QT_BEGIN_NAMESPACE
 #define INSTR_PopScriptContext(op) INSTRUCTION(op, PopScriptContext, 0)
 #define INSTR_PopContext(op) INSTRUCTION(op, PopContext, 0)
 #define INSTR_GetIterator(op) INSTRUCTION(op, GetIterator, 1, iterator)
-#define INSTR_IteratorNext(op) INSTRUCTION(op, IteratorNext, 2, value, done)
-#define INSTR_IteratorClose(op) INSTRUCTION(op, IteratorClose, 1, done)
+#define INSTR_IteratorNext(op) INSTRUCTION(op, IteratorNext, 2, value, offset)
+#define INSTR_IteratorClose(op) INSTRUCTION(op, IteratorClose, 0)
 #define INSTR_DestructureRestElement(op) INSTRUCTION(op, DestructureRestElement, 0)
 #define INSTR_DeleteProperty(op) INSTRUCTION(op, DeleteProperty, 2, base, index)
 #define INSTR_DeleteName(op) INSTRUCTION(op, DeleteName, 1, name)
diff --git a/src/qml/jit/qv4baselinejit.cpp b/src/qml/jit/qv4baselinejit.cpp
index d2895e8bf2..bd2e331cbc 100644
--- a/src/qml/jit/qv4baselinejit.cpp
+++ b/src/qml/jit/qv4baselinejit.cpp
@@ -586,7 +586,7 @@ void BaselineJIT::generate_GetIterator(int iterator)
     BASELINEJIT_GENERATE_RUNTIME_CALL(GetIterator, CallResultDestination::InAccumulator);
 }
 
-void BaselineJIT::generate_IteratorNext(int value, int done)
+void BaselineJIT::generate_IteratorNext(int value, int offset)
 {
     as->saveAccumulatorInFrame();
     as->prepareCallWithArgCount(3);
@@ -594,10 +594,10 @@ void BaselineJIT::generate_IteratorNext(int value, int done)
     as->passAccumulatorAsArg(1);
     as->passEngineAsArg(0);
     BASELINEJIT_GENERATE_RUNTIME_CALL(IteratorNext, CallResultDestination::InAccumulator);
-    as->storeReg(done);
+    labels.insert(as->jumpTrue(absoluteOffset(offset)));
 }
 
-void BaselineJIT::generate_IteratorNextForYieldStar(int iterator, int object)
+void BaselineJIT::generate_IteratorNextForYieldStar(int iterator, int object, int offset)
 {
     as->saveAccumulatorInFrame();
     as->prepareCallWithArgCount(4);
@@ -606,13 +606,13 @@ void BaselineJIT::generate_IteratorNextForYieldStar(int iterator, int object)
     as->passAccumulatorAsArg(1);
     as->passEngineAsArg(0);
     BASELINEJIT_GENERATE_RUNTIME_CALL(IteratorNextForYieldStar, CallResultDestination::InAccumulator);
+    labels.insert(as->jumpTrue(absoluteOffset(offset)));
 }
 
-void BaselineJIT::generate_IteratorClose(int done)
+void BaselineJIT::generate_IteratorClose()
 {
     as->saveAccumulatorInFrame();
-    as->prepareCallWithArgCount(3);
-    as->passJSSlotAsArg(done, 2);
+    as->prepareCallWithArgCount(2);
     as->passAccumulatorAsArg(1);
     as->passEngineAsArg(0);
     BASELINEJIT_GENERATE_RUNTIME_CALL(IteratorClose, CallResultDestination::InAccumulator);
diff --git a/src/qml/jit/qv4baselinejit_p.h b/src/qml/jit/qv4baselinejit_p.h
index c502e4d405..40138ea700 100644
--- a/src/qml/jit/qv4baselinejit_p.h
+++ b/src/qml/jit/qv4baselinejit_p.h
@@ -106,9 +106,9 @@ public:
     void generate_PopScriptContext() override;
     void generate_PopContext() override;
     void generate_GetIterator(int iterator) override;
-    void generate_IteratorNext(int value, int done) override;
-    void generate_IteratorNextForYieldStar(int iterator, int object) override;
-    void generate_IteratorClose(int done) override;
+    void generate_IteratorNext(int value, int offset) override;
+    void generate_IteratorNextForYieldStar(int iterator, int object, int offset) override;
+    void generate_IteratorClose() override;
     void generate_DestructureRestElement() override;
     void generate_DeleteProperty(int base, int index) override;
     void generate_DeleteName(int name) override;
diff --git a/src/qml/jsruntime/qv4arrayobject.cpp b/src/qml/jsruntime/qv4arrayobject.cpp
index 05e73d0295..a32017210a 100644
--- a/src/qml/jsruntime/qv4arrayobject.cpp
+++ b/src/qml/jsruntime/qv4arrayobject.cpp
@@ -194,9 +194,8 @@ ReturnedValue ArrayPrototype::method_from(const FunctionObject *builtin, const V
         // sets them into the created array.
         forever {
             if (k > (static_cast<qint64>(1) << 53) - 1) {
-                ScopedValue falsey(scope, Encode(false));
                 ScopedValue error(scope, scope.engine->throwTypeError());
-                return Runtime::IteratorClose::call(scope.engine, iterator, falsey);
+                return Runtime::IteratorClose::call(scope.engine, iterator);
             }
 
             // Retrieve the next value. If the iteration ends, we're done here.
@@ -218,7 +217,7 @@ ReturnedValue ArrayPrototype::method_from(const FunctionObject *builtin, const V
                 mapArguments[1] = Value::fromDouble(k);
                 mappedValue = mapfn->call(thisArg, mapArguments, 2);
                 if (scope.hasException())
-                    return Runtime::IteratorClose::call(scope.engine, iterator, Value::fromBoolean(false));
+                    return Runtime::IteratorClose::call(scope.engine, iterator);
             } else {
                 mappedValue = *nextValue;
             }
@@ -230,10 +229,8 @@ ReturnedValue ArrayPrototype::method_from(const FunctionObject *builtin, const V
                 scope.engine->throwTypeError(QString::fromLatin1("Cannot redefine property: %1").arg(k));
             }
 
-            if (scope.hasException()) {
-                ScopedValue falsey(scope, Encode(false));
-                return Runtime::IteratorClose::call(scope.engine, iterator, falsey);
-            }
+            if (scope.hasException())
+                return Runtime::IteratorClose::call(scope.engine, iterator);
 
             k++;
         }
diff --git a/src/qml/jsruntime/qv4mapobject.cpp b/src/qml/jsruntime/qv4mapobject.cpp
index 72e66e0e76..4bb9617b93 100644
--- a/src/qml/jsruntime/qv4mapobject.cpp
+++ b/src/qml/jsruntime/qv4mapobject.cpp
@@ -74,8 +74,7 @@ ReturnedValue WeakMapCtor::construct(const FunctionObject *f, const Value *argv,
                 if (scope.hasException())
                     break;
             }
-            ScopedValue falsey(scope, Encode(false));
-            return Runtime::IteratorClose::call(scope.engine, iter, falsey);
+            return Runtime::IteratorClose::call(scope.engine, iter);
         }
     }
     return a->asReturnedValue();
diff --git a/src/qml/jsruntime/qv4promiseobject.cpp b/src/qml/jsruntime/qv4promiseobject.cpp
index 5424545e79..16cffea124 100644
--- a/src/qml/jsruntime/qv4promiseobject.cpp
+++ b/src/qml/jsruntime/qv4promiseobject.cpp
@@ -575,7 +575,7 @@ ReturnedValue PromiseCtor::method_all(const FunctionObject *f, const Value *this
             }
 
             if (!doneValue->toBoolean())
-                completion = Runtime::IteratorClose::call(e, iteratorObject, doneValue);
+                completion = Runtime::IteratorClose::call(e, iteratorObject);
 
             reject->call(newPromise, completion, 1);
             return newPromise.asReturnedValue();
@@ -583,7 +583,9 @@ ReturnedValue PromiseCtor::method_all(const FunctionObject *f, const Value *this
 
         ScopedObject nextPromise(scope, Value::fromReturnedValue(resolve->call(thisObject, nextValue, 1)));
         if (scope.hasException() || !nextPromise) {
-            ScopedValue completion(scope, Runtime::IteratorClose::call(e, iteratorObject, doneValue));
+            ScopedValue completion(scope, doneValue->toBoolean()
+                                           ? Encode::undefined()
+                                           : Runtime::IteratorClose::call(e, iteratorObject));
             if (scope.hasException()) {
                 completion = e->exceptionValue->asReturnedValue();
                 dropException(e);
@@ -605,7 +607,7 @@ ReturnedValue PromiseCtor::method_all(const FunctionObject *f, const Value *this
             }
 
             if (!doneValue->toBoolean())
-                completion = Runtime::IteratorClose::call(scope.engine, iteratorObject, doneValue);
+                completion = Runtime::IteratorClose::call(scope.engine, iteratorObject);
 
             reject->call(newPromise, completion, 1);
             return newPromise.asReturnedValue();
@@ -624,7 +626,7 @@ ReturnedValue PromiseCtor::method_all(const FunctionObject *f, const Value *this
             dropException(e);
 
             if (!doneValue->toBoolean())
-                completion = Runtime::IteratorClose::call(scope.engine, iteratorObject, doneValue);
+                completion = Runtime::IteratorClose::call(scope.engine, iteratorObject);
 
             reject->call(newPromise, completion, 1);
             return newPromise.asReturnedValue();
@@ -686,7 +688,9 @@ ReturnedValue PromiseCtor::method_race(const FunctionObject *f, const Value *thi
         doneValue = Value::fromReturnedValue(Runtime::IteratorNext::call(e, iteratorObject, nextValue));
 
         if (scope.hasException()) {
-            ScopedValue completion(scope, Runtime::IteratorClose::call(e, iteratorObject, doneValue));
+            ScopedValue completion(scope, doneValue->toBoolean()
+                                           ? Encode::undefined()
+                                           : Runtime::IteratorClose::call(e, iteratorObject));
             if (scope.hasException()) {
                 completion = e->exceptionValue->asReturnedValue();
                 dropException(e);
@@ -721,7 +725,7 @@ ReturnedValue PromiseCtor::method_race(const FunctionObject *f, const Value *thi
             }
 
             if (!doneValue->toBoolean())
-                completion = Runtime::IteratorClose::call(e, iteratorObject, doneValue);
+                completion = Runtime::IteratorClose::call(e, iteratorObject);
 
             reject->call(newPromise, completion, 1);
             return newPromise.asReturnedValue();
@@ -729,7 +733,9 @@ ReturnedValue PromiseCtor::method_race(const FunctionObject *f, const Value *thi
 
         ScopedObject nextPromise(scope, Value::fromReturnedValue(resolve->call(thisObject, nextValue, 1)));
         if (scope.hasException() || !nextPromise) {
-            ScopedValue completion(scope, Runtime::IteratorClose::call(e, iteratorObject, doneValue));
+            ScopedValue completion(scope, doneValue->toBoolean()
+                                          ? Encode::undefined()
+                                          : Runtime::IteratorClose::call(e, iteratorObject));
             if (scope.hasException()) {
                 completion = e->exceptionValue->asReturnedValue();
                 dropException(e);
@@ -749,7 +755,7 @@ ReturnedValue PromiseCtor::method_race(const FunctionObject *f, const Value *thi
             }
 
             if (!doneValue->toBoolean())
-                completion = Runtime::IteratorClose::call(e, iteratorObject, doneValue);
+                completion = Runtime::IteratorClose::call(e, iteratorObject);
 
             reject->call(newPromise, completion, 1);
             return newPromise.asReturnedValue();
@@ -768,7 +774,7 @@ ReturnedValue PromiseCtor::method_race(const FunctionObject *f, const Value *thi
             dropException(e);
 
             if (!doneValue->toBoolean())
-                completion = Runtime::IteratorClose::call(e, iteratorObject, doneValue);
+                completion = Runtime::IteratorClose::call(e, iteratorObject);
 
             reject->call(newPromise, completion, 1);
             return newPromise.asReturnedValue();
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index f5b88f662b..01a378406a 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -862,6 +862,8 @@ ReturnedValue Runtime::IteratorNextForYieldStar::call(ExecutionEngine *engine, c
             engine->hasException = false;
 
             ScopedValue ret(scope, static_cast<const Object &>(iterator).get(engine->id_return()));
+            if (engine->hasException)
+                return Encode(true);
             if (ret->isUndefined()) {
                 // propagate return()
                 return Encode::undefined();
@@ -876,14 +878,13 @@ ReturnedValue Runtime::IteratorNextForYieldStar::call(ExecutionEngine *engine, c
 
             ScopedValue t(scope, static_cast<const Object &>(iterator).get(engine->id_throw()));
             if (engine->hasException)
-                return Encode::undefined();
+                return Encode(true);
             if (t->isUndefined()) {
                 // no throw method on the iterator
-                ScopedValue done(scope, Encode(false));
-                IteratorClose::call(engine, iterator, done);
-                if (engine->hasException)
-                    return Encode::undefined();
-                return engine->throwTypeError();
+                IteratorClose::call(engine, iterator);
+                if (!engine->hasException)
+                    engine->throwTypeError();
+                return Encode(true);
             }
             f = t->as<FunctionObject>();
             arg = exceptionValue;
@@ -894,14 +895,18 @@ ReturnedValue Runtime::IteratorNextForYieldStar::call(ExecutionEngine *engine, c
         f = next->as<FunctionObject>();
     }
 
-    if (!f)
-        return engine->throwTypeError();
+    if (!f) {
+        engine->throwTypeError();
+        return Encode(true);
+    }
 
     ScopedObject o(scope, f->call(&iterator, arg, 1));
     if (scope.hasException())
         return Encode(true);
-    if (!o)
-        return engine->throwTypeError();
+    if (!o) {
+        engine->throwTypeError();
+        return Encode(true);
+    }
 
     ScopedValue d(scope, o->get(engine->id_done()));
     if (scope.hasException())
@@ -909,18 +914,15 @@ ReturnedValue Runtime::IteratorNextForYieldStar::call(ExecutionEngine *engine, c
     bool done = d->toBoolean();
     if (done) {
         *object = o->get(engine->id_value());
-        return returnCalled ? Encode::undefined() : Encode(true);
+        return (returnCalled && !engine->hasException) ? Encode::undefined() : Encode(true);
     }
     *object = o;
     return Encode(false);
 }
 
-ReturnedValue Runtime::IteratorClose::call(ExecutionEngine *engine, const Value &iterator, const Value &done)
+ReturnedValue Runtime::IteratorClose::call(ExecutionEngine *engine, const Value &iterator)
 {
     Q_ASSERT(iterator.isObject());
-    Q_ASSERT(done.isBoolean());
-    if (done.booleanValue())
-        return Encode::undefined();
 
     Scope scope(engine);
     ScopedValue e(scope);
diff --git a/src/qml/jsruntime/qv4runtimeapi_p.h b/src/qml/jsruntime/qv4runtimeapi_p.h
index 5e11d15495..797de7e13f 100644
--- a/src/qml/jsruntime/qv4runtimeapi_p.h
+++ b/src/qml/jsruntime/qv4runtimeapi_p.h
@@ -43,7 +43,7 @@ struct Q_QML_PRIVATE_EXPORT Runtime {
         static constexpr bool lastArgumentIsOutputValue = out == LastArgumentIsOutputValue::Yes;
     };
     using PureMethod = Method<Throws::No, ChangesContext::No, Pure::Yes>;
-    using IteratorMethod = Method<Throws::Yes, ChangesContext::No, Pure::No,
+    using IteratorMethod = Method<Throws::No, ChangesContext::No, Pure::No,
                                   LastArgumentIsOutputValue::Yes>;
 
     /* call */
@@ -285,9 +285,9 @@ struct Q_QML_PRIVATE_EXPORT Runtime {
     {
         static ReturnedValue call(ExecutionEngine *, const Value &, const Value &, Value *);
     };
-    struct Q_QML_PRIVATE_EXPORT IteratorClose : Method<Throws::Yes>
+    struct Q_QML_PRIVATE_EXPORT IteratorClose : Method<Throws::No>
     {
-        static ReturnedValue call(ExecutionEngine *, const Value &, const Value &);
+        static ReturnedValue call(ExecutionEngine *, const Value &);
     };
     struct Q_QML_PRIVATE_EXPORT DestructureRestElement : Method<Throws::Yes>
     {
diff --git a/src/qml/jsruntime/qv4setobject.cpp b/src/qml/jsruntime/qv4setobject.cpp
index 2a4cdc1944..01fc62a4d4 100644
--- a/src/qml/jsruntime/qv4setobject.cpp
+++ b/src/qml/jsruntime/qv4setobject.cpp
@@ -54,10 +54,8 @@ ReturnedValue WeakSetCtor::construct(const FunctionObject *f, const Value *argv,
                     return a.asReturnedValue();
 
                 adder->call(a, nextValue, 1);
-                if (scope.hasException()) {
-                    ScopedValue falsey(scope, Encode(false));
-                    return Runtime::IteratorClose::call(scope.engine, iter, falsey);
-                }
+                if (scope.hasException())
+                    return Runtime::IteratorClose::call(scope.engine, iter);
             }
         }
     }
diff --git a/src/qml/jsruntime/qv4typedarray.cpp b/src/qml/jsruntime/qv4typedarray.cpp
index 43dc0fae4f..6c72eaba5f 100644
--- a/src/qml/jsruntime/qv4typedarray.cpp
+++ b/src/qml/jsruntime/qv4typedarray.cpp
@@ -1680,14 +1680,13 @@ ReturnedValue IntrinsicTypedArrayCtor::method_from(const FunctionObject *f, cons
         forever {
             // Here we calculate the length of the iterable range.
             if (iterableLength > (static_cast<qint64>(1) << 53) - 1) {
-                ScopedValue falsey(scope, Encode(false));
                 ScopedValue error(scope, scope.engine->throwTypeError());
-                return Runtime::IteratorClose::call(scope.engine, lengthIterator, falsey);
+                return Runtime::IteratorClose::call(scope.engine, lengthIterator);
             }
             // Retrieve the next value. If the iteration ends, we're done here.
             done = Value::fromReturnedValue(Runtime::IteratorNext::call(scope.engine, lengthIterator, nextValue));
             if (scope.hasException())
-                return Runtime::IteratorClose::call(scope.engine, lengthIterator, Value::fromBoolean(false));
+                return Runtime::IteratorClose::call(scope.engine, lengthIterator);
             if (done->toBoolean()) {
                 break;
             }
@@ -1720,21 +1719,21 @@ ReturnedValue IntrinsicTypedArrayCtor::method_from(const FunctionObject *f, cons
         for (qint64 k = 0; k < iterableLength; ++k) {
             done = Value::fromReturnedValue(Runtime::IteratorNext::call(scope.engine, iterator, nextValue));
             if (scope.hasException())
-                return Runtime::IteratorClose::call(scope.engine, iterator, Value::fromBoolean(false));
+                return Runtime::IteratorClose::call(scope.engine, iterator);
 
             if (mapfn) {
                 mapArguments[0] = *nextValue;
                 mapArguments[1] = Value::fromDouble(k);
                 mappedValue = mapfn->call(thisArg, mapArguments, 2);
                 if (scope.hasException())
-                    return Runtime::IteratorClose::call(scope.engine, iterator, Value::fromBoolean(false));
+                    return Runtime::IteratorClose::call(scope.engine, iterator);
             } else {
                 mappedValue = *nextValue;
             }
 
             a->put(k, mappedValue);
             if (scope.hasException())
-                return Runtime::IteratorClose::call(scope.engine, iterator, Value::fromBoolean(false));
+                return Runtime::IteratorClose::call(scope.engine, iterator);
         }
         return a.asReturnedValue();
     } else {
diff --git a/src/qml/jsruntime/qv4vme_moth.cpp b/src/qml/jsruntime/qv4vme_moth.cpp
index 0d4ba41fee..55f2261b4d 100644
--- a/src/qml/jsruntime/qv4vme_moth.cpp
+++ b/src/qml/jsruntime/qv4vme_moth.cpp
@@ -844,7 +844,8 @@ QV4::ReturnedValue VME::interpret(JSTypesStackFrame *frame, ExecutionEngine *eng
     MOTH_BEGIN_INSTR(IteratorNextForYieldStar)
         STORE_ACC();
         acc = Runtime::IteratorNextForYieldStar::call(engine, accumulator, STACK_VALUE(iterator), &STACK_VALUE(object));
-        CHECK_EXCEPTION;
+        if (ACC.toBoolean())
+            code += offset;
     MOTH_END_INSTR(IteratorNextForYieldStar)
 
     MOTH_BEGIN_INSTR(CallValue)
@@ -1054,15 +1055,14 @@ QV4::ReturnedValue VME::interpret(JSTypesStackFrame *frame, ExecutionEngine *eng
         STORE_IP();
         STORE_ACC();
         acc = Runtime::IteratorNext::call(engine, accumulator, &STACK_VALUE(value));
-        STACK_VALUE(done) = acc;
-        CHECK_EXCEPTION;
+        if (ACC.toBoolean())
+            code += offset;
     MOTH_END_INSTR(IteratorNext)
 
     MOTH_BEGIN_INSTR(IteratorClose)
         STORE_IP();
         STORE_ACC();
-        acc = Runtime::IteratorClose::call(engine, accumulator, STACK_VALUE(done));
-        CHECK_EXCEPTION;
+        acc = Runtime::IteratorClose::call(engine, accumulator);
     MOTH_END_INSTR(IteratorClose)
 
     MOTH_BEGIN_INSTR(DestructureRestElement)
diff --git a/src/qmlcompiler/qqmljscodegenerator.cpp b/src/qmlcompiler/qqmljscodegenerator.cpp
index c33b915441..d62e899dbc 100644
--- a/src/qmlcompiler/qqmljscodegenerator.cpp
+++ b/src/qmlcompiler/qqmljscodegenerator.cpp
@@ -2299,23 +2299,23 @@ void QQmlJSCodeGenerator::generate_GetIterator(int iterator)
     BYTECODE_UNIMPLEMENTED();
 }
 
-void QQmlJSCodeGenerator::generate_IteratorNext(int value, int done)
+void QQmlJSCodeGenerator::generate_IteratorNext(int value, int offset)
 {
     Q_UNUSED(value)
-    Q_UNUSED(done)
+    Q_UNUSED(offset)
     BYTECODE_UNIMPLEMENTED();
 }
 
-void QQmlJSCodeGenerator::generate_IteratorNextForYieldStar(int iterator, int object)
+void QQmlJSCodeGenerator::generate_IteratorNextForYieldStar(int iterator, int object, int offset)
 {
     Q_UNUSED(iterator)
     Q_UNUSED(object)
+    Q_UNUSED(offset)
     BYTECODE_UNIMPLEMENTED();
 }
 
-void QQmlJSCodeGenerator::generate_IteratorClose(int done)
+void QQmlJSCodeGenerator::generate_IteratorClose()
 {
-    Q_UNUSED(done)
     BYTECODE_UNIMPLEMENTED();
 }
 
diff --git a/src/qmlcompiler/qqmljscodegenerator_p.h b/src/qmlcompiler/qqmljscodegenerator_p.h
index 0a743127f9..b6ffd5ac7f 100644
--- a/src/qmlcompiler/qqmljscodegenerator_p.h
+++ b/src/qmlcompiler/qqmljscodegenerator_p.h
@@ -133,9 +133,9 @@ protected:
     void generate_PopScriptContext() override;
     void generate_PopContext() override;
     void generate_GetIterator(int iterator) override;
-    void generate_IteratorNext(int value, int done) override;
-    void generate_IteratorNextForYieldStar(int iterator, int object) override;
-    void generate_IteratorClose(int done) override;
+    void generate_IteratorNext(int value, int offset) override;
+    void generate_IteratorNextForYieldStar(int iterator, int object, int offset) override;
+    void generate_IteratorClose() override;
     void generate_DestructureRestElement() override;
     void generate_DeleteProperty(int base, int index) override;
     void generate_DeleteName(int name) override;
diff --git a/src/qmlcompiler/qqmljscompilepass_p.h b/src/qmlcompiler/qqmljscompilepass_p.h
index ea73169538..05f0816aa7 100644
--- a/src/qmlcompiler/qqmljscompilepass_p.h
+++ b/src/qmlcompiler/qqmljscompilepass_p.h
@@ -411,9 +411,9 @@ protected:
     void generate_GetTemplateObject(int) override {}
     void generate_Increment() override {}
     void generate_InitializeBlockDeadTemporalZone(int, int) override {}
-    void generate_IteratorClose(int) override {}
+    void generate_IteratorClose() override {}
     void generate_IteratorNext(int, int) override {}
-    void generate_IteratorNextForYieldStar(int, int) override {}
+    void generate_IteratorNextForYieldStar(int, int, int) override {}
     void generate_Jump(int) override {}
     void generate_JumpFalse(int) override {}
     void generate_JumpNoException(int) override {}
diff --git a/src/qmlcompiler/qqmljstypepropagator.cpp b/src/qmlcompiler/qqmljstypepropagator.cpp
index 4bddaf470e..3a02cd7714 100644
--- a/src/qmlcompiler/qqmljstypepropagator.cpp
+++ b/src/qmlcompiler/qqmljstypepropagator.cpp
@@ -1897,23 +1897,23 @@ void QQmlJSTypePropagator::generate_GetIterator(int iterator)
     INSTR_PROLOGUE_NOT_IMPLEMENTED();
 }
 
-void QQmlJSTypePropagator::generate_IteratorNext(int value, int done)
+void QQmlJSTypePropagator::generate_IteratorNext(int value, int offset)
 {
     Q_UNUSED(value)
-    Q_UNUSED(done)
+    Q_UNUSED(offset)
     INSTR_PROLOGUE_NOT_IMPLEMENTED();
 }
 
-void QQmlJSTypePropagator::generate_IteratorNextForYieldStar(int iterator, int object)
+void QQmlJSTypePropagator::generate_IteratorNextForYieldStar(int iterator, int object, int offset)
 {
     Q_UNUSED(iterator)
     Q_UNUSED(object)
+    Q_UNUSED(offset)
     INSTR_PROLOGUE_NOT_IMPLEMENTED();
 }
 
-void QQmlJSTypePropagator::generate_IteratorClose(int done)
+void QQmlJSTypePropagator::generate_IteratorClose()
 {
-    Q_UNUSED(done)
     INSTR_PROLOGUE_NOT_IMPLEMENTED();
 }
 
diff --git a/src/qmlcompiler/qqmljstypepropagator_p.h b/src/qmlcompiler/qqmljstypepropagator_p.h
index 6e9ac5e16a..282e3dad35 100644
--- a/src/qmlcompiler/qqmljstypepropagator_p.h
+++ b/src/qmlcompiler/qqmljstypepropagator_p.h
@@ -101,9 +101,9 @@ struct Q_QMLCOMPILER_PRIVATE_EXPORT QQmlJSTypePropagator : public QQmlJSCompileP
     void generate_PopScriptContext() override;
     void generate_PopContext() override;
     void generate_GetIterator(int iterator) override;
-    void generate_IteratorNext(int value, int done) override;
-    void generate_IteratorNextForYieldStar(int iterator, int object) override;
-    void generate_IteratorClose(int done) override;
+    void generate_IteratorNext(int value, int offset) override;
+    void generate_IteratorNextForYieldStar(int iterator, int object, int offset) override;
+    void generate_IteratorClose() override;
     void generate_DestructureRestElement() override;
     void generate_DeleteProperty(int base, int index) override;
     void generate_DeleteName(int name) override;