Some fixes when unwinding inside for-of loops

This is not perfect yet, as the two regressions in TestExpectations
show, but it's an improvement over the current situation.

Change-Id: I82c0ef0f69619562037c573bea1026abc53c1ab3
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 28 insertions, 25 deletions

diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index cbe935c5cd..274917dd0a 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -1134,7 +1134,14 @@ bool Codegen::visit(ArrayPattern *ast)
             BytecodeGenerator::Label done = bytecodeGenerator->newLabel();
 
             {
-                ControlFlowLoop flow(this, &end, &in, /*requiresUnwind*/ true);
+                auto unwind = [this, iterator]() {
+                    Reference iteratorDone = Reference::fromConst(this, Encode(false)).storeOnStack();
+                    iterator.loadInAccumulator();
+                    Instruction::IteratorClose close;
+                    close.done = iteratorDone.stackSlot();
+                    bytecodeGenerator->addInstruction(close);
+                };
+                ControlFlowLoop flow(this, &end, &in, unwind);
                 bytecodeGenerator->jump().link(in);
 
                 BytecodeGenerator::Label body = bytecodeGenerator->label();
@@ -1149,15 +1156,9 @@ bool Codegen::visit(ArrayPattern *ast)
                 bytecodeGenerator->addInstruction(next);
                 bytecodeGenerator->addJumpInstruction(Instruction::JumpFalse()).link(body);
                 bytecodeGenerator->jump().link(done);
-            }
-
-            end.link();
 
-            Reference iteratorDone = Reference::fromConst(this, Encode(false)).storeOnStack();
-            iterator.loadInAccumulator();
-            Instruction::IteratorClose close;
-            close.done = iteratorDone.stackSlot();
-            bytecodeGenerator->addInstruction(close);
+                end.link();
+            }
 
             done.link();
         } else {
@@ -3177,7 +3178,16 @@ bool Codegen::visit(ForEachStatement *ast)
     BytecodeGenerator::Label done = bytecodeGenerator->newLabel();
 
     {
-        ControlFlowLoop flow(this, &end, &in, /*requiresUnwind*/ true);
+        auto unwind = [ast, this, iterator]() {
+            if (ast->type == ForEachType::Of) {
+                Reference iteratorDone = Reference::fromConst(this, Encode(false)).storeOnStack();
+                iterator.loadInAccumulator();
+                Instruction::IteratorClose close;
+                close.done = iteratorDone.stackSlot();
+                bytecodeGenerator->addInstruction(close);
+            }
+        };
+        ControlFlowLoop flow(this, &end, &in, unwind);
         bytecodeGenerator->jump().link(in);
 
         BytecodeGenerator::Label body = bytecodeGenerator->label();
@@ -3220,16 +3230,8 @@ bool Codegen::visit(ForEachStatement *ast)
         bytecodeGenerator->addInstruction(next);
         bytecodeGenerator->addJumpInstruction(Instruction::JumpFalse()).link(body);
         bytecodeGenerator->jump().link(done);
-    }
-
-    end.link();
 
-    if (ast->type == ForEachType::Of) {
-        Reference iteratorDone = Reference::fromConst(this, Encode(false)).storeOnStack();
-        iterator.loadInAccumulator();
-        Instruction::IteratorClose close;
-        close.done = iteratorDone.stackSlot();
-        bytecodeGenerator->addInstruction(close);
+        end.link();
     }
 
     done.link();
diff --git a/src/qml/compiler/qv4compilercontrolflow_p.h b/src/qml/compiler/qv4compilercontrolflow_p.h
index 1ef290ea56..1884b33588 100644
--- a/src/qml/compiler/qv4compilercontrolflow_p.h
+++ b/src/qml/compiler/qv4compilercontrolflow_p.h
@@ -193,27 +193,28 @@ struct ControlFlowLoop : public ControlFlowUnwind
     QString loopLabel;
     BytecodeGenerator::Label *breakLabel = nullptr;
     BytecodeGenerator::Label *continueLabel = nullptr;
-    bool _requiresUnwind;
+    std::function<void()> unwind = nullptr;
 
-    ControlFlowLoop(Codegen *cg, BytecodeGenerator::Label *breakLabel, BytecodeGenerator::Label *continueLabel = nullptr, bool requiresUnwind = false)
-        : ControlFlowUnwind(cg, Loop), loopLabel(ControlFlow::loopLabel()), breakLabel(breakLabel), continueLabel(continueLabel), _requiresUnwind(requiresUnwind)
+    ControlFlowLoop(Codegen *cg, BytecodeGenerator::Label *breakLabel, BytecodeGenerator::Label *continueLabel = nullptr, std::function<void()> unwind = nullptr)
+        : ControlFlowUnwind(cg, Loop), loopLabel(ControlFlow::loopLabel()), breakLabel(breakLabel), continueLabel(continueLabel), unwind(unwind)
     {
-        if (_requiresUnwind) {
+        if (unwind != nullptr) {
             setupUnwindHandler();
             generator()->setUnwindHandler(&unwindLabel);
         }
     }
 
     ~ControlFlowLoop() {
-        if (_requiresUnwind) {
+        if (unwind != nullptr) {
             unwindLabel.link();
             generator()->setUnwindHandler(parentUnwindHandler());
+            unwind();
             emitUnwindHandler();
         }
     }
 
     bool requiresUnwind() override {
-        return _requiresUnwind;
+        return unwind != nullptr;
     }
 
     BytecodeGenerator::Label getUnwindTarget(UnwindType type, const QString &label) override {