Improve releasing of memory allocated from compilation unit strings

Allocate the strings in the compilation unit as regular strings, not as
identifiers. We mark the runtimeStrings in the compilation unit, so when
the unit is released as part of component cache trimming, those strings
can also be collected. The JS object literal class keys have to remain
identifiers though.

However this is just a stop-gap as the real problem is that the
identifier table can be triggered to grow without bounds.

Task-number: QTBUG-61536
Change-Id: I7a2854b7fa9c9953348b5e34a31833f7be67cfbf
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/qml/jsruntime/qv4lookup.cpp b/src/qml/jsruntime/qv4lookup.cpp
index faaa5539ab..7a158ece35 100644
--- a/src/qml/jsruntime/qv4lookup.cpp
+++ b/src/qml/jsruntime/qv4lookup.cpp
@@ -40,6 +40,7 @@
 #include "qv4functionobject_p.h"
 #include "qv4scopedvalue_p.h"
 #include "qv4string_p.h"
+#include <private/qv4identifiertable_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -49,7 +50,7 @@ using namespace QV4;
 ReturnedValue Lookup::lookup(const Value &thisObject, Object *o, PropertyAttributes *attrs)
 {
     ExecutionEngine *engine = o->engine();
-    Identifier *name = engine->current->compilationUnit->runtimeStrings[nameIndex]->identifier;
+    Identifier *name = engine->identifierTable->identifier(engine->current->compilationUnit->runtimeStrings[nameIndex]);
     int i = 0;
     Heap::Object *obj = o->d();
     while (i < Size && obj) {
@@ -85,7 +86,7 @@ ReturnedValue Lookup::lookup(const Object *thisObject, PropertyAttributes *attrs
 {
     Heap::Object *obj = thisObject->d();
     ExecutionEngine *engine = thisObject->engine();
-    Identifier *name = engine->current->compilationUnit->runtimeStrings[nameIndex]->identifier;
+    Identifier *name = engine->identifierTable->identifier(engine->current->compilationUnit->runtimeStrings[nameIndex]);
     int i = 0;
     while (i < Size && obj) {
         classList[i] = obj->internalClass;