Simplify compilation unit tracking in the execution engine

Instead of collecting all compilation units in a hash, let's collect
linked units in a doubly-linked lists that makes the removal at
destruction time dramatically cheaper.

Change-Id: I9fd59600d082be3566f605d90f14a86a58ac9296
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

2 files changed, 6 insertions, 4 deletions

diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 34336e3c87..917f6bffc5 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -951,9 +951,8 @@ void ExecutionEngine::markObjects()
 
     drainMarkStack(this, markBase);
 
-    for (QSet<CompiledData::CompilationUnit*>::ConstIterator it = compilationUnits.constBegin(), end = compilationUnits.constEnd();
-         it != end; ++it) {
-        (*it)->markObjects(this);
+    for (auto compilationUnit: compilationUnits) {
+        compilationUnit->markObjects(this);
         drainMarkStack(this, markBase);
     }
 }
diff --git a/src/qml/jsruntime/qv4engine_p.h b/src/qml/jsruntime/qv4engine_p.h
index 688a58e345..fee06ebc58 100644
--- a/src/qml/jsruntime/qv4engine_p.h
+++ b/src/qml/jsruntime/qv4engine_p.h
@@ -59,6 +59,7 @@
 
 #ifndef V4_BOOTSTRAP
 #  include <private/qv8engine_p.h>
+#  include <private/qv4compileddata_p.h>
 #endif
 
 namespace WTF {
@@ -318,7 +319,9 @@ public:
     String *id_buffer() const { return reinterpret_cast<String *>(jsStrings + String_buffer); }
     String *id_lastIndex() const { return reinterpret_cast<String *>(jsStrings + String_lastIndex); }
 
-    QSet<CompiledData::CompilationUnit*> compilationUnits;
+#ifndef V4_BOOTSTRAP
+    QIntrusiveList<CompiledData::CompilationUnit, &CompiledData::CompilationUnit::nextCompilationUnit> compilationUnits;
+#endif
 
     quint32 m_engineId;