From 55ecfd409ca6aa8018be8cc2697b27928fbd4cc2 Mon Sep 17 00:00:00 2001
From: Simon Hausmann <simon.hausmann@qt.io>
Date: Thu, 5 Oct 2017 11:02:36 +0200
Subject: 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>
---
 src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp | 2 +-
 src/qml/compiler/qv4compileddata.cpp                   | 2 +-
 src/qml/compiler/qv4compileddata_p.h                   | 2 ++
 src/qml/jsruntime/qv4engine.cpp                        | 5 ++---
 src/qml/jsruntime/qv4engine_p.h                        | 5 ++++-
 5 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
index a624cf22a4..a58604526b 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
@@ -274,7 +274,7 @@ GatherSourcesJob::GatherSourcesJob(QV4::ExecutionEngine *engine)
 
 void GatherSourcesJob::run()
 {
-    for (QV4::CompiledData::CompilationUnit *unit : qAsConst(engine->compilationUnits)) {
+    for (QV4::CompiledData::CompilationUnit *unit : engine->compilationUnits) {
         QString fileName = unit->fileName();
         if (!fileName.isEmpty())
             sources.append(fileName);
diff --git a/src/qml/compiler/qv4compileddata.cpp b/src/qml/compiler/qv4compileddata.cpp
index 34491a3a84..294eaa25f5 100644
--- a/src/qml/compiler/qv4compileddata.cpp
+++ b/src/qml/compiler/qv4compileddata.cpp
@@ -212,7 +212,7 @@ QV4::Function *CompilationUnit::linkToEngine(ExecutionEngine *engine)
 void CompilationUnit::unlink()
 {
     if (engine)
-        engine->compilationUnits.erase(engine->compilationUnits.find(this));
+        nextCompilationUnit.remove();
 
     if (isRegisteredWithEngine) {
         Q_ASSERT(data && propertyCaches.count() > 0 && propertyCaches.at(/*root object*/0));
diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index 84777b3533..440dc3e013 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -66,6 +66,7 @@
 #ifndef V4_BOOTSTRAP
 #include <private/qqmltypenamecache_p.h>
 #include <private/qqmlpropertycache_p.h>
+#include "private/qintrusivelist_p.h"
 #endif
 
 QT_BEGIN_NAMESPACE
@@ -837,6 +838,7 @@ struct Q_QML_PRIVATE_EXPORT CompilationUnit : public CompilationUnitBase, public
     virtual QV4::CompiledData::Unit *createUnitData(QmlIR::Document *irDocument);
 
 #ifndef V4_BOOTSTRAP
+    QIntrusiveListNode nextCompilationUnit;
     ExecutionEngine *engine;
     QQmlEnginePrivate *qmlEngine; // only used in QML environment for composite types, not in plain QJSEngine case.
 
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;
 
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