Add a MemoryManager, which does GC for the interpreter.

Todo:
- stack walking for MASM
- fix all TODOs/FIXMEs and hidden treasures (bugs).

Change-Id: I36f8cdc3a545df7287ce1df17b3570a9c017865e
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 184 insertions, 0 deletions

diff --git a/qv4mm.h b/qv4mm.h
new file mode 100644
index 0000000000..ece3765e3b
--- /dev/null
+++ b/qv4mm.h
@@ -0,0 +1,184 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#ifndef QV4GC_H
+#define QV4GC_H
+
+#include "qmljs_objects.h"
+
+#include <QScopedPointer>
+
+#define DETAILED_MM_STATS
+
+namespace QQmlJS {
+namespace VM {
+
+class MemoryManager
+{
+    MemoryManager(const MemoryManager &);
+    MemoryManager &operator=(const MemoryManager&);
+
+    struct Data;
+
+public:
+    class GCBlocker
+    {
+    public:
+        GCBlocker(MemoryManager *mm)
+            : mm(mm)
+            , wasBlocked(mm->isGCBlocked())
+        {
+            mm->setGCBlocked(true);
+        }
+
+        ~GCBlocker()
+        {
+            mm->setGCBlocked(wasBlocked);
+        }
+
+    private:
+        MemoryManager *mm;
+        bool wasBlocked;
+    };
+
+public:
+    MemoryManager();
+    virtual ~MemoryManager() = 0;
+
+    // TODO: this is only for 64bit (and x86 with SSE/AVX), so exend it for other architectures to be slightly more efficient (meaning, align on 8-byte boundaries).
+    // Note: all occurances of "16" in alloc/dealloc are also due to the alignment.
+    static inline std::size_t align(std::size_t size)
+    { return (size + 15) & ~0xf; }
+
+    inline Managed *allocManaged(std::size_t size)
+    {
+        size = align(size);
+        MMObject *o = alloc(size);
+        o->info.needsManagedDestructorCall = 1;
+        Managed *ptr = reinterpret_cast<Managed *>(&o->data);
+        ptr->mm = this;
+        return ptr;
+    }
+
+    inline void deallocManaged(Managed *m)
+    {
+        if (!m)
+            return;
+
+        assert(m->mm == this);
+        dealloc(toObject(m));
+    }
+
+    bool isGCBlocked() const;
+    void setGCBlocked(bool blockGC);
+    std::size_t runGC();
+
+    void setEnableGC(bool enableGC);
+    void setExecutionEngine(ExecutionEngine *engine);
+    void setStringPool(StringPool *stringPool);
+
+    void dumpStats() const;
+
+protected:
+#if 1 // 64bit and x86:
+    struct MMObject;
+    struct MMInfo {
+        std::size_t inUse   :  1;
+        std::size_t markBit :  1;
+        std::size_t needsManagedDestructorCall : 1;
+        std::size_t size    : 61;
+        MMObject *next;
+    };
+    struct MMObject {
+        MMInfo info;
+        std::size_t data;
+    };
+#endif
+#if 0 // for 32bits:
+        // untested!
+    struct MMInfo {
+        std::size_t inUse   :  1;
+        std::size_t markBit :  1;
+        std::size_t size    : 30;
+    };
+    struct MMObject {
+        MMInfo info;
+        union {
+            struct MMObject *next;
+            char data[1];
+        }
+    };
+#endif
+
+protected:
+    static inline MMObject *toObject(void *ptr) { return reinterpret_cast<MMObject *>(reinterpret_cast<char *>(ptr) - sizeof(MMInfo)); }
+
+    /// expects size to be aligned
+    // TODO: try to inline
+    MMObject *alloc(std::size_t size);
+
+    // TODO: try to inline
+    void dealloc(MMObject *ptr);
+
+    void scribble(MMObject *obj, int c) const;
+
+    virtual void collectRootsOnStack(QVector<VM::Object *> &roots) const = 0;
+
+    ExecutionEngine *engine() const;
+
+#ifdef DETAILED_MM_STATS
+    void willAllocate(std::size_t size);
+#endif // DETAILED_MM_STATS
+
+private:
+    void collectRoots(QVector<VM::Object *> &roots) const;
+    static std::size_t mark(const QVector<Object *> &objects);
+    std::size_t sweep(std::size_t &largestFreedBlock);
+    std::size_t sweep(char *chunkStart, std::size_t chunkSize, std::size_t &largestFreedBlock);
+
+private:
+    QScopedPointer<Data> m_d;
+};
+
+class MemoryManagerWithoutGC: public MemoryManager
+{
+public:
+    MemoryManagerWithoutGC()
+    { setEnableGC(false); }
+
+    virtual ~MemoryManagerWithoutGC();
+
+protected:
+    virtual void collectRootsOnStack(QVector<VM::Object *> &roots) const;
+};
+
+} // namespace VM
+} // namespace QQmlJS
+
+#endif // QV4GC_H