Allow delayed deallocation in the executable memory allocator

Allow for allocations to outlive the allocator itself. When the allocator dies,
it invalidates any remaining non-free allocations, making them safe to delete
later.

Change-Id: I6c71cddbbd5dcaff1ad50f3991a3c710d4f96737
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

3 files changed, 22 insertions, 2 deletions

diff --git a/src/3rdparty/masm/stubs/ExecutableAllocator.h b/src/3rdparty/masm/stubs/ExecutableAllocator.h
index 4e3be7ca4a..a8f54df39f 100644
--- a/src/3rdparty/masm/stubs/ExecutableAllocator.h
+++ b/src/3rdparty/masm/stubs/ExecutableAllocator.h
@@ -67,7 +67,7 @@ struct ExecutableMemoryHandle : public RefCounted<ExecutableMemoryHandle> {
     }
     ~ExecutableMemoryHandle()
     {
-        m_allocator->free(m_allocation);
+        m_allocation->deallocate(m_allocator);
     }
 
     inline void shrink(size_t) {
diff --git a/src/qml/jsruntime/qv4executableallocator.cpp b/src/qml/jsruntime/qv4executableallocator.cpp
index 2e80f3a611..e539d62d54 100644
--- a/src/qml/jsruntime/qv4executableallocator.cpp
+++ b/src/qml/jsruntime/qv4executableallocator.cpp
@@ -52,6 +52,14 @@ void *ExecutableAllocator::Allocation::start() const
     return reinterpret_cast<void*>(addr);
 }
 
+void ExecutableAllocator::Allocation::deallocate(ExecutableAllocator *allocator)
+{
+    if (isValid())
+        allocator->free(this);
+    else
+        delete this;
+}
+
 ExecutableAllocator::Allocation *ExecutableAllocator::Allocation::split(size_t dividingSize)
 {
     Allocation *remainder = new Allocation;
@@ -117,7 +125,8 @@ ExecutableAllocator::ChunkOfPages::~ChunkOfPages()
     Allocation *alloc = firstAllocation;
     while (alloc) {
         Allocation *next = alloc->next;
-        delete alloc;
+        if (alloc->isValid())
+            delete alloc;
         alloc = next;
     }
     pages->deallocate();
@@ -142,6 +151,12 @@ ExecutableAllocator::ExecutableAllocator()
 
 ExecutableAllocator::~ExecutableAllocator()
 {
+    foreach (ChunkOfPages *chunk, chunks) {
+        for (Allocation *allocation = chunk->firstAllocation; allocation; allocation = allocation->next)
+            if (!allocation->free)
+                allocation->invalidate();
+    }
+
     qDeleteAll(chunks);
 }
 
diff --git a/src/qml/jsruntime/qv4executableallocator_p.h b/src/qml/jsruntime/qv4executableallocator_p.h
index feba5d7e3d..b4fb2fb0e5 100644
--- a/src/qml/jsruntime/qv4executableallocator_p.h
+++ b/src/qml/jsruntime/qv4executableallocator_p.h
@@ -81,8 +81,13 @@ public:
         {}
 
         void *start() const;
+        void invalidate() { addr = 0; }
+        bool isValid() const { return addr != 0; }
+        void deallocate(ExecutableAllocator *allocator);
 
     private:
+        ~Allocation() {}
+
         friend class ExecutableAllocator;
 
         Allocation *split(size_t dividingSize);