Cycles: Fix guarded allocator issues on Windows

The issue was caused by static vectors allocating some internal
data using rebound element allocator for them, which was causing
access to a non-initialized statistics objects and was failing a
lot when switching Blender to a fully guarded allocation.

Additionally, we were not able to free that internal memory before
Blender exits, which was causing false-positive memory leak prints.

Now we're not using GuardedAllocator for those proxy containers.

Ideally this should be done as a GuardedAllocator::rebind, but
it didn't work for vector<bool> because it seems some internal
parts are converting bool to char32_t, which either makes it so
we can't use GuardedAllocator for those vectors or the compiler
get's confused when we're trying explicitly allow GuardedAllocator
for rebind<char32_t>.

This with current approach we should be fine for the release.

1 files changed, 28 insertions, 0 deletions

diff --git a/intern/cycles/util/util_guarded_allocator.h b/intern/cycles/util/util_guarded_allocator.h
index 484aa3a8cce..ad1eb6f657f 100644
--- a/intern/cycles/util/util_guarded_allocator.h
+++ b/intern/cycles/util/util_guarded_allocator.h
@@ -123,6 +123,34 @@ public:
 
 	inline bool operator==(GuardedAllocator const& /*other*/) { return true; }
 	inline bool operator!=(GuardedAllocator const& other) { return !operator==(other); }
+
+#ifdef _MSC_VER
+	/* Welcome to the black magic here.
+	 *
+	 * The issue is that MSVC C++ allocates container proxy on any
+	 * vector initialization, including static vectors which don't
+	 * have any data yet. This leads to several issues:
+	 *
+	 * - Static objects initialization fiasco (global_stats from
+	 *   util_stats.h might not be initialized yet).
+	 * - If main() function changes allocator type (for example,
+	 *   this might happen with `blender --debug-memory`) nobody
+	 *   will know how to convert already allocated memory to a new
+	 *   guarded allocator.
+	 *
+	 * Here we work this around by making it so container proxy does
+	 * not use guarded allocation. A bit fragile, unfortunately.
+	 */
+	template<>
+	struct rebind<std::_Container_proxy> {
+		typedef std::allocator<std::_Container_proxy> other;
+	};
+
+	operator std::allocator<std::_Container_proxy>() const
+	{
+		return std::allocator<std::_Container_proxy>();
+	}
+#endif
 };
 
 /* Get memory usage and peak from the guarded STL allocator. */