Vulkan: unbacked sparse images for textures too large to back

Title 1 samples an 8192x8192, 12-level, 68-layer array (a sparse virtual
texture, ~23 GB): vkCreateImage failed and Eden aborted, or VMA put it in
system memory and staged a full upload (34 GB private). Images over 2^28
texels are now created sparse-resident with no memory bound; the texture
cache neither uploads nor downloads them. Images merely over the VRAM
budget are allocated without the budget limit instead of failing.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/video_core/vulkan_common/vulkan_wrapper.h b/src/video_core/vulkan_common/vulkan_wrapper.h
index 97d2ba3700..947150648d 100644
--- a/src/video_core/vulkan_common/vulkan_wrapper.h
+++ b/src/video_core/vulkan_common/vulkan_wrapper.h
@@ -689,6 +689,11 @@ public:
           allocation{allocation_}, dld{&dld_} {}
     Image() = default;
 
+    /// True for an image created without memory (an unbacked sparse image).
+    bool IsUnbacked() const noexcept {
+        return handle != VK_NULL_HANDLE && allocation == VK_NULL_HANDLE;
+    }
+
     Image(const Image&) = delete;
     Image& operator=(const Image&) = delete;