vulkan_memory_allocator: Add "download" memory usage hint

Allow users of the allocator to hint memory usage for downloads. This
removes the non-descriptive boolean passed for "host visible" or not
host visible memory commits, and uses an enum to hint device local,
upload and download usages.

2 files changed, 38 insertions, 10 deletions

diff --git a/src/video_core/vulkan_common/vulkan_memory_allocator.cpp b/src/video_core/vulkan_common/vulkan_memory_allocator.cpp
index c1cf292af..8bb15794d 100644
--- a/src/video_core/vulkan_common/vulkan_memory_allocator.cpp
+++ b/src/video_core/vulkan_common/vulkan_memory_allocator.cpp
@@ -156,11 +156,13 @@ MemoryAllocator::MemoryAllocator(const Device& device_)
 
 MemoryAllocator::~MemoryAllocator() = default;
 
-MemoryCommit MemoryAllocator::Commit(const VkMemoryRequirements& requirements, bool host_visible) {
+MemoryCommit MemoryAllocator::Commit(const VkMemoryRequirements& requirements, MemoryUsage usage) {
     const u64 chunk_size = GetAllocationChunkSize(requirements.size);
 
     // When a host visible commit is asked, search for host visible and coherent, otherwise search
     // for a fast device local type.
+    // TODO: Deduce memory types from usage in a better way
+    const bool host_visible = IsHostVisible(usage);
     const VkMemoryPropertyFlags wanted_properties =
         host_visible ? VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT
                      : VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT;
@@ -176,14 +178,14 @@ MemoryCommit MemoryAllocator::Commit(const VkMemoryRequirements& requirements, b
     return TryAllocCommit(requirements, wanted_properties).value();
 }
 
-MemoryCommit MemoryAllocator::Commit(const vk::Buffer& buffer, bool host_visible) {
-    auto commit = Commit(device.GetLogical().GetBufferMemoryRequirements(*buffer), host_visible);
+MemoryCommit MemoryAllocator::Commit(const vk::Buffer& buffer, MemoryUsage usage) {
+    auto commit = Commit(device.GetLogical().GetBufferMemoryRequirements(*buffer), usage);
     buffer.BindMemory(commit.Memory(), commit.Offset());
     return commit;
 }
 
-MemoryCommit MemoryAllocator::Commit(const vk::Image& image, bool host_visible) {
-    auto commit = Commit(device.GetLogical().GetImageMemoryRequirements(*image), host_visible);
+MemoryCommit MemoryAllocator::Commit(const vk::Image& image, MemoryUsage usage) {
+    auto commit = Commit(device.GetLogical().GetImageMemoryRequirements(*image), usage);
     image.BindMemory(commit.Memory(), commit.Offset());
     return commit;
 }
@@ -224,4 +226,16 @@ std::optional<MemoryCommit> MemoryAllocator::TryAllocCommit(
     return std::nullopt;
 }
 
+bool IsHostVisible(MemoryUsage usage) noexcept {
+    switch (usage) {
+    case MemoryUsage::DeviceLocal:
+        return false;
+    case MemoryUsage::Upload:
+    case MemoryUsage::Download:
+        return true;
+    }
+    UNREACHABLE_MSG("Invalid memory usage={}", usage);
+    return false;
+}
+
 } // namespace Vulkan
diff --git a/src/video_core/vulkan_common/vulkan_memory_allocator.h b/src/video_core/vulkan_common/vulkan_memory_allocator.h
index 69a6341e1..efb32167a 100644
--- a/src/video_core/vulkan_common/vulkan_memory_allocator.h
+++ b/src/video_core/vulkan_common/vulkan_memory_allocator.h
@@ -17,7 +17,16 @@ class Device;
 class MemoryMap;
 class MemoryAllocation;
 
-class MemoryCommit final {
+/// Hints and requirements for the backing memory type of a commit
+enum class MemoryUsage {
+    DeviceLocal, ///< Hints device local usages, fastest memory type to read and write from the GPU
+    Upload,      ///< Requires a host visible memory type optimized for CPU to GPU uploads
+    Download,    ///< Requires a host visible memory type optimized for GPU to CPU readbacks
+};
+
+/// Ownership handle of a memory commitment.
+/// Points to a subregion of a memory allocation.
+class MemoryCommit {
 public:
     explicit MemoryCommit() noexcept = default;
     explicit MemoryCommit(const Device& device_, MemoryAllocation* allocation_,
@@ -54,7 +63,9 @@ private:
     std::span<u8> span;             ///< Host visible memory span. Empty if not queried before.
 };
 
-class MemoryAllocator final {
+/// Memory allocator container.
+/// Allocates and releases memory allocations on demand.
+class MemoryAllocator {
 public:
     explicit MemoryAllocator(const Device& device_);
     ~MemoryAllocator();
@@ -71,13 +82,13 @@ public:
      *
      * @returns A memory commit.
      */
-    MemoryCommit Commit(const VkMemoryRequirements& requirements, bool host_visible);
+    MemoryCommit Commit(const VkMemoryRequirements& requirements, MemoryUsage usage);
 
     /// Commits memory required by the buffer and binds it.
-    MemoryCommit Commit(const vk::Buffer& buffer, bool host_visible);
+    MemoryCommit Commit(const vk::Buffer& buffer, MemoryUsage usage);
 
     /// Commits memory required by the image and binds it.
-    MemoryCommit Commit(const vk::Image& image, bool host_visible);
+    MemoryCommit Commit(const vk::Image& image, MemoryUsage usage);
 
 private:
     /// Allocates a chunk of memory.
@@ -92,4 +103,7 @@ private:
     std::vector<std::unique_ptr<MemoryAllocation>> allocations; ///< Current allocations.
 };
 
+/// Returns true when a memory usage is guaranteed to be host visible.
+bool IsHostVisible(MemoryUsage usage) noexcept;
+
 } // namespace Vulkan