Add option to pad resource heaps.

src/gpgmm/d3d12/ResourceAllocatorD3D12.cpp

@@ -770,11 +770,13 @@ namespace gpgmm::d3d12 {
             isAlwaysCommitted = true;
         }
 
-        const bool neverSubAllocate =
+        bool neverSubAllocate =
             allocationDescriptor.Flags & ALLOCATION_FLAG_NEVER_SUBALLOCATE_MEMORY;
 
         const bool isMSAA = resourceDescriptor.SampleDesc.Count > 1;
 
+        const bool requiresPadding = allocationDescriptor.RequireResourceHeapPadding > 0;
+
         // Attempt to allocate using the most effective allocator.;
         MemoryAllocator* allocator = nullptr;
 
@@ -795,6 +797,16 @@ namespace gpgmm::d3d12 {
         request.AlwaysCacheSize = (allocationDescriptor.Flags & ALLOCATION_FLAG_ALWAYS_CACHE_SIZE);
         request.AvailableForAllocation = mCaps->GetMaxResourceHeapSize();
 
+        // Apply extra padding to the resource heap size, if specified.
+        // Padding can only be applied to standalone non-committed resources.
+        if (GPGMM_UNLIKELY(requiresPadding)) {
+            request.SizeInBytes += allocationDescriptor.RequireResourceHeapPadding;
+            if (!neverSubAllocate) {
+                DebugLog() << "Sub-allocation disabled when padding is requested.";
+                neverSubAllocate = true;
+            }
+        }
+
         // Limit available memory to unused budget when residency is enabled.
         if (mResidencyManager != nullptr) {
             const DXGI_MEMORY_SEGMENT_GROUP segment =
@@ -958,6 +970,12 @@ namespace gpgmm::d3d12 {
             return E_OUTOFMEMORY;
         }
 
+        // Committed resources cannot specify resource heap size.
+        if (GPGMM_UNLIKELY(requiresPadding)) {
+            ErrorLog() << "A padding was specified but no resource allocator could be used.";
+            return E_FAIL;
+        }
+
         if (!isAlwaysCommitted) {
             InfoEvent(GetTypename(), EventMessageId::AllocatorFailed)
                 << "Unable to allocate by using a heap, falling back to a committed resource.";

src/gpgmm/d3d12/ResourceAllocatorD3D12.h

@@ -335,6 +335,18 @@ namespace gpgmm::d3d12 {
         */
         D3D12_HEAP_FLAGS ExtraRequiredHeapFlags = D3D12_HEAP_FLAG_NONE;
 
+        /** \brief Require additional bytes to be appended to the resource allocation.
+
+        Resource heap size is guarenteed to increase by at-least this number of bytes.
+        Specifying a padding will disable committed resources and sub-allocated
+        heaps.
+
+        Used to workaround driver bugs related to the heap size being insufficent for the resource.
+
+        Optional parameter. No extra padding is applied by default.
+        */
+        uint64_t RequireResourceHeapPadding = 0;
+
         /** \brief Associates a name with the given allocation.
 
         Optional parameter. By default, no name is associated.

src/tests/end2end/D3D12ResourceAllocatorTests.cpp

@@ -1320,6 +1320,61 @@ TEST_F(D3D12ResourceAllocatorTests, CreateBufferCacheSize) {
     }
 }
 
+// Verify two buffers, with and without padding, allocate the correct size.
+TEST_F(D3D12ResourceAllocatorTests, CreateBufferWithPadding) {
+    ComPtr<ResourceAllocator> resourceAllocator;
+    ASSERT_SUCCEEDED(
+        ResourceAllocator::CreateAllocator(CreateBasicAllocatorDesc(), &resourceAllocator));
+    ASSERT_NE(resourceAllocator, nullptr);
+
+    constexpr uint64_t kBufferSize = GPGMM_MB_TO_BYTES(1);
+
+    ALLOCATION_DESC allocationDesc = {};
+    ComPtr<ResourceAllocation> allocationWithoutPadding;
+    ASSERT_SUCCEEDED(resourceAllocator->CreateResource(
+        allocationDesc, CreateBasicBufferDesc(kBufferSize), D3D12_RESOURCE_STATE_GENERIC_READ,
+        nullptr, &allocationWithoutPadding));
+
+    allocationDesc.RequireResourceHeapPadding = 63;
+    ComPtr<ResourceAllocation> allocationWithPadding;
+    ASSERT_SUCCEEDED(resourceAllocator->CreateResource(
+        allocationDesc, CreateBasicBufferDesc(kBufferSize), D3D12_RESOURCE_STATE_GENERIC_READ,
+        nullptr, &allocationWithPadding));
+
+    EXPECT_GE(allocationWithPadding->GetSize() - allocationWithoutPadding->GetSize(),
+              allocationDesc.RequireResourceHeapPadding);
+
+    // Padded resources are only supported for standalone allocations.
+    EXPECT_EQ(allocationWithPadding->GetMethod(), gpgmm::AllocationMethod::kStandalone);
+}
+
+// Verify two textures, with and without padding, allocate the correct size.
+TEST_F(D3D12ResourceAllocatorTests, CreateTextureWithPadding) {
+    ComPtr<ResourceAllocator> resourceAllocator;
+    ASSERT_SUCCEEDED(
+        ResourceAllocator::CreateAllocator(CreateBasicAllocatorDesc(), &resourceAllocator));
+    ASSERT_NE(resourceAllocator, nullptr);
+
+    ALLOCATION_DESC allocationDesc = {};
+
+    ComPtr<ResourceAllocation> allocationWithoutPadding;
+    ASSERT_SUCCEEDED(resourceAllocator->CreateResource(
+        allocationDesc, CreateBasicTextureDesc(DXGI_FORMAT_R8G8B8A8_UNORM, 1, 1),
+        D3D12_RESOURCE_STATE_GENERIC_READ, nullptr, &allocationWithoutPadding));
+
+    allocationDesc.RequireResourceHeapPadding = 63;
+    ComPtr<ResourceAllocation> allocationWithPadding;
+    ASSERT_SUCCEEDED(resourceAllocator->CreateResource(
+        allocationDesc, CreateBasicTextureDesc(DXGI_FORMAT_R8G8B8A8_UNORM, 1, 1),
+        D3D12_RESOURCE_STATE_GENERIC_READ, nullptr, &allocationWithPadding));
+
+    EXPECT_GE(allocationWithPadding->GetSize() - allocationWithoutPadding->GetSize(),
+              allocationDesc.RequireResourceHeapPadding);
+
+    // Padded resources are only supported for standalone allocations.
+    EXPECT_EQ(allocationWithPadding->GetMethod(), gpgmm::AllocationMethod::kStandalone);
+}
+
 TEST_F(D3D12ResourceAllocatorTests, CheckFeatureSupport) {
     ComPtr<ResourceAllocator> resourceAllocator;
     ASSERT_SUCCEEDED(