Support for small resource placement.

Enables use of 4KB resource alignments where permitted.
This saves heap memory (4KB vs 64KB per allocation) and improves re-use.

BUG=dawn:27

Change-Id: I7a0a30252f480db2d0fa7f5d949207a56e3aa2e9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/12900
Commit-Queue: Bryan Bernhart <bryan.bernhart@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/tests/white_box/D3D12SmallTextureTests.cpp

@@ -0,0 +1,75 @@
+// Copyright 2019 The Dawn Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "tests/DawnTest.h"
+
+#include "dawn_native/d3d12/TextureD3D12.h"
+
+using namespace dawn_native::d3d12;
+
+class D3D12SmallTextureTests : public DawnTest {
+  protected:
+    std::vector<const char*> GetRequiredExtensions() override {
+        mIsBCFormatSupported = SupportsExtensions({"texture_compression_bc"});
+        if (!mIsBCFormatSupported) {
+            return {};
+        }
+
+        return {"texture_compression_bc"};
+    }
+
+    bool IsBCFormatSupported() const {
+        return mIsBCFormatSupported;
+    }
+
+  private:
+    bool mIsBCFormatSupported = false;
+};
+
+// Verify that creating a small compressed textures will be 4KB aligned.
+TEST_P(D3D12SmallTextureTests, AlignSmallCompressedTexture) {
+    DAWN_SKIP_TEST_IF(UsesWire());
+    DAWN_SKIP_TEST_IF(!IsBCFormatSupported());
+    DAWN_SKIP_TEST_IF(IsIntel());
+
+    wgpu::TextureDescriptor descriptor;
+    descriptor.dimension = wgpu::TextureDimension::e2D;
+    descriptor.size.width = 8;
+    descriptor.size.height = 8;
+    descriptor.size.depth = 1;
+    descriptor.arrayLayerCount = 1;
+    descriptor.sampleCount = 1;
+    descriptor.format = wgpu::TextureFormat::BC1RGBAUnorm;
+    descriptor.mipLevelCount = 1;
+    descriptor.usage = wgpu::TextureUsage::Sampled;
+
+    // Create a smaller one that allows use of the smaller alignment.
+    wgpu::Texture texture = device.CreateTexture(&descriptor);
+    Texture* d3dTexture = reinterpret_cast<Texture*>(texture.Get());
+
+    EXPECT_EQ(d3dTexture->GetD3D12Resource()->GetDesc().Alignment,
+              static_cast<uint64_t>(D3D12_SMALL_RESOURCE_PLACEMENT_ALIGNMENT));
+
+    // Create a larger one (>64KB) that forbids use the smaller alignment.
+    descriptor.size.width = 4096;
+    descriptor.size.height = 4096;
+
+    texture = device.CreateTexture(&descriptor);
+    d3dTexture = reinterpret_cast<Texture*>(texture.Get());
+
+    EXPECT_EQ(d3dTexture->GetD3D12Resource()->GetDesc().Alignment,
+              static_cast<uint64_t>(D3D12_DEFAULT_RESOURCE_PLACEMENT_ALIGNMENT));
+}
+
+DAWN_INSTANTIATE_TEST(D3D12SmallTextureTests, D3D12Backend);