Metal: Enable nonzero_clear_resources_on_creation_for_testing on buffer

This patch enables nonzero_clear_resources_on_creation_for_testing
toggle on buffer on Metal backends as a preparation of supporting buffer
lazy-initializations in Dawn.

BUG=dawn:414
TEST=dawn_end2end_tests

Change-Id: Ia7106482922aeb0521affa206f459d40938a0131
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/22861
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>

src/dawn_native/Buffer.h

@@ -39,6 +39,8 @@ namespace dawn_native {
         };
 
       public:
+        enum class ClearValue { Zero, NonZero };
+
         BufferBase(DeviceBase* device, const BufferDescriptor* descriptor);
 
         static BufferBase* MakeError(DeviceBase* device);

src/dawn_native/metal/BufferMTL.h

@@ -43,6 +43,8 @@ namespace dawn_native { namespace metal {
         bool IsMapWritable() const override;
         MaybeError MapAtCreationImpl(uint8_t** mappedPointer) override;
 
+        void ClearBuffer(BufferBase::ClearValue clearValue);
+
         id<MTLBuffer> mMtlBuffer = nil;
     };
 

src/dawn_native/metal/BufferMTL.mm

@@ -71,6 +71,10 @@ namespace dawn_native { namespace metal {
             return DAWN_OUT_OF_MEMORY_ERROR("Buffer allocation failed");
         }
 
+        if (GetDevice()->IsToggleEnabled(Toggle::NonzeroClearResourcesOnCreationForTesting)) {
+            ClearBuffer(BufferBase::ClearValue::NonZero);
+        }
+
         return {};
     }
 
@@ -113,4 +117,16 @@ namespace dawn_native { namespace metal {
         mMtlBuffer = nil;
     }
 
+    void Buffer::ClearBuffer(BufferBase::ClearValue clearValue) {
+        // TODO(jiawei.shao@intel.com): support buffer lazy-initialization to 0.
+        ASSERT(clearValue == BufferBase::ClearValue::NonZero);
+        const uint8_t clearBufferValue = 1;
+
+        Device* device = ToBackend(GetDevice());
+        CommandRecordingContext* commandContext = device->GetPendingCommandContext();
+        [commandContext->EnsureBlit() fillBuffer:mMtlBuffer
+                                           range:NSMakeRange(0, GetSize())
+                                           value:clearBufferValue];
+    }
+
 }}  // namespace dawn_native::metal

src/tests/BUILD.gn

@@ -277,6 +277,7 @@ source_set("dawn_end2end_tests_sources") {
     "end2end/GpuMemorySynchronizationTests.cpp",
     "end2end/IndexFormatTests.cpp",
     "end2end/MultisampledRenderingTests.cpp",
+    "end2end/NonzeroBufferCreationTests.cpp",
     "end2end/NonzeroTextureCreationTests.cpp",
     "end2end/ObjectCachingTests.cpp",
     "end2end/OpArrayLengthTests.cpp",

src/tests/end2end/NonzeroBufferCreationTests.cpp

@@ -0,0 +1,54 @@
+// 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 <vector>
+
+class NonzeroBufferCreationTests : public DawnTest {};
+
+// Verify that each byte of the buffer has all been initialized to 1 with the toggle enabled when it
+// is created with CopyDst usage.
+TEST_P(NonzeroBufferCreationTests, BufferCreationWithCopyDstUsage) {
+    constexpr uint32_t kSize = 32u;
+
+    wgpu::BufferDescriptor descriptor;
+    descriptor.size = kSize;
+    descriptor.usage = wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::CopyDst;
+
+    wgpu::Buffer buffer = device.CreateBuffer(&descriptor);
+
+    std::vector<uint8_t> expectedData(kSize, static_cast<uint8_t>(1u));
+    EXPECT_BUFFER_U32_RANGE_EQ(reinterpret_cast<uint32_t*>(expectedData.data()), buffer, 0,
+                               kSize / sizeof(uint32_t));
+}
+
+// Verify that each byte of the buffer has all been initialized to 1 with the toggle enabled when it
+// is created without CopyDst usage.
+TEST_P(NonzeroBufferCreationTests, BufferCreationWithoutCopyDstUsage) {
+    constexpr uint32_t kSize = 32u;
+
+    wgpu::BufferDescriptor descriptor;
+    descriptor.size = kSize;
+    descriptor.usage = wgpu::BufferUsage::MapWrite | wgpu::BufferUsage::CopySrc;
+
+    wgpu::Buffer buffer = device.CreateBuffer(&descriptor);
+
+    std::vector<uint8_t> expectedData(kSize, static_cast<uint8_t>(1u));
+    EXPECT_BUFFER_U32_RANGE_EQ(reinterpret_cast<uint32_t*>(expectedData.data()), buffer, 0,
+                               kSize / sizeof(uint32_t));
+}
+
+DAWN_INSTANTIATE_TEST(NonzeroBufferCreationTests,
+                      MetalBackend({"nonzero_clear_resources_on_creation_for_testing"}));