[dawn] Fix backends not consuming data of empty WriteBuffer commands

Fixed: 500090141
Change-Id: I3ceb070c59cc9c865c1d5bcc0451c80d25b50d4a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/304675
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Auto-Submit: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Loko Kung <lokokung@google.com>

src/dawn/native/Commands.cpp

diff --git a/src/dawn/native/Commands.cpp b/src/dawn/native/Commands.cpp
index 05d9afa..f131c97 100644
--- a/src/dawn/native/Commands.cpp
+++ b/src/dawn/native/Commands.cpp
@@ -422,9 +422,7 @@
 
         case Command::WriteBuffer: {
             auto cmd = commands->NextCommand<WriteBufferCmd>();
-            if (cmd->size > 0) {
-                commands->NextData<uint8_t>(cmd->size);
-            }
+            commands->NextData<uint8_t>(cmd->size);
             break;
         }
 

src/dawn/native/d3d11/CommandBufferD3D11.cpp

diff --git a/src/dawn/native/d3d11/CommandBufferD3D11.cpp b/src/dawn/native/d3d11/CommandBufferD3D11.cpp
index ee935cd..c74bb8e 100644
--- a/src/dawn/native/d3d11/CommandBufferD3D11.cpp
+++ b/src/dawn/native/d3d11/CommandBufferD3D11.cpp
@@ -502,6 +502,8 @@
 
             case Command::WriteBuffer: {
                 WriteBufferCmd* cmd = mCommands.NextCommand<WriteBufferCmd>();
+                uint8_t* data = mCommands.NextData<uint8_t>(cmd->size);
+
                 if (cmd->size == 0) {
                     // Skip no-op writes.
                     continue;
@@ -509,7 +511,6 @@
 
                 Buffer* dstBuffer = ToBackend(cmd->buffer.Get());
                 DAWN_TRY(dstBuffer->TrackUsage(commandContext, pendingSerial));
-                uint8_t* data = mCommands.NextData<uint8_t>(cmd->size);
                 DAWN_TRY(dstBuffer->Write(commandContext, cmd->offset, data, cmd->size));
 
                 break;

src/dawn/native/d3d12/CommandBufferD3D12.cpp

diff --git a/src/dawn/native/d3d12/CommandBufferD3D12.cpp b/src/dawn/native/d3d12/CommandBufferD3D12.cpp
index 2d6c6b4..28f9822 100644
--- a/src/dawn/native/d3d12/CommandBufferD3D12.cpp
+++ b/src/dawn/native/d3d12/CommandBufferD3D12.cpp
@@ -1389,12 +1389,13 @@
                 WriteBufferCmd* write = mCommands.NextCommand<WriteBufferCmd>();
                 const uint64_t offset = write->offset;
                 const uint64_t size = write->size;
+                uint8_t* data = mCommands.NextData<uint8_t>(size);
+
                 if (size == 0) {
                     continue;
                 }
 
                 Buffer* dstBuffer = ToBackend(write->buffer.Get());
-                uint8_t* data = mCommands.NextData<uint8_t>(size);
 
                 DAWN_TRY(device->GetDynamicUploader()->WithUploadReservation(
                     size, kCopyBufferToBufferOffsetAlignment,

src/dawn/native/metal/CommandBufferMTL.mm

diff --git a/src/dawn/native/metal/CommandBufferMTL.mm b/src/dawn/native/metal/CommandBufferMTL.mm
index a8db888..ed8b4a4 100644
--- a/src/dawn/native/metal/CommandBufferMTL.mm
+++ b/src/dawn/native/metal/CommandBufferMTL.mm
@@ -1513,12 +1513,13 @@
                 WriteBufferCmd* write = mCommands.NextCommand<WriteBufferCmd>();
                 const uint64_t offset = write->offset;
                 const uint64_t size = write->size;
+                uint8_t* data = mCommands.NextData<uint8_t>(size);
+
                 if (size == 0) {
                     continue;
                 }
 
                 Buffer* dstBuffer = ToBackend(write->buffer.Get());
-                uint8_t* data = mCommands.NextData<uint8_t>(size);
                 Device* device = ToBackend(GetDevice());
 
                 DAWN_TRY(device->GetDynamicUploader()->WithUploadReservation(

src/dawn/native/opengl/CommandBufferGL.cpp

diff --git a/src/dawn/native/opengl/CommandBufferGL.cpp b/src/dawn/native/opengl/CommandBufferGL.cpp
index 06d2d6b..6d14648 100644
--- a/src/dawn/native/opengl/CommandBufferGL.cpp
+++ b/src/dawn/native/opengl/CommandBufferGL.cpp
@@ -1139,12 +1139,13 @@
                 WriteBufferCmd* write = mCommands.NextCommand<WriteBufferCmd>();
                 uint64_t offset = write->offset;
                 uint64_t size = write->size;
+                uint8_t* data = mCommands.NextData<uint8_t>(size);
+
                 if (size == 0) {
                     continue;
                 }
 
                 Buffer* dstBuffer = ToBackend(write->buffer.Get());
-                uint8_t* data = mCommands.NextData<uint8_t>(size);
                 DAWN_TRY(dstBuffer->EnsureDataInitializedAsDestination(offset, size));
 
                 DAWN_GL_TRY(gl, BindBuffer(GL_ARRAY_BUFFER, dstBuffer->GetHandle()));

src/dawn/native/vulkan/CommandBufferVk.cpp

diff --git a/src/dawn/native/vulkan/CommandBufferVk.cpp b/src/dawn/native/vulkan/CommandBufferVk.cpp
index f726da9..60438f4 100644
--- a/src/dawn/native/vulkan/CommandBufferVk.cpp
+++ b/src/dawn/native/vulkan/CommandBufferVk.cpp
@@ -1455,12 +1455,13 @@
                 WriteBufferCmd* write = mCommands.NextCommand<WriteBufferCmd>();
                 const uint64_t offset = write->offset;
                 const uint64_t size = write->size;
+                uint8_t* data = mCommands.NextData<uint8_t>(size);
+
                 if (size == 0) {
                     continue;
                 }
 
                 Buffer* dstBuffer = ToBackend(write->buffer.Get());
-                uint8_t* data = mCommands.NextData<uint8_t>(size);
 
                 DAWN_TRY(device->GetDynamicUploader()->WithUploadReservation(
                     size, kCopyBufferToBufferOffsetAlignment,

src/dawn/tests/end2end/CommandEncoderTests.cpp

diff --git a/src/dawn/tests/end2end/CommandEncoderTests.cpp b/src/dawn/tests/end2end/CommandEncoderTests.cpp
index 94be114..258f5ae 100644
--- a/src/dawn/tests/end2end/CommandEncoderTests.cpp
+++ b/src/dawn/tests/end2end/CommandEncoderTests.cpp
@@ -61,6 +61,21 @@
     EXPECT_BUFFER_U32_EQ(0, bufferC, 3 * sizeof(uint32_t));
 }
 
+// Tests an empty WriteBuffer commands.
+TEST_P(CommandEncoderTests, EmptyWriteBuffer) {
+    wgpu::Buffer buffer =
+        utils::CreateBufferFromData(device, wgpu::BufferUsage::CopyDst | wgpu::BufferUsage::CopySrc,
+                                    {
+                                        42,
+                                    });
+
+    wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+    encoder.WriteBuffer(buffer, 0, nullptr, 0);
+    wgpu::CommandBuffer commands = encoder.Finish();
+    queue.Submit(1, &commands);
+
+    EXPECT_BUFFER_U32_EQ(42, buffer, 0);
+}
 DAWN_INSTANTIATE_TEST(CommandEncoderTests,
                       D3D11Backend(),
                       D3D12Backend(),