Emit warning if zero-size dispatch/draw

This CL make sure developers are warned when zero-size dispatches and
draws occur. Even though those are valid, it is good to encourage
developers to avoid them when possible.

Bug: dawn:1786
Change-Id: I99cbe8d556569d2e779b7b9c64739c3e5da8e290
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/132222
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Fr <beaufort.francois@gmail.com>

src/dawn/native/ComputePassEncoder.cpp

@@ -183,6 +183,12 @@ void ComputePassEncoder::APIDispatchWorkgroups(uint32_t workgroupCountX,
         this,
         [&](CommandAllocator* allocator) -> MaybeError {
             if (IsValidationEnabled()) {
+                if (workgroupCountX == 0 || workgroupCountY == 0 || workgroupCountZ == 0) {
+                    GetDevice()->EmitWarningOnce(absl::StrFormat(
+                        "Calling %s.DispatchWorkgroups with a workgroup count of 0 is unusual.",
+                        this));
+                }
+
                 DAWN_TRY(mCommandBufferState.ValidateCanDispatch());
 
                 uint32_t workgroupsPerDimension =

src/dawn/native/Device.cpp

@@ -1436,6 +1436,12 @@ void DeviceBase::EmitDeprecationWarning(const std::string& message) {
     }
 }
 
+void DeviceBase::EmitWarningOnce(const std::string& message) {
+    if (mWarnings.insert(message).second) {
+        this->EmitLog(WGPULoggingType_Warning, message.c_str());
+    }
+}
+
 void DeviceBase::EmitLog(const char* message) {
     this->EmitLog(WGPULoggingType_Info, message);
 }

src/dawn/native/Device.h

@@ -364,6 +364,7 @@ class DeviceBase : public RefCountedWithExternalCount {
     void IncrementLazyClearCountForTesting();
     size_t GetDeprecationWarningCountForTesting();
     void EmitDeprecationWarning(const std::string& warning);
+    void EmitWarningOnce(const std::string& message);
     void EmitLog(const char* message);
     void EmitLog(WGPULoggingType loggingType, const char* message);
     void APIForceLoss(wgpu::DeviceLostReason reason, const char* message);
@@ -597,6 +598,8 @@ class DeviceBase : public RefCountedWithExternalCount {
     struct DeprecationWarnings;
     std::unique_ptr<DeprecationWarnings> mDeprecationWarnings;
 
+    std::unordered_set<std::string> mWarnings;
+
     State mState = State::BeingCreated;
 
     PerObjectType<ApiObjectList> mObjectLists;

src/dawn/native/RenderEncoderBase.cpp

@@ -93,6 +93,15 @@ void RenderEncoderBase::APIDraw(uint32_t vertexCount,
         this,
         [&](CommandAllocator* allocator) -> MaybeError {
             if (IsValidationEnabled()) {
+                if (vertexCount == 0) {
+                    GetDevice()->EmitWarningOnce(absl::StrFormat(
+                        "Calling %s.Draw with a vertex count of 0 is unusual.", this));
+                }
+                if (instanceCount == 0) {
+                    GetDevice()->EmitWarningOnce(absl::StrFormat(
+                        "Calling %s.Draw with an instance count of 0 is unusual.", this));
+                }
+
                 DAWN_TRY(mCommandBufferState.ValidateCanDraw());
 
                 DAWN_INVALID_IF(mDisableBaseInstance && firstInstance != 0,
@@ -127,6 +136,15 @@ void RenderEncoderBase::APIDrawIndexed(uint32_t indexCount,
         this,
         [&](CommandAllocator* allocator) -> MaybeError {
             if (IsValidationEnabled()) {
+                if (indexCount == 0) {
+                    GetDevice()->EmitWarningOnce(absl::StrFormat(
+                        "Calling %s.Draw with an index count of 0 is unusual.", this));
+                }
+                if (instanceCount == 0) {
+                    GetDevice()->EmitWarningOnce(absl::StrFormat(
+                        "Calling %s.Draw with an instance count of 0 is unusual.", this));
+                }
+
                 DAWN_TRY(mCommandBufferState.ValidateCanDrawIndexed());
 
                 DAWN_INVALID_IF(mDisableBaseInstance && firstInstance != 0,