src/dawn_native/BindGroup.cpp - dawn - Git at Google

 // Copyright 2017 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 "dawn_native/BindGroup.h"

 #include "common/Assert.h"
 #include "common/Math.h"
 #include "common/ityp_bitset.h"
 #include "dawn_native/BindGroupLayout.h"
 #include "dawn_native/Buffer.h"
 #include "dawn_native/ChainUtils_autogen.h"
 #include "dawn_native/Device.h"
 #include "dawn_native/ExternalTexture.h"
 #include "dawn_native/Sampler.h"
 #include "dawn_native/Texture.h"

 namespace dawn_native {

     namespace {

         // Helper functions to perform binding-type specific validation

         MaybeError ValidateBufferBinding(const DeviceBase* device,
                                          const BindGroupEntry& entry,
                                          const BindingInfo& bindingInfo) {
             if (entry.buffer == nullptr || entry.sampler != nullptr ||
                 entry.textureView != nullptr || entry.nextInChain != nullptr) {
                 return DAWN_VALIDATION_ERROR("Expected buffer binding");
             }
             DAWN_TRY(device->ValidateObject(entry.buffer));

             ASSERT(bindingInfo.bindingType == BindingInfoType::Buffer);

             wgpu::BufferUsage requiredUsage;
             uint64_t maxBindingSize;
             switch (bindingInfo.buffer.type) {
                 case wgpu::BufferBindingType::Uniform:
                     requiredUsage = wgpu::BufferUsage::Uniform;
                     maxBindingSize = kMaxUniformBufferBindingSize;
                     break;
                 case wgpu::BufferBindingType::Storage:
                 case wgpu::BufferBindingType::ReadOnlyStorage:
                     requiredUsage = wgpu::BufferUsage::Storage;
                     maxBindingSize = std::numeric_limits<uint64_t>::max();
                     break;
                 case wgpu::BufferBindingType::Undefined:
                     UNREACHABLE();
             }

             uint64_t bufferSize = entry.buffer->GetSize();

             // Handle wgpu::WholeSize, avoiding overflows.
             if (entry.offset > bufferSize) {
                 return DAWN_VALIDATION_ERROR("Buffer binding doesn't fit in the buffer");
             }
             uint64_t bindingSize =
                 (entry.size == wgpu::kWholeSize) ? bufferSize - entry.offset : entry.size;

             if (bindingSize > bufferSize) {
                 return DAWN_VALIDATION_ERROR("Buffer binding size larger than the buffer");
             }

             if (bindingSize == 0) {
                 return DAWN_VALIDATION_ERROR("Buffer binding size cannot be zero.");
             }

             // Note that no overflow can happen because we already checked that
             // bufferSize >= bindingSize
             if (entry.offset > bufferSize - bindingSize) {
                 return DAWN_VALIDATION_ERROR("Buffer binding doesn't fit in the buffer");
             }

             if (!IsAligned(entry.offset, 256)) {
                 return DAWN_VALIDATION_ERROR(
                     "Buffer offset for bind group needs to be 256-byte aligned");
             }

             if (!(entry.buffer->GetUsage() & requiredUsage)) {
                 return DAWN_VALIDATION_ERROR("buffer binding usage mismatch");
             }

             if (bindingSize < bindingInfo.buffer.minBindingSize) {
                 return DAWN_VALIDATION_ERROR(
                     "Binding size smaller than minimum buffer size: binding " +
                     std::to_string(entry.binding) + " given " + std::to_string(bindingSize) +
                     " bytes, required " + std::to_string(bindingInfo.buffer.minBindingSize) +
                     " bytes");
             }

             if (bindingSize > maxBindingSize) {
                 return DAWN_VALIDATION_ERROR(
                     "Binding size bigger than maximum uniform buffer binding size: binding " +
                     std::to_string(entry.binding) + " given " + std::to_string(bindingSize) +
                     " bytes, maximum is " + std::to_string(kMaxUniformBufferBindingSize) +
                     " bytes");
             }

             return {};
         }

         MaybeError ValidateTextureBinding(const DeviceBase* device,
                                           const BindGroupEntry& entry,
                                           const BindingInfo& bindingInfo) {
             if (entry.textureView == nullptr || entry.sampler != nullptr ||
                 entry.buffer != nullptr || entry.nextInChain != nullptr) {
                 return DAWN_VALIDATION_ERROR("Expected texture binding");
             }
             DAWN_TRY(device->ValidateObject(entry.textureView));

             TextureViewBase* view = entry.textureView;

             Aspect aspect = view->GetAspects();
             if (!HasOneBit(aspect)) {
                 return DAWN_VALIDATION_ERROR("Texture view must select a single aspect");
             }

             TextureBase* texture = view->GetTexture();
             switch (bindingInfo.bindingType) {
                 case BindingInfoType::Texture: {
                     ComponentTypeBit supportedTypes =
                         texture->GetFormat().GetAspectInfo(aspect).supportedComponentTypes;
                     ComponentTypeBit requiredType =
                         SampleTypeToComponentTypeBit(bindingInfo.texture.sampleType);

                     if (!(texture->GetUsage() & wgpu::TextureUsage::Sampled)) {
                         return DAWN_VALIDATION_ERROR("Texture binding usage mismatch");
                     }

                     if (texture->IsMultisampledTexture() != bindingInfo.texture.multisampled) {
                         return DAWN_VALIDATION_ERROR("Texture multisampling mismatch");
                     }

                     if ((supportedTypes & requiredType) == 0) {
                         return DAWN_VALIDATION_ERROR("Texture component type usage mismatch");
                     }

                     if (entry.textureView->GetDimension() != bindingInfo.texture.viewDimension) {
                         return DAWN_VALIDATION_ERROR("Texture view dimension mismatch");
                     }
                     break;
                 }
                 case BindingInfoType::StorageTexture: {
                     ASSERT(!texture->IsMultisampledTexture());

                     if (!(texture->GetUsage() & wgpu::TextureUsage::Storage)) {
                         return DAWN_VALIDATION_ERROR("Storage Texture binding usage mismatch");
                     }

                     if (texture->GetFormat().format != bindingInfo.storageTexture.format) {
                         return DAWN_VALIDATION_ERROR("Storage texture format mismatch");
                     }
                     if (entry.textureView->GetDimension() !=
                         bindingInfo.storageTexture.viewDimension) {
                         return DAWN_VALIDATION_ERROR("Storage texture view dimension mismatch");
                     }
                     break;
                 }
                 default:
                     UNREACHABLE();
                     break;
             }

             return {};
         }

         MaybeError ValidateSamplerBinding(const DeviceBase* device,
                                           const BindGroupEntry& entry,
                                           const BindingInfo& bindingInfo) {
             if (entry.sampler == nullptr || entry.textureView != nullptr ||
                 entry.buffer != nullptr || entry.nextInChain != nullptr) {
                 return DAWN_VALIDATION_ERROR("Expected sampler binding");
             }
             DAWN_TRY(device->ValidateObject(entry.sampler));

             ASSERT(bindingInfo.bindingType == BindingInfoType::Sampler);

             switch (bindingInfo.sampler.type) {
                 case wgpu::SamplerBindingType::Filtering:
                 case wgpu::SamplerBindingType::NonFiltering:
                     if (entry.sampler->HasCompareFunction()) {
                         return DAWN_VALIDATION_ERROR("Did not expect comparison sampler");
                     }
                     break;
                 case wgpu::SamplerBindingType::Comparison:
                     if (!entry.sampler->HasCompareFunction()) {
                         return DAWN_VALIDATION_ERROR("Expected comparison sampler");
                     }
                     break;
                 default:
                     UNREACHABLE();
                     break;
             }

             return {};
         }

         MaybeError ValidateExternalTextureBinding(const DeviceBase* device,
                                                   const BindGroupEntry& entry,
                                                   const BindingInfo& bindingInfo) {
             const ExternalTextureBindingEntry* externalTextureBindingEntry = nullptr;
             FindInChain(entry.nextInChain, &externalTextureBindingEntry);

             if (entry.sampler != nullptr || entry.textureView != nullptr ||
                 entry.buffer != nullptr || externalTextureBindingEntry == nullptr) {
                 return DAWN_VALIDATION_ERROR("Expected external texture binding");
             }

             DAWN_TRY(ValidateSingleSType(externalTextureBindingEntry->nextInChain,
                                          wgpu::SType::ExternalTextureBindingEntry));

             DAWN_TRY(device->ValidateObject(externalTextureBindingEntry->externalTexture));

             return {};
         }

     }  // anonymous namespace

     MaybeError ValidateBindGroupDescriptor(DeviceBase* device,
                                            const BindGroupDescriptor* descriptor) {
         if (descriptor->nextInChain != nullptr) {
             return DAWN_VALIDATION_ERROR("nextInChain must be nullptr");
         }

         DAWN_TRY(device->ValidateObject(descriptor->layout));

         if (BindingIndex(descriptor->entryCount) != descriptor->layout->GetBindingCount()) {
             return DAWN_VALIDATION_ERROR("numBindings mismatch");
         }

         const BindGroupLayoutBase::BindingMap& bindingMap = descriptor->layout->GetBindingMap();
         ASSERT(bindingMap.size() <= kMaxBindingsPerPipelineLayout);

         ityp::bitset<BindingIndex, kMaxBindingsPerPipelineLayout> bindingsSet;
         for (uint32_t i = 0; i < descriptor->entryCount; ++i) {
             const BindGroupEntry& entry = descriptor->entries[i];

             const auto& it = bindingMap.find(BindingNumber(entry.binding));
             if (it == bindingMap.end()) {
                 return DAWN_VALIDATION_ERROR("setting non-existent binding");
             }
             BindingIndex bindingIndex = it->second;
             ASSERT(bindingIndex < descriptor->layout->GetBindingCount());

             if (bindingsSet[bindingIndex]) {
                 return DAWN_VALIDATION_ERROR("binding set twice");
             }
             bindingsSet.set(bindingIndex);

             const BindingInfo& bindingInfo = descriptor->layout->GetBindingInfo(bindingIndex);

             // Perform binding-type specific validation.
             switch (bindingInfo.bindingType) {
                 case BindingInfoType::Buffer:
                     DAWN_TRY(ValidateBufferBinding(device, entry, bindingInfo));
                     break;
                 case BindingInfoType::Texture:
                 case BindingInfoType::StorageTexture:
                     DAWN_TRY(ValidateTextureBinding(device, entry, bindingInfo));
                     break;
                 case BindingInfoType::Sampler:
                     DAWN_TRY(ValidateSamplerBinding(device, entry, bindingInfo));
                     break;
                 case BindingInfoType::ExternalTexture:
                     DAWN_TRY(ValidateExternalTextureBinding(device, entry, bindingInfo));
                     break;
             }
         }

         // This should always be true because
         //  - numBindings has to match between the bind group and its layout.
         //  - Each binding must be set at most once
         //
         // We don't validate the equality because it wouldn't be possible to cover it with a test.
         ASSERT(bindingsSet.count() == bindingMap.size());

         return {};
     }  // anonymous namespace

     // BindGroup

     BindGroupBase::BindGroupBase(DeviceBase* device,
                                  const BindGroupDescriptor* descriptor,
                                  void* bindingDataStart)
         : ObjectBase(device),
           mLayout(descriptor->layout),
           mBindingData(mLayout->ComputeBindingDataPointers(bindingDataStart)) {
         for (BindingIndex i{0}; i < mLayout->GetBindingCount(); ++i) {
             // TODO(enga): Shouldn't be needed when bindings are tightly packed.
             // This is to fill Ref<ObjectBase> holes with nullptrs.
             new (&mBindingData.bindings[i]) Ref<ObjectBase>();
         }

         for (uint32_t i = 0; i < descriptor->entryCount; ++i) {
             const BindGroupEntry& entry = descriptor->entries[i];

             BindingIndex bindingIndex =
                 descriptor->layout->GetBindingIndex(BindingNumber(entry.binding));
             ASSERT(bindingIndex < mLayout->GetBindingCount());

             // Only a single binding type should be set, so once we found it we can skip to the
             // next loop iteration.

             if (entry.buffer != nullptr) {
                 ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
                 mBindingData.bindings[bindingIndex] = entry.buffer;
                 mBindingData.bufferData[bindingIndex].offset = entry.offset;
                 uint64_t bufferSize = (entry.size == wgpu::kWholeSize)
                                           ? entry.buffer->GetSize() - entry.offset
                                           : entry.size;
                 mBindingData.bufferData[bindingIndex].size = bufferSize;
                 continue;
             }

             if (entry.textureView != nullptr) {
                 ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
                 mBindingData.bindings[bindingIndex] = entry.textureView;
                 continue;
             }

             if (entry.sampler != nullptr) {
                 ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
                 mBindingData.bindings[bindingIndex] = entry.sampler;
                 continue;
             }

             const ExternalTextureBindingEntry* externalTextureBindingEntry = nullptr;
             FindInChain(entry.nextInChain, &externalTextureBindingEntry);
             if (externalTextureBindingEntry != nullptr) {
                 ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
                 mBindingData.bindings[bindingIndex] = externalTextureBindingEntry->externalTexture;
                 continue;
             }
         }

         uint32_t packedIdx = 0;
         for (BindingIndex bindingIndex{0}; bindingIndex < descriptor->layout->GetBufferCount();
              ++bindingIndex) {
             if (descriptor->layout->GetBindingInfo(bindingIndex).buffer.minBindingSize == 0) {
                 mBindingData.unverifiedBufferSizes[packedIdx] =
                     mBindingData.bufferData[bindingIndex].size;
                 ++packedIdx;
             }
         }
     }

     BindGroupBase::~BindGroupBase() {
         if (mLayout != nullptr) {
             ASSERT(!IsError());
             for (BindingIndex i{0}; i < mLayout->GetBindingCount(); ++i) {
                 mBindingData.bindings[i].~Ref<ObjectBase>();
             }
         }
     }

     void BindGroupBase::DeleteThis() {
         // Add another ref to the layout so that if this is the last ref, the layout
         // is destroyed after the bind group. The bind group is slab-allocated inside
         // memory owned by the layout (except for the null backend).
         Ref<BindGroupLayoutBase> layout = mLayout;
         RefCounted::DeleteThis();
     }

     BindGroupBase::BindGroupBase(DeviceBase* device, ObjectBase::ErrorTag tag)
         : ObjectBase(device, tag), mBindingData() {
     }

     // static
     BindGroupBase* BindGroupBase::MakeError(DeviceBase* device) {
         return new BindGroupBase(device, ObjectBase::kError);
     }

     BindGroupLayoutBase* BindGroupBase::GetLayout() {
         ASSERT(!IsError());
         return mLayout.Get();
     }

     const BindGroupLayoutBase* BindGroupBase::GetLayout() const {
         ASSERT(!IsError());
         return mLayout.Get();
     }

     const ityp::span<uint32_t, uint64_t>& BindGroupBase::GetUnverifiedBufferSizes() const {
         ASSERT(!IsError());
         return mBindingData.unverifiedBufferSizes;
     }

     BufferBinding BindGroupBase::GetBindingAsBufferBinding(BindingIndex bindingIndex) {
         ASSERT(!IsError());
         ASSERT(bindingIndex < mLayout->GetBindingCount());
         ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType == BindingInfoType::Buffer);
         BufferBase* buffer = static_cast<BufferBase*>(mBindingData.bindings[bindingIndex].Get());
         return {buffer, mBindingData.bufferData[bindingIndex].offset,
                 mBindingData.bufferData[bindingIndex].size};
     }

     SamplerBase* BindGroupBase::GetBindingAsSampler(BindingIndex bindingIndex) const {
         ASSERT(!IsError());
         ASSERT(bindingIndex < mLayout->GetBindingCount());
         ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType == BindingInfoType::Sampler);
         return static_cast<SamplerBase*>(mBindingData.bindings[bindingIndex].Get());
     }

     TextureViewBase* BindGroupBase::GetBindingAsTextureView(BindingIndex bindingIndex) {
         ASSERT(!IsError());
         ASSERT(bindingIndex < mLayout->GetBindingCount());
         ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType == BindingInfoType::Texture ||
                mLayout->GetBindingInfo(bindingIndex).bindingType ==
                    BindingInfoType::StorageTexture);
         return static_cast<TextureViewBase*>(mBindingData.bindings[bindingIndex].Get());
     }

     ExternalTextureBase* BindGroupBase::GetBindingAsExternalTexture(BindingIndex bindingIndex) {
         ASSERT(!IsError());
         ASSERT(bindingIndex < mLayout->GetBindingCount());
         ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType ==
                BindingInfoType::ExternalTexture);
         return static_cast<ExternalTextureBase*>(mBindingData.bindings[bindingIndex].Get());
     }

 }  // namespace dawn_native
	// Copyright 2017 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 "dawn_native/BindGroup.h"

	#include "common/Assert.h"
	#include "common/Math.h"
	#include "common/ityp_bitset.h"
	#include "dawn_native/BindGroupLayout.h"
	#include "dawn_native/Buffer.h"
	#include "dawn_native/ChainUtils_autogen.h"
	#include "dawn_native/Device.h"
	#include "dawn_native/ExternalTexture.h"
	#include "dawn_native/Sampler.h"
	#include "dawn_native/Texture.h"

	namespace dawn_native {

	namespace {

	// Helper functions to perform binding-type specific validation

	MaybeError ValidateBufferBinding(const DeviceBase* device,
	const BindGroupEntry& entry,
	const BindingInfo& bindingInfo) {
	if (entry.buffer == nullptr \|\| entry.sampler != nullptr \|\|
	entry.textureView != nullptr \|\| entry.nextInChain != nullptr) {
	return DAWN_VALIDATION_ERROR("Expected buffer binding");
	}
	DAWN_TRY(device->ValidateObject(entry.buffer));

	ASSERT(bindingInfo.bindingType == BindingInfoType::Buffer);

	wgpu::BufferUsage requiredUsage;
	uint64_t maxBindingSize;
	switch (bindingInfo.buffer.type) {
	case wgpu::BufferBindingType::Uniform:
	requiredUsage = wgpu::BufferUsage::Uniform;
	maxBindingSize = kMaxUniformBufferBindingSize;
	break;
	case wgpu::BufferBindingType::Storage:
	case wgpu::BufferBindingType::ReadOnlyStorage:
	requiredUsage = wgpu::BufferUsage::Storage;
	maxBindingSize = std::numeric_limits<uint64_t>::max();
	break;
	case wgpu::BufferBindingType::Undefined:
	UNREACHABLE();
	}

	uint64_t bufferSize = entry.buffer->GetSize();

	// Handle wgpu::WholeSize, avoiding overflows.
	if (entry.offset > bufferSize) {
	return DAWN_VALIDATION_ERROR("Buffer binding doesn't fit in the buffer");
	}
	uint64_t bindingSize =
	(entry.size == wgpu::kWholeSize) ? bufferSize - entry.offset : entry.size;

	if (bindingSize > bufferSize) {
	return DAWN_VALIDATION_ERROR("Buffer binding size larger than the buffer");
	}

	if (bindingSize == 0) {
	return DAWN_VALIDATION_ERROR("Buffer binding size cannot be zero.");
	}

	// Note that no overflow can happen because we already checked that
	// bufferSize >= bindingSize
	if (entry.offset > bufferSize - bindingSize) {
	return DAWN_VALIDATION_ERROR("Buffer binding doesn't fit in the buffer");
	}

	if (!IsAligned(entry.offset, 256)) {
	return DAWN_VALIDATION_ERROR(
	"Buffer offset for bind group needs to be 256-byte aligned");
	}

	if (!(entry.buffer->GetUsage() & requiredUsage)) {
	return DAWN_VALIDATION_ERROR("buffer binding usage mismatch");
	}

	if (bindingSize < bindingInfo.buffer.minBindingSize) {
	return DAWN_VALIDATION_ERROR(
	"Binding size smaller than minimum buffer size: binding " +
	std::to_string(entry.binding) + " given " + std::to_string(bindingSize) +
	" bytes, required " + std::to_string(bindingInfo.buffer.minBindingSize) +
	" bytes");
	}

	if (bindingSize > maxBindingSize) {
	return DAWN_VALIDATION_ERROR(
	"Binding size bigger than maximum uniform buffer binding size: binding " +
	std::to_string(entry.binding) + " given " + std::to_string(bindingSize) +
	" bytes, maximum is " + std::to_string(kMaxUniformBufferBindingSize) +
	" bytes");
	}

	return {};
	}

	MaybeError ValidateTextureBinding(const DeviceBase* device,
	const BindGroupEntry& entry,
	const BindingInfo& bindingInfo) {
	if (entry.textureView == nullptr \|\| entry.sampler != nullptr \|\|
	entry.buffer != nullptr \|\| entry.nextInChain != nullptr) {
	return DAWN_VALIDATION_ERROR("Expected texture binding");
	}
	DAWN_TRY(device->ValidateObject(entry.textureView));

	TextureViewBase* view = entry.textureView;

	Aspect aspect = view->GetAspects();
	if (!HasOneBit(aspect)) {
	return DAWN_VALIDATION_ERROR("Texture view must select a single aspect");
	}

	TextureBase* texture = view->GetTexture();
	switch (bindingInfo.bindingType) {
	case BindingInfoType::Texture: {
	ComponentTypeBit supportedTypes =
	texture->GetFormat().GetAspectInfo(aspect).supportedComponentTypes;
	ComponentTypeBit requiredType =
	SampleTypeToComponentTypeBit(bindingInfo.texture.sampleType);

	if (!(texture->GetUsage() & wgpu::TextureUsage::Sampled)) {
	return DAWN_VALIDATION_ERROR("Texture binding usage mismatch");
	}

	if (texture->IsMultisampledTexture() != bindingInfo.texture.multisampled) {
	return DAWN_VALIDATION_ERROR("Texture multisampling mismatch");
	}

	if ((supportedTypes & requiredType) == 0) {
	return DAWN_VALIDATION_ERROR("Texture component type usage mismatch");
	}

	if (entry.textureView->GetDimension() != bindingInfo.texture.viewDimension) {
	return DAWN_VALIDATION_ERROR("Texture view dimension mismatch");
	}
	break;
	}
	case BindingInfoType::StorageTexture: {
	ASSERT(!texture->IsMultisampledTexture());

	if (!(texture->GetUsage() & wgpu::TextureUsage::Storage)) {
	return DAWN_VALIDATION_ERROR("Storage Texture binding usage mismatch");
	}

	if (texture->GetFormat().format != bindingInfo.storageTexture.format) {
	return DAWN_VALIDATION_ERROR("Storage texture format mismatch");
	}
	if (entry.textureView->GetDimension() !=
	bindingInfo.storageTexture.viewDimension) {
	return DAWN_VALIDATION_ERROR("Storage texture view dimension mismatch");
	}
	break;
	}
	default:
	UNREACHABLE();
	break;
	}

	return {};
	}

	MaybeError ValidateSamplerBinding(const DeviceBase* device,
	const BindGroupEntry& entry,
	const BindingInfo& bindingInfo) {
	if (entry.sampler == nullptr \|\| entry.textureView != nullptr \|\|
	entry.buffer != nullptr \|\| entry.nextInChain != nullptr) {
	return DAWN_VALIDATION_ERROR("Expected sampler binding");
	}
	DAWN_TRY(device->ValidateObject(entry.sampler));

	ASSERT(bindingInfo.bindingType == BindingInfoType::Sampler);

	switch (bindingInfo.sampler.type) {
	case wgpu::SamplerBindingType::Filtering:
	case wgpu::SamplerBindingType::NonFiltering:
	if (entry.sampler->HasCompareFunction()) {
	return DAWN_VALIDATION_ERROR("Did not expect comparison sampler");
	}
	break;
	case wgpu::SamplerBindingType::Comparison:
	if (!entry.sampler->HasCompareFunction()) {
	return DAWN_VALIDATION_ERROR("Expected comparison sampler");
	}
	break;
	default:
	UNREACHABLE();
	break;
	}

	return {};
	}

	MaybeError ValidateExternalTextureBinding(const DeviceBase* device,
	const BindGroupEntry& entry,
	const BindingInfo& bindingInfo) {
	const ExternalTextureBindingEntry* externalTextureBindingEntry = nullptr;
	FindInChain(entry.nextInChain, &externalTextureBindingEntry);

	if (entry.sampler != nullptr \|\| entry.textureView != nullptr \|\|
	entry.buffer != nullptr \|\| externalTextureBindingEntry == nullptr) {
	return DAWN_VALIDATION_ERROR("Expected external texture binding");
	}

	DAWN_TRY(ValidateSingleSType(externalTextureBindingEntry->nextInChain,
	wgpu::SType::ExternalTextureBindingEntry));

	DAWN_TRY(device->ValidateObject(externalTextureBindingEntry->externalTexture));

	return {};
	}

	} // anonymous namespace

	MaybeError ValidateBindGroupDescriptor(DeviceBase* device,
	const BindGroupDescriptor* descriptor) {
	if (descriptor->nextInChain != nullptr) {
	return DAWN_VALIDATION_ERROR("nextInChain must be nullptr");
	}

	DAWN_TRY(device->ValidateObject(descriptor->layout));

	if (BindingIndex(descriptor->entryCount) != descriptor->layout->GetBindingCount()) {
	return DAWN_VALIDATION_ERROR("numBindings mismatch");
	}

	const BindGroupLayoutBase::BindingMap& bindingMap = descriptor->layout->GetBindingMap();
	ASSERT(bindingMap.size() <= kMaxBindingsPerPipelineLayout);

	ityp::bitset<BindingIndex, kMaxBindingsPerPipelineLayout> bindingsSet;
	for (uint32_t i = 0; i < descriptor->entryCount; ++i) {
	const BindGroupEntry& entry = descriptor->entries[i];

	const auto& it = bindingMap.find(BindingNumber(entry.binding));
	if (it == bindingMap.end()) {
	return DAWN_VALIDATION_ERROR("setting non-existent binding");
	}
	BindingIndex bindingIndex = it->second;
	ASSERT(bindingIndex < descriptor->layout->GetBindingCount());

	if (bindingsSet[bindingIndex]) {
	return DAWN_VALIDATION_ERROR("binding set twice");
	}
	bindingsSet.set(bindingIndex);

	const BindingInfo& bindingInfo = descriptor->layout->GetBindingInfo(bindingIndex);

	// Perform binding-type specific validation.
	switch (bindingInfo.bindingType) {
	case BindingInfoType::Buffer:
	DAWN_TRY(ValidateBufferBinding(device, entry, bindingInfo));
	break;
	case BindingInfoType::Texture:
	case BindingInfoType::StorageTexture:
	DAWN_TRY(ValidateTextureBinding(device, entry, bindingInfo));
	break;
	case BindingInfoType::Sampler:
	DAWN_TRY(ValidateSamplerBinding(device, entry, bindingInfo));
	break;
	case BindingInfoType::ExternalTexture:
	DAWN_TRY(ValidateExternalTextureBinding(device, entry, bindingInfo));
	break;
	}
	}

	// This should always be true because
	// - numBindings has to match between the bind group and its layout.
	// - Each binding must be set at most once
	//
	// We don't validate the equality because it wouldn't be possible to cover it with a test.
	ASSERT(bindingsSet.count() == bindingMap.size());

	return {};
	} // anonymous namespace

	// BindGroup

	BindGroupBase::BindGroupBase(DeviceBase* device,
	const BindGroupDescriptor* descriptor,
	void* bindingDataStart)
	: ObjectBase(device),
	mLayout(descriptor->layout),
	mBindingData(mLayout->ComputeBindingDataPointers(bindingDataStart)) {
	for (BindingIndex i{0}; i < mLayout->GetBindingCount(); ++i) {
	// TODO(enga): Shouldn't be needed when bindings are tightly packed.
	// This is to fill Ref<ObjectBase> holes with nullptrs.
	new (&mBindingData.bindings[i]) Ref<ObjectBase>();
	}

	for (uint32_t i = 0; i < descriptor->entryCount; ++i) {
	const BindGroupEntry& entry = descriptor->entries[i];

	BindingIndex bindingIndex =
	descriptor->layout->GetBindingIndex(BindingNumber(entry.binding));
	ASSERT(bindingIndex < mLayout->GetBindingCount());

	// Only a single binding type should be set, so once we found it we can skip to the
	// next loop iteration.

	if (entry.buffer != nullptr) {
	ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
	mBindingData.bindings[bindingIndex] = entry.buffer;
	mBindingData.bufferData[bindingIndex].offset = entry.offset;
	uint64_t bufferSize = (entry.size == wgpu::kWholeSize)
	? entry.buffer->GetSize() - entry.offset
	: entry.size;
	mBindingData.bufferData[bindingIndex].size = bufferSize;
	continue;
	}

	if (entry.textureView != nullptr) {
	ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
	mBindingData.bindings[bindingIndex] = entry.textureView;
	continue;
	}

	if (entry.sampler != nullptr) {
	ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
	mBindingData.bindings[bindingIndex] = entry.sampler;
	continue;
	}

	const ExternalTextureBindingEntry* externalTextureBindingEntry = nullptr;
	FindInChain(entry.nextInChain, &externalTextureBindingEntry);
	if (externalTextureBindingEntry != nullptr) {
	ASSERT(mBindingData.bindings[bindingIndex] == nullptr);
	mBindingData.bindings[bindingIndex] = externalTextureBindingEntry->externalTexture;
	continue;
	}
	}

	uint32_t packedIdx = 0;
	for (BindingIndex bindingIndex{0}; bindingIndex < descriptor->layout->GetBufferCount();
	++bindingIndex) {
	if (descriptor->layout->GetBindingInfo(bindingIndex).buffer.minBindingSize == 0) {
	mBindingData.unverifiedBufferSizes[packedIdx] =
	mBindingData.bufferData[bindingIndex].size;
	++packedIdx;
	}
	}
	}

	BindGroupBase::~BindGroupBase() {
	if (mLayout != nullptr) {
	ASSERT(!IsError());
	for (BindingIndex i{0}; i < mLayout->GetBindingCount(); ++i) {
	mBindingData.bindings[i].~Ref<ObjectBase>();
	}
	}
	}

	void BindGroupBase::DeleteThis() {
	// Add another ref to the layout so that if this is the last ref, the layout
	// is destroyed after the bind group. The bind group is slab-allocated inside
	// memory owned by the layout (except for the null backend).
	Ref<BindGroupLayoutBase> layout = mLayout;
	RefCounted::DeleteThis();
	}

	BindGroupBase::BindGroupBase(DeviceBase* device, ObjectBase::ErrorTag tag)
	: ObjectBase(device, tag), mBindingData() {
	}

	// static
	BindGroupBase* BindGroupBase::MakeError(DeviceBase* device) {
	return new BindGroupBase(device, ObjectBase::kError);
	}

	BindGroupLayoutBase* BindGroupBase::GetLayout() {
	ASSERT(!IsError());
	return mLayout.Get();
	}

	const BindGroupLayoutBase* BindGroupBase::GetLayout() const {
	ASSERT(!IsError());
	return mLayout.Get();
	}

	const ityp::span<uint32_t, uint64_t>& BindGroupBase::GetUnverifiedBufferSizes() const {
	ASSERT(!IsError());
	return mBindingData.unverifiedBufferSizes;
	}

	BufferBinding BindGroupBase::GetBindingAsBufferBinding(BindingIndex bindingIndex) {
	ASSERT(!IsError());
	ASSERT(bindingIndex < mLayout->GetBindingCount());
	ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType == BindingInfoType::Buffer);
	BufferBase* buffer = static_cast<BufferBase*>(mBindingData.bindings[bindingIndex].Get());
	return {buffer, mBindingData.bufferData[bindingIndex].offset,
	mBindingData.bufferData[bindingIndex].size};
	}

	SamplerBase* BindGroupBase::GetBindingAsSampler(BindingIndex bindingIndex) const {
	ASSERT(!IsError());
	ASSERT(bindingIndex < mLayout->GetBindingCount());
	ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType == BindingInfoType::Sampler);
	return static_cast<SamplerBase*>(mBindingData.bindings[bindingIndex].Get());
	}

	TextureViewBase* BindGroupBase::GetBindingAsTextureView(BindingIndex bindingIndex) {
	ASSERT(!IsError());
	ASSERT(bindingIndex < mLayout->GetBindingCount());
	ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType == BindingInfoType::Texture \|\|
	mLayout->GetBindingInfo(bindingIndex).bindingType ==
	BindingInfoType::StorageTexture);
	return static_cast<TextureViewBase*>(mBindingData.bindings[bindingIndex].Get());
	}

	ExternalTextureBase* BindGroupBase::GetBindingAsExternalTexture(BindingIndex bindingIndex) {
	ASSERT(!IsError());
	ASSERT(bindingIndex < mLayout->GetBindingCount());
	ASSERT(mLayout->GetBindingInfo(bindingIndex).bindingType ==
	BindingInfoType::ExternalTexture);
	return static_cast<ExternalTextureBase*>(mBindingData.bindings[bindingIndex].Get());
	}

	} // namespace dawn_native