src/dawn_native/PipelineLayout.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/PipelineLayout.h"

 #include "common/Assert.h"
 #include "common/BitSetIterator.h"
 #include "common/ityp_stack_vec.h"
 #include "dawn_native/BindGroupLayout.h"
 #include "dawn_native/Device.h"
 #include "dawn_native/ObjectContentHasher.h"
 #include "dawn_native/ObjectType_autogen.h"
 #include "dawn_native/ShaderModule.h"

 namespace dawn_native {

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

         if (descriptor->bindGroupLayoutCount > kMaxBindGroups) {
             return DAWN_VALIDATION_ERROR("too many bind group layouts");
         }

         BindingCounts bindingCounts = {};
         for (uint32_t i = 0; i < descriptor->bindGroupLayoutCount; ++i) {
             DAWN_TRY(device->ValidateObject(descriptor->bindGroupLayouts[i]));
             if (descriptor->bindGroupLayouts[i]->GetPipelineCompatibilityToken() !=
                 pipelineCompatibilityToken) {
                 return DAWN_VALIDATION_ERROR(
                     "cannot create a pipeline layout using a bind group layout that was created as "
                     "part of a pipeline's default layout");
             }
             AccumulateBindingCounts(&bindingCounts,
                                     descriptor->bindGroupLayouts[i]->GetBindingCountInfo());
         }

         DAWN_TRY(ValidateBindingCounts(bindingCounts));
         return {};
     }

     // PipelineLayoutBase

     PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device,
                                            const PipelineLayoutDescriptor* descriptor,
                                            ApiObjectBase::UntrackedByDeviceTag tag)
         : ApiObjectBase(device, descriptor->label) {
         ASSERT(descriptor->bindGroupLayoutCount <= kMaxBindGroups);
         for (BindGroupIndex group(0); group < BindGroupIndex(descriptor->bindGroupLayoutCount);
              ++group) {
             mBindGroupLayouts[group] = descriptor->bindGroupLayouts[static_cast<uint32_t>(group)];
             mMask.set(group);
         }
     }

     PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device,
                                            const PipelineLayoutDescriptor* descriptor)
         : PipelineLayoutBase(device, descriptor, kUntrackedByDevice) {
         TrackInDevice();
     }

     PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device)
         : ApiObjectBase(device, kLabelNotImplemented) {
         TrackInDevice();
     }

     PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device, ObjectBase::ErrorTag tag)
         : ApiObjectBase(device, tag) {
     }

     PipelineLayoutBase::~PipelineLayoutBase() = default;

     void PipelineLayoutBase::DestroyImpl() {
         if (IsCachedReference()) {
             // Do not uncache the actual cached object if we are a blueprint.
             GetDevice()->UncachePipelineLayout(this);
         }
     }

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

     // static
     ResultOrError<Ref<PipelineLayoutBase>> PipelineLayoutBase::CreateDefault(
         DeviceBase* device,
         std::vector<StageAndDescriptor> stages) {
         using EntryMap = std::map<BindingNumber, BindGroupLayoutEntry>;

         // Merges two entries at the same location, if they are allowed to be merged.
         auto MergeEntries = [](BindGroupLayoutEntry* modifiedEntry,
                                const BindGroupLayoutEntry& mergedEntry) -> MaybeError {
             // Visibility is excluded because we take the OR across stages.
             bool compatible =
                 modifiedEntry->binding == mergedEntry.binding &&
                 modifiedEntry->buffer.type == mergedEntry.buffer.type &&
                 modifiedEntry->sampler.type == mergedEntry.sampler.type &&
                 // Compatibility between these sample types is checked below.
                 (modifiedEntry->texture.sampleType != wgpu::TextureSampleType::Undefined) ==
                     (mergedEntry.texture.sampleType != wgpu::TextureSampleType::Undefined) &&
                 modifiedEntry->storageTexture.access == mergedEntry.storageTexture.access;

             // Minimum buffer binding size excluded because we take the maximum seen across stages.
             if (modifiedEntry->buffer.type != wgpu::BufferBindingType::Undefined) {
                 compatible = compatible && modifiedEntry->buffer.hasDynamicOffset ==
                                                mergedEntry.buffer.hasDynamicOffset;
             }

             if (modifiedEntry->texture.sampleType != wgpu::TextureSampleType::Undefined) {
                 // Sample types are compatible if they are exactly equal,
                 // or if the |modifiedEntry| is Float and the |mergedEntry| is UnfilterableFloat.
                 // Note that the |mergedEntry| never has type Float. Texture bindings all start
                 // as UnfilterableFloat and are promoted to Float if they are statically used with
                 // a sampler.
                 ASSERT(mergedEntry.texture.sampleType != wgpu::TextureSampleType::Float);
                 bool compatibleSampleTypes =
                     modifiedEntry->texture.sampleType == mergedEntry.texture.sampleType ||
                     (modifiedEntry->texture.sampleType == wgpu::TextureSampleType::Float &&
                      mergedEntry.texture.sampleType == wgpu::TextureSampleType::UnfilterableFloat);
                 compatible =
                     compatible && compatibleSampleTypes &&
                     modifiedEntry->texture.viewDimension == mergedEntry.texture.viewDimension &&
                     modifiedEntry->texture.multisampled == mergedEntry.texture.multisampled;
             }

             if (modifiedEntry->storageTexture.access != wgpu::StorageTextureAccess::Undefined) {
                 compatible =
                     compatible &&
                     modifiedEntry->storageTexture.format == mergedEntry.storageTexture.format &&
                     modifiedEntry->storageTexture.viewDimension ==
                         mergedEntry.storageTexture.viewDimension;
             }

             // Check if any properties are incompatible with existing entry
             // If compatible, we will merge some properties
             if (!compatible) {
                 return DAWN_VALIDATION_ERROR(
                     "Duplicate binding in default pipeline layout initialization "
                     "not compatible with previous declaration");
             }

             // Use the max |minBufferBindingSize| we find.
             modifiedEntry->buffer.minBindingSize =
                 std::max(modifiedEntry->buffer.minBindingSize, mergedEntry.buffer.minBindingSize);

             // Use the OR of all the stages at which we find this binding.
             modifiedEntry->visibility |= mergedEntry.visibility;

             return {};
         };

         // Does the trivial conversions from a ShaderBindingInfo to a BindGroupLayoutEntry
         auto ConvertMetadataToEntry =
             [](const ShaderBindingInfo& shaderBinding,
                const ExternalTextureBindingLayout* externalTextureBindingEntry)
             -> BindGroupLayoutEntry {
             BindGroupLayoutEntry entry = {};
             switch (shaderBinding.bindingType) {
                 case BindingInfoType::Buffer:
                     entry.buffer.type = shaderBinding.buffer.type;
                     entry.buffer.hasDynamicOffset = shaderBinding.buffer.hasDynamicOffset;
                     entry.buffer.minBindingSize = shaderBinding.buffer.minBindingSize;
                     break;
                 case BindingInfoType::Sampler:
                     if (shaderBinding.sampler.isComparison) {
                         entry.sampler.type = wgpu::SamplerBindingType::Comparison;
                     } else {
                         entry.sampler.type = wgpu::SamplerBindingType::Filtering;
                     }
                     break;
                 case BindingInfoType::Texture:
                     switch (shaderBinding.texture.compatibleSampleTypes) {
                         case SampleTypeBit::Depth:
                             entry.texture.sampleType = wgpu::TextureSampleType::Depth;
                             break;
                         case SampleTypeBit::Sint:
                             entry.texture.sampleType = wgpu::TextureSampleType::Sint;
                             break;
                         case SampleTypeBit::Uint:
                             entry.texture.sampleType = wgpu::TextureSampleType::Uint;
                             break;
                         case SampleTypeBit::Float:
                         case SampleTypeBit::UnfilterableFloat:
                         case SampleTypeBit::None:
                             UNREACHABLE();
                             break;
                         default:
                             if (shaderBinding.texture.compatibleSampleTypes ==
                                 (SampleTypeBit::Float | SampleTypeBit::UnfilterableFloat)) {
                                 // Default to UnfilterableFloat. It will be promoted to Float if it
                                 // is used with a sampler.
                                 entry.texture.sampleType =
                                     wgpu::TextureSampleType::UnfilterableFloat;
                             } else {
                                 UNREACHABLE();
                             }
                     }
                     entry.texture.viewDimension = shaderBinding.texture.viewDimension;
                     entry.texture.multisampled = shaderBinding.texture.multisampled;
                     break;
                 case BindingInfoType::StorageTexture:
                     entry.storageTexture.access = shaderBinding.storageTexture.access;
                     entry.storageTexture.format = shaderBinding.storageTexture.format;
                     entry.storageTexture.viewDimension = shaderBinding.storageTexture.viewDimension;
                     break;
                 case BindingInfoType::ExternalTexture:
                     entry.nextInChain = externalTextureBindingEntry;
                     break;
             }
             return entry;
         };

         PipelineCompatibilityToken pipelineCompatibilityToken =
             device->GetNextPipelineCompatibilityToken();

         // Creates the BGL from the entries for a stage, checking it is valid.
         auto CreateBGL = [](DeviceBase* device, const EntryMap& entries,
                             PipelineCompatibilityToken pipelineCompatibilityToken)
             -> ResultOrError<Ref<BindGroupLayoutBase>> {
             std::vector<BindGroupLayoutEntry> entryVec;
             entryVec.reserve(entries.size());
             for (auto& it : entries) {
                 entryVec.push_back(it.second);
             }

             BindGroupLayoutDescriptor desc = {};
             desc.entries = entryVec.data();
             desc.entryCount = entryVec.size();

             if (device->IsValidationEnabled()) {
                 DAWN_TRY_CONTEXT(ValidateBindGroupLayoutDescriptor(device, &desc), "validating %s",
                                  &desc);
             }
             return device->GetOrCreateBindGroupLayout(&desc, pipelineCompatibilityToken);
         };

         ASSERT(!stages.empty());

         // Data which BindGroupLayoutDescriptor will point to for creation
         ityp::array<BindGroupIndex, std::map<BindingNumber, BindGroupLayoutEntry>, kMaxBindGroups>
             entryData = {};

         // External texture binding layouts are chained structs that are set as a pointer within
         // the bind group layout entry. We declare an entry here so that it can be used when needed
         // in each BindGroupLayoutEntry and so it can stay alive until the call to
         // GetOrCreateBindGroupLayout. Because ExternalTextureBindingLayout is an empty struct,
         // there's no issue with using the same struct multiple times.
         ExternalTextureBindingLayout externalTextureBindingLayout;

         // Loops over all the reflected BindGroupLayoutEntries from shaders.
         for (const StageAndDescriptor& stage : stages) {
             const EntryPointMetadata& metadata = stage.module->GetEntryPoint(stage.entryPoint);

             for (BindGroupIndex group(0); group < metadata.bindings.size(); ++group) {
                 for (const auto& bindingIt : metadata.bindings[group]) {
                     BindingNumber bindingNumber = bindingIt.first;
                     const ShaderBindingInfo& shaderBinding = bindingIt.second;

                     // Create the BindGroupLayoutEntry
                     BindGroupLayoutEntry entry =
                         ConvertMetadataToEntry(shaderBinding, &externalTextureBindingLayout);
                     entry.binding = static_cast<uint32_t>(bindingNumber);
                     entry.visibility = StageBit(stage.shaderStage);

                     // Add it to our map of all entries, if there is an existing entry, then we
                     // need to merge, if we can.
                     const auto& insertion = entryData[group].insert({bindingNumber, entry});
                     if (!insertion.second) {
                         DAWN_TRY(MergeEntries(&insertion.first->second, entry));
                     }
                 }
             }

             // Promote any Unfilterable textures used with a sampler to Filtering.
             for (const EntryPointMetadata::SamplerTexturePair& pair :
                  metadata.samplerTexturePairs) {
                 BindGroupLayoutEntry* entry = &entryData[pair.texture.group][pair.texture.binding];
                 if (entry->texture.sampleType == wgpu::TextureSampleType::UnfilterableFloat) {
                     entry->texture.sampleType = wgpu::TextureSampleType::Float;
                 }
             }
         }

         // Create the bind group layouts. We need to keep track of the last non-empty BGL because
         // Dawn doesn't yet know that an empty BGL and a null BGL are the same thing.
         // TODO(cwallez@chromium.org): remove this when Dawn knows that empty and null BGL are the
         // same.
         BindGroupIndex pipelineBGLCount = BindGroupIndex(0);
         ityp::array<BindGroupIndex, Ref<BindGroupLayoutBase>, kMaxBindGroups> bindGroupLayouts = {};
         for (BindGroupIndex group(0); group < kMaxBindGroupsTyped; ++group) {
             DAWN_TRY_ASSIGN(bindGroupLayouts[group],
                             CreateBGL(device, entryData[group], pipelineCompatibilityToken));
             if (entryData[group].size() != 0) {
                 pipelineBGLCount = group + BindGroupIndex(1);
             }
         }

         // Create the deduced pipeline layout, validating if it is valid.
         ityp::array<BindGroupIndex, BindGroupLayoutBase*, kMaxBindGroups> bgls = {};
         for (BindGroupIndex group(0); group < pipelineBGLCount; ++group) {
             bgls[group] = bindGroupLayouts[group].Get();
         }

         PipelineLayoutDescriptor desc = {};
         desc.bindGroupLayouts = bgls.data();
         desc.bindGroupLayoutCount = static_cast<uint32_t>(pipelineBGLCount);

         DAWN_TRY(ValidatePipelineLayoutDescriptor(device, &desc, pipelineCompatibilityToken));

         Ref<PipelineLayoutBase> result;
         DAWN_TRY_ASSIGN(result, device->GetOrCreatePipelineLayout(&desc));
         ASSERT(!result->IsError());

         // Sanity check in debug that the pipeline layout is compatible with the current
         // pipeline.
         for (const StageAndDescriptor& stage : stages) {
             const EntryPointMetadata& metadata = stage.module->GetEntryPoint(stage.entryPoint);
             ASSERT(ValidateCompatibilityWithPipelineLayout(device, metadata, result.Get())
                        .IsSuccess());
         }

         return std::move(result);
     }

     ObjectType PipelineLayoutBase::GetType() const {
         return ObjectType::PipelineLayout;
     }

     const BindGroupLayoutBase* PipelineLayoutBase::GetBindGroupLayout(BindGroupIndex group) const {
         ASSERT(!IsError());
         ASSERT(group < kMaxBindGroupsTyped);
         ASSERT(mMask[group]);
         const BindGroupLayoutBase* bgl = mBindGroupLayouts[group].Get();
         ASSERT(bgl != nullptr);
         return bgl;
     }

     BindGroupLayoutBase* PipelineLayoutBase::GetBindGroupLayout(BindGroupIndex group) {
         ASSERT(!IsError());
         ASSERT(group < kMaxBindGroupsTyped);
         ASSERT(mMask[group]);
         BindGroupLayoutBase* bgl = mBindGroupLayouts[group].Get();
         ASSERT(bgl != nullptr);
         return bgl;
     }

     const BindGroupLayoutMask& PipelineLayoutBase::GetBindGroupLayoutsMask() const {
         ASSERT(!IsError());
         return mMask;
     }

     BindGroupLayoutMask PipelineLayoutBase::InheritedGroupsMask(
         const PipelineLayoutBase* other) const {
         ASSERT(!IsError());
         return {(1 << static_cast<uint32_t>(GroupsInheritUpTo(other))) - 1u};
     }

     BindGroupIndex PipelineLayoutBase::GroupsInheritUpTo(const PipelineLayoutBase* other) const {
         ASSERT(!IsError());

         for (BindGroupIndex i(0); i < kMaxBindGroupsTyped; ++i) {
             if (!mMask[i] || mBindGroupLayouts[i].Get() != other->mBindGroupLayouts[i].Get()) {
                 return i;
             }
         }
         return kMaxBindGroupsTyped;
     }

     size_t PipelineLayoutBase::ComputeContentHash() {
         ObjectContentHasher recorder;
         recorder.Record(mMask);

         for (BindGroupIndex group : IterateBitSet(mMask)) {
             recorder.Record(GetBindGroupLayout(group)->GetContentHash());
         }

         return recorder.GetContentHash();
     }

     bool PipelineLayoutBase::EqualityFunc::operator()(const PipelineLayoutBase* a,
                                                       const PipelineLayoutBase* b) const {
         if (a->mMask != b->mMask) {
             return false;
         }

         for (BindGroupIndex group : IterateBitSet(a->mMask)) {
             if (a->GetBindGroupLayout(group) != b->GetBindGroupLayout(group)) {
                 return false;
             }
         }

         return true;
     }

 }  // 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/PipelineLayout.h"

	#include "common/Assert.h"
	#include "common/BitSetIterator.h"
	#include "common/ityp_stack_vec.h"
	#include "dawn_native/BindGroupLayout.h"
	#include "dawn_native/Device.h"
	#include "dawn_native/ObjectContentHasher.h"
	#include "dawn_native/ObjectType_autogen.h"
	#include "dawn_native/ShaderModule.h"

	namespace dawn_native {

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

	if (descriptor->bindGroupLayoutCount > kMaxBindGroups) {
	return DAWN_VALIDATION_ERROR("too many bind group layouts");
	}

	BindingCounts bindingCounts = {};
	for (uint32_t i = 0; i < descriptor->bindGroupLayoutCount; ++i) {
	DAWN_TRY(device->ValidateObject(descriptor->bindGroupLayouts[i]));
	if (descriptor->bindGroupLayouts[i]->GetPipelineCompatibilityToken() !=
	pipelineCompatibilityToken) {
	return DAWN_VALIDATION_ERROR(
	"cannot create a pipeline layout using a bind group layout that was created as "
	"part of a pipeline's default layout");
	}
	AccumulateBindingCounts(&bindingCounts,
	descriptor->bindGroupLayouts[i]->GetBindingCountInfo());
	}

	DAWN_TRY(ValidateBindingCounts(bindingCounts));
	return {};
	}

	// PipelineLayoutBase

	PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device,
	const PipelineLayoutDescriptor* descriptor,
	ApiObjectBase::UntrackedByDeviceTag tag)
	: ApiObjectBase(device, descriptor->label) {
	ASSERT(descriptor->bindGroupLayoutCount <= kMaxBindGroups);
	for (BindGroupIndex group(0); group < BindGroupIndex(descriptor->bindGroupLayoutCount);
	++group) {
	mBindGroupLayouts[group] = descriptor->bindGroupLayouts[static_cast<uint32_t>(group)];
	mMask.set(group);
	}
	}

	PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device,
	const PipelineLayoutDescriptor* descriptor)
	: PipelineLayoutBase(device, descriptor, kUntrackedByDevice) {
	TrackInDevice();
	}

	PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device)
	: ApiObjectBase(device, kLabelNotImplemented) {
	TrackInDevice();
	}

	PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device, ObjectBase::ErrorTag tag)
	: ApiObjectBase(device, tag) {
	}

	PipelineLayoutBase::~PipelineLayoutBase() = default;

	void PipelineLayoutBase::DestroyImpl() {
	if (IsCachedReference()) {
	// Do not uncache the actual cached object if we are a blueprint.
	GetDevice()->UncachePipelineLayout(this);
	}
	}

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

	// static
	ResultOrError<Ref<PipelineLayoutBase>> PipelineLayoutBase::CreateDefault(
	DeviceBase* device,
	std::vector<StageAndDescriptor> stages) {
	using EntryMap = std::map<BindingNumber, BindGroupLayoutEntry>;

	// Merges two entries at the same location, if they are allowed to be merged.
	auto MergeEntries = [](BindGroupLayoutEntry* modifiedEntry,
	const BindGroupLayoutEntry& mergedEntry) -> MaybeError {
	// Visibility is excluded because we take the OR across stages.
	bool compatible =
	modifiedEntry->binding == mergedEntry.binding &&
	modifiedEntry->buffer.type == mergedEntry.buffer.type &&
	modifiedEntry->sampler.type == mergedEntry.sampler.type &&
	// Compatibility between these sample types is checked below.
	(modifiedEntry->texture.sampleType != wgpu::TextureSampleType::Undefined) ==
	(mergedEntry.texture.sampleType != wgpu::TextureSampleType::Undefined) &&
	modifiedEntry->storageTexture.access == mergedEntry.storageTexture.access;

	// Minimum buffer binding size excluded because we take the maximum seen across stages.
	if (modifiedEntry->buffer.type != wgpu::BufferBindingType::Undefined) {
	compatible = compatible && modifiedEntry->buffer.hasDynamicOffset ==
	mergedEntry.buffer.hasDynamicOffset;
	}

	if (modifiedEntry->texture.sampleType != wgpu::TextureSampleType::Undefined) {
	// Sample types are compatible if they are exactly equal,
	// or if the \|modifiedEntry\| is Float and the \|mergedEntry\| is UnfilterableFloat.
	// Note that the \|mergedEntry\| never has type Float. Texture bindings all start
	// as UnfilterableFloat and are promoted to Float if they are statically used with
	// a sampler.
	ASSERT(mergedEntry.texture.sampleType != wgpu::TextureSampleType::Float);
	bool compatibleSampleTypes =
	modifiedEntry->texture.sampleType == mergedEntry.texture.sampleType \|\|
	(modifiedEntry->texture.sampleType == wgpu::TextureSampleType::Float &&
	mergedEntry.texture.sampleType == wgpu::TextureSampleType::UnfilterableFloat);
	compatible =
	compatible && compatibleSampleTypes &&
	modifiedEntry->texture.viewDimension == mergedEntry.texture.viewDimension &&
	modifiedEntry->texture.multisampled == mergedEntry.texture.multisampled;
	}

	if (modifiedEntry->storageTexture.access != wgpu::StorageTextureAccess::Undefined) {
	compatible =
	compatible &&
	modifiedEntry->storageTexture.format == mergedEntry.storageTexture.format &&
	modifiedEntry->storageTexture.viewDimension ==
	mergedEntry.storageTexture.viewDimension;
	}

	// Check if any properties are incompatible with existing entry
	// If compatible, we will merge some properties
	if (!compatible) {
	return DAWN_VALIDATION_ERROR(
	"Duplicate binding in default pipeline layout initialization "
	"not compatible with previous declaration");
	}

	// Use the max \|minBufferBindingSize\| we find.
	modifiedEntry->buffer.minBindingSize =
	std::max(modifiedEntry->buffer.minBindingSize, mergedEntry.buffer.minBindingSize);

	// Use the OR of all the stages at which we find this binding.
	modifiedEntry->visibility \|= mergedEntry.visibility;

	return {};
	};

	// Does the trivial conversions from a ShaderBindingInfo to a BindGroupLayoutEntry
	auto ConvertMetadataToEntry =
	[](const ShaderBindingInfo& shaderBinding,
	const ExternalTextureBindingLayout* externalTextureBindingEntry)
	-> BindGroupLayoutEntry {
	BindGroupLayoutEntry entry = {};
	switch (shaderBinding.bindingType) {
	case BindingInfoType::Buffer:
	entry.buffer.type = shaderBinding.buffer.type;
	entry.buffer.hasDynamicOffset = shaderBinding.buffer.hasDynamicOffset;
	entry.buffer.minBindingSize = shaderBinding.buffer.minBindingSize;
	break;
	case BindingInfoType::Sampler:
	if (shaderBinding.sampler.isComparison) {
	entry.sampler.type = wgpu::SamplerBindingType::Comparison;
	} else {
	entry.sampler.type = wgpu::SamplerBindingType::Filtering;
	}
	break;
	case BindingInfoType::Texture:
	switch (shaderBinding.texture.compatibleSampleTypes) {
	case SampleTypeBit::Depth:
	entry.texture.sampleType = wgpu::TextureSampleType::Depth;
	break;
	case SampleTypeBit::Sint:
	entry.texture.sampleType = wgpu::TextureSampleType::Sint;
	break;
	case SampleTypeBit::Uint:
	entry.texture.sampleType = wgpu::TextureSampleType::Uint;
	break;
	case SampleTypeBit::Float:
	case SampleTypeBit::UnfilterableFloat:
	case SampleTypeBit::None:
	UNREACHABLE();
	break;
	default:
	if (shaderBinding.texture.compatibleSampleTypes ==
	(SampleTypeBit::Float \| SampleTypeBit::UnfilterableFloat)) {
	// Default to UnfilterableFloat. It will be promoted to Float if it
	// is used with a sampler.
	entry.texture.sampleType =
	wgpu::TextureSampleType::UnfilterableFloat;
	} else {
	UNREACHABLE();
	}
	}
	entry.texture.viewDimension = shaderBinding.texture.viewDimension;
	entry.texture.multisampled = shaderBinding.texture.multisampled;
	break;
	case BindingInfoType::StorageTexture:
	entry.storageTexture.access = shaderBinding.storageTexture.access;
	entry.storageTexture.format = shaderBinding.storageTexture.format;
	entry.storageTexture.viewDimension = shaderBinding.storageTexture.viewDimension;
	break;
	case BindingInfoType::ExternalTexture:
	entry.nextInChain = externalTextureBindingEntry;
	break;
	}
	return entry;
	};

	PipelineCompatibilityToken pipelineCompatibilityToken =
	device->GetNextPipelineCompatibilityToken();

	// Creates the BGL from the entries for a stage, checking it is valid.
	auto CreateBGL = [](DeviceBase* device, const EntryMap& entries,
	PipelineCompatibilityToken pipelineCompatibilityToken)
	-> ResultOrError<Ref<BindGroupLayoutBase>> {
	std::vector<BindGroupLayoutEntry> entryVec;
	entryVec.reserve(entries.size());
	for (auto& it : entries) {
	entryVec.push_back(it.second);
	}

	BindGroupLayoutDescriptor desc = {};
	desc.entries = entryVec.data();
	desc.entryCount = entryVec.size();

	if (device->IsValidationEnabled()) {
	DAWN_TRY_CONTEXT(ValidateBindGroupLayoutDescriptor(device, &desc), "validating %s",
	&desc);
	}
	return device->GetOrCreateBindGroupLayout(&desc, pipelineCompatibilityToken);
	};

	ASSERT(!stages.empty());

	// Data which BindGroupLayoutDescriptor will point to for creation
	ityp::array<BindGroupIndex, std::map<BindingNumber, BindGroupLayoutEntry>, kMaxBindGroups>
	entryData = {};

	// External texture binding layouts are chained structs that are set as a pointer within
	// the bind group layout entry. We declare an entry here so that it can be used when needed
	// in each BindGroupLayoutEntry and so it can stay alive until the call to
	// GetOrCreateBindGroupLayout. Because ExternalTextureBindingLayout is an empty struct,
	// there's no issue with using the same struct multiple times.
	ExternalTextureBindingLayout externalTextureBindingLayout;

	// Loops over all the reflected BindGroupLayoutEntries from shaders.
	for (const StageAndDescriptor& stage : stages) {
	const EntryPointMetadata& metadata = stage.module->GetEntryPoint(stage.entryPoint);

	for (BindGroupIndex group(0); group < metadata.bindings.size(); ++group) {
	for (const auto& bindingIt : metadata.bindings[group]) {
	BindingNumber bindingNumber = bindingIt.first;
	const ShaderBindingInfo& shaderBinding = bindingIt.second;

	// Create the BindGroupLayoutEntry
	BindGroupLayoutEntry entry =
	ConvertMetadataToEntry(shaderBinding, &externalTextureBindingLayout);
	entry.binding = static_cast<uint32_t>(bindingNumber);
	entry.visibility = StageBit(stage.shaderStage);

	// Add it to our map of all entries, if there is an existing entry, then we
	// need to merge, if we can.
	const auto& insertion = entryData[group].insert({bindingNumber, entry});
	if (!insertion.second) {
	DAWN_TRY(MergeEntries(&insertion.first->second, entry));
	}
	}
	}

	// Promote any Unfilterable textures used with a sampler to Filtering.
	for (const EntryPointMetadata::SamplerTexturePair& pair :
	metadata.samplerTexturePairs) {
	BindGroupLayoutEntry* entry = &entryData[pair.texture.group][pair.texture.binding];
	if (entry->texture.sampleType == wgpu::TextureSampleType::UnfilterableFloat) {
	entry->texture.sampleType = wgpu::TextureSampleType::Float;
	}
	}
	}

	// Create the bind group layouts. We need to keep track of the last non-empty BGL because
	// Dawn doesn't yet know that an empty BGL and a null BGL are the same thing.
	// TODO(cwallez@chromium.org): remove this when Dawn knows that empty and null BGL are the
	// same.
	BindGroupIndex pipelineBGLCount = BindGroupIndex(0);
	ityp::array<BindGroupIndex, Ref<BindGroupLayoutBase>, kMaxBindGroups> bindGroupLayouts = {};
	for (BindGroupIndex group(0); group < kMaxBindGroupsTyped; ++group) {
	DAWN_TRY_ASSIGN(bindGroupLayouts[group],
	CreateBGL(device, entryData[group], pipelineCompatibilityToken));
	if (entryData[group].size() != 0) {
	pipelineBGLCount = group + BindGroupIndex(1);
	}
	}

	// Create the deduced pipeline layout, validating if it is valid.
	ityp::array<BindGroupIndex, BindGroupLayoutBase*, kMaxBindGroups> bgls = {};
	for (BindGroupIndex group(0); group < pipelineBGLCount; ++group) {
	bgls[group] = bindGroupLayouts[group].Get();
	}

	PipelineLayoutDescriptor desc = {};
	desc.bindGroupLayouts = bgls.data();
	desc.bindGroupLayoutCount = static_cast<uint32_t>(pipelineBGLCount);

	DAWN_TRY(ValidatePipelineLayoutDescriptor(device, &desc, pipelineCompatibilityToken));

	Ref<PipelineLayoutBase> result;
	DAWN_TRY_ASSIGN(result, device->GetOrCreatePipelineLayout(&desc));
	ASSERT(!result->IsError());

	// Sanity check in debug that the pipeline layout is compatible with the current
	// pipeline.
	for (const StageAndDescriptor& stage : stages) {
	const EntryPointMetadata& metadata = stage.module->GetEntryPoint(stage.entryPoint);
	ASSERT(ValidateCompatibilityWithPipelineLayout(device, metadata, result.Get())
	.IsSuccess());
	}

	return std::move(result);
	}

	ObjectType PipelineLayoutBase::GetType() const {
	return ObjectType::PipelineLayout;
	}

	const BindGroupLayoutBase* PipelineLayoutBase::GetBindGroupLayout(BindGroupIndex group) const {
	ASSERT(!IsError());
	ASSERT(group < kMaxBindGroupsTyped);
	ASSERT(mMask[group]);
	const BindGroupLayoutBase* bgl = mBindGroupLayouts[group].Get();
	ASSERT(bgl != nullptr);
	return bgl;
	}

	BindGroupLayoutBase* PipelineLayoutBase::GetBindGroupLayout(BindGroupIndex group) {
	ASSERT(!IsError());
	ASSERT(group < kMaxBindGroupsTyped);
	ASSERT(mMask[group]);
	BindGroupLayoutBase* bgl = mBindGroupLayouts[group].Get();
	ASSERT(bgl != nullptr);
	return bgl;
	}

	const BindGroupLayoutMask& PipelineLayoutBase::GetBindGroupLayoutsMask() const {
	ASSERT(!IsError());
	return mMask;
	}

	BindGroupLayoutMask PipelineLayoutBase::InheritedGroupsMask(
	const PipelineLayoutBase* other) const {
	ASSERT(!IsError());
	return {(1 << static_cast<uint32_t>(GroupsInheritUpTo(other))) - 1u};
	}

	BindGroupIndex PipelineLayoutBase::GroupsInheritUpTo(const PipelineLayoutBase* other) const {
	ASSERT(!IsError());

	for (BindGroupIndex i(0); i < kMaxBindGroupsTyped; ++i) {
	if (!mMask[i] \|\| mBindGroupLayouts[i].Get() != other->mBindGroupLayouts[i].Get()) {
	return i;
	}
	}
	return kMaxBindGroupsTyped;
	}

	size_t PipelineLayoutBase::ComputeContentHash() {
	ObjectContentHasher recorder;
	recorder.Record(mMask);

	for (BindGroupIndex group : IterateBitSet(mMask)) {
	recorder.Record(GetBindGroupLayout(group)->GetContentHash());
	}

	return recorder.GetContentHash();
	}

	bool PipelineLayoutBase::EqualityFunc::operator()(const PipelineLayoutBase* a,
	const PipelineLayoutBase* b) const {
	if (a->mMask != b->mMask) {
	return false;
	}

	for (BindGroupIndex group : IterateBitSet(a->mMask)) {
	if (a->GetBindGroupLayout(group) != b->GetBindGroupLayout(group)) {
	return false;
	}
	}

	return true;
	}

	} // namespace dawn_native