src/dawn/native/IndirectDrawValidationEncoder.cpp - dawn - Git at Google

 // Copyright 2021 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/IndirectDrawValidationEncoder.h"

 #include <algorithm>
 #include <cstdlib>
 #include <limits>
 #include <memory>
 #include <utility>
 #include <vector>

 #include "dawn/common/Constants.h"
 #include "dawn/common/Math.h"
 #include "dawn/native/BindGroup.h"
 #include "dawn/native/BindGroupLayout.h"
 #include "dawn/native/CommandEncoder.h"
 #include "dawn/native/ComputePassEncoder.h"
 #include "dawn/native/ComputePipeline.h"
 #include "dawn/native/Device.h"
 #include "dawn/native/InternalPipelineStore.h"
 #include "dawn/native/Queue.h"
 #include "dawn/native/utils/WGPUHelpers.h"

 namespace dawn::native {

 namespace {
 // NOTE: This must match the workgroup_size attribute on the compute entry point below.
 constexpr uint64_t kWorkgroupSize = 64;

 // Bitmasks for BatchInfo::flags
 constexpr uint32_t kDuplicateBaseVertexInstance = 1;
 constexpr uint32_t kIndexedDraw = 2;
 constexpr uint32_t kValidationEnabled = 4;
 constexpr uint32_t kIndirectFirstInstanceEnabled = 8;

 // Equivalent to the BatchInfo struct defined in the shader below.
 struct BatchInfo {
     uint64_t numIndexBufferElements;
     uint32_t numDraws;
     uint32_t flags;
 };

 // TODO(https://crbug.com/dawn/1108): Propagate validation feedback from this shader in
 // various failure modes.
 static const char sRenderValidationShaderSource[] = R"(

             let kNumDrawIndirectParams = 4u;

             let kIndexCountEntry = 0u;
             let kFirstIndexEntry = 2u;

             // Bitmasks for BatchInfo::flags
             let kDuplicateBaseVertexInstance = 1u;
             let kIndexedDraw = 2u;
             let kValidationEnabled = 4u;
             let kIndirectFirstInstanceEnabled = 8u;

             struct BatchInfo {
                 numIndexBufferElementsLow: u32,
                 numIndexBufferElementsHigh: u32,
                 numDraws: u32,
                 flags: u32,
                 indirectOffsets: array<u32>,
             }

             struct IndirectParams {
                 data: array<u32>,
             }

             @group(0) @binding(0) var<storage, read> batch: BatchInfo;
             @group(0) @binding(1) var<storage, read_write> inputParams: IndirectParams;
             @group(0) @binding(2) var<storage, read_write> outputParams: IndirectParams;

             fn numIndirectParamsPerDrawCallInput() -> u32 {
                 var numParams = kNumDrawIndirectParams;
                 // Indexed Draw has an extra parameter (firstIndex)
                 if (bool(batch.flags & kIndexedDraw)) {
                     numParams = numParams + 1u;
                 }
                 return numParams;
             }

             fn numIndirectParamsPerDrawCallOutput() -> u32 {
                 var numParams = numIndirectParamsPerDrawCallInput();
                 // 2 extra parameter for duplicated first/baseVexter and firstInstance
                 if (bool(batch.flags & kDuplicateBaseVertexInstance)) {
                     numParams = numParams + 2u;
                 }
                 return numParams;
             }

             fn fail(drawIndex: u32) {
                 let numParams = numIndirectParamsPerDrawCallOutput();
                 let index = drawIndex * numParams;
                 for(var i = 0u; i < numParams; i = i + 1u) {
                     outputParams.data[index + i] = 0u;
                 }
             }

             fn pass(drawIndex: u32) {
                 let numInputParams = numIndirectParamsPerDrawCallInput();
                 var outIndex = drawIndex * numIndirectParamsPerDrawCallOutput();
                 let inIndex = batch.indirectOffsets[drawIndex];

                 // The first 2 parameter is reserved for the duplicated first/baseVertex and firstInstance

                 if (bool(batch.flags & kDuplicateBaseVertexInstance)) {
                     // first/baseVertex and firstInstance are always last two parameters
                     let dupIndex = inIndex + numInputParams - 2u;
                     outputParams.data[outIndex] = inputParams.data[dupIndex];
                     outputParams.data[outIndex + 1u] = inputParams.data[dupIndex + 1u];

                     outIndex = outIndex + 2u;
                 }

                 for(var i = 0u; i < numInputParams; i = i + 1u) {
                     outputParams.data[outIndex + i] = inputParams.data[inIndex + i];
                 }
             }

             @compute @workgroup_size(64, 1, 1)
             fn main(@builtin(global_invocation_id) id : vec3<u32>) {
                 if (id.x >= batch.numDraws) {
                     return;
                 }

                 if(!bool(batch.flags & kValidationEnabled)) {
                     pass(id.x);
                     return;
                 }

                 let inputIndex = batch.indirectOffsets[id.x];
                 if(!bool(batch.flags & kIndirectFirstInstanceEnabled)) {
                     // firstInstance is always the last parameter
                     let firstInstance = inputParams.data[inputIndex + numIndirectParamsPerDrawCallInput() - 1u];
                     if (firstInstance != 0u) {
                         fail(id.x);
                         return;
                     }
                 }

                 if (!bool(batch.flags & kIndexedDraw)) {
                     pass(id.x);
                     return;
                 }

                 if (batch.numIndexBufferElementsHigh >= 2u) {
                     // firstIndex and indexCount are both u32. The maximum possible sum of these
                     // values is 0x1fffffffe, which is less than 0x200000000. Nothing to validate.
                     pass(id.x);
                     return;
                 }

                 let firstIndex = inputParams.data[inputIndex + kFirstIndexEntry];
                 if (batch.numIndexBufferElementsHigh == 0u &&
                     batch.numIndexBufferElementsLow < firstIndex) {
                     fail(id.x);
                     return;
                 }

                 // Note that this subtraction may underflow, but only when
                 // numIndexBufferElementsHigh is 1u. The result is still correct in that case.
                 let maxIndexCount = batch.numIndexBufferElementsLow - firstIndex;
                 let indexCount = inputParams.data[inputIndex + kIndexCountEntry];
                 if (indexCount > maxIndexCount) {
                     fail(id.x);
                     return;
                 }
                 pass(id.x);
             }
         )";

 ResultOrError<ComputePipelineBase*> GetOrCreateRenderValidationPipeline(DeviceBase* device) {
     InternalPipelineStore* store = device->GetInternalPipelineStore();

     if (store->renderValidationPipeline == nullptr) {
         // Create compute shader module if not cached before.
         if (store->renderValidationShader == nullptr) {
             DAWN_TRY_ASSIGN(store->renderValidationShader,
                             utils::CreateShaderModule(device, sRenderValidationShaderSource));
         }

         Ref<BindGroupLayoutBase> bindGroupLayout;
         DAWN_TRY_ASSIGN(
             bindGroupLayout,
             utils::MakeBindGroupLayout(
                 device,
                 {
                     {0, wgpu::ShaderStage::Compute, wgpu::BufferBindingType::ReadOnlyStorage},
                     {1, wgpu::ShaderStage::Compute, kInternalStorageBufferBinding},
                     {2, wgpu::ShaderStage::Compute, wgpu::BufferBindingType::Storage},
                 },
                 /* allowInternalBinding */ true));

         Ref<PipelineLayoutBase> pipelineLayout;
         DAWN_TRY_ASSIGN(pipelineLayout, utils::MakeBasicPipelineLayout(device, bindGroupLayout));

         ComputePipelineDescriptor computePipelineDescriptor = {};
         computePipelineDescriptor.layout = pipelineLayout.Get();
         computePipelineDescriptor.compute.module = store->renderValidationShader.Get();
         computePipelineDescriptor.compute.entryPoint = "main";

         DAWN_TRY_ASSIGN(store->renderValidationPipeline,
                         device->CreateComputePipeline(&computePipelineDescriptor));
     }

     return store->renderValidationPipeline.Get();
 }

 size_t GetBatchDataSize(uint32_t numDraws) {
     return sizeof(BatchInfo) + numDraws * sizeof(uint32_t);
 }

 }  // namespace

 uint32_t ComputeMaxDrawCallsPerIndirectValidationBatch(const CombinedLimits& limits) {
     const uint64_t batchDrawCallLimitByDispatchSize =
         static_cast<uint64_t>(limits.v1.maxComputeWorkgroupsPerDimension) * kWorkgroupSize;
     const uint64_t batchDrawCallLimitByStorageBindingSize =
         (limits.v1.maxStorageBufferBindingSize - sizeof(BatchInfo)) / sizeof(uint32_t);
     return static_cast<uint32_t>(
         std::min({batchDrawCallLimitByDispatchSize, batchDrawCallLimitByStorageBindingSize,
                   uint64_t(std::numeric_limits<uint32_t>::max())}));
 }

 MaybeError EncodeIndirectDrawValidationCommands(DeviceBase* device,
                                                 CommandEncoder* commandEncoder,
                                                 RenderPassResourceUsageTracker* usageTracker,
                                                 IndirectDrawMetadata* indirectDrawMetadata) {
     // Since encoding validation commands may create new objects, verify that the device is alive.
     // TODO(dawn:1199): This check is obsolete if device loss causes device.destroy().
     //   - This function only happens within the context of a TryEncode which would catch the
     //     same issue if device loss implied device.destroy().
     DAWN_TRY(device->ValidateIsAlive());

     struct Batch {
         const IndirectDrawMetadata::IndirectValidationBatch* metadata;
         uint64_t numIndexBufferElements;
         uint64_t dataBufferOffset;
         uint64_t dataSize;
         uint64_t inputIndirectOffset;
         uint64_t inputIndirectSize;
         uint64_t outputParamsOffset;
         uint64_t outputParamsSize;
         BatchInfo* batchInfo;
     };

     struct Pass {
         uint32_t flags;
         BufferBase* inputIndirectBuffer;
         uint64_t outputParamsSize = 0;
         uint64_t batchDataSize = 0;
         std::unique_ptr<void, void (*)(void*)> batchData{nullptr, std::free};
         std::vector<Batch> batches;
     };

     // First stage is grouping all batches into passes. We try to pack as many batches into a
     // single pass as possible. Batches can be grouped together as long as they're validating
     // data from the same indirect buffer, but they may still be split into multiple passes if
     // the number of draw calls in a pass would exceed some (very high) upper bound.
     uint64_t outputParamsSize = 0;
     std::vector<Pass> passes;
     IndirectDrawMetadata::IndexedIndirectBufferValidationInfoMap& bufferInfoMap =
         *indirectDrawMetadata->GetIndexedIndirectBufferValidationInfo();
     if (bufferInfoMap.empty()) {
         return {};
     }

     const uint64_t maxStorageBufferBindingSize = device->GetLimits().v1.maxStorageBufferBindingSize;
     const uint32_t minStorageBufferOffsetAlignment =
         device->GetLimits().v1.minStorageBufferOffsetAlignment;

     for (auto& [config, validationInfo] : bufferInfoMap) {
         const uint64_t indirectDrawCommandSize =
             config.drawType == IndirectDrawMetadata::DrawType::Indexed ? kDrawIndexedIndirectSize
                                                                        : kDrawIndirectSize;

         uint64_t outputIndirectSize = indirectDrawCommandSize;
         if (config.duplicateBaseVertexInstance) {
             outputIndirectSize += 2 * sizeof(uint32_t);
         }

         for (const IndirectDrawMetadata::IndirectValidationBatch& batch :
              validationInfo.GetBatches()) {
             const uint64_t minOffsetFromAlignedBoundary =
                 batch.minOffset % minStorageBufferOffsetAlignment;
             const uint64_t minOffsetAlignedDown = batch.minOffset - minOffsetFromAlignedBoundary;

             Batch newBatch;
             newBatch.metadata = &batch;
             newBatch.numIndexBufferElements = config.numIndexBufferElements;
             newBatch.dataSize = GetBatchDataSize(batch.draws.size());
             newBatch.inputIndirectOffset = minOffsetAlignedDown;
             newBatch.inputIndirectSize =
                 batch.maxOffset + indirectDrawCommandSize - minOffsetAlignedDown;

             newBatch.outputParamsSize = batch.draws.size() * outputIndirectSize;
             newBatch.outputParamsOffset = Align(outputParamsSize, minStorageBufferOffsetAlignment);
             outputParamsSize = newBatch.outputParamsOffset + newBatch.outputParamsSize;
             if (outputParamsSize > maxStorageBufferBindingSize) {
                 return DAWN_INTERNAL_ERROR("Too many drawIndexedIndirect calls to validate");
             }

             Pass* currentPass = passes.empty() ? nullptr : &passes.back();
             if (currentPass && currentPass->inputIndirectBuffer == config.inputIndirectBuffer) {
                 uint64_t nextBatchDataOffset =
                     Align(currentPass->batchDataSize, minStorageBufferOffsetAlignment);
                 uint64_t newPassBatchDataSize = nextBatchDataOffset + newBatch.dataSize;
                 if (newPassBatchDataSize <= maxStorageBufferBindingSize) {
                     // We can fit this batch in the current pass.
                     newBatch.dataBufferOffset = nextBatchDataOffset;
                     currentPass->batchDataSize = newPassBatchDataSize;
                     currentPass->batches.push_back(newBatch);
                     continue;
                 }
             }

             // We need to start a new pass for this batch.
             newBatch.dataBufferOffset = 0;

             Pass newPass{};
             newPass.inputIndirectBuffer = config.inputIndirectBuffer;
             newPass.batchDataSize = newBatch.dataSize;
             newPass.batches.push_back(newBatch);
             newPass.flags = 0;
             if (config.duplicateBaseVertexInstance) {
                 newPass.flags |= kDuplicateBaseVertexInstance;
             }
             if (config.drawType == IndirectDrawMetadata::DrawType::Indexed) {
                 newPass.flags |= kIndexedDraw;
             }
             if (device->IsValidationEnabled()) {
                 newPass.flags |= kValidationEnabled;
             }
             if (device->HasFeature(Feature::IndirectFirstInstance)) {
                 newPass.flags |= kIndirectFirstInstanceEnabled;
             }
             passes.push_back(std::move(newPass));
         }
     }

     auto* const store = device->GetInternalPipelineStore();
     ScratchBuffer& outputParamsBuffer = store->scratchIndirectStorage;
     ScratchBuffer& batchDataBuffer = store->scratchStorage;

     uint64_t requiredBatchDataBufferSize = 0;
     for (const Pass& pass : passes) {
         requiredBatchDataBufferSize = std::max(requiredBatchDataBufferSize, pass.batchDataSize);
     }
     DAWN_TRY(batchDataBuffer.EnsureCapacity(requiredBatchDataBufferSize));
     usageTracker->BufferUsedAs(batchDataBuffer.GetBuffer(), wgpu::BufferUsage::Storage);

     DAWN_TRY(outputParamsBuffer.EnsureCapacity(outputParamsSize));
     usageTracker->BufferUsedAs(outputParamsBuffer.GetBuffer(), wgpu::BufferUsage::Indirect);

     // Now we allocate and populate host-side batch data to be copied to the GPU.
     for (Pass& pass : passes) {
         // We use std::malloc here because it guarantees maximal scalar alignment.
         pass.batchData = {std::malloc(pass.batchDataSize), std::free};
         memset(pass.batchData.get(), 0, pass.batchDataSize);
         uint8_t* batchData = static_cast<uint8_t*>(pass.batchData.get());
         for (Batch& batch : pass.batches) {
             batch.batchInfo = new (&batchData[batch.dataBufferOffset]) BatchInfo();
             batch.batchInfo->numIndexBufferElements = batch.numIndexBufferElements;
             batch.batchInfo->numDraws = static_cast<uint32_t>(batch.metadata->draws.size());
             batch.batchInfo->flags = pass.flags;

             uint32_t* indirectOffsets = reinterpret_cast<uint32_t*>(batch.batchInfo + 1);
             uint64_t outputParamsOffset = batch.outputParamsOffset;
             for (auto& draw : batch.metadata->draws) {
                 // The shader uses this to index an array of u32, hence the division by 4 bytes.
                 *indirectOffsets++ =
                     static_cast<uint32_t>((draw.inputBufferOffset - batch.inputIndirectOffset) / 4);

                 draw.cmd->indirectBuffer = outputParamsBuffer.GetBuffer();
                 draw.cmd->indirectOffset = outputParamsOffset;
                 if (pass.flags & kIndexedDraw) {
                     outputParamsOffset += kDrawIndexedIndirectSize;
                 } else {
                     outputParamsOffset += kDrawIndirectSize;
                 }
             }
         }
     }

     ComputePipelineBase* pipeline;
     DAWN_TRY_ASSIGN(pipeline, GetOrCreateRenderValidationPipeline(device));

     Ref<BindGroupLayoutBase> layout;
     DAWN_TRY_ASSIGN(layout, pipeline->GetBindGroupLayout(0));

     BindGroupEntry bindings[3];
     BindGroupEntry& bufferDataBinding = bindings[0];
     bufferDataBinding.binding = 0;
     bufferDataBinding.buffer = batchDataBuffer.GetBuffer();

     BindGroupEntry& inputIndirectBinding = bindings[1];
     inputIndirectBinding.binding = 1;

     BindGroupEntry& outputParamsBinding = bindings[2];
     outputParamsBinding.binding = 2;
     outputParamsBinding.buffer = outputParamsBuffer.GetBuffer();

     BindGroupDescriptor bindGroupDescriptor = {};
     bindGroupDescriptor.layout = layout.Get();
     bindGroupDescriptor.entryCount = 3;
     bindGroupDescriptor.entries = bindings;

     // Finally, we can now encode our validation and duplication passes. Each pass first does a
     // two WriteBuffer to get batch and pass data over to the GPU, followed by a single compute
     // pass. The compute pass encodes a separate SetBindGroup and Dispatch command for each
     // batch.
     for (const Pass& pass : passes) {
         commandEncoder->APIWriteBuffer(batchDataBuffer.GetBuffer(), 0,
                                        static_cast<const uint8_t*>(pass.batchData.get()),
                                        pass.batchDataSize);

         Ref<ComputePassEncoder> passEncoder = commandEncoder->BeginComputePass();
         passEncoder->APISetPipeline(pipeline);

         inputIndirectBinding.buffer = pass.inputIndirectBuffer;

         for (const Batch& batch : pass.batches) {
             bufferDataBinding.offset = batch.dataBufferOffset;
             bufferDataBinding.size = batch.dataSize;
             inputIndirectBinding.offset = batch.inputIndirectOffset;
             inputIndirectBinding.size = batch.inputIndirectSize;
             outputParamsBinding.offset = batch.outputParamsOffset;
             outputParamsBinding.size = batch.outputParamsSize;

             Ref<BindGroupBase> bindGroup;
             DAWN_TRY_ASSIGN(bindGroup, device->CreateBindGroup(&bindGroupDescriptor));

             const uint32_t numDrawsRoundedUp =
                 (batch.batchInfo->numDraws + kWorkgroupSize - 1) / kWorkgroupSize;
             passEncoder->APISetBindGroup(0, bindGroup.Get());
             passEncoder->APIDispatchWorkgroups(numDrawsRoundedUp);
         }

         passEncoder->APIEnd();
     }

     return {};
 }

 }  // namespace dawn::native
	// Copyright 2021 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/IndirectDrawValidationEncoder.h"

	#include <algorithm>
	#include <cstdlib>
	#include <limits>
	#include <memory>
	#include <utility>
	#include <vector>

	#include "dawn/common/Constants.h"
	#include "dawn/common/Math.h"
	#include "dawn/native/BindGroup.h"
	#include "dawn/native/BindGroupLayout.h"
	#include "dawn/native/CommandEncoder.h"
	#include "dawn/native/ComputePassEncoder.h"
	#include "dawn/native/ComputePipeline.h"
	#include "dawn/native/Device.h"
	#include "dawn/native/InternalPipelineStore.h"
	#include "dawn/native/Queue.h"
	#include "dawn/native/utils/WGPUHelpers.h"

	namespace dawn::native {

	namespace {
	// NOTE: This must match the workgroup_size attribute on the compute entry point below.
	constexpr uint64_t kWorkgroupSize = 64;

	// Bitmasks for BatchInfo::flags
	constexpr uint32_t kDuplicateBaseVertexInstance = 1;
	constexpr uint32_t kIndexedDraw = 2;
	constexpr uint32_t kValidationEnabled = 4;
	constexpr uint32_t kIndirectFirstInstanceEnabled = 8;

	// Equivalent to the BatchInfo struct defined in the shader below.
	struct BatchInfo {
	uint64_t numIndexBufferElements;
	uint32_t numDraws;
	uint32_t flags;
	};

	// TODO(https://crbug.com/dawn/1108): Propagate validation feedback from this shader in
	// various failure modes.
	static const char sRenderValidationShaderSource[] = R"(

	let kNumDrawIndirectParams = 4u;

	let kIndexCountEntry = 0u;
	let kFirstIndexEntry = 2u;

	// Bitmasks for BatchInfo::flags
	let kDuplicateBaseVertexInstance = 1u;
	let kIndexedDraw = 2u;
	let kValidationEnabled = 4u;
	let kIndirectFirstInstanceEnabled = 8u;

	struct BatchInfo {
	numIndexBufferElementsLow: u32,
	numIndexBufferElementsHigh: u32,
	numDraws: u32,
	flags: u32,
	indirectOffsets: array<u32>,
	}

	struct IndirectParams {
	data: array<u32>,
	}

	@group(0) @binding(0) var<storage, read> batch: BatchInfo;
	@group(0) @binding(1) var<storage, read_write> inputParams: IndirectParams;
	@group(0) @binding(2) var<storage, read_write> outputParams: IndirectParams;

	fn numIndirectParamsPerDrawCallInput() -> u32 {
	var numParams = kNumDrawIndirectParams;
	// Indexed Draw has an extra parameter (firstIndex)
	if (bool(batch.flags & kIndexedDraw)) {
	numParams = numParams + 1u;
	}
	return numParams;
	}

	fn numIndirectParamsPerDrawCallOutput() -> u32 {
	var numParams = numIndirectParamsPerDrawCallInput();
	// 2 extra parameter for duplicated first/baseVexter and firstInstance
	if (bool(batch.flags & kDuplicateBaseVertexInstance)) {
	numParams = numParams + 2u;
	}
	return numParams;
	}

	fn fail(drawIndex: u32) {
	let numParams = numIndirectParamsPerDrawCallOutput();
	let index = drawIndex * numParams;
	for(var i = 0u; i < numParams; i = i + 1u) {
	outputParams.data[index + i] = 0u;
	}
	}

	fn pass(drawIndex: u32) {
	let numInputParams = numIndirectParamsPerDrawCallInput();
	var outIndex = drawIndex * numIndirectParamsPerDrawCallOutput();
	let inIndex = batch.indirectOffsets[drawIndex];

	// The first 2 parameter is reserved for the duplicated first/baseVertex and firstInstance

	if (bool(batch.flags & kDuplicateBaseVertexInstance)) {
	// first/baseVertex and firstInstance are always last two parameters
	let dupIndex = inIndex + numInputParams - 2u;
	outputParams.data[outIndex] = inputParams.data[dupIndex];
	outputParams.data[outIndex + 1u] = inputParams.data[dupIndex + 1u];

	outIndex = outIndex + 2u;
	}

	for(var i = 0u; i < numInputParams; i = i + 1u) {
	outputParams.data[outIndex + i] = inputParams.data[inIndex + i];
	}
	}

	@compute @workgroup_size(64, 1, 1)
	fn main(@builtin(global_invocation_id) id : vec3<u32>) {
	if (id.x >= batch.numDraws) {
	return;
	}

	if(!bool(batch.flags & kValidationEnabled)) {
	pass(id.x);
	return;
	}

	let inputIndex = batch.indirectOffsets[id.x];
	if(!bool(batch.flags & kIndirectFirstInstanceEnabled)) {
	// firstInstance is always the last parameter
	let firstInstance = inputParams.data[inputIndex + numIndirectParamsPerDrawCallInput() - 1u];
	if (firstInstance != 0u) {
	fail(id.x);
	return;
	}
	}

	if (!bool(batch.flags & kIndexedDraw)) {
	pass(id.x);
	return;
	}

	if (batch.numIndexBufferElementsHigh >= 2u) {
	// firstIndex and indexCount are both u32. The maximum possible sum of these
	// values is 0x1fffffffe, which is less than 0x200000000. Nothing to validate.
	pass(id.x);
	return;
	}

	let firstIndex = inputParams.data[inputIndex + kFirstIndexEntry];
	if (batch.numIndexBufferElementsHigh == 0u &&
	batch.numIndexBufferElementsLow < firstIndex) {
	fail(id.x);
	return;
	}

	// Note that this subtraction may underflow, but only when
	// numIndexBufferElementsHigh is 1u. The result is still correct in that case.
	let maxIndexCount = batch.numIndexBufferElementsLow - firstIndex;
	let indexCount = inputParams.data[inputIndex + kIndexCountEntry];
	if (indexCount > maxIndexCount) {
	fail(id.x);
	return;
	}
	pass(id.x);
	}
	)";

	ResultOrError<ComputePipelineBase> GetOrCreateRenderValidationPipeline(DeviceBase device) {
	InternalPipelineStore* store = device->GetInternalPipelineStore();

	if (store->renderValidationPipeline == nullptr) {
	// Create compute shader module if not cached before.
	if (store->renderValidationShader == nullptr) {
	DAWN_TRY_ASSIGN(store->renderValidationShader,
	utils::CreateShaderModule(device, sRenderValidationShaderSource));
	}

	Ref<BindGroupLayoutBase> bindGroupLayout;
	DAWN_TRY_ASSIGN(
	bindGroupLayout,
	utils::MakeBindGroupLayout(
	device,
	{
	{0, wgpu::ShaderStage::Compute, wgpu::BufferBindingType::ReadOnlyStorage},
	{1, wgpu::ShaderStage::Compute, kInternalStorageBufferBinding},
	{2, wgpu::ShaderStage::Compute, wgpu::BufferBindingType::Storage},
	},
	/* allowInternalBinding */ true));

	Ref<PipelineLayoutBase> pipelineLayout;
	DAWN_TRY_ASSIGN(pipelineLayout, utils::MakeBasicPipelineLayout(device, bindGroupLayout));

	ComputePipelineDescriptor computePipelineDescriptor = {};
	computePipelineDescriptor.layout = pipelineLayout.Get();
	computePipelineDescriptor.compute.module = store->renderValidationShader.Get();
	computePipelineDescriptor.compute.entryPoint = "main";

	DAWN_TRY_ASSIGN(store->renderValidationPipeline,
	device->CreateComputePipeline(&computePipelineDescriptor));
	}

	return store->renderValidationPipeline.Get();
	}

	size_t GetBatchDataSize(uint32_t numDraws) {
	return sizeof(BatchInfo) + numDraws * sizeof(uint32_t);
	}

	} // namespace

	uint32_t ComputeMaxDrawCallsPerIndirectValidationBatch(const CombinedLimits& limits) {
	const uint64_t batchDrawCallLimitByDispatchSize =
	static_cast<uint64_t>(limits.v1.maxComputeWorkgroupsPerDimension) * kWorkgroupSize;
	const uint64_t batchDrawCallLimitByStorageBindingSize =
	(limits.v1.maxStorageBufferBindingSize - sizeof(BatchInfo)) / sizeof(uint32_t);
	return static_cast<uint32_t>(
	std::min({batchDrawCallLimitByDispatchSize, batchDrawCallLimitByStorageBindingSize,
	uint64_t(std::numeric_limits<uint32_t>::max())}));
	}

	MaybeError EncodeIndirectDrawValidationCommands(DeviceBase* device,
	CommandEncoder* commandEncoder,
	RenderPassResourceUsageTracker* usageTracker,
	IndirectDrawMetadata* indirectDrawMetadata) {
	// Since encoding validation commands may create new objects, verify that the device is alive.
	// TODO(dawn:1199): This check is obsolete if device loss causes device.destroy().
	// - This function only happens within the context of a TryEncode which would catch the
	// same issue if device loss implied device.destroy().
	DAWN_TRY(device->ValidateIsAlive());

	struct Batch {
	const IndirectDrawMetadata::IndirectValidationBatch* metadata;
	uint64_t numIndexBufferElements;
	uint64_t dataBufferOffset;
	uint64_t dataSize;
	uint64_t inputIndirectOffset;
	uint64_t inputIndirectSize;
	uint64_t outputParamsOffset;
	uint64_t outputParamsSize;
	BatchInfo* batchInfo;
	};

	struct Pass {
	uint32_t flags;
	BufferBase* inputIndirectBuffer;
	uint64_t outputParamsSize = 0;
	uint64_t batchDataSize = 0;
	std::unique_ptr<void, void ()(void)> batchData{nullptr, std::free};
	std::vector<Batch> batches;
	};

	// First stage is grouping all batches into passes. We try to pack as many batches into a
	// single pass as possible. Batches can be grouped together as long as they're validating
	// data from the same indirect buffer, but they may still be split into multiple passes if
	// the number of draw calls in a pass would exceed some (very high) upper bound.
	uint64_t outputParamsSize = 0;
	std::vector<Pass> passes;
	IndirectDrawMetadata::IndexedIndirectBufferValidationInfoMap& bufferInfoMap =
	*indirectDrawMetadata->GetIndexedIndirectBufferValidationInfo();
	if (bufferInfoMap.empty()) {
	return {};
	}

	const uint64_t maxStorageBufferBindingSize = device->GetLimits().v1.maxStorageBufferBindingSize;
	const uint32_t minStorageBufferOffsetAlignment =
	device->GetLimits().v1.minStorageBufferOffsetAlignment;

	for (auto& [config, validationInfo] : bufferInfoMap) {
	const uint64_t indirectDrawCommandSize =
	config.drawType == IndirectDrawMetadata::DrawType::Indexed ? kDrawIndexedIndirectSize
	: kDrawIndirectSize;

	uint64_t outputIndirectSize = indirectDrawCommandSize;
	if (config.duplicateBaseVertexInstance) {
	outputIndirectSize += 2 * sizeof(uint32_t);
	}

	for (const IndirectDrawMetadata::IndirectValidationBatch& batch :
	validationInfo.GetBatches()) {
	const uint64_t minOffsetFromAlignedBoundary =
	batch.minOffset % minStorageBufferOffsetAlignment;
	const uint64_t minOffsetAlignedDown = batch.minOffset - minOffsetFromAlignedBoundary;

	Batch newBatch;
	newBatch.metadata = &batch;
	newBatch.numIndexBufferElements = config.numIndexBufferElements;
	newBatch.dataSize = GetBatchDataSize(batch.draws.size());
	newBatch.inputIndirectOffset = minOffsetAlignedDown;
	newBatch.inputIndirectSize =
	batch.maxOffset + indirectDrawCommandSize - minOffsetAlignedDown;

	newBatch.outputParamsSize = batch.draws.size() * outputIndirectSize;
	newBatch.outputParamsOffset = Align(outputParamsSize, minStorageBufferOffsetAlignment);
	outputParamsSize = newBatch.outputParamsOffset + newBatch.outputParamsSize;
	if (outputParamsSize > maxStorageBufferBindingSize) {
	return DAWN_INTERNAL_ERROR("Too many drawIndexedIndirect calls to validate");
	}

	Pass* currentPass = passes.empty() ? nullptr : &passes.back();
	if (currentPass && currentPass->inputIndirectBuffer == config.inputIndirectBuffer) {
	uint64_t nextBatchDataOffset =
	Align(currentPass->batchDataSize, minStorageBufferOffsetAlignment);
	uint64_t newPassBatchDataSize = nextBatchDataOffset + newBatch.dataSize;
	if (newPassBatchDataSize <= maxStorageBufferBindingSize) {
	// We can fit this batch in the current pass.
	newBatch.dataBufferOffset = nextBatchDataOffset;
	currentPass->batchDataSize = newPassBatchDataSize;
	currentPass->batches.push_back(newBatch);
	continue;
	}
	}

	// We need to start a new pass for this batch.
	newBatch.dataBufferOffset = 0;

	Pass newPass{};
	newPass.inputIndirectBuffer = config.inputIndirectBuffer;
	newPass.batchDataSize = newBatch.dataSize;
	newPass.batches.push_back(newBatch);
	newPass.flags = 0;
	if (config.duplicateBaseVertexInstance) {
	newPass.flags \|= kDuplicateBaseVertexInstance;
	}
	if (config.drawType == IndirectDrawMetadata::DrawType::Indexed) {
	newPass.flags \|= kIndexedDraw;
	}
	if (device->IsValidationEnabled()) {
	newPass.flags \|= kValidationEnabled;
	}
	if (device->HasFeature(Feature::IndirectFirstInstance)) {
	newPass.flags \|= kIndirectFirstInstanceEnabled;
	}
	passes.push_back(std::move(newPass));
	}
	}

	auto* const store = device->GetInternalPipelineStore();
	ScratchBuffer& outputParamsBuffer = store->scratchIndirectStorage;
	ScratchBuffer& batchDataBuffer = store->scratchStorage;

	uint64_t requiredBatchDataBufferSize = 0;
	for (const Pass& pass : passes) {
	requiredBatchDataBufferSize = std::max(requiredBatchDataBufferSize, pass.batchDataSize);
	}
	DAWN_TRY(batchDataBuffer.EnsureCapacity(requiredBatchDataBufferSize));
	usageTracker->BufferUsedAs(batchDataBuffer.GetBuffer(), wgpu::BufferUsage::Storage);

	DAWN_TRY(outputParamsBuffer.EnsureCapacity(outputParamsSize));
	usageTracker->BufferUsedAs(outputParamsBuffer.GetBuffer(), wgpu::BufferUsage::Indirect);

	// Now we allocate and populate host-side batch data to be copied to the GPU.
	for (Pass& pass : passes) {
	// We use std::malloc here because it guarantees maximal scalar alignment.
	pass.batchData = {std::malloc(pass.batchDataSize), std::free};
	memset(pass.batchData.get(), 0, pass.batchDataSize);
	uint8_t* batchData = static_cast<uint8_t*>(pass.batchData.get());
	for (Batch& batch : pass.batches) {
	batch.batchInfo = new (&batchData[batch.dataBufferOffset]) BatchInfo();
	batch.batchInfo->numIndexBufferElements = batch.numIndexBufferElements;
	batch.batchInfo->numDraws = static_cast<uint32_t>(batch.metadata->draws.size());
	batch.batchInfo->flags = pass.flags;

	uint32_t* indirectOffsets = reinterpret_cast<uint32_t*>(batch.batchInfo + 1);
	uint64_t outputParamsOffset = batch.outputParamsOffset;
	for (auto& draw : batch.metadata->draws) {
	// The shader uses this to index an array of u32, hence the division by 4 bytes.
	*indirectOffsets++ =
	static_cast<uint32_t>((draw.inputBufferOffset - batch.inputIndirectOffset) / 4);

	draw.cmd->indirectBuffer = outputParamsBuffer.GetBuffer();
	draw.cmd->indirectOffset = outputParamsOffset;
	if (pass.flags & kIndexedDraw) {
	outputParamsOffset += kDrawIndexedIndirectSize;
	} else {
	outputParamsOffset += kDrawIndirectSize;
	}
	}
	}
	}

	ComputePipelineBase* pipeline;
	DAWN_TRY_ASSIGN(pipeline, GetOrCreateRenderValidationPipeline(device));

	Ref<BindGroupLayoutBase> layout;
	DAWN_TRY_ASSIGN(layout, pipeline->GetBindGroupLayout(0));

	BindGroupEntry bindings[3];
	BindGroupEntry& bufferDataBinding = bindings[0];
	bufferDataBinding.binding = 0;
	bufferDataBinding.buffer = batchDataBuffer.GetBuffer();

	BindGroupEntry& inputIndirectBinding = bindings[1];
	inputIndirectBinding.binding = 1;

	BindGroupEntry& outputParamsBinding = bindings[2];
	outputParamsBinding.binding = 2;
	outputParamsBinding.buffer = outputParamsBuffer.GetBuffer();

	BindGroupDescriptor bindGroupDescriptor = {};
	bindGroupDescriptor.layout = layout.Get();
	bindGroupDescriptor.entryCount = 3;
	bindGroupDescriptor.entries = bindings;

	// Finally, we can now encode our validation and duplication passes. Each pass first does a
	// two WriteBuffer to get batch and pass data over to the GPU, followed by a single compute
	// pass. The compute pass encodes a separate SetBindGroup and Dispatch command for each
	// batch.
	for (const Pass& pass : passes) {
	commandEncoder->APIWriteBuffer(batchDataBuffer.GetBuffer(), 0,
	static_cast<const uint8_t*>(pass.batchData.get()),
	pass.batchDataSize);

	Ref<ComputePassEncoder> passEncoder = commandEncoder->BeginComputePass();
	passEncoder->APISetPipeline(pipeline);

	inputIndirectBinding.buffer = pass.inputIndirectBuffer;

	for (const Batch& batch : pass.batches) {
	bufferDataBinding.offset = batch.dataBufferOffset;
	bufferDataBinding.size = batch.dataSize;
	inputIndirectBinding.offset = batch.inputIndirectOffset;
	inputIndirectBinding.size = batch.inputIndirectSize;
	outputParamsBinding.offset = batch.outputParamsOffset;
	outputParamsBinding.size = batch.outputParamsSize;

	Ref<BindGroupBase> bindGroup;
	DAWN_TRY_ASSIGN(bindGroup, device->CreateBindGroup(&bindGroupDescriptor));

	const uint32_t numDrawsRoundedUp =
	(batch.batchInfo->numDraws + kWorkgroupSize - 1) / kWorkgroupSize;
	passEncoder->APISetBindGroup(0, bindGroup.Get());
	passEncoder->APIDispatchWorkgroups(numDrawsRoundedUp);
	}

	passEncoder->APIEnd();
	}

	return {};
	}

	} // namespace dawn::native