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

 // Copyright 2019 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/CommandValidation.h"

 #include "common/BitSetIterator.h"
 #include "dawn_native/BindGroup.h"
 #include "dawn_native/Buffer.h"
 #include "dawn_native/CommandBufferStateTracker.h"
 #include "dawn_native/Commands.h"
 #include "dawn_native/Device.h"
 #include "dawn_native/PassResourceUsage.h"
 #include "dawn_native/QuerySet.h"
 #include "dawn_native/RenderBundle.h"
 #include "dawn_native/RenderPipeline.h"
 #include "dawn_native/ValidationUtils_autogen.h"

 namespace dawn_native {

     // Performs validation of the "synchronization scope" rules of WebGPU.
     MaybeError ValidateSyncScopeResourceUsage(const SyncScopeResourceUsage& scope) {
         // Buffers can only be used as single-write or multiple read.
         for (wgpu::BufferUsage usage : scope.bufferUsages) {
             bool readOnly = IsSubset(usage, kReadOnlyBufferUsages);
             bool singleUse = wgpu::HasZeroOrOneBits(usage);

             if (!readOnly && !singleUse) {
                 return DAWN_VALIDATION_ERROR(
                     "Buffer used as writable usage and another usage in the same synchronization "
                     "scope");
             }
         }

         // Check that every single subresource is used as either a single-write usage or a
         // combination of readonly usages.
         for (const TextureSubresourceUsage& textureUsage : scope.textureUsages) {
             MaybeError error = {};
             textureUsage.Iterate([&](const SubresourceRange&, const wgpu::TextureUsage& usage) {
                 bool readOnly = IsSubset(usage, kReadOnlyTextureUsages);
                 bool singleUse = wgpu::HasZeroOrOneBits(usage);
                 if (!readOnly && !singleUse && !error.IsError()) {
                     error = DAWN_VALIDATION_ERROR(
                         "Texture used as writable usage and another usage in the same "
                         "synchronization scope");
                 }
             });
             DAWN_TRY(std::move(error));
         }
         return {};
     }

     MaybeError ValidateTimestampQuery(QuerySetBase* querySet, uint32_t queryIndex) {
         if (querySet->GetQueryType() != wgpu::QueryType::Timestamp) {
             return DAWN_VALIDATION_ERROR("The type of query set must be Timestamp");
         }

         if (queryIndex >= querySet->GetQueryCount()) {
             return DAWN_VALIDATION_ERROR("Query index exceeds the number of queries in query set");
         }

         return {};
     }

     MaybeError ValidateWriteBuffer(const DeviceBase* device,
                                    const BufferBase* buffer,
                                    uint64_t bufferOffset,
                                    uint64_t size) {
         DAWN_TRY(device->ValidateObject(buffer));

         if (bufferOffset % 4 != 0) {
             return DAWN_VALIDATION_ERROR("WriteBuffer bufferOffset must be a multiple of 4");
         }
         if (size % 4 != 0) {
             return DAWN_VALIDATION_ERROR("WriteBuffer size must be a multiple of 4");
         }

         uint64_t bufferSize = buffer->GetSize();
         if (bufferOffset > bufferSize || size > (bufferSize - bufferOffset)) {
             return DAWN_VALIDATION_ERROR("WriteBuffer out of range");
         }

         if (!(buffer->GetUsage() & wgpu::BufferUsage::CopyDst)) {
             return DAWN_VALIDATION_ERROR("Buffer needs the CopyDst usage bit");
         }

         return {};
     }

     bool IsRangeOverlapped(uint32_t startA, uint32_t startB, uint32_t length) {
         uint32_t maxStart = std::max(startA, startB);
         uint32_t minStart = std::min(startA, startB);
         return static_cast<uint64_t>(minStart) + static_cast<uint64_t>(length) >
                static_cast<uint64_t>(maxStart);
     }

     template <typename A, typename B>
     DAWN_FORCE_INLINE uint64_t Safe32x32(A a, B b) {
         static_assert(std::is_same<A, uint32_t>::value, "'a' must be uint32_t");
         static_assert(std::is_same<B, uint32_t>::value, "'b' must be uint32_t");
         return uint64_t(a) * uint64_t(b);
     }

     ResultOrError<uint64_t> ComputeRequiredBytesInCopy(const TexelBlockInfo& blockInfo,
                                                        const Extent3D& copySize,
                                                        uint32_t bytesPerRow,
                                                        uint32_t rowsPerImage) {
         ASSERT(copySize.width % blockInfo.width == 0);
         ASSERT(copySize.height % blockInfo.height == 0);
         uint32_t widthInBlocks = copySize.width / blockInfo.width;
         uint32_t heightInBlocks = copySize.height / blockInfo.height;
         uint64_t bytesInLastRow = Safe32x32(widthInBlocks, blockInfo.byteSize);

         if (copySize.depthOrArrayLayers == 0) {
             return 0;
         }

         // Check for potential overflows for the rest of the computations. We have the following
         // inequalities:
         //
         //   bytesInLastRow <= bytesPerRow
         //   heightInBlocks <= rowsPerImage
         //
         // So:
         //
         //   bytesInLastImage  = bytesPerRow * (heightInBlocks - 1) + bytesInLastRow
         //                    <= bytesPerRow * heightInBlocks
         //                    <= bytesPerRow * rowsPerImage
         //                    <= bytesPerImage
         //
         // This means that if the computation of depth * bytesPerImage doesn't overflow, none of the
         // computations for requiredBytesInCopy will. (and it's not a very pessimizing check)
         ASSERT(copySize.depthOrArrayLayers <= 1 || (bytesPerRow != wgpu::kCopyStrideUndefined &&
                                                     rowsPerImage != wgpu::kCopyStrideUndefined));
         uint64_t bytesPerImage = Safe32x32(bytesPerRow, rowsPerImage);
         if (bytesPerImage > std::numeric_limits<uint64_t>::max() / copySize.depthOrArrayLayers) {
             return DAWN_VALIDATION_ERROR("requiredBytesInCopy is too large.");
         }

         uint64_t requiredBytesInCopy = bytesPerImage * (copySize.depthOrArrayLayers - 1);
         if (heightInBlocks > 0) {
             ASSERT(heightInBlocks <= 1 || bytesPerRow != wgpu::kCopyStrideUndefined);
             uint64_t bytesInLastImage = Safe32x32(bytesPerRow, heightInBlocks - 1) + bytesInLastRow;
             requiredBytesInCopy += bytesInLastImage;
         }
         return requiredBytesInCopy;
     }

     MaybeError ValidateCopySizeFitsInBuffer(const Ref<BufferBase>& buffer,
                                             uint64_t offset,
                                             uint64_t size) {
         uint64_t bufferSize = buffer->GetSize();
         bool fitsInBuffer = offset <= bufferSize && (size <= (bufferSize - offset));
         if (!fitsInBuffer) {
             return DAWN_VALIDATION_ERROR("Copy would overflow the buffer");
         }

         return {};
     }

     // Replace wgpu::kCopyStrideUndefined with real values, so backends don't have to think about
     // it.
     void ApplyDefaultTextureDataLayoutOptions(TextureDataLayout* layout,
                                               const TexelBlockInfo& blockInfo,
                                               const Extent3D& copyExtent) {
         ASSERT(layout != nullptr);
         ASSERT(copyExtent.height % blockInfo.height == 0);
         uint32_t heightInBlocks = copyExtent.height / blockInfo.height;

         if (layout->bytesPerRow == wgpu::kCopyStrideUndefined) {
             ASSERT(copyExtent.width % blockInfo.width == 0);
             uint32_t widthInBlocks = copyExtent.width / blockInfo.width;
             uint32_t bytesInLastRow = widthInBlocks * blockInfo.byteSize;

             ASSERT(heightInBlocks <= 1 && copyExtent.depthOrArrayLayers <= 1);
             layout->bytesPerRow = Align(bytesInLastRow, kTextureBytesPerRowAlignment);
         }
         if (layout->rowsPerImage == wgpu::kCopyStrideUndefined) {
             ASSERT(copyExtent.depthOrArrayLayers <= 1);
             layout->rowsPerImage = heightInBlocks;
         }
     }

     MaybeError ValidateLinearTextureData(const TextureDataLayout& layout,
                                          uint64_t byteSize,
                                          const TexelBlockInfo& blockInfo,
                                          const Extent3D& copyExtent) {
         ASSERT(copyExtent.height % blockInfo.height == 0);
         uint32_t heightInBlocks = copyExtent.height / blockInfo.height;

         if (copyExtent.depthOrArrayLayers > 1 &&
             (layout.bytesPerRow == wgpu::kCopyStrideUndefined ||
              layout.rowsPerImage == wgpu::kCopyStrideUndefined)) {
             return DAWN_VALIDATION_ERROR(
                 "If copy depth > 1, bytesPerRow and rowsPerImage must be specified.");
         }
         if (heightInBlocks > 1 && layout.bytesPerRow == wgpu::kCopyStrideUndefined) {
             return DAWN_VALIDATION_ERROR("If heightInBlocks > 1, bytesPerRow must be specified.");
         }

         // Validation for other members in layout:
         ASSERT(copyExtent.width % blockInfo.width == 0);
         uint32_t widthInBlocks = copyExtent.width / blockInfo.width;
         ASSERT(Safe32x32(widthInBlocks, blockInfo.byteSize) <=
                std::numeric_limits<uint32_t>::max());
         uint32_t bytesInLastRow = widthInBlocks * blockInfo.byteSize;

         // These != wgpu::kCopyStrideUndefined checks are technically redundant with the > checks,
         // but they should get optimized out.
         if (layout.bytesPerRow != wgpu::kCopyStrideUndefined &&
             bytesInLastRow > layout.bytesPerRow) {
             return DAWN_VALIDATION_ERROR("The byte size of each row must be <= bytesPerRow.");
         }
         if (layout.rowsPerImage != wgpu::kCopyStrideUndefined &&
             heightInBlocks > layout.rowsPerImage) {
             return DAWN_VALIDATION_ERROR(
                 "The height of each image, in blocks, must be <= rowsPerImage.");
         }

         // We compute required bytes in copy after validating texel block alignments
         // because the divisibility conditions are necessary for the algorithm to be valid,
         // also the bytesPerRow bound is necessary to avoid overflows.
         uint64_t requiredBytesInCopy;
         DAWN_TRY_ASSIGN(requiredBytesInCopy,
                         ComputeRequiredBytesInCopy(blockInfo, copyExtent, layout.bytesPerRow,
                                                    layout.rowsPerImage));

         bool fitsInData =
             layout.offset <= byteSize && (requiredBytesInCopy <= (byteSize - layout.offset));
         if (!fitsInData) {
             return DAWN_VALIDATION_ERROR(
                 "Required size for texture data layout exceeds the linear data size.");
         }

         return {};
     }

     MaybeError ValidateImageCopyBuffer(DeviceBase const* device,
                                        const ImageCopyBuffer& imageCopyBuffer) {
         DAWN_TRY(device->ValidateObject(imageCopyBuffer.buffer));
         if (imageCopyBuffer.layout.bytesPerRow != wgpu::kCopyStrideUndefined) {
             if (imageCopyBuffer.layout.bytesPerRow % kTextureBytesPerRowAlignment != 0) {
                 return DAWN_VALIDATION_ERROR("bytesPerRow must be a multiple of 256");
             }
         }

         return {};
     }

     MaybeError ValidateImageCopyTexture(DeviceBase const* device,
                                         const ImageCopyTexture& textureCopy,
                                         const Extent3D& copySize) {
         const TextureBase* texture = textureCopy.texture;
         DAWN_TRY(device->ValidateObject(texture));
         if (textureCopy.mipLevel >= texture->GetNumMipLevels()) {
             return DAWN_VALIDATION_ERROR("mipLevel out of range");
         }

         DAWN_TRY(ValidateTextureAspect(textureCopy.aspect));
         if (SelectFormatAspects(texture->GetFormat(), textureCopy.aspect) == Aspect::None) {
             return DAWN_VALIDATION_ERROR("Texture does not have selected aspect for texture copy.");
         }

         if (texture->GetSampleCount() > 1 || texture->GetFormat().HasDepthOrStencil()) {
             Extent3D subresourceSize = texture->GetMipLevelPhysicalSize(textureCopy.mipLevel);
             ASSERT(texture->GetDimension() == wgpu::TextureDimension::e2D);
             if (textureCopy.origin.x != 0 || textureCopy.origin.y != 0 ||
                 subresourceSize.width != copySize.width ||
                 subresourceSize.height != copySize.height) {
                 return DAWN_VALIDATION_ERROR(
                     "The entire subresource must be copied when using a depth/stencil texture, or "
                     "when sample count is greater than 1.");
             }
         }

         return {};
     }

     MaybeError ValidateTextureCopyRange(DeviceBase const* device,
                                         const ImageCopyTexture& textureCopy,
                                         const Extent3D& copySize) {
         const TextureBase* texture = textureCopy.texture;

         ASSERT(texture->GetDimension() != wgpu::TextureDimension::e1D);

         // Validation for the copy being in-bounds:
         Extent3D mipSize = texture->GetMipLevelPhysicalSize(textureCopy.mipLevel);
         // For 1D/2D textures, include the array layer as depth so it can be checked with other
         // dimensions.
         if (texture->GetDimension() != wgpu::TextureDimension::e3D) {
             mipSize.depthOrArrayLayers = texture->GetArrayLayers();
         }
         // All texture dimensions are in uint32_t so by doing checks in uint64_t we avoid
         // overflows.
         if (static_cast<uint64_t>(textureCopy.origin.x) + static_cast<uint64_t>(copySize.width) >
                 static_cast<uint64_t>(mipSize.width) ||
             static_cast<uint64_t>(textureCopy.origin.y) + static_cast<uint64_t>(copySize.height) >
                 static_cast<uint64_t>(mipSize.height) ||
             static_cast<uint64_t>(textureCopy.origin.z) +
                     static_cast<uint64_t>(copySize.depthOrArrayLayers) >
                 static_cast<uint64_t>(mipSize.depthOrArrayLayers)) {
             return DAWN_VALIDATION_ERROR("Touching outside of the texture");
         }

         // Validation for the texel block alignments:
         const Format& format = textureCopy.texture->GetFormat();
         if (format.isCompressed) {
             const TexelBlockInfo& blockInfo = format.GetAspectInfo(textureCopy.aspect).block;
             if (textureCopy.origin.x % blockInfo.width != 0) {
                 return DAWN_VALIDATION_ERROR(
                     "Offset.x must be a multiple of compressed texture format block width");
             }
             if (textureCopy.origin.y % blockInfo.height != 0) {
                 return DAWN_VALIDATION_ERROR(
                     "Offset.y must be a multiple of compressed texture format block height");
             }
             if (copySize.width % blockInfo.width != 0) {
                 return DAWN_VALIDATION_ERROR(
                     "copySize.width must be a multiple of compressed texture format block width");
             }

             if (copySize.height % blockInfo.height != 0) {
                 return DAWN_VALIDATION_ERROR(
                     "copySize.height must be a multiple of compressed texture format block height");
             }
         }

         return {};
     }

     // Always returns a single aspect (color, stencil, depth, or ith plane for multi-planar
     // formats).
     ResultOrError<Aspect> SingleAspectUsedByImageCopyTexture(const ImageCopyTexture& view) {
         const Format& format = view.texture->GetFormat();
         switch (view.aspect) {
             case wgpu::TextureAspect::All:
                 if (HasOneBit(format.aspects)) {
                     Aspect single = format.aspects;
                     return single;
                 }
                 return DAWN_VALIDATION_ERROR(
                     "A single aspect must be selected for multi-planar formats in "
                     "texture <-> linear data copies");
             case wgpu::TextureAspect::DepthOnly:
                 ASSERT(format.aspects & Aspect::Depth);
                 return Aspect::Depth;
             case wgpu::TextureAspect::StencilOnly:
                 ASSERT(format.aspects & Aspect::Stencil);
                 return Aspect::Stencil;
             case wgpu::TextureAspect::Plane0Only:
             case wgpu::TextureAspect::Plane1Only:
                 break;
         }
         UNREACHABLE();
     }

     MaybeError ValidateLinearToDepthStencilCopyRestrictions(const ImageCopyTexture& dst) {
         Aspect aspectUsed;
         DAWN_TRY_ASSIGN(aspectUsed, SingleAspectUsedByImageCopyTexture(dst));
         if (aspectUsed == Aspect::Depth) {
             return DAWN_VALIDATION_ERROR("Cannot copy into the depth aspect of a texture");
         }

         return {};
     }

     MaybeError ValidateTextureToTextureCopyCommonRestrictions(const ImageCopyTexture& src,
                                                               const ImageCopyTexture& dst,
                                                               const Extent3D& copySize) {
         const uint32_t srcSamples = src.texture->GetSampleCount();
         const uint32_t dstSamples = dst.texture->GetSampleCount();

         if (srcSamples != dstSamples) {
             return DAWN_VALIDATION_ERROR(
                 "Source and destination textures must have matching sample counts.");
         }

         // Metal cannot select a single aspect for texture-to-texture copies.
         const Format& format = src.texture->GetFormat();
         if (SelectFormatAspects(format, src.aspect) != format.aspects) {
             return DAWN_VALIDATION_ERROR(
                 "Source aspect doesn't select all the aspects of the source format.");
         }
         if (SelectFormatAspects(format, dst.aspect) != format.aspects) {
             return DAWN_VALIDATION_ERROR(
                 "Destination aspect doesn't select all the aspects of the destination format.");
         }

         if (src.texture == dst.texture && src.mipLevel == dst.mipLevel) {
             wgpu::TextureDimension dimension = src.texture->GetDimension();
             ASSERT(dimension != wgpu::TextureDimension::e1D);
             if ((dimension == wgpu::TextureDimension::e2D &&
                  IsRangeOverlapped(src.origin.z, dst.origin.z, copySize.depthOrArrayLayers)) ||
                 dimension == wgpu::TextureDimension::e3D) {
                 return DAWN_VALIDATION_ERROR(
                     "Cannot copy between overlapping subresources of the same texture.");
             }
         }

         return {};
     }

     MaybeError ValidateTextureToTextureCopyRestrictions(const ImageCopyTexture& src,
                                                         const ImageCopyTexture& dst,
                                                         const Extent3D& copySize) {
         if (src.texture->GetFormat().format != dst.texture->GetFormat().format) {
             // Metal requires texture-to-texture copies be the same format
             return DAWN_VALIDATION_ERROR("Source and destination texture formats must match.");
         }

         return ValidateTextureToTextureCopyCommonRestrictions(src, dst, copySize);
     }

     // CopyTextureForBrowser could handle color conversion during the copy and it
     // requires the source must be sampleable and the destination must be writable
     // using a render pass
     MaybeError ValidateCopyTextureForBrowserRestrictions(const ImageCopyTexture& src,
                                                          const ImageCopyTexture& dst,
                                                          const Extent3D& copySize) {
         if (!(src.texture->GetUsage() & wgpu::TextureUsage::TextureBinding)) {
             return DAWN_VALIDATION_ERROR("Source texture must have sampled usage");
         }

         if (!(dst.texture->GetUsage() & wgpu::TextureUsage::RenderAttachment)) {
             return DAWN_VALIDATION_ERROR("Dest texture must have RenderAttachment usage");
         }

         return ValidateTextureToTextureCopyCommonRestrictions(src, dst, copySize);
     }

     MaybeError ValidateCanUseAs(const TextureBase* texture, wgpu::TextureUsage usage) {
         ASSERT(wgpu::HasZeroOrOneBits(usage));
         if (!(texture->GetUsage() & usage)) {
             return DAWN_VALIDATION_ERROR("texture doesn't have the required usage.");
         }

         return {};
     }

     MaybeError ValidateInternalCanUseAs(const TextureBase* texture, wgpu::TextureUsage usage) {
         ASSERT(wgpu::HasZeroOrOneBits(usage));
         if (!(texture->GetInternalUsage() & usage)) {
             return DAWN_VALIDATION_ERROR("texture doesn't have the required usage.");
         }

         return {};
     }

     MaybeError ValidateCanUseAs(const BufferBase* buffer, wgpu::BufferUsage usage) {
         ASSERT(wgpu::HasZeroOrOneBits(usage));
         if (!(buffer->GetUsage() & usage)) {
             return DAWN_VALIDATION_ERROR("buffer doesn't have the required usage.");
         }

         return {};
     }

 }  // namespace dawn_native
	// Copyright 2019 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/CommandValidation.h"

	#include "common/BitSetIterator.h"
	#include "dawn_native/BindGroup.h"
	#include "dawn_native/Buffer.h"
	#include "dawn_native/CommandBufferStateTracker.h"
	#include "dawn_native/Commands.h"
	#include "dawn_native/Device.h"
	#include "dawn_native/PassResourceUsage.h"
	#include "dawn_native/QuerySet.h"
	#include "dawn_native/RenderBundle.h"
	#include "dawn_native/RenderPipeline.h"
	#include "dawn_native/ValidationUtils_autogen.h"

	namespace dawn_native {

	// Performs validation of the "synchronization scope" rules of WebGPU.
	MaybeError ValidateSyncScopeResourceUsage(const SyncScopeResourceUsage& scope) {
	// Buffers can only be used as single-write or multiple read.
	for (wgpu::BufferUsage usage : scope.bufferUsages) {
	bool readOnly = IsSubset(usage, kReadOnlyBufferUsages);
	bool singleUse = wgpu::HasZeroOrOneBits(usage);

	if (!readOnly && !singleUse) {
	return DAWN_VALIDATION_ERROR(
	"Buffer used as writable usage and another usage in the same synchronization "
	"scope");
	}
	}

	// Check that every single subresource is used as either a single-write usage or a
	// combination of readonly usages.
	for (const TextureSubresourceUsage& textureUsage : scope.textureUsages) {
	MaybeError error = {};
	textureUsage.Iterate([&](const SubresourceRange&, const wgpu::TextureUsage& usage) {
	bool readOnly = IsSubset(usage, kReadOnlyTextureUsages);
	bool singleUse = wgpu::HasZeroOrOneBits(usage);
	if (!readOnly && !singleUse && !error.IsError()) {
	error = DAWN_VALIDATION_ERROR(
	"Texture used as writable usage and another usage in the same "
	"synchronization scope");
	}
	});
	DAWN_TRY(std::move(error));
	}
	return {};
	}

	MaybeError ValidateTimestampQuery(QuerySetBase* querySet, uint32_t queryIndex) {
	if (querySet->GetQueryType() != wgpu::QueryType::Timestamp) {
	return DAWN_VALIDATION_ERROR("The type of query set must be Timestamp");
	}

	if (queryIndex >= querySet->GetQueryCount()) {
	return DAWN_VALIDATION_ERROR("Query index exceeds the number of queries in query set");
	}

	return {};
	}

	MaybeError ValidateWriteBuffer(const DeviceBase* device,
	const BufferBase* buffer,
	uint64_t bufferOffset,
	uint64_t size) {
	DAWN_TRY(device->ValidateObject(buffer));

	if (bufferOffset % 4 != 0) {
	return DAWN_VALIDATION_ERROR("WriteBuffer bufferOffset must be a multiple of 4");
	}
	if (size % 4 != 0) {
	return DAWN_VALIDATION_ERROR("WriteBuffer size must be a multiple of 4");
	}

	uint64_t bufferSize = buffer->GetSize();
	if (bufferOffset > bufferSize \|\| size > (bufferSize - bufferOffset)) {
	return DAWN_VALIDATION_ERROR("WriteBuffer out of range");
	}

	if (!(buffer->GetUsage() & wgpu::BufferUsage::CopyDst)) {
	return DAWN_VALIDATION_ERROR("Buffer needs the CopyDst usage bit");
	}

	return {};
	}

	bool IsRangeOverlapped(uint32_t startA, uint32_t startB, uint32_t length) {
	uint32_t maxStart = std::max(startA, startB);
	uint32_t minStart = std::min(startA, startB);
	return static_cast<uint64_t>(minStart) + static_cast<uint64_t>(length) >
	static_cast<uint64_t>(maxStart);
	}

	template <typename A, typename B>
	DAWN_FORCE_INLINE uint64_t Safe32x32(A a, B b) {
	static_assert(std::is_same<A, uint32_t>::value, "'a' must be uint32_t");
	static_assert(std::is_same<B, uint32_t>::value, "'b' must be uint32_t");
	return uint64_t(a) * uint64_t(b);
	}

	ResultOrError<uint64_t> ComputeRequiredBytesInCopy(const TexelBlockInfo& blockInfo,
	const Extent3D& copySize,
	uint32_t bytesPerRow,
	uint32_t rowsPerImage) {
	ASSERT(copySize.width % blockInfo.width == 0);
	ASSERT(copySize.height % blockInfo.height == 0);
	uint32_t widthInBlocks = copySize.width / blockInfo.width;
	uint32_t heightInBlocks = copySize.height / blockInfo.height;
	uint64_t bytesInLastRow = Safe32x32(widthInBlocks, blockInfo.byteSize);

	if (copySize.depthOrArrayLayers == 0) {
	return 0;
	}

	// Check for potential overflows for the rest of the computations. We have the following
	// inequalities:
	//
	// bytesInLastRow <= bytesPerRow
	// heightInBlocks <= rowsPerImage
	//
	// So:
	//
	// bytesInLastImage = bytesPerRow * (heightInBlocks - 1) + bytesInLastRow
	// <= bytesPerRow * heightInBlocks
	// <= bytesPerRow * rowsPerImage
	// <= bytesPerImage
	//
	// This means that if the computation of depth * bytesPerImage doesn't overflow, none of the
	// computations for requiredBytesInCopy will. (and it's not a very pessimizing check)
	ASSERT(copySize.depthOrArrayLayers <= 1 \|\| (bytesPerRow != wgpu::kCopyStrideUndefined &&
	rowsPerImage != wgpu::kCopyStrideUndefined));
	uint64_t bytesPerImage = Safe32x32(bytesPerRow, rowsPerImage);
	if (bytesPerImage > std::numeric_limits<uint64_t>::max() / copySize.depthOrArrayLayers) {
	return DAWN_VALIDATION_ERROR("requiredBytesInCopy is too large.");
	}

	uint64_t requiredBytesInCopy = bytesPerImage * (copySize.depthOrArrayLayers - 1);
	if (heightInBlocks > 0) {
	ASSERT(heightInBlocks <= 1 \|\| bytesPerRow != wgpu::kCopyStrideUndefined);
	uint64_t bytesInLastImage = Safe32x32(bytesPerRow, heightInBlocks - 1) + bytesInLastRow;
	requiredBytesInCopy += bytesInLastImage;
	}
	return requiredBytesInCopy;
	}

	MaybeError ValidateCopySizeFitsInBuffer(const Ref<BufferBase>& buffer,
	uint64_t offset,
	uint64_t size) {
	uint64_t bufferSize = buffer->GetSize();
	bool fitsInBuffer = offset <= bufferSize && (size <= (bufferSize - offset));
	if (!fitsInBuffer) {
	return DAWN_VALIDATION_ERROR("Copy would overflow the buffer");
	}

	return {};
	}

	// Replace wgpu::kCopyStrideUndefined with real values, so backends don't have to think about
	// it.
	void ApplyDefaultTextureDataLayoutOptions(TextureDataLayout* layout,
	const TexelBlockInfo& blockInfo,
	const Extent3D& copyExtent) {
	ASSERT(layout != nullptr);
	ASSERT(copyExtent.height % blockInfo.height == 0);
	uint32_t heightInBlocks = copyExtent.height / blockInfo.height;

	if (layout->bytesPerRow == wgpu::kCopyStrideUndefined) {
	ASSERT(copyExtent.width % blockInfo.width == 0);
	uint32_t widthInBlocks = copyExtent.width / blockInfo.width;
	uint32_t bytesInLastRow = widthInBlocks * blockInfo.byteSize;

	ASSERT(heightInBlocks <= 1 && copyExtent.depthOrArrayLayers <= 1);
	layout->bytesPerRow = Align(bytesInLastRow, kTextureBytesPerRowAlignment);
	}
	if (layout->rowsPerImage == wgpu::kCopyStrideUndefined) {
	ASSERT(copyExtent.depthOrArrayLayers <= 1);
	layout->rowsPerImage = heightInBlocks;
	}
	}

	MaybeError ValidateLinearTextureData(const TextureDataLayout& layout,
	uint64_t byteSize,
	const TexelBlockInfo& blockInfo,
	const Extent3D& copyExtent) {
	ASSERT(copyExtent.height % blockInfo.height == 0);
	uint32_t heightInBlocks = copyExtent.height / blockInfo.height;

	if (copyExtent.depthOrArrayLayers > 1 &&
	(layout.bytesPerRow == wgpu::kCopyStrideUndefined \|\|
	layout.rowsPerImage == wgpu::kCopyStrideUndefined)) {
	return DAWN_VALIDATION_ERROR(
	"If copy depth > 1, bytesPerRow and rowsPerImage must be specified.");
	}
	if (heightInBlocks > 1 && layout.bytesPerRow == wgpu::kCopyStrideUndefined) {
	return DAWN_VALIDATION_ERROR("If heightInBlocks > 1, bytesPerRow must be specified.");
	}

	// Validation for other members in layout:
	ASSERT(copyExtent.width % blockInfo.width == 0);
	uint32_t widthInBlocks = copyExtent.width / blockInfo.width;
	ASSERT(Safe32x32(widthInBlocks, blockInfo.byteSize) <=
	std::numeric_limits<uint32_t>::max());
	uint32_t bytesInLastRow = widthInBlocks * blockInfo.byteSize;

	// These != wgpu::kCopyStrideUndefined checks are technically redundant with the > checks,
	// but they should get optimized out.
	if (layout.bytesPerRow != wgpu::kCopyStrideUndefined &&
	bytesInLastRow > layout.bytesPerRow) {
	return DAWN_VALIDATION_ERROR("The byte size of each row must be <= bytesPerRow.");
	}
	if (layout.rowsPerImage != wgpu::kCopyStrideUndefined &&
	heightInBlocks > layout.rowsPerImage) {
	return DAWN_VALIDATION_ERROR(
	"The height of each image, in blocks, must be <= rowsPerImage.");
	}

	// We compute required bytes in copy after validating texel block alignments
	// because the divisibility conditions are necessary for the algorithm to be valid,
	// also the bytesPerRow bound is necessary to avoid overflows.
	uint64_t requiredBytesInCopy;
	DAWN_TRY_ASSIGN(requiredBytesInCopy,
	ComputeRequiredBytesInCopy(blockInfo, copyExtent, layout.bytesPerRow,
	layout.rowsPerImage));

	bool fitsInData =
	layout.offset <= byteSize && (requiredBytesInCopy <= (byteSize - layout.offset));
	if (!fitsInData) {
	return DAWN_VALIDATION_ERROR(
	"Required size for texture data layout exceeds the linear data size.");
	}

	return {};
	}

	MaybeError ValidateImageCopyBuffer(DeviceBase const* device,
	const ImageCopyBuffer& imageCopyBuffer) {
	DAWN_TRY(device->ValidateObject(imageCopyBuffer.buffer));
	if (imageCopyBuffer.layout.bytesPerRow != wgpu::kCopyStrideUndefined) {
	if (imageCopyBuffer.layout.bytesPerRow % kTextureBytesPerRowAlignment != 0) {
	return DAWN_VALIDATION_ERROR("bytesPerRow must be a multiple of 256");
	}
	}

	return {};
	}

	MaybeError ValidateImageCopyTexture(DeviceBase const* device,
	const ImageCopyTexture& textureCopy,
	const Extent3D& copySize) {
	const TextureBase* texture = textureCopy.texture;
	DAWN_TRY(device->ValidateObject(texture));
	if (textureCopy.mipLevel >= texture->GetNumMipLevels()) {
	return DAWN_VALIDATION_ERROR("mipLevel out of range");
	}

	DAWN_TRY(ValidateTextureAspect(textureCopy.aspect));
	if (SelectFormatAspects(texture->GetFormat(), textureCopy.aspect) == Aspect::None) {
	return DAWN_VALIDATION_ERROR("Texture does not have selected aspect for texture copy.");
	}

	if (texture->GetSampleCount() > 1 \|\| texture->GetFormat().HasDepthOrStencil()) {
	Extent3D subresourceSize = texture->GetMipLevelPhysicalSize(textureCopy.mipLevel);
	ASSERT(texture->GetDimension() == wgpu::TextureDimension::e2D);
	if (textureCopy.origin.x != 0 \|\| textureCopy.origin.y != 0 \|\|
	subresourceSize.width != copySize.width \|\|
	subresourceSize.height != copySize.height) {
	return DAWN_VALIDATION_ERROR(
	"The entire subresource must be copied when using a depth/stencil texture, or "
	"when sample count is greater than 1.");
	}
	}

	return {};
	}

	MaybeError ValidateTextureCopyRange(DeviceBase const* device,
	const ImageCopyTexture& textureCopy,
	const Extent3D& copySize) {
	const TextureBase* texture = textureCopy.texture;

	ASSERT(texture->GetDimension() != wgpu::TextureDimension::e1D);

	// Validation for the copy being in-bounds:
	Extent3D mipSize = texture->GetMipLevelPhysicalSize(textureCopy.mipLevel);
	// For 1D/2D textures, include the array layer as depth so it can be checked with other
	// dimensions.
	if (texture->GetDimension() != wgpu::TextureDimension::e3D) {
	mipSize.depthOrArrayLayers = texture->GetArrayLayers();
	}
	// All texture dimensions are in uint32_t so by doing checks in uint64_t we avoid
	// overflows.
	if (static_cast<uint64_t>(textureCopy.origin.x) + static_cast<uint64_t>(copySize.width) >
	static_cast<uint64_t>(mipSize.width) \|\|
	static_cast<uint64_t>(textureCopy.origin.y) + static_cast<uint64_t>(copySize.height) >
	static_cast<uint64_t>(mipSize.height) \|\|
	static_cast<uint64_t>(textureCopy.origin.z) +
	static_cast<uint64_t>(copySize.depthOrArrayLayers) >
	static_cast<uint64_t>(mipSize.depthOrArrayLayers)) {
	return DAWN_VALIDATION_ERROR("Touching outside of the texture");
	}

	// Validation for the texel block alignments:
	const Format& format = textureCopy.texture->GetFormat();
	if (format.isCompressed) {
	const TexelBlockInfo& blockInfo = format.GetAspectInfo(textureCopy.aspect).block;
	if (textureCopy.origin.x % blockInfo.width != 0) {
	return DAWN_VALIDATION_ERROR(
	"Offset.x must be a multiple of compressed texture format block width");
	}
	if (textureCopy.origin.y % blockInfo.height != 0) {
	return DAWN_VALIDATION_ERROR(
	"Offset.y must be a multiple of compressed texture format block height");
	}
	if (copySize.width % blockInfo.width != 0) {
	return DAWN_VALIDATION_ERROR(
	"copySize.width must be a multiple of compressed texture format block width");
	}

	if (copySize.height % blockInfo.height != 0) {
	return DAWN_VALIDATION_ERROR(
	"copySize.height must be a multiple of compressed texture format block height");
	}
	}

	return {};
	}

	// Always returns a single aspect (color, stencil, depth, or ith plane for multi-planar
	// formats).
	ResultOrError<Aspect> SingleAspectUsedByImageCopyTexture(const ImageCopyTexture& view) {
	const Format& format = view.texture->GetFormat();
	switch (view.aspect) {
	case wgpu::TextureAspect::All:
	if (HasOneBit(format.aspects)) {
	Aspect single = format.aspects;
	return single;
	}
	return DAWN_VALIDATION_ERROR(
	"A single aspect must be selected for multi-planar formats in "
	"texture <-> linear data copies");
	case wgpu::TextureAspect::DepthOnly:
	ASSERT(format.aspects & Aspect::Depth);
	return Aspect::Depth;
	case wgpu::TextureAspect::StencilOnly:
	ASSERT(format.aspects & Aspect::Stencil);
	return Aspect::Stencil;
	case wgpu::TextureAspect::Plane0Only:
	case wgpu::TextureAspect::Plane1Only:
	break;
	}
	UNREACHABLE();
	}

	MaybeError ValidateLinearToDepthStencilCopyRestrictions(const ImageCopyTexture& dst) {
	Aspect aspectUsed;
	DAWN_TRY_ASSIGN(aspectUsed, SingleAspectUsedByImageCopyTexture(dst));
	if (aspectUsed == Aspect::Depth) {
	return DAWN_VALIDATION_ERROR("Cannot copy into the depth aspect of a texture");
	}

	return {};
	}

	MaybeError ValidateTextureToTextureCopyCommonRestrictions(const ImageCopyTexture& src,
	const ImageCopyTexture& dst,
	const Extent3D& copySize) {
	const uint32_t srcSamples = src.texture->GetSampleCount();
	const uint32_t dstSamples = dst.texture->GetSampleCount();

	if (srcSamples != dstSamples) {
	return DAWN_VALIDATION_ERROR(
	"Source and destination textures must have matching sample counts.");
	}

	// Metal cannot select a single aspect for texture-to-texture copies.
	const Format& format = src.texture->GetFormat();
	if (SelectFormatAspects(format, src.aspect) != format.aspects) {
	return DAWN_VALIDATION_ERROR(
	"Source aspect doesn't select all the aspects of the source format.");
	}
	if (SelectFormatAspects(format, dst.aspect) != format.aspects) {
	return DAWN_VALIDATION_ERROR(
	"Destination aspect doesn't select all the aspects of the destination format.");
	}

	if (src.texture == dst.texture && src.mipLevel == dst.mipLevel) {
	wgpu::TextureDimension dimension = src.texture->GetDimension();
	ASSERT(dimension != wgpu::TextureDimension::e1D);
	if ((dimension == wgpu::TextureDimension::e2D &&
	IsRangeOverlapped(src.origin.z, dst.origin.z, copySize.depthOrArrayLayers)) \|\|
	dimension == wgpu::TextureDimension::e3D) {
	return DAWN_VALIDATION_ERROR(
	"Cannot copy between overlapping subresources of the same texture.");
	}
	}

	return {};
	}

	MaybeError ValidateTextureToTextureCopyRestrictions(const ImageCopyTexture& src,
	const ImageCopyTexture& dst,
	const Extent3D& copySize) {
	if (src.texture->GetFormat().format != dst.texture->GetFormat().format) {
	// Metal requires texture-to-texture copies be the same format
	return DAWN_VALIDATION_ERROR("Source and destination texture formats must match.");
	}

	return ValidateTextureToTextureCopyCommonRestrictions(src, dst, copySize);
	}

	// CopyTextureForBrowser could handle color conversion during the copy and it
	// requires the source must be sampleable and the destination must be writable
	// using a render pass
	MaybeError ValidateCopyTextureForBrowserRestrictions(const ImageCopyTexture& src,
	const ImageCopyTexture& dst,
	const Extent3D& copySize) {
	if (!(src.texture->GetUsage() & wgpu::TextureUsage::TextureBinding)) {
	return DAWN_VALIDATION_ERROR("Source texture must have sampled usage");
	}

	if (!(dst.texture->GetUsage() & wgpu::TextureUsage::RenderAttachment)) {
	return DAWN_VALIDATION_ERROR("Dest texture must have RenderAttachment usage");
	}

	return ValidateTextureToTextureCopyCommonRestrictions(src, dst, copySize);
	}

	MaybeError ValidateCanUseAs(const TextureBase* texture, wgpu::TextureUsage usage) {
	ASSERT(wgpu::HasZeroOrOneBits(usage));
	if (!(texture->GetUsage() & usage)) {
	return DAWN_VALIDATION_ERROR("texture doesn't have the required usage.");
	}

	return {};
	}

	MaybeError ValidateInternalCanUseAs(const TextureBase* texture, wgpu::TextureUsage usage) {
	ASSERT(wgpu::HasZeroOrOneBits(usage));
	if (!(texture->GetInternalUsage() & usage)) {
	return DAWN_VALIDATION_ERROR("texture doesn't have the required usage.");
	}

	return {};
	}

	MaybeError ValidateCanUseAs(const BufferBase* buffer, wgpu::BufferUsage usage) {
	ASSERT(wgpu::HasZeroOrOneBits(usage));
	if (!(buffer->GetUsage() & usage)) {
	return DAWN_VALIDATION_ERROR("buffer doesn't have the required usage.");
	}

	return {};
	}

	} // namespace dawn_native