Appendix A: Vulkan Environment for SPIR-V

Shaders for Vulkan are defined by the Khronos SPIR-V Specification as well as the Khronos SPIR-V Extended Instructions for GLSL Specification. This appendix defines additional SPIR-V requirements applying to Vulkan shaders.

Versions and Formats

A Vulkan 1.1 implementation must support the 1.0, 1.1, 1.2, and 1.3 versions of SPIR-V and the 1.0 version of the SPIR-V Extended Instructions for GLSL.

A SPIR-V module passed into vkCreateShaderModule is interpreted as a series of 32-bit words in host endianness, with literal strings packed as described in section 2.2 of the SPIR-V Specification. The first few words of the SPIR-V module must be a magic number and a SPIR-V version number, as described in section 2.3 of the SPIR-V Specification.

Capabilities

The table below lists the set of SPIR-V capabilities that may be supported in Vulkan implementations. The application must not use any of these capabilities in SPIR-V passed to vkCreateShaderModule unless one of the following conditions is met for the VkDevice specified in the device parameter of vkCreateShaderModule:

  • The corresponding field in the table is blank.

  • Any corresponding Vulkan feature is enabled.

  • Any corresponding Vulkan extension is enabled.

  • Any corresponding Vulkan property is supported.

  • The corresponding core version is supported (as returned by VkPhysicalDeviceProperties::apiVersion).

Table 60. List of SPIR-V Capabilities and corresponding Vulkan features, extensions, or core version
SPIR-V OpCapability
                Vulkan feature, extension, or core version

Matrix
                VK_API_VERSION_1_0

Shader
                VK_API_VERSION_1_0

InputAttachment
                VK_API_VERSION_1_0

Sampled1D
                VK_API_VERSION_1_0

Image1D
                VK_API_VERSION_1_0

SampledBuffer
                VK_API_VERSION_1_0

ImageBuffer
                VK_API_VERSION_1_0

ImageQuery
                VK_API_VERSION_1_0

DerivativeControl
                VK_API_VERSION_1_0

Geometry
                VkPhysicalDeviceFeatures::geometryShader

Tessellation
                VkPhysicalDeviceFeatures::tessellationShader

Float64
                VkPhysicalDeviceFeatures::shaderFloat64

Int64
                VkPhysicalDeviceFeatures::shaderInt64

Int16
                VkPhysicalDeviceFeatures::shaderInt16

TessellationPointSize
                VkPhysicalDeviceFeatures::shaderTessellationAndGeometryPointSize

GeometryPointSize
                VkPhysicalDeviceFeatures::shaderTessellationAndGeometryPointSize

ImageGatherExtended
                VkPhysicalDeviceFeatures::shaderImageGatherExtended

StorageImageMultisample
                VkPhysicalDeviceFeatures::shaderStorageImageMultisample

UniformBufferArrayDynamicIndexing
                VkPhysicalDeviceFeatures::shaderUniformBufferArrayDynamicIndexing

SampledImageArrayDynamicIndexing
                VkPhysicalDeviceFeatures::shaderSampledImageArrayDynamicIndexing

StorageBufferArrayDynamicIndexing
                VkPhysicalDeviceFeatures::shaderStorageBufferArrayDynamicIndexing

StorageImageArrayDynamicIndexing
                VkPhysicalDeviceFeatures::shaderStorageImageArrayDynamicIndexing

ClipDistance
                VkPhysicalDeviceFeatures::shaderClipDistance

CullDistance
                VkPhysicalDeviceFeatures::shaderCullDistance

ImageCubeArray
                VkPhysicalDeviceFeatures::imageCubeArray

SampleRateShading
                VkPhysicalDeviceFeatures::sampleRateShading

SparseResidency
                VkPhysicalDeviceFeatures::shaderResourceResidency

MinLod
                VkPhysicalDeviceFeatures::shaderResourceMinLod

SampledCubeArray
                VkPhysicalDeviceFeatures::imageCubeArray

ImageMSArray
                VkPhysicalDeviceFeatures::shaderStorageImageMultisample

StorageImageExtendedFormats
                VK_API_VERSION_1_0

InterpolationFunction
                VkPhysicalDeviceFeatures::sampleRateShading

StorageImageReadWithoutFormat
                VkPhysicalDeviceFeatures::shaderStorageImageReadWithoutFormat

StorageImageWriteWithoutFormat
                VkPhysicalDeviceFeatures::shaderStorageImageWriteWithoutFormat

MultiViewport
                VkPhysicalDeviceFeatures::multiViewport

DrawParameters
                VkPhysicalDeviceShaderDrawParametersFeatures::shaderDrawParameters

DeviceGroup
                VK_API_VERSION_1_1

GroupNonUniform
                VK_SUBGROUP_FEATURE_BASIC_BIT

GroupNonUniformVote
                VK_SUBGROUP_FEATURE_VOTE_BIT

GroupNonUniformArithmetic
                VK_SUBGROUP_FEATURE_ARITHMETIC_BIT

GroupNonUniformBallot
                VK_SUBGROUP_FEATURE_BALLOT_BIT

GroupNonUniformShuffle
                VK_SUBGROUP_FEATURE_SHUFFLE_BIT

GroupNonUniformShuffleRelative
                VK_SUBGROUP_FEATURE_SHUFFLE_RELATIVE_BIT

GroupNonUniformClustered
                VK_SUBGROUP_FEATURE_CLUSTERED_BIT

GroupNonUniformQuad
                VK_SUBGROUP_FEATURE_QUAD_BIT

The application must not pass a SPIR-V module containing any of the following to vkCreateShaderModule:

  • any OpCapability not listed above,

  • an unsupported capability, or

  • a capability which corresponds to a Vulkan feature or extension which has not been enabled.

SPIR-V Extensions

The following table lists SPIR-V extensions that implementations may support. The application must not pass a SPIR-V module to vkCreateShaderModule that uses the following SPIR-V extensions unless one of the following conditions is met for the VkDevice specified in the device parameter of vkCreateShaderModule:

  • Any corresponding Vulkan extension is enabled.

  • The corresponding core version is supported (as returned by VkPhysicalDeviceProperties::apiVersion).

Table 61. List of SPIR-V Extensions and corresponding Vulkan extensions or core version
SPIR-V OpExtension
                Vulkan extension or core version

SPV_KHR_variable_pointers
                VK_API_VERSION_1_1

SPV_KHR_shader_draw_parameters
                VK_API_VERSION_1_1

SPV_KHR_16bit_storage
                VK_API_VERSION_1_1

SPV_KHR_storage_buffer_storage_class
                VK_API_VERSION_1_1

SPV_KHR_multiview
                VK_API_VERSION_1_1

Validation Rules within a Module

A SPIR-V module passed to vkCreateShaderModule must conform to the following rules:

Standalone SPIR-V Validation

The following rules can be validated with only the SPIR-V module itself. They do not depend on knowledge of the implementation and its capabilities or knowledge of runtime information, such as enabled features.

Valid Usage
  • VUID-StandaloneSpirv-None-04633
    Every entry point must have no return value and accept no arguments

  • VUID-StandaloneSpirv-None-04634
    The static function-call graph for an entry point must not contain cycles; that is, static recursion is not allowed

  • VUID-StandaloneSpirv-None-04635
    The Logical or PhysicalStorageBuffer64 addressing model must be selected

  • VUID-StandaloneSpirv-None-04636
    Scope for execution must be limited to Workgroup or Subgroup

  • VUID-StandaloneSpirv-None-04637
    If the Scope for execution is Workgroup, then it must only be used in the task, mesh, tessellation control, or compute execution models

  • VUID-StandaloneSpirv-None-04638
    Scope for memory must be limited to Device, QueueFamily, Workgroup, ShaderCallKHR, Subgroup, or Invocation

  • VUID-StandaloneSpirv-None-04639
    If the Scope for memory is Workgroup, then it must only be used in the task, mesh, or compute execution models

  • VUID-StandaloneSpirv-None-04640
    If the Scope for memory is ShaderCallKHR, then it must only be used in ray generation, intersection, closest hit, any-hit, miss, and callable execution models

  • VUID-StandaloneSpirv-None-04641
    If the Scope for memory is Invocation, then memory semantics must be None

  • VUID-StandaloneSpirv-None-04642
    Scope for Non Uniform Group Operations must be limited to Subgroup

  • VUID-StandaloneSpirv-None-04643
    Storage Class must be limited to UniformConstant, Input, Uniform, Output, Workgroup, Private, Function, PushConstant, Image, StorageBuffer, RayPayloadKHR, IncomingRayPayloadKHR, HitAttributeKHR, CallableDataKHR, IncomingCallableDataKHR, ShaderRecordBufferKHR, or PhysicalStorageBuffer

  • VUID-StandaloneSpirv-None-04644
    If the Storage Class is Output, then it must not be used in the GlCompute, RayGenerationKHR, IntersectionKHR, AnyHitKHR, ClosestHitKHR, MissKHR, or CallableKHR execution models

  • VUID-StandaloneSpirv-None-04645
    If the Storage Class is Workgroup, then it must only be used in the task, mesh, or compute execution models

  • VUID-StandaloneSpirv-OpAtomicStore-04730
    OpAtomicStore must not use Acquire, AcquireRelease, or SequentiallyConsistent memory semantics

  • VUID-StandaloneSpirv-OpAtomicLoad-04731
    OpAtomicLoad must not use Release, AcquireRelease, or SequentiallyConsistent memory semantics

  • VUID-StandaloneSpirv-OpMemoryBarrier-04732
    OpMemoryBarrier must use one of Acquire, Release, AcquireRelease, or SequentiallyConsistent memory semantics

  • VUID-StandaloneSpirv-OpMemoryBarrier-04733
    OpMemoryBarrier must include at least one storage class

  • VUID-StandaloneSpirv-OpControlBarrier-04650
    If the semantics for OpControlBarrier includes one of Acquire, Release, AcquireRelease, or SequentiallyConsistent memory semantics, then it must include at least one storage class

  • VUID-StandaloneSpirv-OpVariable-04651
    Any OpVariable with an Initializer operand must have Output, Private, Function, or Workgroup as its Storage Class operand

  • VUID-StandaloneSpirv-OpVariable-04734
    Any OpVariable with an Initializer operand and Workgroup as its Storage Class operand must use OpConstantNull as the initializer.

  • VUID-StandaloneSpirv-OpReadClockKHR-04652
    Scope for OpReadClockKHR must be limited to Subgroup or Device

  • VUID-StandaloneSpirv-OriginLowerLeft-04653
    The OriginLowerLeft execution mode must not be used; fragment entry points must declare OriginUpperLeft

  • VUID-StandaloneSpirv-PixelCenterInteger-04654
    The PixelCenterInteger execution mode must not be used (pixels are always centered at half-integer coordinates)

  • VUID-StandaloneSpirv-UniformConstant-04655
    Any variable in the UniformConstant storage class must be typed as either OpTypeImage, OpTypeSampler, OpTypeSampledImage, OpTypeAccelerationStructureKHR, or an array of one of these types

  • VUID-StandaloneSpirv-OpTypeImage-04656
    OpTypeImage must declare a scalar 32-bit float, 64-bit integer, or 32-bit integer type for the “Sampled Type” (RelaxedPrecision can be applied to a sampling instruction and to the variable holding the result of a sampling instruction)

  • VUID-StandaloneSpirv-OpTypeImage-04657
    OpTypeImage must have a “Sampled” operand of 1 (sampled image) or 2 (storage image)

  • VUID-StandaloneSpirv-OpImageTexelPointer-04658
    If an OpImageTexelPointer is used in an atomic operation, the image type of the image parameter to OpImageTexelPointer must have an image format of R64i, R64ui, R32f, R32i, or R32ui

  • VUID-StandaloneSpirv-OpImageQuerySizeLod-04659
    OpImageQuerySizeLod, OpImageQueryLod, and OpImageQueryLevels must only consume an “Image” operand whose type has its “Sampled” operand set to 1

  • VUID-StandaloneSpirv-SubpassData-04660
    The (u,v) coordinates used for a SubpassData must be the <id> of a constant vector (0,0), or if a layer coordinate is used, must be a vector that was formed with constant 0 for the u and v components

  • VUID-StandaloneSpirv-OpTypeImage-04661
    Objects of types OpTypeImage, OpTypeSampler, OpTypeSampledImage, and arrays of these types must not be stored to or modified

  • VUID-StandaloneSpirv-Offset-04662
    Any image operation must use at most one of the Offset, ConstOffset, and ConstOffsets image operands

  • VUID-StandaloneSpirv-Offset-04663
    Image operand Offset must only be used with OpImage*Gather instructions

  • VUID-StandaloneSpirv-Offset-04865
    Any image instruction which uses an Offset, ConstOffset, or ConstOffsets image operand, must only consume a “Sampled Image” operand whose type has its “Sampled” operand set to 1

  • VUID-StandaloneSpirv-OpImageGather-04664
    The “Component” operand of OpImageGather, and OpImageSparseGather must be the <id> of a constant instruction

  • VUID-StandaloneSpirv-OpImage-04777
    OpImage*Dref must not consume an image whose Dim is 3D.

  • VUID-StandaloneSpirv-OpTypeAccelerationStructureKHR-04665
    Objects of types OpTypeAccelerationStructureKHR and arrays of this type must not be stored to or modified

  • VUID-StandaloneSpirv-OpReportIntersectionKHR-04666
    The value of the “Hit Kind” operand of OpReportIntersectionKHR must be in the range [0,127]

  • VUID-StandaloneSpirv-None-04667
    Structure types must not contain opaque types

  • VUID-StandaloneSpirv-BuiltIn-04668
    Any BuiltIn decoration not listed in Built-In Variables must not be used

  • VUID-StandaloneSpirv-Location-04915
    The Location or Component decorations must not be used with BuiltIn

  • VUID-StandaloneSpirv-Location-04916
    The Location decorations must be used on user-defined variables

  • VUID-StandaloneSpirv-Location-04917
    The Location decorations must be used on an OpVariable with a structure type that is not a block

  • VUID-StandaloneSpirv-Location-04918
    The Location decorations must not be used on the members of OpVariable with a structure type that is a block decorated with Location

  • VUID-StandaloneSpirv-Location-04919
    The Location decorations must be used on each member of OpVariable with a structure type that is a block not decorated with Location

  • VUID-StandaloneSpirv-Component-04920
    The Component decoration value must not be greater than 3

  • VUID-StandaloneSpirv-Component-04921
    If the Component decoration is used on an OpVariable that has a OpTypeVector type with a Component Type with a Width that is less than or equal to 32, the sum of its Component Count and the Component decoration value must be less than 4

  • VUID-StandaloneSpirv-Component-04922
    If the Component decoration is used on an OpVariable that has a OpTypeVector type with a Component Type with a Width that is equal to 64, the sum of two times its Component Count and the Component decoration value must be less than 4

  • VUID-StandaloneSpirv-Component-04923
    The Component decorations value must not be 1 or 3 for scalar or two-component 64-bit data types

  • VUID-StandaloneSpirv-Component-04924
    The Component decorations must not used with any type that is not a scalar or vector

  • VUID-StandaloneSpirv-GLSLShared-04669
    The GLSLShared and GLSLPacked decorations must not be used

  • VUID-StandaloneSpirv-Flat-04670
    The Flat, NoPerspective, Sample, and Centroid decorations must not be used on variables with storage class other than Input or on variables used in the interface of non-fragment shader entry points

  • VUID-StandaloneSpirv-Flat-04744
    The Flat decorations must be used on variables with storage class of Input in a fragment shader stage that are a scalar integer, vector of integer, or any double-precision floating-point type

  • VUID-StandaloneSpirv-ViewportRelativeNV-04672
    The ViewportRelativeNV decoration must only be used on a variable decorated with Layer in the vertex, tessellation evaluation, or geometry shader stages

  • VUID-StandaloneSpirv-ViewportRelativeNV-04673
    The ViewportRelativeNV decoration must not be used unless a variable decorated with one of ViewportIndex or ViewportMaskNV is also statically used by the same OpEntryPoint

  • VUID-StandaloneSpirv-ViewportMaskNV-04674
    The ViewportMaskNV and ViewportIndex decorations must not both be statically used by one or more OpEntryPoint’s that form the vertex processing stages of a graphics pipeline

  • VUID-StandaloneSpirv-FPRoundingMode-04675
    Rounding modes other than round-to-nearest-even and round-towards-zero must not be used for the FPRoundingMode decoration

  • VUID-StandaloneSpirv-FPRoundingMode-04676
    The FPRoundingMode decoration must only be used for a width-only conversion instruction whose only uses are Object operands of OpStore instructions storing through a pointer to a 16-bit floating-point object in the StorageBuffer, PhysicalStorageBuffer, Uniform, or Output storage class

  • VUID-StandaloneSpirv-Invariant-04677
    Variables decorated with Invariant and variables with structure types that have any members decorated with Invariant must be in the Output or Input storage class, Invariant used on an Input storage class variable or structure member has no effect

  • VUID-StandaloneSpirv-VulkanMemoryModel-04678
    If the VulkanMemoryModel capability is not declared, the Volatile decoration must be used on any variable declaration that includes one of the SMIDNV, WarpIDNV, SubgroupSize, SubgroupLocalInvocationId, SubgroupEqMask, SubgroupGeMask, SubgroupGtMask, SubgroupLeMask, or SubgroupLtMask BuiltIn decorations when used in the ray generation, closest hit, miss, intersection, or callable shaders, or with the RayTmaxKHR Builtin decoration when used in an intersection shader

  • VUID-StandaloneSpirv-VulkanMemoryModel-04679
    If the VulkanMemoryModel capability is declared, the OpLoad instruction must use the Volatile memory semantics when it accesses into any variable that includes one of the SMIDNV, WarpIDNV, SubgroupSize, SubgroupLocalInvocationId, SubgroupEqMask, SubgroupGeMask, SubgroupGtMask, SubgroupLeMask, or SubgroupLtMask BuiltIn decorations when used in the ray generation, closest hit, miss, intersection, or callable shaders, or with the RayTmaxKHR Builtin decoration when used in an intersection shader

  • VUID-StandaloneSpirv-OpTypeRuntimeArray-04680
    OpTypeRuntimeArray must only be used for the last member of an OpTypeStruct that is in the StorageBuffer or PhysicalStorageBuffer storage class decorated as Block, or that is in the Uniform storage class decorated as BufferBlock

  • VUID-StandaloneSpirv-Function-04681
    A type T that is an array sized with a specialization constant must neither be, nor be contained in, the type T2 of a variable V, unless either: a) T is equal to T2, b) V is declared in the Function, or Private storage classes, c) V is a non-Block variable in the Workgroup storage class, or d) V is an interface variable with an additional level of arrayness, as described in interface matching, and T is the member type of the array type T2.

  • VUID-StandaloneSpirv-OpControlBarrier-04682
    If OpControlBarrier is used in ray generation, intersection, any-hit, closest hit, miss, fragment, vertex, tessellation evaluation, or geometry shaders, the execution Scope must be Subgroup

  • VUID-StandaloneSpirv-LocalSize-04683
    For each compute shader entry point, either a LocalSize execution mode or an object decorated with the WorkgroupSize decoration must be specified

  • VUID-StandaloneSpirv-DerivativeGroupQuadsNV-04684
    For compute shaders using the DerivativeGroupQuadsNV execution mode, the first two dimensions of the local workgroup size must be a multiple of two

  • VUID-StandaloneSpirv-DerivativeGroupLinearNV-04778
    For compute shaders using the DerivativeGroupLinearNV execution mode, the product of the dimensions of the local workgroup size must be a multiple of four

  • VUID-StandaloneSpirv-OpGroupNonUniformBallotBitCount-04685
    If OpGroupNonUniformBallotBitCount is used, the group operation must be limited to Reduce, InclusiveScan, or ExclusiveScan

  • VUID-StandaloneSpirv-None-04686
    The Pointer operand of all atomic instructions must have a Storage Class limited to Uniform, Workgroup, Image, StorageBuffer, or PhysicalStorageBuffer

  • VUID-StandaloneSpirv-Offset-04687
    Output variables or block members decorated with Offset that have a 64-bit type, or a composite type containing a 64-bit type, must specify an Offset value aligned to a 8 byte boundary

  • VUID-StandaloneSpirv-Offset-04689
    The size of any output block containing any member decorated with Offset that is a 64-bit type must be a multiple of 8

  • VUID-StandaloneSpirv-Offset-04690
    The first member of an output block that specifies a Offset decoration must specify a Offset value that is aligned to an 8 byte boundary if that block contains any member decorated with Offset and is a 64-bit type

  • VUID-StandaloneSpirv-Offset-04691
    Output variables or block members decorated with Offset that have a 32-bit type, or a composite type contains a 32-bit type, must specify an Offset value aligned to a 4 byte boundary

  • VUID-StandaloneSpirv-Offset-04692
    Output variables, blocks or block members decorated with Offset must only contain base types that have components that are either 32-bit or 64-bit in size

  • VUID-StandaloneSpirv-Offset-04716
    Only variables or block members in the output interface decorated with Offset can be captured for transform feedback, and those variables or block members must also be decorated with XfbBuffer and XfbStride, or inherit XfbBuffer and XfbStride decorations from a block containing them

  • VUID-StandaloneSpirv-XfbBuffer-04693
    All variables or block members in the output interface of the entry point being compiled decorated with a specific XfbBuffer value must all be decorated with identical XfbStride values

  • VUID-StandaloneSpirv-Stream-04694
    If any variables or block members in the output interface of the entry point being compiled are decorated with Stream, then all variables belonging to the same XfbBuffer must specify the same Stream value

  • VUID-StandaloneSpirv-XfbBuffer-04696
    For any two variables or block members in the output interface of the entry point being compiled with the same XfbBuffer value, the ranges determined by the Offset decoration and the size of the type must not overlap

  • VUID-StandaloneSpirv-XfbBuffer-04697
    All block members in the output interface of the entry point being compiled that are in the same block and have a declared or inherited XfbBuffer decoration must specify the same XfbBuffer value

  • VUID-StandaloneSpirv-RayPayloadKHR-04698
    RayPayloadKHR storage class must only be used in ray generation, closest hit or miss shaders

  • VUID-StandaloneSpirv-IncomingRayPayloadKHR-04699
    IncomingRayPayloadKHR storage class must only be used in closest hit, any-hit, or miss shaders

  • VUID-StandaloneSpirv-IncomingRayPayloadKHR-04700
    There must be at most one variable with the IncomingRayPayloadKHR storage class in the input interface of an entry point

  • VUID-StandaloneSpirv-HitAttributeKHR-04701
    HitAttributeKHR storage class must only be used in intersection, any-hit, or closest hit shaders

  • VUID-StandaloneSpirv-HitAttributeKHR-04702
    There must be at most one variable with the HitAttributeKHR storage class in the input interface of an entry point

  • VUID-StandaloneSpirv-HitAttributeKHR-04703
    A variable with HitAttributeKHR storage class must only be written to in an intersection shader

  • VUID-StandaloneSpirv-CallableDataKHR-04704
    CallableDataKHR storage class must only be used in ray generation, closest hit, miss, and callable shaders

  • VUID-StandaloneSpirv-IncomingCallableDataKHR-04705
    IncomingCallableDataKHR storage class must only be used in callable shaders

  • VUID-StandaloneSpirv-IncomingCallableDataKHR-04706
    There must be at most one variable with the IncomingCallableDataKHR storage class in the input interface of an entry point

  • VUID-StandaloneSpirv-Base-04707
    The Base operand of OpPtrAccessChain must point to one of the following: Workgroup, if VariablePointers is enabled; StorageBuffer, if VariablePointers or VariablePointersStorageBuffer is enabled; PhysicalStorageBuffer, if the PhysicalStorageBuffer64 addressing model is enabled

  • VUID-StandaloneSpirv-PhysicalStorageBuffer64-04708
    If the PhysicalStorageBuffer64 addressing model is enabled, all instructions that support memory access operands and that use a physical pointer must include the Aligned operand

  • VUID-StandaloneSpirv-PhysicalStorageBuffer64-04709
    If the PhysicalStorageBuffer64 addressing model is enabled, any access chain instruction that accesses into a RowMajor matrix must only be used as the Pointer operand to OpLoad or OpStore

  • VUID-StandaloneSpirv-PhysicalStorageBuffer64-04710
    If the PhysicalStorageBuffer64 addressing model is enabled, OpConvertUToPtr and OpConvertPtrToU must use an integer type whose Width is 64

  • VUID-StandaloneSpirv-OpTypeForwardPointer-04711
    OpTypeForwardPointer must have a storage class of PhysicalStorageBuffer

  • VUID-StandaloneSpirv-None-04745
    All variables with a storage class of PushConstant declared as an array must only be accessed by dynamically uniform indices

  • VUID-StandaloneSpirv-Result-04780
    The Result Type operand of any OpImageRead or OpImageSparseRead instruction must be a vector of four components

  • VUID-StandaloneSpirv-Base-04781
    The Base operand of any OpBitCount, OpBitReverse, OpBitFieldInsert, OpBitFieldSExtract, or OpBitFieldUExtract instruction must be a 32-bit integer scalar or a vector of 32-bit integers

Runtime SPIR-V Validation

The following rules must be validated at runtime. These rules depend on knowledge of the implementation and its capabilities and knowledge of runtime information, such as enabled features.

  • The converted bit width, signedness, and numeric type of the Image Format operand of an OpTypeImage must match the Sampled Type, as defined in Image Format and Type Matching.

  • If shaderStorageImageWriteWithoutFormat is not enabled and an OpTypeImage has “Image Format” operand of Unknown, any variables created with the given type must be decorated with NonWritable.

  • If shaderStorageImageReadWithoutFormat is not enabled and an OpTypeImage has “Image Format” operand of Unknown, any variables created with the given type must be decorated with NonReadable.

  • Any BuiltIn decoration that corresponds only to Vulkan features or extensions that have not been enabled must not be used.

  • The Location decoration value must be less than the value for the matching Execution Model defined in Shader Input and Output Locations

  • Result Type for Non Uniform Group Operations must be limited to 32-bit floating-point, 32-bit integer, boolean, or vectors of these types.

    • If the Float64 capability is enabled, 64-bit floating-point and vector of 64-bit floating-point types are also permitted.

  • shaderBufferFloat32Atomics or shaderBufferFloat32AtomicAdd or shaderBufferFloat64Atomics or shaderBufferFloat64AtomicAdd must be enabled for floating-point atomic operations to be supported on a Pointer with a Storage Class of StorageBuffer.

  • DescriptorSet and Binding decorations must obey the constraints on storage class, type, and descriptor type described in DescriptorSet and Binding Assignment

  • Atomic instructions must declare a scalar 32-bit integer type, or a scalar 64-bit integer type if the Int64Atomics capability is enabled, for the value pointed to by Pointer.

  • If fragmentStoresAndAtomics is not enabled, then all storage image, storage texel buffer, and storage buffer variables in the fragment stage must be decorated with the NonWritable decoration.

  • If vertexPipelineStoresAndAtomics is not enabled, then all storage image, storage texel buffer, and storage buffer variables in the vertex, tessellation, and geometry stages must be decorated with the NonWritable decoration.

  • If subgroupQuadOperationsInAllStages is VK_FALSE, then quad subgroup operations must not be used except for in fragment and compute stages.

  • Group operations with subgroup scope must not be used if the shader stage is not in subgroupSupportedStages.

  • The first element of the Offset operand of InterpolateAtOffset must be greater than or equal to:

    fragwidth × minInterpolationOffset

    where fragwidth is the width of the current fragment in pixels.

  • The first element of the Offset operand of InterpolateAtOffset must be less than or equal to:

    fragwidth × (maxInterpolationOffset + ULP ) - ULP

    where fragwidth is the width of the current fragment in pixels and ULP = 1 / 2subPixelInterpolationOffsetBits.

  • The second element of the Offset operand of InterpolateAtOffset must be greater than or equal to:

    fragheight × minInterpolationOffset

    where fragheight is the height of the current fragment in pixels.

  • The second element of the Offset operand of InterpolateAtOffset must be less than or equal to:

    fragheight × (maxInterpolationOffset + ULP ) - ULP

    where fragheight is the height of the current fragment in pixels and ULP = 1 / 2subPixelInterpolationOffsetBits.

  • The x size in LocalSize must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupSize[0]

  • The y size in LocalSize must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupSize[1]

  • The z size in LocalSize must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupSize[2]

  • The product of x size, y size, and z size in LocalSize must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupInvocations

  • Any OpVariable with Workgroup as its Storage Class must not have an Initializer operand

  • If an OpImage*Gather operation has an image operand of Offset, ConstOffset, or ConstOffsets the offset value must be greater than or equal to minTexelGatherOffset

  • If an OpImage*Gather operation has an image operand of Offset, ConstOffset, or ConstOffsets the offset value must be less than or equal to maxTexelGatherOffset

Precision and Operation of SPIR-V Instructions

The following rules apply to half, single, and double-precision floating point instructions:

  • Positive and negative infinities and positive and negative zeros are generated as dictated by IEEE 754, but subject to the precisions allowed in the following table.

  • Dividing a non-zero by a zero results in the appropriately signed IEEE 754 infinity.

  • Signaling NaNs are not required to be generated and exceptions are never raised. Signaling NaN may be converted to quiet NaNs values by any floating point instruction.

  • By default, the implementation may perform optimizations on half, single, or double-precision floating-point instructions that ignore sign of a zero, or assume that arguments and results are not NaNs or infinities.

  • The following instructions must not flush denormalized values: OpConstant, OpConstantComposite, OpSpecConstant, OpSpecConstantComposite, OpLoad, OpStore, OpBitcast, OpPhi, OpSelect, OpFunctionCall, OpReturnValue, OpVectorExtractDynamic, OpVectorInsertDynamic, OpVectorShuffle, OpCompositeConstruct, OpCompositeExtract, OpCompositeInsert, OpCopyMemory, OpCopyObject.

  • Any denormalized value input into a shader or potentially generated by any instruction in a shader (except those listed above) may be flushed to 0.

  • The rounding mode cannot be set, and results will be correctly rounded, as described below.

  • NaNs may not be generated. Instructions that operate on a NaN may not result in a NaN.

The precision of double-precision instructions is at least that of single precision.

The precision of operations is defined either in terms of rounding, as an error bound in ULP, or as inherited from a formula as follows.

Correctly Rounded

Operations described as “correctly rounded” will return the infinitely precise result, x, rounded so as to be representable in floating-point. The rounding mode used is not defined but must obey the following rules. If x is exactly representable then x will be returned. Otherwise, either the floating-point value closest to and no less than x or the value closest to and no greater than x will be returned.

ULP

Where an error bound of n ULP (units in the last place) is given, for an operation with infinitely precise result x the value returned must be in the range [x - n × ulp(x), x + n × ulp(x)]. The function ulp(x) is defined as follows:

If there exist non-equal floating-point numbers a and b such that a ≤ x ≤ b then ulp(x) is the minimum possible distance between such numbers, . If such numbers do not exist then ulp(x) is defined to be the difference between the two finite floating-point numbers nearest to x.

Where the range of allowed return values includes any value of magnitude larger than that of the largest representable finite floating-point number, operations may, additionally, return either an infinity of the appropriate sign or the finite number with the largest magnitude of the appropriate sign. If the infinitely precise result of the operation is not mathematically defined then the value returned is undefined.

Inherited From …​

Where an operation’s precision is described as being inherited from a formula, the result returned must be at least as accurate as the result of computing an approximation to x using a formula equivalent to the given formula applied to the supplied inputs. Specifically, the formula given may be transformed using the mathematical associativity, commutativity and distributivity of the operators involved to yield an equivalent formula. The SPIR-V precision rules, when applied to each such formula and the given input values, define a range of permitted values. If NaN is one of the permitted values then the operation may return any result, otherwise let the largest permitted value in any of the ranges be Fmax and the smallest be Fmin. The operation must return a value in the range [x - E, x + E] where .

For single precision (32 bit) instructions, precisions are required to be at least as follows, unless decorated with RelaxedPrecision:

Table 62. Precision of core SPIR-V Instructions
Instruction Precision

OpFAdd

Correctly rounded.

OpFSub

Correctly rounded.

OpFMul, OpVectorTimesScalar, OpMatrixTimesScalar

Correctly rounded.

OpFOrdEqual, OpFUnordEqual

Correct result.

OpFOrdLessThan, OpFUnordLessThan

Correct result.

OpFOrdGreaterThan, OpFUnordGreaterThan

Correct result.

OpFOrdLessThanEqual, OpFUnordLessThanEqual

Correct result.

OpFOrdGreaterThanEqual, OpFUnordGreaterThanEqual

Correct result.

OpFDiv(x,y)

2.5 ULP for |y| in the range [2-126, 2126].

conversions between types

Correctly rounded.

Table 63. Precision of GLSL.std.450 Instructions
Instruction Precision

fma()

Inherited from OpFMul followed by OpFAdd.

exp(x), exp2(x)

3 + 2 × |x| ULP.

log(), log2()

3 ULP outside the range [0.5, 2.0]. Absolute error < 2-21 inside the range [0.5, 2.0].

pow(x, y)

Inherited from exp2(y × log2(x)).

sqrt()

Inherited from 1.0 / inversesqrt().

inversesqrt()

2 ULP.

GLSL.std.450 extended instructions specifically defined in terms of the above instructions inherit the above errors. GLSL.std.450 extended instructions not listed above and not defined in terms of the above have undefined precision.

For the OpSRem and OpSMod instructions, if either operand is negative the result is undefined.

Note

While the OpSRem and OpSMod instructions are supported by the Vulkan environment, they require non-negative values and thus do not enable additional functionality beyond what OpUMod provides.

Image Format and Type Matching

When specifying the Image Format as anything other than Unknown, the converted bit width, type, and signedness as shown in the table below, must match the Sampled Type.

Note

Formatted accesses are always converted from a shader readable type to the resource’s format or vice versa via Format Conversion for reads and Texel Output Format Conversion for writes. As such, the bit width and format below do not necessarily match 1:1 with what might be expected for some formats.

For a given Image Format, the Sampled Type must be the type described in the Type column of the below table, with its Literal Width set to that in the Bit Width column, and its Literal Signedness to that in the Signedness column (where applicable).

Image Format Type Bit Width Signedness

Unknown

Any

Any

Any

Rgba32f

OpTypeFloat

32

N/A

Rg32f

R32f

Rgba16f

Rg16f

R16f

Rgba16

Rg16

R16

Rgba16Snorm

Rg16Snorm

R16Snorm

Rgb10A2

R11fG11fB10f

Rgba8

Rg8

R8

Rgba8Snorm

Rg8Snorm

R8Snorm

Rgba32i

OpTypeInt

32

1

Rg32i

R32i

Rgba16i

Rg16i

R16i

Rgba8i

Rg8i

R8i

Rgba32ui

0

Rg32ui

R32ui

Rgba16ui

Rg16ui

R16ui

Rgb10a2ui

Rgba8ui

Rg8ui

R8ui

Compatibility Between SPIR-V Image Formats And Vulkan Formats

SPIR-V Image Format values are compatible with VkFormat values as defined below:

Table 64. SPIR-V and Vulkan Image Format Compatibility
SPIR-V Image Format Compatible Vulkan Format

Unknown

Any

Rgba32f

VK_FORMAT_R32G32B32A32_SFLOAT

Rgba16f

VK_FORMAT_R16G16B16A16_SFLOAT

R32f

VK_FORMAT_R32_SFLOAT

Rgba8

VK_FORMAT_R8G8B8A8_UNORM

Rgba8Snorm

VK_FORMAT_R8G8B8A8_SNORM

Rg32f

VK_FORMAT_R32G32_SFLOAT

Rg16f

VK_FORMAT_R16G16_SFLOAT

R11fG11fB10f

VK_FORMAT_B10G11R11_UFLOAT_PACK32

R16f

VK_FORMAT_R16_SFLOAT

Rgba16

VK_FORMAT_R16G16B16A16_UNORM

Rgb10A2

VK_FORMAT_A2B10G10R10_UNORM_PACK32

Rg16

VK_FORMAT_R16G16_UNORM

Rg8

VK_FORMAT_R8G8_UNORM

R16

VK_FORMAT_R16_UNORM

R8

VK_FORMAT_R8_UNORM

Rgba16Snorm

VK_FORMAT_R16G16B16A16_SNORM

Rg16Snorm

VK_FORMAT_R16G16_SNORM

Rg8Snorm

VK_FORMAT_R8G8_SNORM

R16Snorm

VK_FORMAT_R16_SNORM

R8Snorm

VK_FORMAT_R8_SNORM

Rgba32i

VK_FORMAT_R32G32B32A32_SINT

Rgba16i

VK_FORMAT_R16G16B16A16_SINT

Rgba8i

VK_FORMAT_R8G8B8A8_SINT

R32i

VK_FORMAT_R32_SINT

Rg32i

VK_FORMAT_R32G32_SINT

Rg16i

VK_FORMAT_R16G16_SINT

Rg8i

VK_FORMAT_R8G8_SINT

R16i

VK_FORMAT_R16_SINT

R8i

VK_FORMAT_R8_SINT

Rgba32ui

VK_FORMAT_R32G32B32A32_UINT

Rgba16ui

VK_FORMAT_R16G16B16A16_UINT

Rgba8ui

VK_FORMAT_R8G8B8A8_UINT

R32ui

VK_FORMAT_R32_UINT

Rgb10a2ui

VK_FORMAT_A2B10G10R10_UINT_PACK32

Rg32ui

VK_FORMAT_R32G32_UINT

Rg16ui

VK_FORMAT_R16G16_UINT

Rg8ui

VK_FORMAT_R8G8_UINT

R16ui

VK_FORMAT_R16_UINT

R8ui

VK_FORMAT_R8_UINT