253 lines
13 KiB
Plaintext
253 lines
13 KiB
Plaintext
// Copyright (c) 2015-2016 The Khronos Group Inc.
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// Copyright notice at https://www.khronos.org/registry/speccopyright.html
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[appendix]
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[[spirvenv]]
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= Vulkan Environment for SPIR-V
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Shaders for Vulkan are defined by the <<Khronos SPIR-V Specification>> as
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well as the <<Khronos SPIR-V Extended Instructions for GLSL Specification>>.
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This appendix defines additional SPIR-V requirements applying to Vulkan
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shaders.
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== Required Versions and Formats
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A Vulkan 1.0 implementation must: support the 1.0 version of SPIR-V and
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the 1.0 version of the SPIR-V Extended Instructions for GLSL.
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A SPIR-V module passed into flink:vkCreateShaderModule is interpreted as
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a series of 32-bit words in host endianness, with literal strings packed
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as described in section 2.2 of the SPIR-V Specification. The first few words
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of the SPIR-V module must: be a magic number and a SPIR-V version number, as
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described in section 2.3 of the SPIR-V Specification.
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[[spirvenv-capabilities]]
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== Capabilities
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Implementations must: support the following capability operands declared by
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code:OpCapability:
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- code:Matrix
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- code:Shader
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- code:InputAttachment
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- code:Sampled1D
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- code:Image1D
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- code:SampledBuffer
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- code:ImageBuffer
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- code:ImageQuery
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- code:DerivativeControl
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Implementations may: support features that are not required: by the
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Specification, as described in the <<features-features,Features>> chapter.
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If such a feature is supported, then any capability operand(s) corresponding
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to that feature must: also be supported.
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[[spirvenv-capabilities-table]]
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.SPIR-V Capabilities which are not required:, and corresponding feature names
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[options="header"]
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|====
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| SPIR-V OpCapability | Vulkan feature name
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| code:Geometry | <<features-features-geometryShader,geometryShader>>
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| code:Tessellation | <<features-features-tessellationShader,tessellationShader>>
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| code:Float64 | <<features-features-shaderFloat64,shaderFloat64>>
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| code:Int64 | <<features-features-shaderInt64,shaderInt64>>
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| code:Int16 | <<features-features-shaderInt16,shaderInt16>>
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| code:TessellationPointSize | <<features-features-shaderTessellationAndGeometryPointSize,shaderTessellationAndGeometryPointSize>>
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| code:GeometryPointSize | <<features-features-shaderTessellationAndGeometryPointSize,shaderTessellationAndGeometryPointSize>>
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| code:ImageGatherExtended | <<features-features-shaderImageGatherExtended,shaderImageGatherExtended>>
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| code:StorageImageMultisample | <<features-features-shaderStorageImageMultisample,shaderStorageImageMultisample>>
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| code:UniformBufferArrayDynamicIndexing | <<features-features-shaderUniformBufferArrayDynamicIndexing,shaderUniformBufferArrayDynamicIndexing>>
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| code:SampledImageArrayDynamicIndexing | <<features-features-shaderSampledImageArrayDynamicIndexing,shaderSampledImageArrayDynamicIndexing>>
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| code:StorageBufferArrayDynamicIndexing | <<features-features-shaderStorageBufferArrayDynamicIndexing,shaderStorageBufferArrayDynamicIndexing>>
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| code:StorageImageArrayDynamicIndexing | <<features-features-shaderStorageImageArrayDynamicIndexing,shaderStorageImageArrayDynamicIndexing>>
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| code:ClipDistance | <<features-features-shaderClipDistance,shaderClipDistance>>
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| code:CullDistance | <<features-features-shaderCullDistance,shaderCullDistance>>
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| code:ImageCubeArray | <<features-features-imageCubeArray,imageCubeArray>>
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| code:SampleRateShading | <<features-features-sampleRateShading,sampleRateShading>>
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| code:SparseResidency | <<features-features-shaderResourceResidency,shaderResourceResidency>>
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| code:MinLod | <<features-features-shaderResourceMinLod,shaderResourceMinLod>>
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| code:SampledCubeArray | <<features-features-imageCubeArray,imageCubeArray>>
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| code:ImageMSArray | <<features-features-shaderStorageImageMultisample,shaderStorageImageMultisample>>
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| code:StorageImageExtendedFormats | <<features-features-shaderStorageImageExtendedFormats,shaderStorageImageExtendedFormats>>
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| code:InterpolationFunction | <<features-features-sampleRateShading,sampleRateShading>>
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| code:StorageImageReadWithoutFormat | <<features-features-shaderStorageImageReadWithoutFormat,shaderStorageImageReadWithoutFormat>>
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| code:StorageImageWriteWithoutFormat | <<features-features-shaderStorageImageWriteWithoutFormat,shaderStorageImageWriteWithoutFormat>>
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| code:MultiViewport | <<features-features-multiViewport,multiViewport>>
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|====
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The application mustnot: pass a SPIR-V module containing any of the
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following to flink:vkCreateShaderModule:
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- any OpCapability not listed above,
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- an unsupported capability, or
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- a capability which corresponds to a Vulkan feature which has not been
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enabled.
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[[spirvenv-module-validation]]
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== Validation Rules within a Module
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A SPIR-V module passed to flink:vkCreateShaderModule must: conform to the
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following rules:
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* Every entry point must: have no return value and accept no arguments.
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* The *Logical* addressing model must: be selected.
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* *Scope* for execution must: be limited to:
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** *Workgroup*
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** *Subgroup*
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* *Scope* for memory must: be limited to:
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** *Device*
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** *Workgroup*
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** *Invocation*
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* The code:OriginLowerLeft execution mode mustnot: be used; fragment entry
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points must: declare code:OriginUpperLeft.
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* The code:PixelCenterInteger execution mode mustnot: be used. Pixels are
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always centered at half-integer coordinates.
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* Images
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** code:OpTypeImage must: declare a scalar 32-bit float or 32-bit integer
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type for the ``Sampled Type''. (code:RelaxedPrecision can: be applied
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to a sampling instruction and to the variable holding the result of a
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sampling instruction.)
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** code:OpSampledImage must: only consume an ``Image'' operand whose type
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has its ``Sampled'' operand set to 1.
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** The ``(u, v)'' coordinates used for a code:SubpassData must: be the <id>
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of a constant vector (0, 0), or if a layer coordinate is used, must: be
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a vector that was formed with constant 0 for the ``u'' and ``v''
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components.
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** The ``Depth'' operand of code:OpTypeImage is ignored.
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* Decorations
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** The code:GLSLShared and code:GLSLPacked decorations mustnot: be used.
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** The code:Flat, code:NoPerspective, code:Sample, and code:Centroid
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decorations mustnot: be used on variables with storage class other than
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code:Input or on variables used in the interface of non-fragment shader
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entry points.
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** The code:Patch decoration mustnot: be used on variables in the
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interface of a vertex, geometry, or fragment shader stage's entry
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point.
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* code:OpTypeRuntimeArray must: only be used for the last member of an
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code:OpTypeStruct in the code:Uniform storage class.
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* Linkage: See <<interfaces,Shader Interfaces>> for additional linking and
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validation rules.
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* Compute Shaders
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** For each compute shader entry point, either a code:LocalSize execution mode
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or an object decorated with the code:WorkgroupSize decoration must: be
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specified.
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[[spirvenv-precision-operation]]
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== Precision and Operation of SPIR-V Instructions
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The following rules apply to both single and double-precision floating point
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instructions:
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- Positive and negative infinities and positive and negative zeros are
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generated as dictated by <<IEEE 754>>, but subject to the precisions
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allowed in the following table.
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- Dividing a non-zero by a zero results in the appropriately signed <<IEEE
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754>> infinity.
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- Any denormalized value input into a shader or potentially generated by
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any instruction in a shader may: be flushed to 0.
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- The rounding mode cannot: be set and is undefined.
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- NaNs may: not be generated. Instructions that operate on a NaN may: not
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result in a NaN.
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- Support for signaling NaNs is optional: and exceptions are never raised.
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The precision of double-precision instructions is at least that of single
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precision. For single precision (32 bit) instructions, precisions are
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required: to be at least as follows, unless decorated with RelaxedPrecision:
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.Precision of core SPIR-V Instructions
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[options="header"]
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|====
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| Instruction | Precision
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| code:OpFAdd | Correctly rounded.
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| code:OpFSub | Correctly rounded.
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| code:OpFMul | Correctly rounded.
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| code:OpFOrdEqual, code:OpFUnordEqual | Correct result.
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| code:OpFOrdLessThan, code:OpFUnordLessThan | Correct result.
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| code:OpFOrdGreaterThan, code:OpFUnordGreaterThan | Correct result.
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| code:OpFOrdLessThanEqual, code:OpFUnordLessThanEqual | Correct result.
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| code:OpFOrdGreaterThanEqual, code:OpFUnordGreaterThanEqual| Correct result.
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| code:OpFDiv | 2.5 ULP for b in the range [2^-126^, 2^126^].
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| conversions between types | Correctly rounded.
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|====
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Precision of GLSL.std.450 Instructions
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[options="header"]
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|====
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|Instruction | Precision
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| code:fma() | Inherited from code:OpFMul followed by code:OpFAdd.
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| code:exp(x), code:exp2(x) | latexmath:[$(3 + 2 \times \|x\|)$] ULP.
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| code:log(), code:log2() | 3 ULP outside the range [0.5, 2.0]. Absolute error < 2^-21^ inside the range [0.5, 2.0].
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| code:pow(x, y) | Inherited from code:exp2(y × code:log2(x)).
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| code:sqrt() | Inherited from 1.0 / code:inversesqrt().
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| code:inversesqrt() | 2 ULP.
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|====
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GLSL.std.450 extended instructions specifically defined in terms of the
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above instructions inherit the above errors. GLSL.std.450 extended
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instructions not listed above and not defined in terms of the above have
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undefined precision. These include, for example, the trigonometric functions
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and determinant.
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For the code:OpSRem and code:OpSMod instructions, if either operand is
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negative the result is undefined.
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[NOTE]
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.Note
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====
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While the code:OpSRem and code:OpSMod instructions are supported by the
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Vulkan environment, they require non-negative values and thus do not
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enable additional functionality beyond what code:OpUMod provides.
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====
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[[spirvenv-image-formats]]
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Compatibility Between SPIR-V Image Formats And Vulkan Formats
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-------------------------------------------------------------
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[cols="2*", options="header"]
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|===
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|SPIR-V Image Format |Vulkan Format
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|code:Rgba32f |ename:VK_FORMAT_R32G32B32A32_SFLOAT
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|code:Rgba16f |ename:VK_FORMAT_R16G16B16A16_SFLOAT
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|code:R32f |ename:VK_FORMAT_R32_SFLOAT
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|code:Rgba8 |ename:VK_FORMAT_R8G8B8A8_UNORM
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|code:Rgba8Snorm |ename:VK_FORMAT_R8G8B8A8_SNORM
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|code:Rg32f |ename:VK_FORMAT_R32G32_SFLOAT
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|code:Rg16f |ename:VK_FORMAT_R16G16_SFLOAT
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|code:R11fG11fB10f |ename:VK_FORMAT_B10G11R11_UFLOAT_PACK32
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|code:R16f |ename:VK_FORMAT_R16_SFLOAT
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|code:Rgba16 |ename:VK_FORMAT_R16G16B16A16_UNORM
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|code:Rgb10A2 |ename:VK_FORMAT_A2B10G10R10_UNORM_PACK32
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|code:Rg16 |ename:VK_FORMAT_R16G16_UNORM
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|code:Rg8 |ename:VK_FORMAT_R8G8_UNORM
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|code:R16 |ename:VK_FORMAT_R16_UNORM
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|code:R8 |ename:VK_FORMAT_R8_UNORM
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|code:Rgba16Snorm |ename:VK_FORMAT_R16G16B16A16_SNORM
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|code:Rg16Snorm |ename:VK_FORMAT_R16G16_SNORM
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|code:Rg8Snorm |ename:VK_FORMAT_R8G8_SNORM
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|code:R16Snorm |ename:VK_FORMAT_R16_SNORM
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|code:R8Snorm |ename:VK_FORMAT_R8_SNORM
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|code:Rgba32i |ename:VK_FORMAT_R32G32B32A32_SINT
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|code:Rgba16i |ename:VK_FORMAT_R16G16B16A16_SINT
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|code:Rgba8i |ename:VK_FORMAT_R8G8B8A8_SINT
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|code:R32i |ename:VK_FORMAT_R32_SINT
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|code:Rg32i |ename:VK_FORMAT_R32G32_SINT
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|code:Rg16i |ename:VK_FORMAT_R16G16_SINT
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|code:Rg8i |ename:VK_FORMAT_R8G8_SINT
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|code:R16i |ename:VK_FORMAT_R16_SINT
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|code:R8i |ename:VK_FORMAT_R8_SINT
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|code:Rgba32ui |ename:VK_FORMAT_R32G32B32A32_UINT
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|code:Rgba16ui |ename:VK_FORMAT_R16G16B16A16_UINT
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|code:Rgba8ui |ename:VK_FORMAT_R8G8B8A8_UINT
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|code:R32ui |ename:VK_FORMAT_R32_UINT
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|code:Rgb10a2ui |ename:VK_FORMAT_A2B10G10R10_UINT_PACK32
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|code:Rg32ui |ename:VK_FORMAT_R32G32_UINT
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|code:Rg16ui |ename:VK_FORMAT_R16G16_UINT
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|code:Rg8ui |ename:VK_FORMAT_R8G8_UINT
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|code:R16ui |ename:VK_FORMAT_R16_UINT
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|code:R8ui |ename:VK_FORMAT_R8_UINT
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|===
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