Name Strings

SPV_NV_bindless_texture

Contact

See Issues list in the Khronos SPIRV-Headers repository: https://github.com/KhronosGroup/SPIRV-Headers

Contributors

  • Jeff Bolz, NVIDIA

  • Pankaj Mistry, NVIDIA

  • Ashwin Lele, NVIDIA

Status

  • Completed

Version

Last Modified Date

2021-05-26

Revision

1

Dependencies

This extension is written against the SPIR-V Specification, Version 1.5 Revision 2.

This extension requires SPIR-V 1.0.

Overview

This extension adds new capabilities to support the GL_NV_bindless_texture extensions in SPIR-V.

Extension Name

To use this extension within a SPIR-V module, the following OpExtension must be present in the module:

OpExtension "SPV_NV_bindless_texture"

New Capabilities

This extension introduces a new capability:

BindlessTextureNV

New Instructions

Instructions added under the BindlessTextureNV capability:

OpConvertUToImageNV
OpConvertUToSamplerNV
OpConvertUToSampledImageNV
OpConvertImageToUNV
OpConvertSamplerToUNV
OpConvertSampledImageToUNV
OpSamplerImageAddressingModeNV

Token Number Assignments

BindlessTextureNV

5390

OpConvertUToImageNV

5391

OpConvertUToSamplerNV

5392

OpConvertImageToUNV

5393

OpConvertSamplerToUNV

5394

OpConvertUToSampledImageNV

5395

OpConvertSampledImageToUNV

5396

OpSamplerImageAddressingModeNV

5397

BindlessSamplerNV

5398

BindlessImageNV

5399

BoundSamplerNV

5400

BoundImageNV

5401

Modifications to the SPIR-V Specification, Version 1.3

Capability Implicitly Declares

5390

BindlessTextureNV
(Modify Section 2.2.2, Types)

Update concrete type definition to include OpTypeSampledImage, OpTypeImage and OpTypeSampler:

Concrete Type: A numerical scalar, vector, or matrix type, or physical pointer type, or an image type, or sampler type or sampled image type, or any aggregate containing only these types.

(Modify Section 2.4, Logical layout of a Module)

Modify the layout and insert after OpMemoryModel the address mode of sampler/image type variables. Below is the new fifth entry in the SPIRV layout. Everything gets moved below by a number. Below text shows the 4th, 5th and 6th elements of the updated layout

  1. The single required OpMemoryModel instruction

  2. Sampler/Image type variable addressing mode defined with OpSamplerImageAddressingModeNV

  3. All entry point declarations, using OpEntryPoint.

(Modify Section 2.16.1, Universal Validation Rules)

Update the ninth bullet under "Data rules" to relax the restriction on OpSampledImage instructions such that, it can appear as an operand of OpPhi and OpSelect instructions.

Removes the statement: All OpSampledImage instructions must be in the same block in which their Result <id> are consumed. Result <id> from OpSampledImage instructions must not appear as operands to OpPhi instructions or OpSelect instructions

Rephrases the validation rule as follows:

  • OpSampledImage instructions must not appear as operands to any instructions other than:

    • the image lookup and image query instructions specified to take an operand whose type is OpTypeSampledImage

    • OpPhi and OpSelect instructions whose operand and result type can be one of OpTypeSampledImage, OpTypeImage or OpTypeSampler. Result and operand type must be same.

Update the tenth bullet under "Data rules" to relax the restriction on image or sampler type data in a composite, to be allowed as operands to OpPhi instructions or OpSelect instructions

Rephrases the validation rule as follows:

– Instructions for extracting a scalar image or scalar sampler out of a composite must only use dynamically-uniform indexes. Result <id> extracted from these composite of type OpTypeImage, OpTypeSampler or OpTypeSampledImage can appear as operands to OpPhi instructions or OpSelect instructions or other image instructions. Such Result <id> must not appear as operands to any other instructions specified to operate on them.

(Add New Subsection 3.32.<TBD>, Bindless Texture cast Instructions)

OpConvertUToImageNV

Convert an unsigned integer to image type.

If OpSamplerImageAddressingModeNV has a literal value of 64, Operand should be specified either as 64-bit unsigned integer type or vector of 2 unsigned 32-bit integer type.

If OpSamplerImageAddressingModeNV has a literal value of 32, Operand should be specified as a 32-bit unsigned integer type.

Result Type must be of type OpTypeImage

4

5391

<id> Result Type

<id> Result

<id> Operand

OpConvertUToSamplerNV

Convert an unsigned integer to sampler type.

If OpSamplerImageAddressingModeNV has a literal value of 64, Operand should be specified either as 64-bit unsigned integer type or vector of 2 unsigned 32-bit integer type.

If OpSamplerImageAddressingModeNV has a literal value of 32, Operand should be specified as a 32-bit unsigned integer type.

Result Type is of type OpTypeSampler

4

5392

<id> Result Type

<id> Result

<id> Operand

OpConvertImageToUNV

Convert an image type to unsigned integer.

Operand is of type OpTypeImage.

If OpSamplerImageAddressingModeNV has a literal value of 64, Result Type should be specified either as 64-bit unsigned integer type or vector of 2 unsigned 32-bit integer type.

If OpSamplerImageAddressingModeNV has a literal value of 32, Result Type should be specified as 32-bit unsigned integer type.

4

5393

<id> Result Type

<id> Result

<id> Operand

OpConvertSamplerToUNV

Convert a sampler type to unsigned integer.

Operand is of type OpTypeSampler

If OpSamplerImageAddressingModeNV has a literal value of 64, Result Type should be specified either as 64-bit unsigned integer type or vector of 2 unsigned 32-bit integer type.

If OpSamplerImageAddressingModeNV has a literal value of 32, Result Type should be specified as 32-bit unsigned integer type.

4

5394

<id> Result Type

<id> Result

<id> Operand

OpConvertUToSampledImageNV

Convert an unsigned integer to sampled image type.

If OpSamplerImageAddressingModeNV has a literal value of 64, Operand should be specified either as 64-bit unsigned integer type or vector of 2 unsigned 32-bit integer type.

If OpSamplerImageAddressingModeNV has a literal value of 32, Operand should be specified as a 32-bit unsigned integer type.

Result Type is of type OpTypeSampledImage

4

5395

<id> Result Type

<id> Result

<id> Operand

OpConvertSampledImageToUNV

Convert a sampled image type to unsigned integer.

Operand is of type OpTypeSampledImage

If OpSamplerImageAddressingModeNV has a literal value of 64, Result Type should be specified either as 64-bit unsigned integer type or vector of 2 unsigned 32-bit integer type.

If OpSamplerImageAddressingModeNV has a literal value of 32, Result Type should be specified as 32-bit unsigned integer type.

4

5396

<id> Result Type

<id> Result

<id> Operand

OpSamplerImageAddressingModeNV

Sets up the addressing mode for variables of type OpTypeSampledImage, OpTypeImage and OpTypeSampler.

Bit Width takes either a value of 32 or 64, any other value is invalid.

It indicates size of the opaque type variable in memory.

2

5397

<Literal> Bit Width
(Modify Subsection 3.32.15, OpSelect Instruction)

As part of the extension, Update OpSelect instruction to accept OpTypeSampledImage as operand and result

OpSelect

Select between two objects. Before version 1.4, results are only computed per component.

Before version 1.4, Result Type must be a pointer, scalar, or vector. Starting with version 1.4, Result Type can additionally be a composite type other than a vector. Starting with version 1.5, Result Type can additionally be of type OpTypeSampledImage, OpTypeImage and OpTypeSampler.

The types of Object 1 and Object 2 must be the same as Result Type.

Condition must be a scalar or vector of Boolean type.

If Condition is a scalar and true, the result is Object 1. If Condition is a scalar and false, the result is Object 2.

If Condition is a vector, Result Type must be a vector with the same number of components as _Condition and the result is a mix of Object 1 and Object 2: When a component of Condition is true, the corresponding component in the result is taken from Object 1, otherwise it is taken from Object 2.

6

169

<id> Result Type

Result <id>

<id> Condition

<id> Object 1

<id> Object 2
(Add to Decorations: list in Section 3.20) 
DecorationBindlessSamplerNV
DecorationBindlessImageNV
DecorationBoundSamplerNV
DecorationBoundImageNV

Decoration

Extra Operands

Enabling Capabilities

5398

BindlessSamplerNV
Applies to a sampler type variable as a layout qualifier, indicating it is bindless. Behavior is defined by the runtime environment.

Also see SPV_NV_bindless_texture

5399

BindlessImageNV
Applies to an image type variable as a layout qualifier, indicating it is bindless. Behavior is defined by the runtime environment.

Also see SPV_NV_bindless_texture

5400

BoundSamplerNV
Applies to a sampler type variable as a layout qualifier, indicating it is bound. Behavior is defined by the runtime environment.

Also see SPV_NV_bindless_texture

5401

BoundImageNV
Applies to an image type variable as a layout qualifier, indicating it is bound. Behavior is defined by the runtime environment.

Also see SPV_NV_bindless_texture

Validation Rules

An OpExtension must be added to SPIR-V for validation layers to check legal use of this extension:

OpExtension "SPV_NV_bindless_texture"

Issues

  1. How does this extension interact with GL_NV_bindless_texture ?

    RESOLVED: This extension defines the SPIRV instructions and decorations needed to implement GL_NV_bindless_texture.

Revision History

Rev Date Author Changes

1

2021-05-26

Pankaj Mistry

Initial version