Name Strings

SPV_KHR_no_integer_wrap_decoration

Contact

To report problems with this extension, please open a new issue at:

https://github.com/KhronosGroup/SPIRV-Registry

Contributors

  • Pawel Jurek, Intel

  • Mariusz Merecki, Intel

  • Ben Ashbaugh, Intel

  • Faith Ekstrand, Intel

  • Neil Henning, AMD

  • John Kessenich, Google

  • Graeme Leese, Broadcom

  • Ruihao Zhang, Qualcomm

Notice

Copyright (c) 2018 The Khronos Group Inc. Copyright terms at http://www.khronos.org/registry/speccopyright.html

Status

  • Approved by the SPIR Working Group: 2018-10-03

  • Ratified by Khronos 2018-11-16

Version

Last Modified Date

2018-09-11

Revision

4

Dependencies

This extension is written against the SPIR-V Specification, Version 1.3, Revision 3, Unified

This extension is written against the SPIR-V Extended Instructions for GLSL, Version 1.00, Revision 7

This extension is written against the OpenCL Extended Instruction Set Specification, Version 1.00, Revision 4

This extension requires SPIR-V 1.0.

Overview

This extension adds new decorations to indicate that a given instruction does not cause integer wrapping to occur, in the form of overflow or underflow.

Extension Name

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

OpExtension "SPV_KHR_no_integer_wrap_decoration"

New Decorations

This extension introduces the following new decorations:

NoSignedWrap
NoUnsignedWrap

Token Number Assignments

NoSignedWrap

4469

NoUnsignedWrap

4470

Modifications to the SPIR-V Specification, Version 1.3, Revision 3, Unified

Validation Rules

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

OpExtension "SPV_KHR_no_integer_wrap_decoration"

Modify Section 2.16.1, Universal Validation Rules, adding the following rules:

  • NoSignedWrap decoration defined in this extension can be applied only to the following instructions:

    • OpIAdd

    • OpISub

    • OpIMul

    • OpShiftLeftLogical

    • OpSNegate

    • OpExtInst with instruction numbers specified in the extended instruction-set specifications as accepting the decoration.

  • NoUnsignedWrap decoration defined in this extension can be applied only to the following instructions:

    • OpIAdd

    • OpISub

    • OpIMul

    • OpShiftLeftLogical

    • OpExtInst with instruction numbers specified in the extended instruction-set specifications as accepting the decoration.

Decorations

Modify Section 3.20, "Decoration", adding these rows to the Decoration table:

Decoration Enabling Capabilities Extra Operands

4469

NoSignedWrap
Apply to an instruction to indicate that it doesn’t cause signed integer wrapping to occur, in the form of overflow or underflow.

If the instruction decorated with NoSignedWrap does overflow or underflow, the behavior is undefined.

4470

NoUnsignedWrap
Apply to an instruction to indicate that it doesn’t cause unsigned integer wrapping to occur, in the form of overflow or underflow.

If the instruction decorated with NoUnsignedWrap does overflow or underflow, the behavior is undefined.

Modifications to the SPIR-V Extended Instructions for GLSL, Version 1.00, Revision 7

Modify Section 2, "Binary Form", adding the following text to the SAbs instruction description in the Extended instructions table:

This instruction can be decorated with NoSignedWrap decoration.

Modifications to the OpenCL Extended Instruction Set Specification, Version 1.00, Revision 4

Modify Section 2.2, "Integer Instructions", adding the following text to the s_abs instruction description:

This instruction can be decorated with NoSignedWrap decoration.

Issues

1) Should we add a floating point version of the decoration?

RESOLVED: No. A new decoration would provide the same information as FP Fast Math Mode.

Revision History

Rev Date Author Changes

1

2018-08-10

Pawel Jurek

Initial revision

2

2018-08-23

Mariusz Merecki

Rename to KHR, remove the capability, allow new decorations on OpUDiv, OpUMod, OpSNegate, OpSDiv, OpSMod and OpSRem.

3

2018-08-29

Mariusz Merecki

Use the term wrap instead of overflow in the extension name and new decorations, remove OpUMod, OpSMod and OpSRem from the list of instructions allowed to be decorated with new decorations.

4

2018-09-11

Mariusz Merecki

Remove OpUDiv and OpSDiv from the list of instructions allowed to be decorated with new decorations.