SPV_INTEL_memory_access

Name Strings

SPV_INTEL_memory_access_aliasing

Contact

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

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

Contributors

Dmitry Sidorov, Intel
Alexey Sotkin, Intel
Qi Ye, Intel

Notice

Status

Shipping

Version

Last Modified Date

2026-08-05

Revision

Dependencies

This extension is written against the SPIR-V Specification, Version 1.6 Revision 7.

This extension requires SPIR-V 1.2.

Overview

This extension adds AliasDomainDeclINTEL, AliasScopeDeclINTEL and AliasScopeListDeclINTEL instructions that serve a purpose to specify aliasing scopes within which annotated memory accesses don’t alias. Also the extension adds AliasScopeINTEL and NoAliasINTEL decorations and Memory Operands mask to annotate memory access instructions. The decorations and Memory Operands value use result IDs of the new instructions to specify noalias memory-access set.

When evaluating an aliasing query if two memory access instructions that have AliasScopeINTEL or NoAliasINTEL memory operands or decorated with AliasScopeINTEL or NoAliasINTEL decorations and if for some domain, the set of scopes with that domain in one instruction’s aliasing scope list is a subset of (or equal to) the set of scopes for that domain in another instruction’s noalias list, then the two memory accesses are assumed not to alias. If this assumption is violated in runtime - the behaviour is undefined.

The extension helps generating more efficient code (for example helps auto-vectorization) and doesn’t affect semantics of the user’s program.

This functionality is equal to LLVM’s alias.scope and noalias metadata, see: https://llvm.org/docs/LangRef.html#noalias-and-alias-scope-metadata .

Extension Name

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

OpExtension "SPV_INTEL_memory_access_aliasing"

Modifications to the SPIR-V Specification, Version 1.6

Capabilities

Modify Section 3.2.30, "Capability", adding these rows to the Capability table:

Capability	Depends On
5910	MemoryAccessAliasingINTEL Allow to use OpAliasDomainDeclINTEL, OpAliasScopeDeclINTEL and OpAliasScopeListDeclINTEL instructions, AliasScopeINTEL and NoAliasINTEL decorations and AliasScopeINTEL and NoAliasINTEL Memory Operands.

Capability

Depends On

5910

MemoryAccessAliasingINTEL
Allow to use OpAliasDomainDeclINTEL, OpAliasScopeDeclINTEL and OpAliasScopeListDeclINTEL instructions, AliasScopeINTEL and NoAliasINTEL decorations and AliasScopeINTEL and NoAliasINTEL Memory Operands.

Instructions

Modify Section 3.3.3, "Annotation Instructions", adding to the end of the list of instructions:

OpAliasDomainDeclINTEL
The instruction declares an aliasing domain.

The Result is used by OpAliasScopeDeclINTEL instruction to form aliasing scope.

Capability: MemoryAccessAliasingINTEL

5911

<id> Result

OpAliasScopeDeclINTEL
The instruction declares an aliasing scope.

The Result is used by OpAliasScopeListDeclINTEL instruction to form aliasing scope list.

<id> AliasDomain parameter specifies aliasing domain within this aliasing scope, it must be the result id of OpAliasDomainDeclINTEL instruction.

Capability: MemoryAccessAliasingINTEL

5912

<id> Result

<id> AliasDomain

OpAliasScopeListDeclINTEL
The instruction declares a list of aliasing scopes.

The Result is used by AliasScopeINTEL and NoAliasINTEL decorations and AliasScopeINTEL and NoAliasINTEL memory operands.

<id> AliasScope1, … , <id> AliasScopeN parameters specifies aliasing scopes that form aliasing list of scopes, it must be the result id of OpAliasScopeDeclINTEL.

Capability: MemoryAccessAliasingINTEL

5913

<id> Result

<id> AliasScope1, <id> AliasScope2, … , <id> AliasScopeN

Decorations

Modify Section 3.2.19 "Decoration", adding these rows to Decoration table:

Decoration	Extra Operands	Enabling Capabilities
5914	AliasScopeINTEL Can only be applied to OpFunctionCall and Atomic instructions. Has Aliasing Scopes List <id> operand pointing to a result of OpAliasScopeListDeclINTEL instruction, that specifies a set of aliasing scopes in which memory access instruction is assumed to be not aliased with any other memory instructions with intersecting aliasing scopes in case if these accesses are decorated with NoAliasINTEL decoration or have NoAliasINTEL memory operand.	<id> Aliasing Scopes List	MemoryAccessAliasingINTEL
5915	NoAliasINTEL Can only be applied to OpFunctionCall and Atomic instructions. Has Aliasing Scopes List <id> operand pointing on a result of OpAliasScopeListDeclINTEL instruction, that specifies a set of aliasing scopes in which memory access instruction is assumed to be not aliased with any other memory instructions with intersecting aliasing scopes in case if these accesses are decorated with AliasScopeINTEL decoration or have AliasScopeINTEL memory operand.	<id> Aliasing Scopes List	MemoryAccessAliasingINTEL

Decoration

Extra Operands

Enabling Capabilities

5914

AliasScopeINTEL
Can only be applied to OpFunctionCall and Atomic instructions. Has Aliasing Scopes List <id> operand pointing to a result of OpAliasScopeListDeclINTEL instruction, that specifies a set of aliasing scopes in which memory access instruction is assumed to be not aliased with any other memory instructions with intersecting aliasing scopes in case if these accesses are decorated with NoAliasINTEL decoration or have NoAliasINTEL memory operand.

<id> Aliasing Scopes List

MemoryAccessAliasingINTEL

5915

NoAliasINTEL
Can only be applied to OpFunctionCall and Atomic instructions. Has Aliasing Scopes List <id> operand pointing on a result of OpAliasScopeListDeclINTEL instruction, that specifies a set of aliasing scopes in which memory access instruction is assumed to be not aliased with any other memory instructions with intersecting aliasing scopes in case if these accesses are decorated with AliasScopeINTEL decoration or have AliasScopeINTEL memory operand.

<id> Aliasing Scopes List

MemoryAccessAliasingINTEL

Annotation Instructions

Modify Section 3.3.3, "Annotation Instructions", in the description of OpDecorateId, replacing:

"All such <id> Extra Operands must be constant instructions or OpVariable instructions."

with:

"All such <id> Extra Operands must be constant instructions or OpVariable instructions, except for the AliasScopeINTEL and NoAliasINTEL decorations, whose <id> Extra Operand must be an OpAliasScopeListDeclINTEL instruction."

Memory Operands

Modify Section 3.2.25 "Memory Operands", adding these rows to Memory Operands table:

Memory Operands	Extra Operands	Enabling Capabilities
0x10000	AliasScopeINTEL Defines aliasing rules for memory access in the current aliasing scope. Assume that the memory access doesn’t alias with any other memory accesses with aliasing scopes in Aliasing Scopes List intersecting with the current one in case if these accesses have NoAliasINTEL memory operand or are decorated with NoAliasINTEL decoration.	<id> Aliasing Scopes List	MemoryAccessAliasingINTEL
0x20000	NoAliasINTEL Defines aliasing rules for memory access in the current aliasing scope. Assume that the memory access doesn’t alias with any other memory accesses with aliasing scopes in Aliasing Scopes List intersecting with the current one in case if these accesses have AliasScopeINTEL memory operand or are decorated with AliasScopeINTEL decoration.	<id> Aliasing Scopes List	MemoryAccessAliasingINTEL

Memory Operands

Extra Operands

Enabling Capabilities

0x10000

AliasScopeINTEL
Defines aliasing rules for memory access in the current aliasing scope. Assume that the memory access doesn’t alias with any other memory accesses with aliasing scopes in Aliasing Scopes List intersecting with the current one in case if these accesses have NoAliasINTEL memory operand or are decorated with NoAliasINTEL decoration.

<id> Aliasing Scopes List

MemoryAccessAliasingINTEL

0x20000

NoAliasINTEL
Defines aliasing rules for memory access in the current aliasing scope. Assume that the memory access doesn’t alias with any other memory accesses with aliasing scopes in Aliasing Scopes List intersecting with the current one in case if these accesses have AliasScopeINTEL memory operand or are decorated with AliasScopeINTEL decoration.

<id> Aliasing Scopes List

MemoryAccessAliasingINTEL

Issues

Revision History

Rev	Date	Author	Changes
1	2021-02-15	Dmitry Sidorov	Initial revision
2	2022-01-24	Dmitry Sidorov	Remove mutually exclusive restriction
3	2026-08-05	Qi Ye	Prepare for publication