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Enable MSVC support for AArch64 code paths and Windows build fixes - #1305

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ARM-software:mainfrom
Harishmcw:win_arm64
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Enable MSVC support for AArch64 code paths and Windows build fixes#1305
Harishmcw wants to merge 2 commits into
ARM-software:mainfrom
Harishmcw:win_arm64

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@Harishmcw

@Harishmcw Harishmcw commented Jul 29, 2026 •
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Summary

This PR improves MSVC compatibility for Windows on Arm64 by extending AArch64-specific code paths to also recognize _M_ARM64, and fixes the SCons build system to work correctly on native ARM64 Windows hosts.

Motivation

  • While building OpenVINO for Windows on Arm64 using MSVC, several compilation failures and runtime crashes were encountered in ARM Compute Library due to ARM64-specific code being guarded only by aarch64.
  • MSVC defines _M_ARM64 instead of aarch64, causing those code paths to be excluded.
    This resulted in compilation errors such as:
error C2039: 'NEReorderLayer': is not a member of 'arm_compute'
error C3646: unknown override specifier
error C4430: missing type specifier
  • Additionally, the SCons build fails on native ARM64 Windows hosts because the assembler command template defaults to POSIX-style flags (-o) instead of MSVC-style (/Fo) that clang-cl expects.

Fix

This PR updates ARM64-specific code paths to support both GCC/Clang and MSVC by replacing architecture guards of the form:

#ifdef __aarch64__

with

#if defined(__aarch64__) || defined(_M_ARM64)

The changes include:

  • ActivationLayerInfo.h — Enables ARM64-specific members and introduces an MSVC-compatible float16_t alias.
  • LUTManager.h — Enables ARM64 lookup table definitions for MSVC.
  • QuantizationInfo.h — Applies the ARM64 rounding policy for MSVC builds.
  • NEReorderLayer.h — Makes NEReorderLayer available for _M_ARM64.

SConstruct

  • Explicitly sets ASCOM and ASPPCOM for the Windows build. The os == 'windows' block already overrides AS to clang-cl, but doesn't set the command template.
  • On native ARM64 Windows hosts, SCons fails to auto-detect MSVC and falls back to POSIX-style flags (-o), which clang-cl rejects. This fix completes the existing Windows overrides.

@Harishmcw Harishmcw changed the title Enable MSVC support for AArch64 code paths Enable MSVC support for AArch64 code paths and Windows build fixes Aug 5, 2026
Harishmcw added a commit to Harishmcw/openvino that referenced this pull request Aug 11, 2026
@Harishmcw
Submodule: point oneDNN, ComputeLibrary, kleidiai to forks with pendi…
c8d3af5 
…ng WoA/MSVC fixes (TEMPORARY)

These three submodules require patches for their builds to succeed
under MSVC on Windows ARM64. The fixes have been submitted upstream
but are not yet merged:

  oneDNN:          openvinotoolkit/oneDNN#318            - in review
  ComputeLibrary:  ARM-software/ComputeLibrary#1305      - in review
  kleidiai:        https://gitlab.arm.com/kleidi/kleidiai/-/merge_requests/769   - in review

Point each submodule at a personal fork carrying those patches so CI
for this PR can actually build and run to validate the rest of the
changes, until the upstream fixes land. This is NOT intended to merge
as-is: revert .gitmodules to the upstream URLs once the corresponding
upstream PRs are merged.

This PR is kept in draft until all three are resolved.
Harishmcw added a commit to Harishmcw/openvino that referenced this pull request Aug 11, 2026
@Harishmcw
Submodule: point oneDNN, ComputeLibrary, kleidiai to forks with pendi…
fb70695 
…ng WoA/MSVC fixes (TEMPORARY)

These three submodules require patches for their builds to succeed
under MSVC on Windows ARM64. The fixes have been submitted upstream
but are not yet merged:

  oneDNN:          openvinotoolkit/oneDNN#318            - in review
  ComputeLibrary:  ARM-software/ComputeLibrary#1305      - in review
  kleidiai:        https://gitlab.arm.com/kleidi/kleidiai/-/merge_requests/769   - in review

Point each submodule at a personal fork carrying those patches so CI
for this PR can actually build and run to validate the rest of the
changes, until the upstream fixes land.

This PR is kept in draft until all three are resolved.
@Harishmcw Harishmcw mentioned this pull request Aug 11, 2026
Open
Harishmcw added a commit to Harishmcw/openvino that referenced this pull request Aug 17, 2026
@Harishmcw
Submodule: point oneDNN, ComputeLibrary to forks with pending WoA/MSV…
6641141 
…C fixes (TEMPORARY)

These two submodules require patches for their builds to succeed
under MSVC on Windows ARM64. The fixes have been submitted upstream
but are not yet merged:

  oneDNN:          openvinotoolkit/oneDNN#318            - in review
  ComputeLibrary:  ARM-software/ComputeLibrary#1305      - in review

Point each submodule at a personal fork carrying those patches so CI
for this PR can actually build and run to validate the rest of the
changes, until the upstream fixes land.

This PR is kept in draft until all three are resolved.
@Harishmcw

Harishmcw commented Aug 17, 2026

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Hi, just a quick ping on this PR. Could you please take a look when you get a chance?

Thanks!

Harishmcw added a commit to Harishmcw/openvino that referenced this pull request Aug 18, 2026
@Harishmcw
Submodule: point ComputeLibrary to forks with pending WoA/MSVC fixes …
ad43c87 
…(TEMPORARY)

This submodule require patches for their builds to succeed
under MSVC on Windows ARM64. The fixes have been submitted upstream
but are not yet merged:

  ComputeLibrary:  ARM-software/ComputeLibrary#1305      - in review

Point each submodule at a personal fork carrying those patches so CI
for this PR can actually build and run to validate the rest of the
changes, until the upstream fixes land.

This PR is kept in draft until all three are resolved.
Harishmcw added a commit to Harishmcw/openvino that referenced this pull request Aug 18, 2026
@Harishmcw
Submodule: point ComputeLibrary to forks with pending WoA/MSVC fixes …
f7dbbdb 
…(TEMPORARY)

This submodule require patches for their builds to succeed
under MSVC on Windows ARM64. The fixes have been submitted upstream
but are not yet merged:

  ComputeLibrary:  ARM-software/ComputeLibrary#1305      - in review

Point each submodule at a personal fork carrying those patches so CI
for this PR can actually build and run to validate the rest of the
changes, until the upstream fixes land.

This PR is kept in draft until all three are resolved.
Harishmcw added a commit to Harishmcw/openvino that referenced this pull request Aug 19, 2026
@Harishmcw
Submodule: point ComputeLibrary to fork, with pending WoA/MSVC fixes …
efea108 
…(TEMPORARY)

This submodule require patches for their build to succeed
under MSVC on Windows ARM64. The fixes have been submitted upstream
but are not yet merged:

  ComputeLibrary:  ARM-software/ComputeLibrary#1305      - in review

Point ComputeLibrary submodule at a personal fork carrying those patches so CI
for this PR can actually build and run to validate the rest of the
changes, until the upstream fixes land.

This PR is kept in draft until this gets resolved.
Harishmcw added a commit to Harishmcw/openvino that referenced this pull request Aug 19, 2026
@Harishmcw
Submodule: point ComputeLibrary to fork, with pending WoA/MSVC fixes …
f7ee04c 
…(TEMPORARY)

This submodule require patches for their build to succeed
under MSVC on Windows ARM64. The fixes have been submitted upstream
but are not yet merged:

  ComputeLibrary:  ARM-software/ComputeLibrary#1305      - in review

Point ComputeLibrary submodule at a personal fork carrying those patches so CI
for this PR can actually build and run to validate the rest of the
changes, until the upstream fixes land.

This PR is kept in draft until this gets resolved.
@morgolock

morgolock commented Aug 21, 2026

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Contributor

Hi @Harishmcw

I'm confused, are you trying to build with MSVC/ cl.exe ? If so, this is not supported, building ACL natively on Windows requires clang

@Harishmcw

Harishmcw commented Aug 24, 2026

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Hi @morgolock,

Yes, we are building ACL itself using clang-cl via SCons, not trying to build ACL with MSVC.

The issue is that ACL is used as a dependency by OpenVINO, which is built with MSVC (cl.exe). When OpenVINO includes ACL's public headers, they are parsed by the MSVC compiler. MSVC defines _M_ARM64 rather than __aarch64__, so the AArch64-specific declarations in the headers are skipped by the preprocessor. This causes the downstream OpenVINO MSVC build to fail because it cannot see the declarations exposed by the clang-cl-compiled ACL library.

The changes in this PR are to make the ACL headers compatible with this use case.

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2 participants

@Harishmcw @morgolock