From 002249c0ed9c7a683d40342b01423df22d90cefe Mon Sep 17 00:00:00 2001
From: John Kleinschmidt <jkleinsc@electronjs.org>
Date: Mon, 27 Apr 2026 12:04:20 -0700
Subject: [PATCH] ci: Revert "build: use 32-core Windows ARC runners for build
 jobs (#51256)" (#51341)

* Revert "build: use 32-core Windows ARC runners for build jobs (#51256)"

This reverts commit 099c5c00388fd229a642fd0e0b21ed77bb8cb7bb.

* chore: put back siso patch

* Revert "fix: route ThinLTO cache through junction outside bindflt mount (#51328)"

This reverts commit 9e7a343f39291dd930931c342012d92d7db028a3.

* Revert "fix: pre-create thinlto-cache dir on Windows to avoid bindflt race (#51292)"

This reverts commit 98e91ca5551e832a9166b7352f22c3ea1c69fd8f.
---
 .github/actions/build-electron/action.yml | 30 -----------------------
 .github/workflows/build.yml               |  6 ++---
 .github/workflows/windows-publish.yml     |  6 ++---
 3 files changed, 6 insertions(+), 36 deletions(-)

diff --git a/.github/actions/build-electron/action.yml b/.github/actions/build-electron/action.yml
index f068d45510..bf6a4973bb 100644
--- a/.github/actions/build-electron/action.yml
+++ b/.github/actions/build-electron/action.yml
@@ -107,36 +107,6 @@ runs:
         git pack-refs
         cd ..
 
-        # Route the ThinLTO cache out of the bindflt filter driver mount.
-        # The runner workspace under C:\actions-runner\_work\ is exposed via
-        # bindflt, which intermittently returns ERROR_INVALID_PARAMETER on
-        # CreateFileW/CreateDirectoryW under the concurrent I/O lld-link
-        # generates (ThinLTO writes thousands of cache files in parallel).
-        # Pre-creating the cache directory dodged CreateDirectoryW; opening
-        # individual cache files inside it still raced. Replace the directory
-        # with a junction to a path outside the bindflt mount so lld's cache
-        # I/O bypasses the filter driver entirely.
-        #
-        # $env:TEMP on ARC runners lives under
-        # C:\Users\ContainerAdministrator\AppData\Local\Temp and is not
-        # bindflt-mounted. The link path mirrors `cache_dir` in Chromium's
-        # build/config/compiler/BUILD.gn (the `/lldltocache:` ldflag passed
-        # to lld-link); if upstream ever relocates `cache_dir`, update the
-        # link path here.
-        $thinltoCacheLink = "out\Default\thinlto-cache"
-        $thinltoCacheTarget = Join-Path $env:TEMP "electron-thinlto-cache"
-        New-Item -ItemType Directory -Force -Path (Split-Path $thinltoCacheLink) | Out-Null
-        New-Item -ItemType Directory -Force -Path $thinltoCacheTarget | Out-Null
-        if (Test-Path $thinltoCacheLink) {
-          $existing = Get-Item $thinltoCacheLink -Force
-          if ($existing.Attributes -band [System.IO.FileAttributes]::ReparsePoint) {
-            cmd /c rmdir $thinltoCacheLink | Out-Null
-          } else {
-            Remove-Item -Recurse -Force $thinltoCacheLink
-          }
-        }
-        cmd /c mklink /J $thinltoCacheLink $thinltoCacheTarget | Out-Null
-
         $env:NINJA_SUMMARIZE_BUILD = 1
         if ("${{ inputs.is-release }}" -eq "true") {          
           e build --target electron:release_build
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 261f81125e..c03ccfc6fb 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -398,7 +398,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     if: ${{ needs.setup.outputs.src == 'true' && !inputs.skip-windows }}
     with:
-      build-runs-on: electron-arc-centralus-windows-amd64-32core
+      build-runs-on: electron-arc-centralus-windows-amd64-16core
       clang-tidy-runs-on: electron-arc-centralus-linux-amd64-8core
       test-runs-on: windows-latest
       clang-tidy-container: '{"image":"ghcr.io/electron/build:${{ needs.checkout-windows.outputs.build-image-sha }}","options":"--user root --device /dev/fuse --cap-add SYS_ADMIN","volumes":["/mnt/win-cache:/mnt/win-cache"]}'
@@ -419,7 +419,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     if: ${{ needs.setup.outputs.src == 'true' && !inputs.skip-windows }}
     with:
-      build-runs-on: electron-arc-centralus-windows-amd64-32core
+      build-runs-on: electron-arc-centralus-windows-amd64-16core
       test-runs-on: windows-latest
       target-platform: win
       target-arch: x86
@@ -438,7 +438,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     if: ${{ needs.setup.outputs.src == 'true' && !inputs.skip-windows }}
     with:
-      build-runs-on: electron-arc-centralus-windows-amd64-32core
+      build-runs-on: electron-arc-centralus-windows-amd64-16core
       test-runs-on: windows-11-arm
       target-platform: win
       target-arch: arm64
diff --git a/.github/workflows/windows-publish.yml b/.github/workflows/windows-publish.yml
index 748b9c86c1..d156488ffa 100644
--- a/.github/workflows/windows-publish.yml
+++ b/.github/workflows/windows-publish.yml
@@ -82,7 +82,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     with:
       environment: production-release
-      build-runs-on: electron-arc-centralus-windows-amd64-32core
+      build-runs-on: electron-arc-centralus-windows-amd64-16core
       target-platform: win
       target-arch: x64
       is-release: true
@@ -101,7 +101,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     with:
       environment: production-release
-      build-runs-on: electron-arc-centralus-windows-amd64-32core
+      build-runs-on: electron-arc-centralus-windows-amd64-16core
       target-platform: win
       target-arch: arm64
       is-release: true
@@ -120,7 +120,7 @@ jobs:
     needs: [checkout-windows, build-siso-windows]
     with:
       environment: production-release
-      build-runs-on: electron-arc-centralus-windows-amd64-32core
+      build-runs-on: electron-arc-centralus-windows-amd64-16core
       target-platform: win
       target-arch: x86
       is-release: true