From ebea2aa2aeda5d2dd401c5301ca2c019be812bc2 Mon Sep 17 00:00:00 2001
From: Damyan Pepper <damyanp@microsoft.com>
Date: Wed, 15 Jul 2026 10:55:10 -0700
Subject: [PATCH 01/16] Allow ARM64 builds on any Windows runner

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 94ff14fb-6023-4436-8382-29a19a4c54b0
---
 .../workflows/build-and-test-callable.yaml    | 166 +++++++++++++++---
 docs/offload-distribution.md                  |   7 +
 2 files changed, 152 insertions(+), 21 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index fbfa2e3e5..4500db5e8 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -126,14 +126,15 @@ jobs:
   build:
     permissions:
       checks: write
-    # When SplitBuild is true, build on any available runner of
-    # the right architecture. Otherwise, build on the GPU runner.
+    # When SplitBuild is true, build on any available runner that can produce
+    # the requested target. windows-qc targets ARM64 but may cross-compile on
+    # an X64 Windows builder. Otherwise, build on the GPU runner.
     runs-on: >-
       ${{ fromJSON(
         inputs.SplitBuild != true
           && format('["self-hosted", "hlsl-{0}"]', inputs.SKU)
         || inputs.SKU == 'windows-qc'
-          && '["self-hosted", "ARM64", "Windows"]'
+          && '["self-hosted", "Windows"]'
         || inputs.SKU == 'macos'
           && '["self-hosted", "hlsl-macos"]'
         || '["self-hosted", "Windows", "X64"]'
@@ -168,16 +169,67 @@ jobs:
           ref: main
           path: golden-images
           fetch-depth: 1
-      - name: Setup Windows x64
-        if: inputs.OS == 'windows' && runner.arch != 'ARM64'
+      - name: Setup Python
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        with:
+          pip-install: -r ${{ github.workspace }}/OffloadTest/test/requirements.txt
+      - name: Setup Windows host tools
+        if: >-
+          inputs.OS == 'windows'
+          && inputs.SplitBuild == true
+          && inputs.SKU == 'windows-qc'
+          && runner.arch != 'ARM64'
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: amd64
-      - name: Setup Windows
-        if: inputs.OS == 'windows' && runner.arch == 'ARM64'
+      - name: Build native host tools
+        if: >-
+          inputs.OS == 'windows'
+          && inputs.SplitBuild == true
+          && inputs.SKU == 'windows-qc'
+          && runner.arch != 'ARM64'
+        shell: bash
+        run: |
+            set -euxo pipefail
+
+            cmake -G Ninja \
+              -S "$GITHUB_WORKSPACE/DXC" \
+              -B "$GITHUB_WORKSPACE/DXC/host-build" \
+              -DCMAKE_BUILD_TYPE=Release \
+              -DLLVM_ENABLE_ASSERTIONS=Off \
+              -C "$GITHUB_WORKSPACE/DXC/cmake/caches/PredefinedParams.cmake" \
+              -C "$GITHUB_WORKSPACE/OffloadTest/cmake/caches/sccache.cmake" \
+              -DHLSL_DISABLE_SOURCE_GENERATION=On
+            cmake --build "$GITHUB_WORKSPACE/DXC/host-build" \
+              --target llvm-tblgen clang-tblgen llvm-config
+
+            cmake -G Ninja \
+              -S "$GITHUB_WORKSPACE/llvm-project/llvm" \
+              -B "$GITHUB_WORKSPACE/llvm-project/host-build" \
+              -DCMAKE_BUILD_TYPE=Release \
+              -DLLVM_ENABLE_ASSERTIONS=Off \
+              -DLLVM_ENABLE_PROJECTS=clang \
+              -DLLVM_TARGETS_TO_BUILD=Native \
+              -C "$GITHUB_WORKSPACE/OffloadTest/cmake/caches/sccache.cmake"
+            cmake --build "$GITHUB_WORKSPACE/llvm-project/host-build" \
+              --target llvm-tblgen clang-tblgen llvm-config
+      - name: Setup Windows x64 target
+        if: inputs.OS == 'windows' && inputs.SKU != 'windows-qc'
+        uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
+        with:
+          arch: amd64
+      - name: Setup Windows ARM64 target
+        if: inputs.OS == 'windows' && inputs.SKU == 'windows-qc'
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: arm64
+      - name: Report Windows build architecture
+        if: inputs.OS == 'windows'
+        shell: bash
+        run: |
+          echo "Runner architecture: ${{ runner.arch }}"
+          echo "MSVC host architecture: ${VSCMD_ARG_HOST_ARCH:-unknown}"
+          echo "MSVC target architecture: ${VSCMD_ARG_TGT_ARCH:-unknown}"
       # When SplitBuild is enabled, force clang into the build set even if
       # the TestTarget doesn't use it. Reason: install-distribution depends
       # on clang (it ships in the install prefix), so if clang isn't part
@@ -189,24 +241,96 @@ jobs:
         shell: bash
         if: contains(inputs.TestTarget, 'clang') || inputs.SplitBuild == true
         run: echo TEST_CLANG=On >> $GITHUB_OUTPUT
-      - name: Setup Python
-        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
-        with:
-          pip-install: -r ${{ github.workspace }}/OffloadTest/test/requirements.txt
       - name: Build DXC
+        shell: bash
         run: |
-            cd DXC
-            mkdir build
-            cd build
-            cmake -G Ninja -DCMAKE_BUILD_TYPE=${{ inputs.BuildType }} -DLLVM_ENABLE_ASSERTIONS=On -C ${{ github.workspace }}/DXC/cmake/caches/PredefinedParams.cmake -C ${{ github.workspace }}/OffloadTest/cmake/caches/sccache.cmake -DHLSL_DISABLE_SOURCE_GENERATION=On ${{ github.workspace }}/DXC/
-            ninja
+            set -euxo pipefail
+            cross_args=()
+            if [ '${{ inputs.SplitBuild }}' = 'true' ] \
+              && [ '${{ inputs.SKU }}' = 'windows-qc' ] \
+              && [ '${{ runner.arch }}' != 'ARM64' ]; then
+              cross_args=(
+                -DCMAKE_SYSTEM_NAME=Windows
+                -DCMAKE_SYSTEM_PROCESSOR=ARM64
+                "-DLLVM_NATIVE_BUILD=$GITHUB_WORKSPACE/DXC/host-build"
+                "-DLLVM_TABLEGEN=$GITHUB_WORKSPACE/DXC/host-build/bin/llvm-tblgen.exe"
+                "-DCLANG_TABLEGEN=$GITHUB_WORKSPACE/DXC/host-build/bin/clang-tblgen.exe"
+              )
+            fi
+            cmake -G Ninja \
+              -S "$GITHUB_WORKSPACE/DXC" \
+              -B "$GITHUB_WORKSPACE/DXC/build" \
+              -DCMAKE_BUILD_TYPE=${{ inputs.BuildType }} \
+              -DLLVM_ENABLE_ASSERTIONS=On \
+              -C "$GITHUB_WORKSPACE/DXC/cmake/caches/PredefinedParams.cmake" \
+              -C "$GITHUB_WORKSPACE/OffloadTest/cmake/caches/sccache.cmake" \
+              -DHLSL_DISABLE_SOURCE_GENERATION=On \
+              "${cross_args[@]}"
+            cmake --build "$GITHUB_WORKSPACE/DXC/build"
       - name: Build LLVM
+        shell: bash
         run: |
-            cd llvm-project
-            mkdir build
-            cd build
-            cmake -G Ninja ${{ inputs.LLVM-ExtraCMakeArgs }} -DCMAKE_BUILD_TYPE=${{ inputs.BuildType }} -DLLVM_ENABLE_ASSERTIONS=On -DLLVM_EXTERNAL_PROJECTS="OffloadTest" -DHLSL_ENABLE_OFFLOAD_DISTRIBUTION=${{ inputs.SplitBuild == true && 'On' || 'Off' }} -C ${{ github.workspace }}/llvm-project/clang/cmake/caches/HLSL.cmake -C ${{ github.workspace }}/OffloadTest/cmake/caches/sccache.cmake -DDXC_DIR=${{ github.workspace }}/DXC/build/bin -DLLVM_EXTERNAL_OFFLOADTEST_SOURCE_DIR=${{ github.workspace }}/OffloadTest -DLLVM_LIT_ARGS="--xunit-xml-output=testresults.xunit.xml -v" -DOFFLOADTEST_TEST_CLANG=${{steps.Test-Clang.outputs.TEST_CLANG || 'Off' }} -DGOLDENIMAGE_DIR=${{ github.workspace }}/golden-images -DCMAKE_INSTALL_PREFIX=${{ github.workspace }}/install ${{ github.workspace }}/llvm-project/llvm/
-            ninja hlsl-test-depends
+            set -euxo pipefail
+            cross_args=()
+            if [ '${{ inputs.SplitBuild }}' = 'true' ] \
+              && [ '${{ inputs.SKU }}' = 'windows-qc' ] \
+              && [ '${{ runner.arch }}' != 'ARM64' ]; then
+              cross_args=(
+                -DCMAKE_SYSTEM_NAME=Windows
+                -DCMAKE_SYSTEM_PROCESSOR=ARM64
+                -DCMAKE_C_COMPILER_TARGET=arm64-pc-windows-msvc
+                -DCMAKE_CXX_COMPILER_TARGET=arm64-pc-windows-msvc
+                "-DLLVM_NATIVE_BUILD=$GITHUB_WORKSPACE/llvm-project/host-build"
+                "-DLLVM_NATIVE_TOOL_DIR=$GITHUB_WORKSPACE/llvm-project/host-build/bin"
+              )
+            fi
+            cmake -G Ninja \
+              -S "$GITHUB_WORKSPACE/llvm-project/llvm" \
+              -B "$GITHUB_WORKSPACE/llvm-project/build" \
+              ${{ inputs.LLVM-ExtraCMakeArgs }} \
+              -DCMAKE_BUILD_TYPE=${{ inputs.BuildType }} \
+              -DLLVM_ENABLE_ASSERTIONS=On \
+              -DLLVM_EXTERNAL_PROJECTS="OffloadTest" \
+              -DHLSL_ENABLE_OFFLOAD_DISTRIBUTION=${{ inputs.SplitBuild == true && 'On' || 'Off' }} \
+              -C "$GITHUB_WORKSPACE/llvm-project/clang/cmake/caches/HLSL.cmake" \
+              -C "$GITHUB_WORKSPACE/OffloadTest/cmake/caches/sccache.cmake" \
+              "-DDXC_DIR=$GITHUB_WORKSPACE/DXC/build/bin" \
+              "-DLLVM_EXTERNAL_OFFLOADTEST_SOURCE_DIR=$GITHUB_WORKSPACE/OffloadTest" \
+              -DLLVM_LIT_ARGS="--xunit-xml-output=testresults.xunit.xml -v" \
+              -DOFFLOADTEST_TEST_CLANG=${{steps.Test-Clang.outputs.TEST_CLANG || 'Off' }} \
+              "-DGOLDENIMAGE_DIR=$GITHUB_WORKSPACE/golden-images" \
+              "-DCMAKE_INSTALL_PREFIX=$GITHUB_WORKSPACE/install" \
+              "${cross_args[@]}"
+            cmake --build "$GITHUB_WORKSPACE/llvm-project/build" \
+              --target hlsl-test-depends
+      - name: Verify ARM64 build artifacts
+        if: >-
+          inputs.OS == 'windows'
+          && inputs.SplitBuild == true
+          && inputs.SKU == 'windows-qc'
+        shell: powershell
+        run: |
+          $expectedMachine = 0xAA64
+          $files = @(
+            "$env:GITHUB_WORKSPACE\DXC\build\bin\dxc.exe",
+            "$env:GITHUB_WORKSPACE\llvm-project\build\bin\clang.exe"
+          )
+          foreach ($file in $files) {
+            $stream = [System.IO.File]::OpenRead($file)
+            try {
+              $reader = [System.IO.BinaryReader]::new($stream)
+              $stream.Position = 0x3c
+              $peOffset = $reader.ReadInt32()
+              $stream.Position = $peOffset + 4
+              $machine = $reader.ReadUInt16()
+            } finally {
+              $stream.Dispose()
+            }
+            if ($machine -ne $expectedMachine) {
+              throw "$file has PE machine 0x$($machine.ToString('X4')); expected ARM64 (0xAA64)"
+            }
+            Write-Host "$file is ARM64"
+          }
       # Surface sccache cache state after the heavy compile work so we can
       # track hit rate / cache size across runs and diagnose cold-cache
       # blowups on new builders. Always-runs so we still get stats on
diff --git a/docs/offload-distribution.md b/docs/offload-distribution.md
index d2859adb3..f793ef8cf 100644
--- a/docs/offload-distribution.md
+++ b/docs/offload-distribution.md
@@ -185,3 +185,10 @@ The reusable workflow `.github/workflows/build-and-test-callable.yaml`
 implements this flow when invoked with `SplitBuild=true`. The build job
 produces two artifacts (`build-<sku>-<target>` and `dxc-<sku>-<target>`)
 and the test job consumes both.
+
+For the `windows-qc` SKU, the build job targets ARM64 independently of the
+build host architecture. It is scheduled on the generic self-hosted Windows
+pool: an ARM64 host builds natively, while an X64 host first builds the native
+LLVM/DXC generator tools and then cross-compiles the packaged binaries for
+Windows ARM64. The workflow verifies the PE machine type before uploading the
+artifacts. The test job remains pinned to the ARM64 `hlsl-windows-qc` runner.

From 9e6c15984c4db7e497be3af43028b37910a87ed3 Mon Sep 17 00:00:00 2001
From: Damyan Pepper <damyanp@microsoft.com>
Date: Wed, 15 Jul 2026 11:04:48 -0700
Subject: [PATCH 02/16] Fix cross-runner build environments

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 94ff14fb-6023-4436-8382-29a19a4c54b0
---
 .../workflows/build-and-test-callable.yaml    | 25 ++++++++++++++++---
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 4500db5e8..3c7f42292 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -218,11 +218,28 @@ jobs:
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: amd64
-      - name: Setup Windows ARM64 target
-        if: inputs.OS == 'windows' && inputs.SKU == 'windows-qc'
+      - name: Setup Windows ARM64 cross target
+        if: >-
+          inputs.OS == 'windows'
+          && inputs.SKU == 'windows-qc'
+          && runner.arch != 'ARM64'
+        uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
+        with:
+          # setup-windows forwards this input to VsDevCmd.bat after -arch=.
+          arch: arm64 -host_arch=amd64
+      - name: Setup Windows ARM64 native target
+        if: >-
+          inputs.OS == 'windows'
+          && inputs.SKU == 'windows-qc'
+          && runner.arch == 'ARM64'
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: arm64
+      # VsDevCmd replaces PATH. Run setup-python after the final target setup
+      # so Python and Git Bash are available to the remaining workflow steps.
+      - name: Restore Python and Git Bash paths
+        if: inputs.OS == 'windows'
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
       - name: Report Windows build architecture
         if: inputs.OS == 'windows'
         shell: bash
@@ -244,7 +261,7 @@ jobs:
       - name: Build DXC
         shell: bash
         run: |
-            set -euxo pipefail
+            set -exo pipefail
             cross_args=()
             if [ '${{ inputs.SplitBuild }}' = 'true' ] \
               && [ '${{ inputs.SKU }}' = 'windows-qc' ] \
@@ -270,7 +287,7 @@ jobs:
       - name: Build LLVM
         shell: bash
         run: |
-            set -euxo pipefail
+            set -exo pipefail
             cross_args=()
             if [ '${{ inputs.SplitBuild }}' = 'true' ] \
               && [ '${{ inputs.SKU }}' = 'windows-qc' ] \

From cd99223286c39b86fae72d81c08c3835516736d6 Mon Sep 17 00:00:00 2001
From: Damyan Pepper <damyanp@microsoft.com>
Date: Wed, 15 Jul 2026 11:24:55 -0700
Subject: [PATCH 03/16] Restore Git Bash after Windows setup

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 94ff14fb-6023-4436-8382-29a19a4c54b0
---
 .../workflows/build-and-test-callable.yaml    | 22 ++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 3c7f42292..ff6834528 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -182,6 +182,16 @@ jobs:
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: amd64
+      - name: Restore Git Bash for host tools
+        if: >-
+          inputs.OS == 'windows'
+          && inputs.SplitBuild == true
+          && inputs.SKU == 'windows-qc'
+          && runner.arch != 'ARM64'
+        shell: powershell
+        run: |
+          "C:\Program Files\Git\bin" >> $env:GITHUB_PATH
+          "C:\Program Files\Git\usr\bin" >> $env:GITHUB_PATH
       - name: Build native host tools
         if: >-
           inputs.OS == 'windows'
@@ -235,11 +245,17 @@ jobs:
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: arm64
-      # VsDevCmd replaces PATH. Run setup-python after the final target setup
-      # so Python and Git Bash are available to the remaining workflow steps.
-      - name: Restore Python and Git Bash paths
+      # VsDevCmd replaces PATH. Restore the tool paths required by the
+      # remaining workflow steps after the final target setup.
+      - name: Restore Python path
         if: inputs.OS == 'windows'
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+      - name: Restore Git Bash path
+        if: inputs.OS == 'windows'
+        shell: powershell
+        run: |
+          "C:\Program Files\Git\bin" >> $env:GITHUB_PATH
+          "C:\Program Files\Git\usr\bin" >> $env:GITHUB_PATH
       - name: Report Windows build architecture
         if: inputs.OS == 'windows'
         shell: bash

From 31476d2e259b6a24b55ac37bb766fabf62ea7af3 Mon Sep 17 00:00:00 2001
From: Damyan Pepper <damyanp@microsoft.com>
Date: Wed, 15 Jul 2026 11:38:51 -0700
Subject: [PATCH 04/16] Isolate native host tool setup

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 94ff14fb-6023-4436-8382-29a19a4c54b0
---
 .../workflows/build-and-test-callable.yaml    | 67 +++++++------------
 1 file changed, 26 insertions(+), 41 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index ff6834528..ecd8f99c8 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -173,56 +173,41 @@ jobs:
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
         with:
           pip-install: -r ${{ github.workspace }}/OffloadTest/test/requirements.txt
-      - name: Setup Windows host tools
-        if: >-
-          inputs.OS == 'windows'
-          && inputs.SplitBuild == true
-          && inputs.SKU == 'windows-qc'
-          && runner.arch != 'ARM64'
-        uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
-        with:
-          arch: amd64
-      - name: Restore Git Bash for host tools
-        if: >-
-          inputs.OS == 'windows'
-          && inputs.SplitBuild == true
-          && inputs.SKU == 'windows-qc'
-          && runner.arch != 'ARM64'
-        shell: powershell
-        run: |
-          "C:\Program Files\Git\bin" >> $env:GITHUB_PATH
-          "C:\Program Files\Git\usr\bin" >> $env:GITHUB_PATH
       - name: Build native host tools
         if: >-
           inputs.OS == 'windows'
           && inputs.SplitBuild == true
           && inputs.SKU == 'windows-qc'
           && runner.arch != 'ARM64'
-        shell: bash
+        shell: cmd
         run: |
-            set -euxo pipefail
+          for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath`) do set "InstallDir=%%i"
+          call "%InstallDir%\Common7\Tools\VsDevCmd.bat" -arch=amd64 -host_arch=amd64
 
-            cmake -G Ninja \
-              -S "$GITHUB_WORKSPACE/DXC" \
-              -B "$GITHUB_WORKSPACE/DXC/host-build" \
-              -DCMAKE_BUILD_TYPE=Release \
-              -DLLVM_ENABLE_ASSERTIONS=Off \
-              -C "$GITHUB_WORKSPACE/DXC/cmake/caches/PredefinedParams.cmake" \
-              -C "$GITHUB_WORKSPACE/OffloadTest/cmake/caches/sccache.cmake" \
-              -DHLSL_DISABLE_SOURCE_GENERATION=On
-            cmake --build "$GITHUB_WORKSPACE/DXC/host-build" \
-              --target llvm-tblgen clang-tblgen llvm-config
+          cmake -G Ninja ^
+            -S "%GITHUB_WORKSPACE%\DXC" ^
+            -B "%GITHUB_WORKSPACE%\DXC\host-build" ^
+            -DCMAKE_BUILD_TYPE=Release ^
+            -DLLVM_ENABLE_ASSERTIONS=Off ^
+            -C "%GITHUB_WORKSPACE%\DXC\cmake\caches\PredefinedParams.cmake" ^
+            -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake" ^
+            -DHLSL_DISABLE_SOURCE_GENERATION=On
+          if errorlevel 1 exit /b 1
+          cmake --build "%GITHUB_WORKSPACE%\DXC\host-build" ^
+            --target llvm-tblgen clang-tblgen llvm-config
+          if errorlevel 1 exit /b 1
 
-            cmake -G Ninja \
-              -S "$GITHUB_WORKSPACE/llvm-project/llvm" \
-              -B "$GITHUB_WORKSPACE/llvm-project/host-build" \
-              -DCMAKE_BUILD_TYPE=Release \
-              -DLLVM_ENABLE_ASSERTIONS=Off \
-              -DLLVM_ENABLE_PROJECTS=clang \
-              -DLLVM_TARGETS_TO_BUILD=Native \
-              -C "$GITHUB_WORKSPACE/OffloadTest/cmake/caches/sccache.cmake"
-            cmake --build "$GITHUB_WORKSPACE/llvm-project/host-build" \
-              --target llvm-tblgen clang-tblgen llvm-config
+          cmake -G Ninja ^
+            -S "%GITHUB_WORKSPACE%\llvm-project\llvm" ^
+            -B "%GITHUB_WORKSPACE%\llvm-project\host-build" ^
+            -DCMAKE_BUILD_TYPE=Release ^
+            -DLLVM_ENABLE_ASSERTIONS=Off ^
+            -DLLVM_ENABLE_PROJECTS=clang ^
+            -DLLVM_TARGETS_TO_BUILD=Native ^
+            -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake"
+          if errorlevel 1 exit /b 1
+          cmake --build "%GITHUB_WORKSPACE%\llvm-project\host-build" ^
+            --target llvm-tblgen clang-tblgen llvm-config
       - name: Setup Windows x64 target
         if: inputs.OS == 'windows' && inputs.SKU != 'windows-qc'
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main

From 8d6da50bd60e4a4ad98b64859f1a6c4667a282c6 Mon Sep 17 00:00:00 2001
From: Damyan Pepper <damyanp@microsoft.com>
Date: Wed, 15 Jul 2026 13:13:34 -0700
Subject: [PATCH 05/16] Use x64-hosted ARM64 cross tools

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 94ff14fb-6023-4436-8382-29a19a4c54b0
---
 .github/workflows/build-and-test-callable.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index ecd8f99c8..5deef3b58 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -221,7 +221,7 @@ jobs:
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           # setup-windows forwards this input to VsDevCmd.bat after -arch=.
-          arch: arm64 -host_arch=amd64
+          arch: arm64 -host_arch=x64
       - name: Setup Windows ARM64 native target
         if: >-
           inputs.OS == 'windows'

From 073bcb91ef854b925a7309ad4efd6b981750bc47 Mon Sep 17 00:00:00 2001
From: Damyan Pepper <damyanp@microsoft.com>
Date: Wed, 15 Jul 2026 14:40:53 -0700
Subject: [PATCH 06/16] Target ARM64 explicitly in DXC cross builds

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 94ff14fb-6023-4436-8382-29a19a4c54b0
---
 .github/workflows/build-and-test-callable.yaml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 5deef3b58..cc5c9edc7 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -270,6 +270,10 @@ jobs:
               cross_args=(
                 -DCMAKE_SYSTEM_NAME=Windows
                 -DCMAKE_SYSTEM_PROCESSOR=ARM64
+                -DCMAKE_C_COMPILER=clang-cl
+                -DCMAKE_CXX_COMPILER=clang-cl
+                -DCMAKE_C_COMPILER_TARGET=arm64-pc-windows-msvc
+                -DCMAKE_CXX_COMPILER_TARGET=arm64-pc-windows-msvc
                 "-DLLVM_NATIVE_BUILD=$GITHUB_WORKSPACE/DXC/host-build"
                 "-DLLVM_TABLEGEN=$GITHUB_WORKSPACE/DXC/host-build/bin/llvm-tblgen.exe"
                 "-DCLANG_TABLEGEN=$GITHUB_WORKSPACE/DXC/host-build/bin/clang-tblgen.exe"

From 440ecaa04500f1c859c19f2dc061858fae387d58 Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Mon, 20 Jul 2026 17:23:09 -0700
Subject: [PATCH 07/16] add arm64 latest libs to all machines, and force
 machines to use latest msvc version. Reuse the pinned latest version

---
 .../workflows/build-and-test-callable.yaml    | 23 ++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index cc5c9edc7..e75fd3dae 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -173,6 +173,23 @@ jobs:
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
         with:
           pip-install: -r ${{ github.workspace }}/OffloadTest/test/requirements.txt
+      - name: Pin MSVC toolset
+        # The runner's default v143 toolset (Microsoft.VCToolsVersion.v143.default.txt)
+        # can lag Microsoft.VCToolsVersion.default.txt and lack the x64/ARM64 base
+        # libraries, which breaks host and cross builds depending on which runner
+        # picks up the job. Pin every VsDevCmd in this job to the default (latest)
+        # toolset, which VS keeps complete.
+        if: >-
+          inputs.OS == 'windows'
+          && inputs.SplitBuild == true
+          && inputs.SKU == 'windows-qc'
+        shell: pwsh
+        run: |
+          $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+          $vs = & $vswhere -latest -property installationPath
+          $ver = (Get-Content "$vs\VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt").Trim()
+          "VCToolsVersion=$ver" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding utf8
+          Write-Host "Pinned VCToolsVersion=$ver"
       - name: Build native host tools
         if: >-
           inputs.OS == 'windows'
@@ -182,7 +199,7 @@ jobs:
         shell: cmd
         run: |
           for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath`) do set "InstallDir=%%i"
-          call "%InstallDir%\Common7\Tools\VsDevCmd.bat" -arch=amd64 -host_arch=amd64
+          call "%InstallDir%\Common7\Tools\VsDevCmd.bat" -arch=amd64 -host_arch=amd64 -vcvars_ver=%VCToolsVersion%
 
           cmake -G Ninja ^
             -S "%GITHUB_WORKSPACE%\DXC" ^
@@ -221,7 +238,7 @@ jobs:
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           # setup-windows forwards this input to VsDevCmd.bat after -arch=.
-          arch: arm64 -host_arch=x64
+          arch: arm64 -host_arch=x64 -vcvars_ver=${{ env.VCToolsVersion }}
       - name: Setup Windows ARM64 native target
         if: >-
           inputs.OS == 'windows'
@@ -229,7 +246,7 @@ jobs:
           && runner.arch == 'ARM64'
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
-          arch: arm64
+          arch: arm64 -vcvars_ver=${{ env.VCToolsVersion }}
       # VsDevCmd replaces PATH. Restore the tool paths required by the
       # remaining workflow steps after the final target setup.
       - name: Restore Python path

From 7ac4f7f327efa65c549b9434c0a6803f8e273c87 Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Tue, 21 Jul 2026 13:42:48 -0700
Subject: [PATCH 08/16] self review: simplify, and x64 builds arm64 bins, no
 more native arm64 bin builders

---
 .../workflows/build-and-test-callable.yaml    | 64 +++++++------------
 docs/offload-distribution.md                  | 35 ++++++++--
 2 files changed, 51 insertions(+), 48 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index e75fd3dae..0ae327f66 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -126,15 +126,12 @@ jobs:
   build:
     permissions:
       checks: write
-    # When SplitBuild is true, build on any available runner that can produce
-    # the requested target. windows-qc targets ARM64 but may cross-compile on
-    # an X64 Windows builder. Otherwise, build on the GPU runner.
+    # Split builds run on any X64 Windows runner (windows-qc targets ARM64 but
+    # is always cross-compiled on X64). Non-split builds run on the GPU runner.
     runs-on: >-
       ${{ fromJSON(
         inputs.SplitBuild != true
           && format('["self-hosted", "hlsl-{0}"]', inputs.SKU)
-        || inputs.SKU == 'windows-qc'
-          && '["self-hosted", "Windows"]'
         || inputs.SKU == 'macos'
           && '["self-hosted", "hlsl-macos"]'
         || '["self-hosted", "Windows", "X64"]'
@@ -174,15 +171,9 @@ jobs:
         with:
           pip-install: -r ${{ github.workspace }}/OffloadTest/test/requirements.txt
       - name: Pin MSVC toolset
-        # The runner's default v143 toolset (Microsoft.VCToolsVersion.v143.default.txt)
-        # can lag Microsoft.VCToolsVersion.default.txt and lack the x64/ARM64 base
-        # libraries, which breaks host and cross builds depending on which runner
-        # picks up the job. Pin every VsDevCmd in this job to the default (latest)
-        # toolset, which VS keeps complete.
-        if: >-
-          inputs.OS == 'windows'
-          && inputs.SplitBuild == true
-          && inputs.SKU == 'windows-qc'
+        # The default v143 toolset can lag the complete default toolset and lack
+        # x64/ARM64 base libs. Pin every VsDevCmd to the default (latest) toolset.
+        if: inputs.OS == 'windows'
         shell: pwsh
         run: |
           $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
@@ -190,12 +181,19 @@ jobs:
           $ver = (Get-Content "$vs\VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt").Trim()
           "VCToolsVersion=$ver" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding utf8
           Write-Host "Pinned VCToolsVersion=$ver"
+      - name: Compute build mode
+        # Single source of truth for the ARM64 cross build: SplitBuild + windows-qc
+        # builds on X64 and targets ARM64. Cross steps key off env.ARM64_CROSS.
+        if: inputs.OS == 'windows'
+        shell: bash
+        run: |
+          cross=false
+          if [ '${{ inputs.SplitBuild }}' = 'true' ] && [ '${{ inputs.SKU }}' = 'windows-qc' ]; then
+            cross=true
+          fi
+          echo "ARM64_CROSS=$cross" >> "$GITHUB_ENV"
       - name: Build native host tools
-        if: >-
-          inputs.OS == 'windows'
-          && inputs.SplitBuild == true
-          && inputs.SKU == 'windows-qc'
-          && runner.arch != 'ARM64'
+        if: env.ARM64_CROSS == 'true'
         shell: cmd
         run: |
           for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath`) do set "InstallDir=%%i"
@@ -229,24 +227,13 @@ jobs:
         if: inputs.OS == 'windows' && inputs.SKU != 'windows-qc'
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
-          arch: amd64
+          arch: amd64 -vcvars_ver=${{ env.VCToolsVersion }}
       - name: Setup Windows ARM64 cross target
-        if: >-
-          inputs.OS == 'windows'
-          && inputs.SKU == 'windows-qc'
-          && runner.arch != 'ARM64'
+        if: env.ARM64_CROSS == 'true'
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           # setup-windows forwards this input to VsDevCmd.bat after -arch=.
           arch: arm64 -host_arch=x64 -vcvars_ver=${{ env.VCToolsVersion }}
-      - name: Setup Windows ARM64 native target
-        if: >-
-          inputs.OS == 'windows'
-          && inputs.SKU == 'windows-qc'
-          && runner.arch == 'ARM64'
-        uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
-        with:
-          arch: arm64 -vcvars_ver=${{ env.VCToolsVersion }}
       # VsDevCmd replaces PATH. Restore the tool paths required by the
       # remaining workflow steps after the final target setup.
       - name: Restore Python path
@@ -281,9 +268,7 @@ jobs:
         run: |
             set -exo pipefail
             cross_args=()
-            if [ '${{ inputs.SplitBuild }}' = 'true' ] \
-              && [ '${{ inputs.SKU }}' = 'windows-qc' ] \
-              && [ '${{ runner.arch }}' != 'ARM64' ]; then
+            if [ "$ARM64_CROSS" = 'true' ]; then
               cross_args=(
                 -DCMAKE_SYSTEM_NAME=Windows
                 -DCMAKE_SYSTEM_PROCESSOR=ARM64
@@ -311,9 +296,7 @@ jobs:
         run: |
             set -exo pipefail
             cross_args=()
-            if [ '${{ inputs.SplitBuild }}' = 'true' ] \
-              && [ '${{ inputs.SKU }}' = 'windows-qc' ] \
-              && [ '${{ runner.arch }}' != 'ARM64' ]; then
+            if [ "$ARM64_CROSS" = 'true' ]; then
               cross_args=(
                 -DCMAKE_SYSTEM_NAME=Windows
                 -DCMAKE_SYSTEM_PROCESSOR=ARM64
@@ -343,10 +326,7 @@ jobs:
             cmake --build "$GITHUB_WORKSPACE/llvm-project/build" \
               --target hlsl-test-depends
       - name: Verify ARM64 build artifacts
-        if: >-
-          inputs.OS == 'windows'
-          && inputs.SplitBuild == true
-          && inputs.SKU == 'windows-qc'
+        if: env.ARM64_CROSS == 'true'
         shell: powershell
         run: |
           $expectedMachine = 0xAA64
diff --git a/docs/offload-distribution.md b/docs/offload-distribution.md
index f793ef8cf..2b583489a 100644
--- a/docs/offload-distribution.md
+++ b/docs/offload-distribution.md
@@ -186,9 +186,32 @@ implements this flow when invoked with `SplitBuild=true`. The build job
 produces two artifacts (`build-<sku>-<target>` and `dxc-<sku>-<target>`)
 and the test job consumes both.
 
-For the `windows-qc` SKU, the build job targets ARM64 independently of the
-build host architecture. It is scheduled on the generic self-hosted Windows
-pool: an ARM64 host builds natively, while an X64 host first builds the native
-LLVM/DXC generator tools and then cross-compiles the packaged binaries for
-Windows ARM64. The workflow verifies the PE machine type before uploading the
-artifacts. The test job remains pinned to the ARM64 `hlsl-windows-qc` runner.
+For the `windows-qc` SKU, the build job targets ARM64 but is always scheduled
+on an X64 self-hosted Windows builder (we do not build ARM64 natively). The
+builder first compiles the native LLVM/DXC generator tools, then cross-compiles
+the packaged binaries for Windows ARM64. The workflow verifies the PE machine
+type before uploading the artifacts. The test job remains pinned to the ARM64
+`hlsl-windows-qc` runner.
+
+The `Compute build mode` step is the single source of truth for whether a job
+cross-compiles: it sets `ARM64_CROSS=true` only when `SplitBuild` is enabled and
+the SKU is `windows-qc`. Every cross-specific step (native host-tools build,
+ARM64 target setup, the `cmake` cross flags, and the PE-machine verification)
+keys off `env.ARM64_CROSS`, so the cross path is defined in exactly one place.
+
+### MSVC toolset pinning
+
+Windows builders can carry a v143 default toolset
+(`Microsoft.VCToolsVersion.v143.default.txt`) that lags the complete default
+toolset (`Microsoft.VCToolsVersion.default.txt`) and is missing the x64 and/or
+ARM64 base libraries (for example `msvcrtd.lib` and `oldnames.lib`). When a job
+lands on such a runner, both the native host build and the ARM64 cross build can
+fail to link, and because jobs are scheduled across a heterogeneous pool the
+failure is intermittent and runner-dependent.
+
+To make builds deterministic, the `Pin MSVC toolset` step reads the default
+(latest) toolset version, which VS keeps complete, and exports it as
+`VCToolsVersion` for the whole job. Every `VsDevCmd` invocation in the job then
+passes `-vcvars_ver=%VCToolsVersion%` (host-tools setup, `Setup Windows x64
+target`, and `Setup Windows ARM64 cross target`) so they all resolve the same
+complete toolset regardless of which runner picks up the job.

From f16be1f115d4303ee437a466c4a7d6efc3d22f72 Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Tue, 21 Jul 2026 13:52:39 -0700
Subject: [PATCH 09/16] repair pwsh

---
 .github/workflows/build-and-test-callable.yaml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 0ae327f66..93ffb7f2e 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -174,12 +174,12 @@ jobs:
         # The default v143 toolset can lag the complete default toolset and lack
         # x64/ARM64 base libs. Pin every VsDevCmd to the default (latest) toolset.
         if: inputs.OS == 'windows'
-        shell: pwsh
+        shell: powershell
         run: |
           $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
           $vs = & $vswhere -latest -property installationPath
           $ver = (Get-Content "$vs\VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt").Trim()
-          "VCToolsVersion=$ver" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding utf8
+          "VCToolsVersion=$ver" | Out-File -FilePath $env:GITHUB_ENV -Append -Encoding ascii
           Write-Host "Pinned VCToolsVersion=$ver"
       - name: Compute build mode
         # Single source of truth for the ARM64 cross build: SplitBuild + windows-qc

From 03dc0c014242196862ed18076a37837fcb595f14 Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Tue, 21 Jul 2026 15:37:29 -0700
Subject: [PATCH 10/16] turn off warnings as errors on spirvtools for arm64
 cross, since it uses clang-cl as the compiler

---
 .github/workflows/build-and-test-callable.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 93ffb7f2e..192d923bb 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -276,6 +276,9 @@ jobs:
                 -DCMAKE_CXX_COMPILER=clang-cl
                 -DCMAKE_C_COMPILER_TARGET=arm64-pc-windows-msvc
                 -DCMAKE_CXX_COMPILER_TARGET=arm64-pc-windows-msvc
+                # clang-cl reads DXC's -Wall as -Weverything; disable DXC warnings
+                # so SPIRV-Tools' hardcoded /WX doesn't fail on -Wc++98-compat.
+                -DLLVM_ENABLE_WARNINGS=OFF
                 "-DLLVM_NATIVE_BUILD=$GITHUB_WORKSPACE/DXC/host-build"
                 "-DLLVM_TABLEGEN=$GITHUB_WORKSPACE/DXC/host-build/bin/llvm-tblgen.exe"
                 "-DCLANG_TABLEGEN=$GITHUB_WORKSPACE/DXC/host-build/bin/clang-tblgen.exe"

From dbb68a4c7325e5510aae9c780c9979d9c2fdbb03 Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Tue, 21 Jul 2026 18:10:02 -0700
Subject: [PATCH 11/16] subtle tweaks and fixes

---
 .github/workflows/build-and-test-callable.yaml |  9 ++++++++-
 docs/offload-distribution.md                   | 17 +++++++++++++----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 192d923bb..8b41a9809 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -62,7 +62,7 @@ on:
       SplitBuild:
         description: 'Split build and test into separate jobs (build on any runner, test on GPU runner)'
         required: false
-        default: false
+        default: true
         type: boolean
       LLVM-ExtraCMakeArgs:
         description: 'Extra CMake Args for LLVM'
@@ -234,6 +234,13 @@ jobs:
         with:
           # setup-windows forwards this input to VsDevCmd.bat after -arch=.
           arch: arm64 -host_arch=x64 -vcvars_ver=${{ env.VCToolsVersion }}
+      - name: Setup Windows ARM64 native target
+        # Non-split windows-qc builds natively on the ARM64 device
+        # (split qc cross-compiles on X64 via the step above).
+        if: inputs.OS == 'windows' && inputs.SKU == 'windows-qc' && env.ARM64_CROSS != 'true'
+        uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
+        with:
+          arch: arm64 -vcvars_ver=${{ env.VCToolsVersion }}
       # VsDevCmd replaces PATH. Restore the tool paths required by the
       # remaining workflow steps after the final target setup.
       - name: Restore Python path
diff --git a/docs/offload-distribution.md b/docs/offload-distribution.md
index 2b583489a..03ae6e62d 100644
--- a/docs/offload-distribution.md
+++ b/docs/offload-distribution.md
@@ -186,18 +186,27 @@ implements this flow when invoked with `SplitBuild=true`. The build job
 produces two artifacts (`build-<sku>-<target>` and `dxc-<sku>-<target>`)
 and the test job consumes both.
 
-For the `windows-qc` SKU, the build job targets ARM64 but is always scheduled
-on an X64 self-hosted Windows builder (we do not build ARM64 natively). The
+For the `windows-qc` SKU with `SplitBuild=true`, the build job targets ARM64
+but is always scheduled on an X64 self-hosted Windows builder (we do not build
+ARM64 natively in the split flow). The
 builder first compiles the native LLVM/DXC generator tools, then cross-compiles
 the packaged binaries for Windows ARM64. The workflow verifies the PE machine
 type before uploading the artifacts. The test job remains pinned to the ARM64
 `hlsl-windows-qc` runner.
 
+A non-split `windows-qc` run (`SplitBuild=false`, e.g. a manual
+`workflow_dispatch`) instead runs entirely on the ARM64 `hlsl-windows-qc`
+device and builds natively via the `Setup Windows ARM64 native target` step.
+The `workflow_dispatch` default is `SplitBuild=true`, so manual runs take the
+X64 cross path unless explicitly overridden.
+
 The `Compute build mode` step is the single source of truth for whether a job
 cross-compiles: it sets `ARM64_CROSS=true` only when `SplitBuild` is enabled and
 the SKU is `windows-qc`. Every cross-specific step (native host-tools build,
-ARM64 target setup, the `cmake` cross flags, and the PE-machine verification)
-keys off `env.ARM64_CROSS`, so the cross path is defined in exactly one place.
+ARM64 cross-target setup, the `cmake` cross flags, and the PE-machine
+verification) keys off `env.ARM64_CROSS`, so the cross path is defined in
+exactly one place. The native-ARM64 setup step runs on the complementary case
+(`windows-qc` with `ARM64_CROSS != 'true'`).
 
 ### MSVC toolset pinning
 

From 531d6b041033be62f31d3de87d562b5a72372961 Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Tue, 21 Jul 2026 23:35:00 -0700
Subject: [PATCH 12/16] freeze version.inc in native builds

---
 .github/workflows/build-and-test-callable.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 8b41a9809..91973600c 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -204,6 +204,7 @@ jobs:
             -B "%GITHUB_WORKSPACE%\DXC\host-build" ^
             -DCMAKE_BUILD_TYPE=Release ^
             -DLLVM_ENABLE_ASSERTIONS=Off ^
+            -DLLVM_APPEND_VC_REV=Off ^
             -C "%GITHUB_WORKSPACE%\DXC\cmake\caches\PredefinedParams.cmake" ^
             -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake" ^
             -DHLSL_DISABLE_SOURCE_GENERATION=On
@@ -217,6 +218,7 @@ jobs:
             -B "%GITHUB_WORKSPACE%\llvm-project\host-build" ^
             -DCMAKE_BUILD_TYPE=Release ^
             -DLLVM_ENABLE_ASSERTIONS=Off ^
+            -DLLVM_APPEND_VC_REV=Off ^
             -DLLVM_ENABLE_PROJECTS=clang ^
             -DLLVM_TARGETS_TO_BUILD=Native ^
             -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake"

From 271c88f44e9c43eff342bc7495e97cd727d5ad5b Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Wed, 22 Jul 2026 09:59:02 -0700
Subject: [PATCH 13/16] add x64 libs to LIB

---
 .github/workflows/build-and-test-callable.yaml | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 91973600c..ed8d2d494 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -204,7 +204,6 @@ jobs:
             -B "%GITHUB_WORKSPACE%\DXC\host-build" ^
             -DCMAKE_BUILD_TYPE=Release ^
             -DLLVM_ENABLE_ASSERTIONS=Off ^
-            -DLLVM_APPEND_VC_REV=Off ^
             -C "%GITHUB_WORKSPACE%\DXC\cmake\caches\PredefinedParams.cmake" ^
             -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake" ^
             -DHLSL_DISABLE_SOURCE_GENERATION=On
@@ -218,7 +217,6 @@ jobs:
             -B "%GITHUB_WORKSPACE%\llvm-project\host-build" ^
             -DCMAKE_BUILD_TYPE=Release ^
             -DLLVM_ENABLE_ASSERTIONS=Off ^
-            -DLLVM_APPEND_VC_REV=Off ^
             -DLLVM_ENABLE_PROJECTS=clang ^
             -DLLVM_TARGETS_TO_BUILD=Native ^
             -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake"
@@ -243,6 +241,16 @@ jobs:
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: arm64 -vcvars_ver=${{ env.VCToolsVersion }}
+      - name: Add x64 libs to LIB for native host-tool relinks
+        # Cross steps relink native x64 tools (llvm-config) under the ARM64 env;
+        # append x64 lib dirs so those links resolve the x64 CRT.
+        if: env.ARM64_CROSS == 'true'
+        shell: cmd
+        run: |
+          for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath`) do set "InstallDir=%%i"
+          set "ARM64_LIB=%LIB%"
+          call "%InstallDir%\Common7\Tools\VsDevCmd.bat" -arch=amd64 -host_arch=amd64 -vcvars_ver=%VCToolsVersion% >nul
+          echo LIB=%ARM64_LIB%;%LIB%>>%GITHUB_ENV%
       # VsDevCmd replaces PATH. Restore the tool paths required by the
       # remaining workflow steps after the final target setup.
       - name: Restore Python path

From 418dfcafdd3912da9d46cd995c87b16947815f28 Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Wed, 22 Jul 2026 10:49:44 -0700
Subject: [PATCH 14/16] more libpath %LIB% investigation

---
 .../workflows/build-and-test-callable.yaml    | 24 +++++++++----------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index ed8d2d494..e6633834c 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -199,6 +199,14 @@ jobs:
           for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath`) do set "InstallDir=%%i"
           call "%InstallDir%\Common7\Tools\VsDevCmd.bat" -arch=amd64 -host_arch=amd64 -vcvars_ver=%VCToolsVersion%
 
+          rem Bake x64 lib dirs into host tool links so the cross Build DXC step's
+          rem native llvm-config relink resolves the x64 CRT under the ARM64 env.
+          setlocal enabledelayedexpansion
+          set "LFLAGS="
+          for %%d in ("%LIB:;=" "%") do if not "%%~d"=="" set LFLAGS=!LFLAGS! /LIBPATH:"%%~d"
+          > "%GITHUB_WORKSPACE%\host-linkflags.cmake" echo set(_extra_libpaths [=[!LFLAGS!]=])
+          >> "%GITHUB_WORKSPACE%\host-linkflags.cmake" echo set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${_extra_libpaths}" CACHE STRING "" FORCE)
+
           cmake -G Ninja ^
             -S "%GITHUB_WORKSPACE%\DXC" ^
             -B "%GITHUB_WORKSPACE%\DXC\host-build" ^
@@ -206,7 +214,8 @@ jobs:
             -DLLVM_ENABLE_ASSERTIONS=Off ^
             -C "%GITHUB_WORKSPACE%\DXC\cmake\caches\PredefinedParams.cmake" ^
             -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake" ^
-            -DHLSL_DISABLE_SOURCE_GENERATION=On
+            -DHLSL_DISABLE_SOURCE_GENERATION=On ^
+            -C "%GITHUB_WORKSPACE%\host-linkflags.cmake"
           if errorlevel 1 exit /b 1
           cmake --build "%GITHUB_WORKSPACE%\DXC\host-build" ^
             --target llvm-tblgen clang-tblgen llvm-config
@@ -219,7 +228,8 @@ jobs:
             -DLLVM_ENABLE_ASSERTIONS=Off ^
             -DLLVM_ENABLE_PROJECTS=clang ^
             -DLLVM_TARGETS_TO_BUILD=Native ^
-            -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake"
+            -C "%GITHUB_WORKSPACE%\OffloadTest\cmake\caches\sccache.cmake" ^
+            -C "%GITHUB_WORKSPACE%\host-linkflags.cmake"
           if errorlevel 1 exit /b 1
           cmake --build "%GITHUB_WORKSPACE%\llvm-project\host-build" ^
             --target llvm-tblgen clang-tblgen llvm-config
@@ -241,16 +251,6 @@ jobs:
         uses: llvm/actions/setup-windows@89a8cf80982d830faab019237860b344a6390c30 # main
         with:
           arch: arm64 -vcvars_ver=${{ env.VCToolsVersion }}
-      - name: Add x64 libs to LIB for native host-tool relinks
-        # Cross steps relink native x64 tools (llvm-config) under the ARM64 env;
-        # append x64 lib dirs so those links resolve the x64 CRT.
-        if: env.ARM64_CROSS == 'true'
-        shell: cmd
-        run: |
-          for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath`) do set "InstallDir=%%i"
-          set "ARM64_LIB=%LIB%"
-          call "%InstallDir%\Common7\Tools\VsDevCmd.bat" -arch=amd64 -host_arch=amd64 -vcvars_ver=%VCToolsVersion% >nul
-          echo LIB=%ARM64_LIB%;%LIB%>>%GITHUB_ENV%
       # VsDevCmd replaces PATH. Restore the tool paths required by the
       # remaining workflow steps after the final target setup.
       - name: Restore Python path

From cd52555de71eaee5da7860b0e92edc4b138203ee Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Wed, 22 Jul 2026 12:18:36 -0700
Subject: [PATCH 15/16] use arm64 vulkan sdk libs

---
 .github/workflows/build-and-test-callable.yaml | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index e6633834c..1159c98ee 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -269,6 +269,23 @@ jobs:
           echo "Runner architecture: ${{ runner.arch }}"
           echo "MSVC host architecture: ${VSCMD_ARG_HOST_ARCH:-unknown}"
           echo "MSVC target architecture: ${VSCMD_ARG_TGT_ARCH:-unknown}"
+      - name: Generate ARM64 Vulkan import lib
+        # x64 Vulkan SDK ships only an x64 vulkan-1.lib; synthesize an ARM64
+        # import lib from the arch-neutral loader DLL for the cross link.
+        if: env.ARM64_CROSS == 'true'
+        shell: powershell
+        run: |
+          $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+          $vs = & $vswhere -latest -property installationPath
+          Import-Module "$vs\Common7\Tools\Microsoft.VisualStudio.DevShell.dll"
+          Enter-VsDevShell -VsInstallPath $vs -DevCmdArguments '-arch=x64' -SkipAutomaticLocation
+          $out = "$env:GITHUB_WORKSPACE\vulkan-arm64"
+          New-Item -ItemType Directory -Force $out | Out-Null
+          $names = & dumpbin /exports "$env:VULKAN_SDK\Bin\vulkan-1.dll" |
+            Select-String '^\s+\d+\s+[0-9A-Fa-f]+\s+[0-9A-Fa-f]+\s+(\S+)$' |
+            ForEach-Object { $_.Matches[0].Groups[1].Value }
+          @('EXPORTS') + $names | Set-Content "$out\vulkan-1.def"
+          lib /def:"$out\vulkan-1.def" /machine:arm64 /out:"$out\vulkan-1.lib"
       # When SplitBuild is enabled, force clang into the build set even if
       # the TestTarget doesn't use it. Reason: install-distribution depends
       # on clang (it ships in the install prefix), so if clang isn't part
@@ -324,6 +341,7 @@ jobs:
                 -DCMAKE_CXX_COMPILER_TARGET=arm64-pc-windows-msvc
                 "-DLLVM_NATIVE_BUILD=$GITHUB_WORKSPACE/llvm-project/host-build"
                 "-DLLVM_NATIVE_TOOL_DIR=$GITHUB_WORKSPACE/llvm-project/host-build/bin"
+                "-DVulkan_LIBRARY=$GITHUB_WORKSPACE/vulkan-arm64/vulkan-1.lib"
               )
             fi
             cmake -G Ninja \

From 93234f43d7992c0079d7035fa9cae87c1526df5d Mon Sep 17 00:00:00 2001
From: Joshua Batista <jbatista@microsoft.com>
Date: Wed, 22 Jul 2026 14:44:55 -0700
Subject: [PATCH 16/16] fix lib search regex

---
 .github/workflows/build-and-test-callable.yaml | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/build-and-test-callable.yaml b/.github/workflows/build-and-test-callable.yaml
index 1159c98ee..38b0da8ac 100644
--- a/.github/workflows/build-and-test-callable.yaml
+++ b/.github/workflows/build-and-test-callable.yaml
@@ -271,7 +271,7 @@ jobs:
           echo "MSVC target architecture: ${VSCMD_ARG_TGT_ARCH:-unknown}"
       - name: Generate ARM64 Vulkan import lib
         # x64 Vulkan SDK ships only an x64 vulkan-1.lib; synthesize an ARM64
-        # import lib from the arch-neutral loader DLL for the cross link.
+        # import lib from its arch-neutral export names for the cross link.
         if: env.ARM64_CROSS == 'true'
         shell: powershell
         run: |
@@ -281,9 +281,11 @@ jobs:
           Enter-VsDevShell -VsInstallPath $vs -DevCmdArguments '-arch=x64' -SkipAutomaticLocation
           $out = "$env:GITHUB_WORKSPACE\vulkan-arm64"
           New-Item -ItemType Directory -Force $out | Out-Null
-          $names = & dumpbin /exports "$env:VULKAN_SDK\Bin\vulkan-1.dll" |
-            Select-String '^\s+\d+\s+[0-9A-Fa-f]+\s+[0-9A-Fa-f]+\s+(\S+)$' |
+          $names = & dumpbin /exports "$env:VULKAN_SDK\Lib\vulkan-1.lib" |
+            Select-String '^\s+(vk\w+)\s*$' |
             ForEach-Object { $_.Matches[0].Groups[1].Value }
+          if ($names.Count -eq 0) { throw "No Vulkan exports found; cannot build ARM64 import lib" }
+          Write-Host "Captured $($names.Count) Vulkan exports"
           @('EXPORTS') + $names | Set-Content "$out\vulkan-1.def"
           lib /def:"$out\vulkan-1.def" /machine:arm64 /out:"$out\vulkan-1.lib"
       # When SplitBuild is enabled, force clang into the build set even if