From 0dfd312baa3cb12b997d64d4f2c3c79d79eb9c1c Mon Sep 17 00:00:00 2001
From: Brice Videau <bvideau@anl.gov>
Date: Tue, 18 Oct 2022 17:28:27 -0700
Subject: [PATCH 1/4] Try caching Windows Haders build.

---
 .github/workflows/windows.yml | 82 ++++++++++++++++++++++++++---------
 1 file changed, 62 insertions(+), 20 deletions(-)

diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index f084fa5a..d9a60c74 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -3,15 +3,17 @@ name: Windows
 on: [push, pull_request]
 
 jobs:
-  msvc:
+
+  headers:
+    name: Build and cache Headers
     runs-on: windows-2022
     strategy:
       matrix:
-        VER: [v141, v142, v143]
-        EXT: [ON, OFF]
-        GEN: [Visual Studio 17 2022, Ninja Multi-Config]
-        BIN: [x64, x86]
-        STD: [90, 11, 17]
+        VER: [v143]
+        EXT: [ON]
+        GEN: [Visual Studio 17 2022]
+        BIN: [x64]
+        STD: [17]
         CMAKE: [3.22.0]
     env:
       CMAKE_URL: https://github.com/Kitware/CMake/releases/download/v${{matrix.CMAKE}}/cmake-${{matrix.CMAKE}}-windows-x86_64.zip
@@ -21,16 +23,24 @@ jobs:
       NINJA_EXE: C:\Tools\Ninja\ninja.exe
 
     steps:
-    - name: Checkout OpenCL-ICD-Loader
-      uses: actions/checkout@v2
+    - uses: actions/cache@v2
+      name: Restore Headers
+      id: headers
+      env:
+        cache-name: cache-headers
+      with:
+        path: external/OpenCL-Headers/install
+        key: ${{ runner.os }}-build-${{ env.cache-name }}
 
     - name: Checkout OpenCL-Headers
+      if: steps.headers.outputs.cache-hit != 'true'
       uses: actions/checkout@v2
       with:
         repository: KhronosGroup/OpenCL-Headers
         path: external/OpenCL-Headers
 
     - name: Create Build Environment
+      if: steps.headers.outputs.cache-hit != 'true'
       shell: pwsh
       run: |
         Invoke-WebRequest ${env:CMAKE_URL} -OutFile ~\Downloads\cmake-${{matrix.CMAKE}}-windows-x86_64.zip
@@ -42,8 +52,9 @@ jobs:
         & ${env:CMAKE_EXE} --version
         & ${env:NINJA_EXE} --version
 
+
     - name: Build & install OpenCL-Headers (MSBuild)
-      if: matrix.GEN == 'Visual Studio 17 2022'
+      if: steps.headers.outputs.cache-hit != 'true'
       shell: cmd
       run: |
         set C_FLAGS="/W4 /WX"
@@ -51,18 +62,49 @@ jobs:
         %CMAKE_EXE% -G "${{matrix.GEN}}" -A %BIN% -T ${{matrix.VER}} -D CMAKE_C_FLAGS=%C_FLAGS% -D CMAKE_C_STANDARD=${{matrix.STD}} -D CMAKE_C_EXTENSIONS=${{matrix.EXT}} -D CMAKE_INSTALL_PREFIX=%GITHUB_WORKSPACE%\external\OpenCL-Headers\install -S %GITHUB_WORKSPACE%\external\OpenCL-Headers -B %GITHUB_WORKSPACE%\external\OpenCL-Headers\build
         %CMAKE_EXE% --build %GITHUB_WORKSPACE%/external/OpenCL-Headers/build --target install --config Release -- /verbosity:minimal /maxCpuCount /noLogo
 
-    - name: Build & install OpenCL-Headers (Ninja Multi-Config)
-      if: matrix.GEN == 'Ninja Multi-Config'
-      shell: cmd
+
+  msvc:
+    needs: [headers]
+    runs-on: windows-2022
+    strategy:
+      matrix:
+        VER: [v141, v142, v143]
+        EXT: [ON, OFF]
+        GEN: [Visual Studio 17 2022, Ninja Multi-Config]
+        BIN: [x64, x86]
+        STD: [90, 11, 17]
+        CMAKE: [3.22.0]
+    env:
+      CMAKE_URL: https://github.com/Kitware/CMake/releases/download/v${{matrix.CMAKE}}/cmake-${{matrix.CMAKE}}-windows-x86_64.zip
+      CMAKE_EXE: C:\Tools\Kitware\CMake\${{matrix.CMAKE}}\bin\cmake.exe
+      CTEST_EXE: C:\Tools\Kitware\CMake\${{matrix.CMAKE}}\bin\ctest.exe
+      NINJA_URL: https://github.com/ninja-build/ninja/releases/download/v1.10.2/ninja-win.zip
+      NINJA_EXE: C:\Tools\Ninja\ninja.exe
+
+    steps:
+    - name: Checkout OpenCL-ICD-Loader
+      uses: actions/checkout@v2
+
+    - uses: actions/cache@v2
+      name: Restore Headers
+      id: headers
+      env:
+        cache-name: cache-headers
+      with:
+        path: external/OpenCL-Headers/install
+        key: ${{ runner.os }}-build-${{ env.cache-name }}
+
+    - name: Create Build Environment
+      shell: pwsh
       run: |
-        set C_FLAGS="/W4 /WX"
-        if /I "${{matrix.VER}}"=="v140" (set VER=14.0)
-        if /I "${{matrix.VER}}"=="v141" (set VER=14.1)
-        if /I "${{matrix.VER}}"=="v142" (set VER=14.2)
-        if /I "${{matrix.VER}}"=="v143" (set VER=14.3)
-        call "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvarsall.bat" ${{matrix.BIN}} /vcvars_ver=%VER%
-        %CMAKE_EXE% -G "${{matrix.GEN}}" -D CMAKE_MAKE_PROGRAM=%NINJA_EXE% -D CMAKE_C_FLAGS=%C_FLAGS% -D CMAKE_C_STANDARD=${{matrix.STD}} -D CMAKE_C_EXTENSIONS=${{matrix.EXT}} -D CMAKE_INSTALL_PREFIX=%GITHUB_WORKSPACE%\external\OpenCL-Headers\install -S %GITHUB_WORKSPACE%\external\OpenCL-Headers -B %GITHUB_WORKSPACE%\external\OpenCL-Headers\build
-        %CMAKE_EXE% --build %GITHUB_WORKSPACE%/external/OpenCL-Headers/build --target install -- -j%NUMBER_OF_PROCESSORS%
+        Invoke-WebRequest ${env:CMAKE_URL} -OutFile ~\Downloads\cmake-${{matrix.CMAKE}}-windows-x86_64.zip
+        Expand-Archive ~\Downloads\cmake-${{matrix.CMAKE}}-windows-x86_64.zip -DestinationPath C:\Tools\Kitware\CMake\
+        Rename-Item C:\Tools\Kitware\CMake\* ${{matrix.CMAKE}}
+        Invoke-WebRequest ${env:NINJA_URL} -OutFile ~\Downloads\ninja-win.zip
+        Expand-Archive ~\Downloads\ninja-win.zip -DestinationPath C:\Tools\Ninja\
+        Remove-Item ~\Downloads\*
+        & ${env:CMAKE_EXE} --version
+        & ${env:NINJA_EXE} --version
 
     - name: Configure (MSBuild)
       if: matrix.GEN == 'Visual Studio 17 2022'

From 946631eb1b7c27cc7eda942136279b913033520d Mon Sep 17 00:00:00 2001
From: Brice Videau <bvideau@anl.gov>
Date: Tue, 18 Oct 2022 20:05:35 -0700
Subject: [PATCH 2/4] Cache Headers for MacOS.

---
 .github/workflows/macos.yml | 58 +++++++++++++++++++++++++++++++------
 1 file changed, 49 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 4144a2bb..4d4d7d98 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -3,33 +3,43 @@ name: MacOS
 on: [push, pull_request]
 
 jobs:
-  macos-gcc:
+
+  headers:
+    name: Build and cache Headers
     runs-on: macos-latest
     strategy:
       matrix:
-        VER: [9, 10, 11]
-        EXT: [ON, OFF]
-        GEN: [Xcode, Ninja Multi-Config]
-        STD: [99, 11] # 90 results in errors
+        VER: [11]
+        EXT: [ON]
+        GEN: [Xcode]
+        STD: [11] # 90 results in errors
 
     steps:
-    - name: Checkout OpenCL-ICD-Loader
-      uses: actions/checkout@v2
+    - uses: actions/cache@v2
+      name: Restore Headers
+      id: headers
+      env:
+        cache-name: cache-headers
+      with:
+        path: external/OpenCL-Headers/install
+        key: ${{ runner.os }}-build-${{ env.cache-name }}
 
     - name: Checkout OpenCL-Headers
+      if: steps.headers.outputs.cache-hit != 'true'
       uses: actions/checkout@v2
       with:
         repository: KhronosGroup/OpenCL-Headers
         path: external/OpenCL-Headers
 
     - name: Create Build Environment
+      if: steps.headers.outputs.cache-hit != 'true'
       run: |
         cmake -E make_directory $GITHUB_WORKSPACE/build;
         cmake -E make_directory $GITHUB_WORKSPACE/install;
         if [[ "${{matrix.GEN}}" == "Ninja Multi-Config" && ! `which ninja` ]]; then brew install ninja; fi;
-        # Install Ninja only if it's the selected generator and it's not available.
 
     - name: Build & install OpenCL-Headers
+      if: steps.headers.outputs.cache-hit != 'true'
       run: cmake
         -G "${{matrix.GEN}}"
         -D CMAKE_C_FLAGS="-w"
@@ -45,6 +55,36 @@ jobs:
         --config Release
         --parallel `sysctl -n hw.logicalcpu`
 
+  macos-gcc:
+    needs: [headers]
+    runs-on: macos-latest
+    strategy:
+      matrix:
+        VER: [9, 10, 11]
+        EXT: [ON, OFF]
+        GEN: [Xcode, Ninja Multi-Config]
+        STD: [99, 11] # 90 results in errors
+
+    steps:
+    - name: Checkout OpenCL-ICD-Loader
+      uses: actions/checkout@v2
+
+    - uses: actions/cache@v2
+      name: Restore Headers
+      id: headers
+      env:
+        cache-name: cache-headers
+      with:
+        path: external/OpenCL-Headers/install
+        key: ${{ runner.os }}-build-${{ env.cache-name }}
+
+    - name: Create Build Environment
+      run: |
+        cmake -E make_directory $GITHUB_WORKSPACE/build;
+        cmake -E make_directory $GITHUB_WORKSPACE/install;
+        if [[ "${{matrix.GEN}}" == "Ninja Multi-Config" && ! `which ninja` ]]; then brew install ninja; fi;
+        # Install Ninja only if it's the selected generator and it's not available.
+
     - name: Configure CMake
       # no -Werror during configuration because:
       # warning: ISO C forbids assignment between function pointer and ‘void *’ [-Wpedantic]
@@ -93,4 +133,4 @@ jobs:
       if: matrix.GEN == 'Ninja Multi-Config'
       shell: bash
       run: |
-        cmake --build $GITHUB_WORKSPACE/build --config Release --target install
\ No newline at end of file
+        cmake --build $GITHUB_WORKSPACE/build --config Release --target install

From d53346edd5dfd1eda0c724586afbabcc68ece00f Mon Sep 17 00:00:00 2001
From: Brice Videau <bvideau@anl.gov>
Date: Tue, 18 Oct 2022 20:40:10 -0700
Subject: [PATCH 3/4] Added Header cache for Linux.

---
 .github/workflows/linux.yml | 105 ++++++++++++++++++++++++------------
 1 file changed, 71 insertions(+), 34 deletions(-)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 32703836..0c8def82 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -3,29 +3,36 @@ name: Linux
 on: [push, pull_request]
 
 jobs:
-  cmake-minimum:
+  headers:
+    name: Build and cache Headers
     runs-on: ${{ matrix.OS }}
     strategy:
       matrix:
-        OS: [ubuntu-18.04]
-        COMPILER: [gcc-7, gcc-8, clang-8, clang-10]
-        EXT: [ON, OFF]
+        OS: [ubuntu-18.04, ubuntu-20.04]
+        COMPILER: [gcc]
+        EXT: [ON]
         GEN: [Unix Makefiles]
-        CONFIG: [Debug, Release]
-        STD: [99, 11]
-        BIN: [32, 64]
-        CMAKE: [3.1.3, 3.21.2]
+        CONFIG: [Release]
+        STD: [99]
+        BIN: [64]
+        CMAKE: [3.21.2]
     env:
       CMAKE_URL: https://github.com/Kitware/CMake/releases/download/v${{ matrix.CMAKE }}/cmake-${{ matrix.CMAKE }}-Linux-x86_64.tar.gz
       CMAKE_EXE: /opt/Kitware/CMake/${{ matrix.CMAKE }}/bin/cmake
       CTEST_EXE: /opt/Kitware/CMake/${{ matrix.CMAKE }}/bin/ctest
 
-
     steps:
-    - name: Checkout OpenCL-ICD-Loader
-      uses: actions/checkout@v2
+    - uses: actions/cache@v2
+      name: Restore Headers
+      id: headers
+      env:
+        cache-name: cache-headers
+      with:
+        path: external/OpenCL-Headers/install
+        key: ${{ runner.os }}-build-${{ env.cache-name }}
 
     - name: Checkout OpenCL-Headers
+      if: steps.headers.outputs.cache-hit != 'true'
       uses: actions/checkout@v2
       with:
         repository: KhronosGroup/OpenCL-Headers
@@ -40,8 +47,7 @@ jobs:
         mkdir -p /opt/Kitware/CMake;
         wget -c $CMAKE_URL -O - | tar -xz --directory /opt/Kitware/CMake;
         mv /opt/Kitware/CMake/cmake-${{ matrix.CMAKE }}-* /opt/Kitware/CMake/${{ matrix.CMAKE }}
-      # Install Ninja only if it's the selected generator and it's not available.
-
+ 
     - name: Build & install OpenCL-Headers
       run: $CMAKE_EXE
         -G "${{matrix.GEN}}"
@@ -59,6 +65,50 @@ jobs:
         --
         -j`nproc`
 
+
+  cmake-minimum:
+    needs: [headers]
+    runs-on: ${{ matrix.OS }}
+    strategy:
+      matrix:
+        OS: [ubuntu-18.04]
+        COMPILER: [gcc-7, gcc-8, clang-8, clang-10]
+        EXT: [ON, OFF]
+        GEN: [Unix Makefiles]
+        CONFIG: [Debug, Release]
+        STD: [99, 11]
+        BIN: [32, 64]
+        CMAKE: [3.1.3, 3.21.2]
+    env:
+      CMAKE_URL: https://github.com/Kitware/CMake/releases/download/v${{ matrix.CMAKE }}/cmake-${{ matrix.CMAKE }}-Linux-x86_64.tar.gz
+      CMAKE_EXE: /opt/Kitware/CMake/${{ matrix.CMAKE }}/bin/cmake
+      CTEST_EXE: /opt/Kitware/CMake/${{ matrix.CMAKE }}/bin/ctest
+
+
+    steps:
+    - name: Checkout OpenCL-ICD-Loader
+      uses: actions/checkout@v2
+
+    - uses: actions/cache@v2
+      name: Restore Headers
+      id: headers
+      env:
+        cache-name: cache-headers
+      with:
+        path: external/OpenCL-Headers/install
+        key: ${{ runner.os }}-build-${{ env.cache-name }}
+
+    - name: Create Build Environment
+      run: sudo apt-get update -q;
+        if [[ "${{matrix.GEN}}" =~ "Ninja" && ! `which ninja` ]]; then sudo apt install -y ninja-build; fi;
+        sudo apt install -y ${{matrix.COMPILER}};
+        if [[ "${{matrix.BIN}}" == "32" && "${{matrix.COMPILER}}" =~ "gcc" ]]; then sudo apt install -y ${{matrix.COMPILER}}-multilib; fi;
+        if [[ "${{matrix.BIN}}" == "32" && "${{matrix.COMPILER}}" =~ "clang" ]]; then sudo apt install -y gcc-multilib ; fi;
+        mkdir -p /opt/Kitware/CMake;
+        wget -c $CMAKE_URL -O - | tar -xz --directory /opt/Kitware/CMake;
+        mv /opt/Kitware/CMake/cmake-${{ matrix.CMAKE }}-* /opt/Kitware/CMake/${{ matrix.CMAKE }}
+      # Install Ninja only if it's the selected generator and it's not available.
+
     - name: Configure
       shell: bash
       run: $CMAKE_EXE
@@ -137,6 +187,7 @@ jobs:
 
 
   cmake-latest:
+    needs: [headers]
     runs-on: ${{ matrix.OS }}
     strategy:
       matrix:
@@ -157,11 +208,14 @@ jobs:
     - name: Checkout OpenCL-ICD-Loader
       uses: actions/checkout@v2
 
-    - name: Checkout OpenCL-Headers
-      uses: actions/checkout@v2
+    - uses: actions/cache@v2
+      name: Restore Headers
+      id: headers
+      env:
+        cache-name: cache-headers
       with:
-        repository: KhronosGroup/OpenCL-Headers
-        path: external/OpenCL-Headers
+        path: external/OpenCL-Headers/install
+        key: ${{ runner.os }}-build-${{ env.cache-name }}
 
     - name: Create Build Environment
       run: sudo apt-get update -q;
@@ -176,23 +230,6 @@ jobs:
         mv /opt/Kitware/CMake/cmake-${{ matrix.CMAKE }}-* /opt/Kitware/CMake/${{ matrix.CMAKE }}
       # Install Ninja only if it's the selected generator and it's not available.
 
-    - name: Build & install OpenCL-Headers
-      run: $CMAKE_EXE
-        -G "${{matrix.GEN}}"
-        -D CMAKE_C_FLAGS="-w -m${{matrix.BIN}}"
-        -D CMAKE_C_COMPILER=${{matrix.COMPILER}}
-        -D CMAKE_C_STANDARD=${{matrix.STD}}
-        -D CMAKE_C_EXTENSIONS=${{matrix.EXT}}
-        -D CMAKE_INSTALL_PREFIX=$GITHUB_WORKSPACE/external/OpenCL-Headers/install
-        -B $GITHUB_WORKSPACE/external/OpenCL-Headers/build
-        -S $GITHUB_WORKSPACE/external/OpenCL-Headers;
-        $CMAKE_EXE
-        --build $GITHUB_WORKSPACE/external/OpenCL-Headers/build
-        --target install
-        --config Release
-        --
-        -j`nproc`
-
     - name: Configure
       shell: bash
       run: $CMAKE_EXE

From 5eb5a5b9d2ac973a6fd2971b9a1ebcef9e1beb51 Mon Sep 17 00:00:00 2001
From: Brice Videau <bvideau@anl.gov>
Date: Tue, 18 Oct 2022 21:24:17 -0700
Subject: [PATCH 4/4] Refresh cache on Headers change.

---
 .github/workflows/linux.yml   | 25 +++++++++++++++++++++----
 .github/workflows/macos.yml   | 16 +++++++++++++---
 .github/workflows/windows.yml | 16 +++++++++++++---
 3 files changed, 47 insertions(+), 10 deletions(-)

diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 0c8def82..dcda8a95 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -22,14 +22,19 @@ jobs:
       CTEST_EXE: /opt/Kitware/CMake/${{ matrix.CMAKE }}/bin/ctest
 
     steps:
+    - name: Get sha of Headers
+      id: get-sha
+      run: |
+        echo ::set-output name=sha::$( curl -u "u:${{github.token}}" https://api.github.com/repos/KhronosGroup/OpenCL-Headers/git/ref/heads/main | jq .object.sha | tr -d '"' )
+
     - uses: actions/cache@v2
-      name: Restore Headers
+      name: Cache Headers
       id: headers
       env:
         cache-name: cache-headers
       with:
         path: external/OpenCL-Headers/install
-        key: ${{ runner.os }}-build-${{ env.cache-name }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ steps.get-sha.outputs.sha }}
 
     - name: Checkout OpenCL-Headers
       if: steps.headers.outputs.cache-hit != 'true'
@@ -39,6 +44,7 @@ jobs:
         path: external/OpenCL-Headers
 
     - name: Create Build Environment
+      if: steps.headers.outputs.cache-hit != 'true'
       run: sudo apt-get update -q;
         if [[ "${{matrix.GEN}}" =~ "Ninja" && ! `which ninja` ]]; then sudo apt install -y ninja-build; fi;
         sudo apt install -y ${{matrix.COMPILER}};
@@ -49,6 +55,7 @@ jobs:
         mv /opt/Kitware/CMake/cmake-${{ matrix.CMAKE }}-* /opt/Kitware/CMake/${{ matrix.CMAKE }}
  
     - name: Build & install OpenCL-Headers
+      if: steps.headers.outputs.cache-hit != 'true'
       run: $CMAKE_EXE
         -G "${{matrix.GEN}}"
         -D CMAKE_BUILD_TYPE=${{matrix.CONFIG}}
@@ -89,6 +96,11 @@ jobs:
     - name: Checkout OpenCL-ICD-Loader
       uses: actions/checkout@v2
 
+    - name: Get sha of Headers
+      id: get-sha
+      run: |
+        echo ::set-output name=sha::$( curl -u "u:${{github.token}}" https://api.github.com/repos/KhronosGroup/OpenCL-Headers/git/ref/heads/main | jq .object.sha | tr -d '"' )
+
     - uses: actions/cache@v2
       name: Restore Headers
       id: headers
@@ -96,7 +108,7 @@ jobs:
         cache-name: cache-headers
       with:
         path: external/OpenCL-Headers/install
-        key: ${{ runner.os }}-build-${{ env.cache-name }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ steps.get-sha.outputs.sha }}
 
     - name: Create Build Environment
       run: sudo apt-get update -q;
@@ -208,6 +220,11 @@ jobs:
     - name: Checkout OpenCL-ICD-Loader
       uses: actions/checkout@v2
 
+    - name: Get sha of Headers
+      id: get-sha
+      run: |
+        echo ::set-output name=sha::$( curl -u "u:${{github.token}}" https://api.github.com/repos/KhronosGroup/OpenCL-Headers/git/ref/heads/main | jq .object.sha | tr -d '"' )
+
     - uses: actions/cache@v2
       name: Restore Headers
       id: headers
@@ -215,7 +232,7 @@ jobs:
         cache-name: cache-headers
       with:
         path: external/OpenCL-Headers/install
-        key: ${{ runner.os }}-build-${{ env.cache-name }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ steps.get-sha.outputs.sha }}
 
     - name: Create Build Environment
       run: sudo apt-get update -q;
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 4d4d7d98..5c1efd0e 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -15,14 +15,19 @@ jobs:
         STD: [11] # 90 results in errors
 
     steps:
+    - name: Get sha of Headers
+      id: get-sha
+      run: |
+        echo ::set-output name=sha::$( curl -u "u:${{github.token}}" https://api.github.com/repos/KhronosGroup/OpenCL-Headers/git/ref/heads/main | jq .object.sha | tr -d '"' )
+
     - uses: actions/cache@v2
-      name: Restore Headers
+      name: Cache Headers
       id: headers
       env:
         cache-name: cache-headers
       with:
         path: external/OpenCL-Headers/install
-        key: ${{ runner.os }}-build-${{ env.cache-name }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ steps.get-sha.outputs.sha }}
 
     - name: Checkout OpenCL-Headers
       if: steps.headers.outputs.cache-hit != 'true'
@@ -69,6 +74,11 @@ jobs:
     - name: Checkout OpenCL-ICD-Loader
       uses: actions/checkout@v2
 
+    - name: Get sha of Headers
+      id: get-sha
+      run: |
+        echo ::set-output name=sha::$( curl -u "u:${{github.token}}" https://api.github.com/repos/KhronosGroup/OpenCL-Headers/git/ref/heads/main | jq .object.sha | tr -d '"' )
+
     - uses: actions/cache@v2
       name: Restore Headers
       id: headers
@@ -76,7 +86,7 @@ jobs:
         cache-name: cache-headers
       with:
         path: external/OpenCL-Headers/install
-        key: ${{ runner.os }}-build-${{ env.cache-name }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ steps.get-sha.outputs.sha }}
 
     - name: Create Build Environment
       run: |
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index d9a60c74..11cb0346 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -23,14 +23,19 @@ jobs:
       NINJA_EXE: C:\Tools\Ninja\ninja.exe
 
     steps:
+    - name: Get sha of Headers
+      id: get-sha
+      run: |
+        echo ::set-output name=sha::$( curl -u "u:${{github.token}}" https://api.github.com/repos/KhronosGroup/OpenCL-Headers/git/ref/heads/main | jq .object.sha | tr -d '"' )
+
     - uses: actions/cache@v2
-      name: Restore Headers
+      name: Cache Headers
       id: headers
       env:
         cache-name: cache-headers
       with:
         path: external/OpenCL-Headers/install
-        key: ${{ runner.os }}-build-${{ env.cache-name }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ steps.get-sha.outputs.sha }}
 
     - name: Checkout OpenCL-Headers
       if: steps.headers.outputs.cache-hit != 'true'
@@ -85,6 +90,11 @@ jobs:
     - name: Checkout OpenCL-ICD-Loader
       uses: actions/checkout@v2
 
+    - name: Get sha of Headers
+      id: get-sha
+      run: |
+        echo ::set-output name=sha::$( curl -u "u:${{github.token}}" https://api.github.com/repos/KhronosGroup/OpenCL-Headers/git/ref/heads/main | jq .object.sha | tr -d '"' )
+
     - uses: actions/cache@v2
       name: Restore Headers
       id: headers
@@ -92,7 +102,7 @@ jobs:
         cache-name: cache-headers
       with:
         path: external/OpenCL-Headers/install
-        key: ${{ runner.os }}-build-${{ env.cache-name }}
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ steps.get-sha.outputs.sha }}
 
     - name: Create Build Environment
       shell: pwsh