workflows: use ccache to speed up code coverage

ccache requires the build paths, e.g., for include directories to
be identical in order to reuse the cache between the two builds.

Setting the CCACHE_BASEDIR environment variable to the respective build
directory does not seem to have any effect and does not reuse the cache.

Signed-off-by: Peter Colberg <peter.colberg@intel.com>
(cherry picked from commit 17d8f6b)

Author: pcolberg

.github/workflows/coverage.yml

@@ -3,13 +3,9 @@
 
 # https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions
 
-name: delta coverage checks
+name: code coverage
 
 permissions:
-  # Grant read permissions to repository in case it is not a forked public
-  # repository, but a private repository that was created manually.
-  contents: read
-
   # Grant read permissions to private container images.
   packages: read
 
@@ -32,43 +28,46 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
 
     container:
-      image: ghcr.io/intel/fpga-runtime-for-opencl/ubuntu-20.04-dev:main
-
-    env:
-      TMP_DIR: /home/build
+      image: ghcr.io/intel/fpga-runtime-for-opencl/ubuntu-22.04-dev:main
 
     steps:
       - name: checkout main branch
         uses: actions/checkout@v3
         with:
           ref: ${{ github.base_ref }}
-      
-      - name: create build directories
-        run: mkdir "$TMP_DIR/child_build" "$TMP_DIR/parent_build"
+
+      - name: create build directory
+        run: mkdir build
 
       - name: create parent build files
-        run: cd "$TMP_DIR/parent_build" && cmake -G Ninja "$GITHUB_WORKSPACE" -DCMAKE_BUILD_TYPE=Debug -DACL_CODE_COVERAGE=ON
+        run: cd build && cmake -G Ninja "$GITHUB_WORKSPACE" -DCMAKE_BUILD_TYPE=Debug -DACL_CODE_COVERAGE=ON -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
 
       - name: build parent runtime
-        run: cd "$TMP_DIR/parent_build" && ninja -v -k0
+        run: cd build && ninja -v -k0
 
       - name: parent runtime coverage scan
-        run: cd "$TMP_DIR/parent_build" && ctest -T Test -T Coverage
+        run: cd build && ctest -T Test -T Coverage
+      
+      - name: save build directory for later comparison
+        run: mv -t "$RUNNER_TEMP" build
 
       - name: checkout current branch
         uses: actions/checkout@v3
 
+      - name: create build directory
+        run: mkdir build
+
       - name: create child build files
-        run: cd "$TMP_DIR/child_build" && cmake -G Ninja "$GITHUB_WORKSPACE" -DCMAKE_BUILD_TYPE=Debug -DACL_CODE_COVERAGE=ON
+        run: cd build && cmake -G Ninja "$GITHUB_WORKSPACE" -DCMAKE_BUILD_TYPE=Debug -DACL_CODE_COVERAGE=ON -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
 
       - name: build child runtime
-        run: cd "$TMP_DIR/child_build" && ninja -v -k0
+        run: cd build && ninja -v -k0
 
       - name: child runtime coverage scan
-        run: cd "$TMP_DIR/child_build" && ctest -T Test -T Coverage
+        run: cd build && ctest -T Test -T Coverage
 
       - name: coverage status
-        run: ./scripts/coverage_diff.py "$TMP_DIR/child_build" "$TMP_DIR/parent_build"
+        run: ./scripts/coverage_diff.py build "$RUNNER_TEMP"/build