GitHub actions: avoid trashing caches

1. We must use the same build configuration when sharing a particular
   cache.
2. Don't create additional cache entries when we can safely use one of
   the existing ones.

Author: tautschnig

.github/workflows/build-and-test-Linux.yaml

@@ -20,18 +20,18 @@ jobs:
           DEBIAN_FRONTEND: noninteractive
         run: |
           sudo apt-get update
-          sudo apt-get install --no-install-recommends -y g++ flex bison cmake ninja-build maven jq libxml2-utils dpkg-dev ccache
+          sudo apt-get install --no-install-recommends -y clang-10 clang++-10 flex bison cmake ninja-build maven jq libxml2-utils dpkg-dev ccache
           sudo apt-get install --no-install-recommends -y libssl-dev libelf-dev libudev-dev libpci-dev libiberty-dev autoconf
           sudo apt-get install --no-install-recommends -y gawk jq
 
       - name: Prepare ccache
         uses: actions/cache@v3
         with:
           path: .ccache
-          key: ${{ runner.os }}-20.04-make-${{ github.ref }}-${{ github.sha }}-KERNEL
+          key: ${{ runner.os }}-20.04-make-clang-${{ github.ref }}-${{ github.sha }}-KERNEL
           restore-keys: |
-            ${{ runner.os }}-20.04-make-${{ github.ref }}
-            ${{ runner.os }}-20.04-make
+            ${{ runner.os }}-20.04-make-clang-${{ github.ref }}
+            ${{ runner.os }}-20.04-make-clang
       - name: ccache environment
         run: |
           echo "CCACHE_BASEDIR=$PWD" >> $GITHUB_ENV
@@ -41,7 +41,7 @@ jobs:
       - name: Build CBMC tools
         run: |
           make -C src minisat2-download
-          make -C src CXX='ccache /usr/bin/g++' cbmc.dir goto-cc.dir goto-diff.dir -j2
+          make -C src CXX='ccache /usr/bin/clang++' cbmc.dir goto-cc.dir goto-diff.dir -j2
       - name: Print ccache stats
         run: ccache -s
 

.github/workflows/build-and-test-Xen.yaml

@@ -21,16 +21,16 @@ jobs:
           sudo apt-get update
           sudo apt-get install --no-install-recommends -y build-essential git flex bison software-properties-common curl python
           sudo apt-get install --no-install-recommends -y bin86 gdb bcc liblzma-dev python-dev gettext iasl uuid-dev libncurses5-dev libncursesw5-dev pkg-config
-          sudo apt-get install --no-install-recommends -y libgtk2.0-dev libyajl-dev time ccache
+          sudo apt-get install --no-install-recommends -y libgtk2.0-dev libyajl-dev time ccache clang-10 clang++-10
 
       - name: Prepare ccache
         uses: actions/cache@v3
         with:
           path: .ccache
-          key: ${{ runner.os }}-20.04-make-${{ github.ref }}-${{ github.sha }}-XEN
+          key: ${{ runner.os }}-20.04-make-clang-${{ github.ref }}-${{ github.sha }}-XEN
           restore-keys: |
-            ${{ runner.os }}-20.04-make-${{ github.ref }}
-            ${{ runner.os }}-20.04-make
+            ${{ runner.os }}-20.04-make-clang-${{ github.ref }}
+            ${{ runner.os }}-20.04-make-clang
       - name: ccache environment
         run: |
           echo "CCACHE_BASEDIR=$PWD" >> $GITHUB_ENV
@@ -40,7 +40,7 @@ jobs:
       - name: Build CBMC tools
         run: |
           make -C src minisat2-download
-          make -C src CXX='ccache /usr/bin/g++' cbmc.dir goto-cc.dir goto-diff.dir -j2
+          make -C src CXX='ccache /usr/bin/clang++' cbmc.dir goto-cc.dir goto-diff.dir -j2
       - name: Print ccache stats
         run: ccache -s
 

.github/workflows/pull-request-checks.yaml

@@ -174,10 +174,10 @@ jobs:
         uses: actions/cache@v3
         with:
           path: .ccache
-          key: ${{ runner.os }}-20.04-make-clang-smt-z3-${{ github.ref }}-${{ github.sha }}-PR
+          key: ${{ runner.os }}-20.04-make-clang-${{ github.ref }}-${{ github.sha }}-PR
           restore-keys: |
-            ${{ runner.os }}-20.04-make-clang-smt-z3-${{ github.ref }}
-            ${{ runner.os }}-20.04-make-clang-smt-z3
+            ${{ runner.os }}-20.04-make-clang-${{ github.ref }}
+            ${{ runner.os }}-20.04-make-clang
       - name: ccache environment
         run: |
           echo "CCACHE_BASEDIR=$PWD" >> $GITHUB_ENV
@@ -335,7 +335,7 @@ jobs:
           echo "CCACHE_BASEDIR=$PWD" >> $GITHUB_ENV
           echo "CCACHE_DIR=$PWD/.ccache" >> $GITHUB_ENV
       - name: Configure using CMake
-        run: cmake -H. -Bbuild -G Ninja
+        run: cmake -H. -Bbuild -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=/usr/bin/gcc -DCMAKE_CXX_COMPILER=/usr/bin/g++
       - name: Zero ccache stats and limit in size
         run: ccache -z --max-size=500M
       - name: Build with Ninja
@@ -381,7 +381,7 @@ jobs:
           echo "CCACHE_BASEDIR=$PWD" >> $GITHUB_ENV
           echo "CCACHE_DIR=$PWD/.ccache" >> $GITHUB_ENV
       - name: Configure using CMake
-        run: cmake -H. -Bbuild -G Ninja
+        run: cmake -H. -Bbuild -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=/usr/bin/gcc -DCMAKE_CXX_COMPILER=/usr/bin/g++
       - name: Zero ccache stats and limit in size
         run: ccache -z --max-size=500M
       - name: Build with Ninja