[CI] Remove ccache from Linux CI Container

.ci/monolithic-linux.sh

@@ -21,12 +21,7 @@ BUILD_DIR="${BUILD_DIR:=${MONOREPO_ROOT}/build}"
 INSTALL_DIR="${BUILD_DIR}/install"
 rm -rf "${BUILD_DIR}"
 
-ccache --zero-stats
-
-if [[ -n "${CLEAR_CACHE:-}" ]]; then
-  echo "clearing cache"
-  ccache --clear
-fi
+sccache --zero-stats
 
 mkdir -p artifacts/reproducers
 
@@ -36,7 +31,7 @@ export CLANG_CRASH_DIAGNOSTICS_DIR=`realpath artifacts/reproducers`
 function at-exit {
   retcode=$?
 
-  ccache --print-stats > artifacts/ccache_stats.txt
+  sccache --show-stats > artifacts/sccache_stats.txt
   cp "${BUILD_DIR}"/.ninja_log artifacts/.ninja_log
   cp "${BUILD_DIR}"/test-results.*.xml artifacts/ || :
 
@@ -78,7 +73,8 @@ cmake -S "${MONOREPO_ROOT}"/llvm -B "${BUILD_DIR}" \
       -D LLVM_LIT_ARGS="${lit_args}" \
       -D LLVM_ENABLE_LLD=ON \
       -D CMAKE_CXX_FLAGS=-gmlt \
-      -D LLVM_CCACHE_BUILD=ON \
+      -D CMAKE_C_COMPILER_LAUNCHER=sccache \
+      -D CMAKE_CXX_COMPILER_LAUNCHER=sccache \
       -D LIBCXX_CXX_ABI=libcxxabi \
       -D MLIR_ENABLE_BINDINGS_PYTHON=ON \
       -D LLDB_ENABLE_PYTHON=ON \

.ci/monolithic-windows.sh

@@ -21,11 +21,6 @@ BUILD_DIR="${BUILD_DIR:=${MONOREPO_ROOT}/build}"
 
 rm -rf "${BUILD_DIR}"
 
-if [[ -n "${CLEAR_CACHE:-}" ]]; then
-  echo "clearing sccache"
-  rm -rf "$SCCACHE_DIR"
-fi
-
 sccache --zero-stats
 function at-exit {
   retcode=$?

.github/workflows/containers/github-action-ci/Dockerfile

@@ -58,16 +58,23 @@ RUN apt-get update && \
     python3-psutil \
     sudo \
     # These are needed by the premerge pipeline. Pip is used to install
-    # dependent python packages and ccache is used for build caching. File and
+    # dependent python packages and sccache is used for build caching. File and
     # tzdata are used for tests.
     python3-pip \
-    ccache \
     file \
-    tzdata \
-    sccache && \
+    tzdata && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/*
 
+# We need sccache for caching. We cannot use the apt repository version because
+# it is too old and has bugs related to features we require (particularly GCS
+# caching), so we manually install it here.
+RUN curl -L 'https://github.com/mozilla/sccache/releases/download/v0.10.0/sccache-v0.10.0-x86_64-unknown-linux-musl.tar.gz' > /tmp/sccache.tar.gz && \
+    echo "1fbb35e135660d04a2d5e42b59c7874d39b3deb17de56330b25b713ec59f849b /tmp/sccache.tar.gz" | sha256sum -c && \
+    tar xzf /tmp/sccache.tar.gz -O --wildcards '*/sccache' > '/usr/local/bin/sccache' && \
+    rm /tmp/sccache.tar.gz && \
+    chmod +x /usr/local/bin/sccache
+
 ENV LLVM_SYSROOT=$LLVM_SYSROOT
 ENV PATH=${LLVM_SYSROOT}/bin:${PATH}