[clang][ci] Remove unnecessary BuildKite jobs for Clang (#93233)

1. Remove the format-checking job from the BuildKite pipeline. We now
have a monorepo-wide format checker implemented with Github Actions, so
that should not be necessary anymore.

2. Stop building and testing Clang on Windows via the clang-ci pipeline.
We already do that in the github-pull-requests pipeline, so that's just
duplicate work.

3. Stop testing Clang on Linux in the clang-ci pipeline. We already do
that in the github-pull-requests pipeline too, so that's also duplicate
work. For now we still build Clang because the other jobs in the
clang-ci pipeline require its artifacts, but that could be improved.

Author: ldionne

clang/utils/ci/buildkite-pipeline.yml

@@ -17,18 +17,7 @@ env:
     # LLVM RELEASE bump version
     LLVM_HEAD_VERSION: "17"
 steps:
-  - label: "Format"
-    commands:
-      - "clang/utils/ci/run-buildbot check-format"
-    agents:
-      queue: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Building and testing clang (Linux)"
+  - label: "Building Clang (Linux)"
     commands:
       - "clang/utils/ci/run-buildbot build-clang"
     agents:
@@ -39,21 +28,9 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Building and testing clang (Windows)"
-    commands:
-      - "C:\\BuildTools\\Common7\\Tools\\VsDevCmd.bat -arch=amd64 -host_arch=amd64"
-      - "bash clang/utils/ci/run-buildbot build-clang-windows"
-    agents:
-      queue: "windows"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
   - wait
 
-  - label: "Running libc++ test suite in C++03"
+  - label: "Testing libc++ with just-built Clang (C++03)"
     commands:
       - "clang/utils/ci/run-buildbot generic-cxx03"
     artifact_paths:
@@ -70,7 +47,7 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Running libc++ test suite in C++26"
+  - label: "Testing libc++ with just-built Clang (C++26)"
     commands:
       - "clang/utils/ci/run-buildbot generic-cxx26"
     artifact_paths:
@@ -87,7 +64,7 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - label: "Running libc++ test suite with Clang Modules"
+  - label: "Testing libc++ with just-built Clang (w/ Clang Modules)"
     commands:
       - "clang/utils/ci/run-buildbot generic-modules"
     artifact_paths:

clang/utils/ci/run-buildbot

@@ -69,13 +69,6 @@ cmake --version
 ninja --version
 
 case "${BUILDER}" in
-check-format)
-    echo "*** Checking for trailing whitespace left in Clang source files ***"
-    if grep -rnI '[[:blank:]]$' clang/lib clang/include clang/docs; then
-        echo "*** Trailing whitespace has been found in Clang source files as described above ***"
-        exit 1
-    fi
-;;
 build-clang)
     mkdir install
     # We use Release here to avoid including debug information. Otherwise, the
@@ -90,29 +83,13 @@ build-clang)
         -DCMAKE_CXX_COMPILER_LAUNCHER="ccache"                                 \
         -DCMAKE_BUILD_TYPE=Release                                             \
         -DCMAKE_INSTALL_PREFIX=install                                         \
+        -DLLVM_TARGETS_TO_BUILD=Native                                         \
         -DLLVM_ENABLE_PROJECTS="clang;compiler-rt"                             \
 
     ninja -C ${BUILD_DIR} install-clang install-clang-resource-headers
     ccache -s
     tar -cJvf install.tar.xz install/
     buildkite-agent artifact upload --debug install.tar.xz
-
-    ninja -C ${BUILD_DIR} check-clang
-;;
-build-clang-windows)
-    cmake -S llvm -B ${BUILD_DIR} -G Ninja                                      \
-        -D CMAKE_C_COMPILER_LAUNCHER=sccache                                    \
-        -D CMAKE_CXX_COMPILER_LAUNCHER=sccache                                  \
-        -D CMAKE_BUILD_TYPE=Release                                             \
-        -D CMAKE_INSTALL_PREFIX=install-windows                                 \
-        -D LLVM_ENABLE_PROJECTS="clang;compiler-rt"                             \
-        -D LLVM_ENABLE_ASSERTIONS=ON                                            \
-        -D LLVM_BUILD_EXAMPLES=ON                                               \
-        -D COMPILER_RT_BUILD_LIBFUZZER=OFF                                      \
-        -D COMPILER_RT_BUILD_ORC=OFF
-
-    ninja -C ${BUILD_DIR} install-clang install-clang-resource-headers
-    ninja -C ${BUILD_DIR} check-clang
 ;;
 generic-cxx03)
     buildkite-agent artifact download install.tar.xz .