[ci] Make libc++ and Clang CI scripts independent

This simply moves existing CI-related scripts for Clang outside of libc++
to make the two projects independent with respect to CI.

The reason for making this change is that libc++'s CI pipeline history
was full of Clang runs, making it a lot harder to figure out information
about libc++'s own jobs. I created a pipeline for Clang and this patch
will run pre-commit CI for Clang inside that pipeline instead.

Differential Revision: https://reviews.llvm.org/D155078

Author: ldionne

.ci/generate-buildkite-pipeline-premerge

@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+#
+# This file generates a Buildkite pipeline that triggers the various CI jobs for
+# the LLVM project during pre-commit CI (each time a Phabricator diff is uploaded).
+#
+# See https://buildkite.com/docs/agent/v3/cli-pipeline#pipeline-format.
+#
+
+if ! git diff --name-only HEAD~1 | grep -q -E "^libcxx/|^libcxxabi/|^libunwind/|^runtimes/|^cmake/|^clang/"; then
+  # libcxx/, libcxxabi/, libunwind/, runtimes/, cmake/ or clang/ are not affected
+  exit 0
+fi
+
+reviewID="$(git log --format=%B -n 1 | sed -nE 's/^Review-ID:[[:space:]]*(.+)$/\1/p')"
+if [[ "${reviewID}" != "" ]]; then
+  buildMessage="https://llvm.org/${reviewID}"
+else
+  buildMessage="Push to branch ${BUILDKITE_BRANCH}"
+fi
+
+cat <<EOF
+steps:
+EOF
+
+# If libc++ or one of the runtimes directories changed
+if git diff --name-only HEAD~1 | grep -q -E "^libcxx/|^libcxxabi/|^libunwind/|^runtimes/|^cmake/"; then
+  cat <<EOF
+  - trigger: "libcxx-ci"
+    build:
+      message: "${buildMessage}"
+      commit: "${BUILDKITE_COMMIT}"
+      branch: "${BUILDKITE_BRANCH}"
+EOF
+fi
+
+# If clang changed
+if git diff --name-only HEAD~1 | grep -q -E "^clang/"; then
+  cat <<EOF
+  - trigger: "clang-ci"
+    build:
+      message: "${buildMessage}"
+      commit: "${BUILDKITE_COMMIT}"
+      branch: "${BUILDKITE_BRANCH}"
+EOF
+fi

.ci/generate-buildkite-pipeline-scheduled

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+#
+# This file generates a Buildkite pipeline that triggers the various CI jobs for
+# the LLVM project on scheduled builds.
+#
+# See https://buildkite.com/docs/agent/v3/cli-pipeline#pipeline-format.
+#
+
+cat <<EOF
+steps:
+  - trigger: "libcxx-ci"
+    build:
+      message: "${BUILDKITE_MESSAGE}"
+      commit: "${BUILDKITE_COMMIT}"
+      branch: "${BUILDKITE_BRANCH}"
+
+  - trigger: "clang-ci"
+    build:
+      message: "${BUILDKITE_MESSAGE}"
+      commit: "${BUILDKITE_COMMIT}"
+      branch: "${BUILDKITE_BRANCH}"
+EOF

libcxx/utils/ci/buildkite-pipeline-premerge.sh

@@ -7,32 +7,5 @@
 #
 #===----------------------------------------------------------------------===##
 
-#
-# This file generates a Buildkite pipeline that triggers the libc++ CI
-# job(s) if needed.
-# See https://buildkite.com/docs/agent/v3/cli-pipeline#pipeline-format.
-#
-# Invoked by CI on pre-merge check for a commit.
-#
-
-if ! git diff --name-only HEAD~1 | grep -q -E "^libcxx/|^libcxxabi/|^libunwind/|^runtimes/|^cmake/|^clang/"; then
-  # libcxx/, libcxxabi/, libunwind/, runtimes/, cmake/ or clang/ are not affected
-  exit 0
-fi
-
-reviewID="$(git log --format=%B -n 1 | sed -nE 's/^Review-ID:[[:space:]]*(.+)$/\1/p')"
-if [[ "${reviewID}" != "" ]]; then
-  buildMessage="https://llvm.org/${reviewID}"
-else
-  buildMessage="Push to branch ${BUILDKITE_BRANCH}"
-fi
-
-
-cat <<EOF
-steps:
-  - trigger: "libcxx-ci"
-    build:
-      message: "${buildMessage}"
-      commit: "${BUILDKITE_COMMIT}"
-      branch: "${BUILDKITE_BRANCH}"
-EOF
+# TODO: Remove this once the premerge checks invoke the script below directly.
+./.ci/generate-buildkite-pipeline-premerge

libcxx/utils/ci/buildkite-pipeline-snapshot.sh

@@ -7,18 +7,5 @@
 #
 #===----------------------------------------------------------------------===##
 
-#
-# This file generates a Buildkite pipeline that triggers the libc++ CI jobs.
-# See https://buildkite.com/docs/agent/v3/cli-pipeline#pipeline-format.
-#
-# Invoked by CI on full builds.
-#
-
-cat <<EOF
-steps:
-  - trigger: "libcxx-ci"
-    build:
-      message: "${BUILDKITE_MESSAGE}"
-      commit: "${BUILDKITE_COMMIT}"
-      branch: "${BUILDKITE_BRANCH}"
-EOF
+# TODO: Remove this once the premerge checks invoke the script below directly.
+./.ci/generate-buildkite-pipeline-scheduled

libcxx/utils/ci/generate-buildkite-pipeline

@@ -9,18 +9,9 @@
 
 #
 # This script generates the appropriate libc++ CI pipeline based on which project(s) were changed.
+# TODO: Remove this once the libcxx CI pipeline uploads the buildkite-pipeline.yml file directly.
 #
 
 if git diff --name-only HEAD~1 | grep -q -E "^libcxx/|^libcxxabi/|^libunwind/|^runtimes/|^cmake/"; then
-  LIBCXX_CHANGED=true
-fi
-
-if git diff --name-only HEAD~1 | grep -q -E "^clang/"; then
-  CLANG_CHANGED=true
-fi
-
-if [[ "${CLANG_CHANGED}" == "true" && "${LIBCXX_CHANGED}" != "true" ]]; then
-  cat clang/utils/ci/buildkite-pipeline.yml
-else
   cat libcxx/utils/ci/buildkite-pipeline.yml
 fi