[libcxx] [llvm] [libc++] Add a job that runs the benchmarks as part of the CI (PR #157567)

Louis Dionne via llvm-commits llvm-commits at lists.llvm.org
Thu Sep 11 11:45:42 PDT 2025


https://github.com/ldionne updated https://github.com/llvm/llvm-project/pull/157567

>From c7306f453076f0c8a962281ed406aad6ce6e21eb Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Mon, 8 Sep 2025 18:12:17 -0400
Subject: [PATCH 01/17] [libc++] Add a job that runs the benchmarks as part of
 the CI

This will make it easier to see the performance impact of individual
patches. This is a first step towards better performance tracking, but
many things still need to be figured out:
- We should get a dedicated set of machines to run these tests on
- We could probably reuse regularly-generated baseline results published
  to LNT instead of re-generating the baselines in this job every time.
---
 .github/workflows/libcxx-build-and-test.yaml | 22 ++++++++++++++++++++
 libcxx/utils/ci/run-buildbot                 | 18 ++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 2e6ff7f91b6fc..80da80bdc59e7 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -284,3 +284,25 @@ jobs:
       - name: Build and test
         run: |
           bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+
+  benchmarks:
+    runs-on: llvm-premerge-libcxx-next-runners # TODO: This should run on a dedicated set of machines
+    # needs: [ stage3 ] # TODO: Run this at the end of the pipeline once we're done testing the job
+    steps:
+      - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - name: benchmarks
+        run: libcxx/utils/ci/run-buildbot benchmark-comparison
+        env:
+          CC: clang-22
+          CXX: clang++-22
+      - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
+        if: always()
+        with:
+          name: benchmarks-results
+          path: |
+            **/test-results.xml
+            **/*.abilist
+            **/CMakeConfigureLog.yaml
+            **/CMakeError.log
+            **/CMakeOutput.log
+            **/crash_diagnostics/*
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index 57ecf1e49dbf2..6a776b6645723 100755
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -542,6 +542,24 @@ generic-optimized-speed)
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-optimized-speed.cmake"
     check-runtimes
 ;;
+benchmark-comparison)
+    clean
+    LIT_ARGS="-sv -j1 --param optimization=speed libcxx/test/benchmarks/hash.bench.cpp libcxx/test/benchmarks/join_view.bench.cpp"
+
+    baseline_commit=$(git merge-base main HEAD)
+    step "Building and running the baseline at ${baseline_commit}"
+    rm -rf "${BUILD_DIR}-baseline"
+    ./libcxx/utils/test-at-commit --commit ${baseline_commit} -B "${BUILD_DIR}-baseline" -- ${LIT_ARGS}
+
+    # Build and run the candidate
+    step "Building and running the candidate"
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-optimized-speed.cmake"
+    ./libcxx/utils/libcxx-lit "${BUILD_DIR}" ${LIT_ARGS}
+
+    step "Comparison of the baseline and the candidate"
+    ./libcxx/utils/compare-benchmarks <(./libcxx/utils/consolidate-benchmarks "${BUILD_DIR}-baseline") \
+                                      <(./libcxx/utils/consolidate-benchmarks "${BUILD_DIR}")
+;;
 apple-configuration)
     clean
 

>From 567efcabb14f4b695a9b267b505443d0d592c05b Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 12:25:40 -0400
Subject: [PATCH 02/17] Try to fix baseline commit

---
 libcxx/utils/ci/run-buildbot | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index 6a776b6645723..b888faed975da 100755
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -546,10 +546,12 @@ benchmark-comparison)
     clean
     LIT_ARGS="-sv -j1 --param optimization=speed libcxx/test/benchmarks/hash.bench.cpp libcxx/test/benchmarks/join_view.bench.cpp"
 
-    baseline_commit=$(git merge-base main HEAD)
-    step "Building and running the baseline at ${baseline_commit}"
+    if [[ "${BASELINE_COMMIT}" == "" ]]; then
+        BASELINE_COMMIT=$(git merge-base main HEAD)
+    fi
+    step "Building and running the baseline at ${BASELINE_COMMIT}"
     rm -rf "${BUILD_DIR}-baseline"
-    ./libcxx/utils/test-at-commit --commit ${baseline_commit} -B "${BUILD_DIR}-baseline" -- ${LIT_ARGS}
+    ./libcxx/utils/test-at-commit --commit ${BASELINE_COMMIT} -B "${BUILD_DIR}-baseline" -- ${LIT_ARGS}
 
     # Build and run the candidate
     step "Building and running the candidate"

>From 9ac9dc92978a281f2e0d0e652aca74250be2858d Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 12:31:40 -0400
Subject: [PATCH 03/17] Try again

---
 libcxx/utils/ci/run-buildbot | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index b888faed975da..373e298183d86 100755
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -546,12 +546,15 @@ benchmark-comparison)
     clean
     LIT_ARGS="-sv -j1 --param optimization=speed libcxx/test/benchmarks/hash.bench.cpp libcxx/test/benchmarks/join_view.bench.cpp"
 
-    if [[ "${BASELINE_COMMIT}" == "" ]]; then
-        BASELINE_COMMIT=$(git merge-base main HEAD)
+    if [[ "${GITHUB_BASE_REF}" != "" ]]; then # triggered from a PR
+        baseline_commit=$(git merge-base ${GITHUB_BASE_REF} ${GITHUB_SHA})
+    else
+        baseline_commit=$(git merge-base main HEAD)
     fi
-    step "Building and running the baseline at ${BASELINE_COMMIT}"
+
+    step "Building and running the baseline at ${baseline_commit}"
     rm -rf "${BUILD_DIR}-baseline"
-    ./libcxx/utils/test-at-commit --commit ${BASELINE_COMMIT} -B "${BUILD_DIR}-baseline" -- ${LIT_ARGS}
+    ./libcxx/utils/test-at-commit --commit ${baseline_commit} -B "${BUILD_DIR}-baseline" -- ${LIT_ARGS}
 
     # Build and run the candidate
     step "Building and running the candidate"

>From f16b1a7988c3f0e90a75a3fce868f11d30672292 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 12:45:04 -0400
Subject: [PATCH 04/17] Try to fix the fetch

---
 .github/workflows/libcxx-build-and-test.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 80da80bdc59e7..73e01611025ef 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -290,6 +290,8 @@ jobs:
     # needs: [ stage3 ] # TODO: Run this at the end of the pipeline once we're done testing the job
     steps:
       - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
       - name: benchmarks
         run: libcxx/utils/ci/run-buildbot benchmark-comparison
         env:

>From 354e90385aaaa20031a10b47b1111012823c1284 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 13:05:07 -0400
Subject: [PATCH 05/17] Try fetching tags

---
 .github/workflows/libcxx-build-and-test.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 73e01611025ef..cd125e7e1a52f 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -292,6 +292,7 @@ jobs:
       - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
           fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
+          fetch-tags: true
       - name: benchmarks
         run: libcxx/utils/ci/run-buildbot benchmark-comparison
         env:

>From 716aa962b46afcd9926de8f4818bf4c4d662addf Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 13:15:59 -0400
Subject: [PATCH 06/17] Try to fix merge base

---
 libcxx/utils/ci/run-buildbot | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index 373e298183d86..1b3d1a7861c48 100755
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -547,7 +547,7 @@ benchmark-comparison)
     LIT_ARGS="-sv -j1 --param optimization=speed libcxx/test/benchmarks/hash.bench.cpp libcxx/test/benchmarks/join_view.bench.cpp"
 
     if [[ "${GITHUB_BASE_REF}" != "" ]]; then # triggered from a PR
-        baseline_commit=$(git merge-base ${GITHUB_BASE_REF} ${GITHUB_SHA})
+        baseline_commit=$(git merge-base refs/heads/${GITHUB_BASE_REF} ${GITHUB_SHA})
     else
         baseline_commit=$(git merge-base main HEAD)
     fi

>From a9b70dfc099e95cb838b78c05e83fc8720bb3e91 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 13:26:57 -0400
Subject: [PATCH 07/17] Try checkout main

---
 .github/workflows/libcxx-build-and-test.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index cd125e7e1a52f..6ede9a312e443 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -293,6 +293,7 @@ jobs:
         with:
           fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
           fetch-tags: true
+          ref: main
       - name: benchmarks
         run: libcxx/utils/ci/run-buildbot benchmark-comparison
         env:

>From dcc96726f024caa13f6334bcae0b2f63af8b146b Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 13:39:00 -0400
Subject: [PATCH 08/17] Try to fix checkout

---
 .github/workflows/libcxx-build-and-test.yaml | 2 +-
 libcxx/utils/ci/run-buildbot                 | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 6ede9a312e443..b30e126181a83 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -293,7 +293,7 @@ jobs:
         with:
           fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
           fetch-tags: true
-          ref: main
+          # ref: main
       - name: benchmarks
         run: libcxx/utils/ci/run-buildbot benchmark-comparison
         env:
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
index 1b3d1a7861c48..3daf524503710 100755
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -547,7 +547,7 @@ benchmark-comparison)
     LIT_ARGS="-sv -j1 --param optimization=speed libcxx/test/benchmarks/hash.bench.cpp libcxx/test/benchmarks/join_view.bench.cpp"
 
     if [[ "${GITHUB_BASE_REF}" != "" ]]; then # triggered from a PR
-        baseline_commit=$(git merge-base refs/heads/${GITHUB_BASE_REF} ${GITHUB_SHA})
+        baseline_commit=$(git merge-base refs/remotes/origin/${GITHUB_BASE_REF} ${GITHUB_SHA})
     else
         baseline_commit=$(git merge-base main HEAD)
     fi

>From 900f6b520de8746db135db7eff4bfcb2b78edaae Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 13:48:18 -0400
Subject: [PATCH 09/17] Install python requirements'

---
 .github/workflows/libcxx-build-and-test.yaml | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index b30e126181a83..7cb5c0609d56d 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -293,9 +293,12 @@ jobs:
         with:
           fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
           fetch-tags: true
-          # ref: main
       - name: benchmarks
-        run: libcxx/utils/ci/run-buildbot benchmark-comparison
+        run: |
+          python3 -m venv .venv
+          source .venv/bin/activate
+          python -m pip install -r libcxx/utils/requirements.txt
+          libcxx/utils/ci/run-buildbot benchmark-comparison
         env:
           CC: clang-22
           CXX: clang++-22

>From 38eab49b1af376b7b76379a47f1fc87c07e97dc2 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 13:55:51 -0400
Subject: [PATCH 10/17] Try to fix issue with venv

---
 .github/workflows/libcxx-build-and-test.yaml | 2 ++
 libcxx/utils/ci/Dockerfile                   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 7cb5c0609d56d..1ea99abaa7c8e 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -294,7 +294,9 @@ jobs:
           fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
           fetch-tags: true
       - name: benchmarks
+        # TODO: python3-venv should be taken from the Docker image instead
         run: |
+          sudo apt-get install -y python3-venv
           python3 -m venv .venv
           source .venv/bin/activate
           python -m pip install -r libcxx/utils/requirements.txt
diff --git a/libcxx/utils/ci/Dockerfile b/libcxx/utils/ci/Dockerfile
index 79e11569c0d08..03c830499a0fd 100644
--- a/libcxx/utils/ci/Dockerfile
+++ b/libcxx/utils/ci/Dockerfile
@@ -100,6 +100,7 @@ RUN sudo apt-get update \
         python3-packaging \
         python3-setuptools \
         python3-psutil \
+        python3-venv \
         software-properties-common \
         swig \
         unzip \

>From 28cfc5b8f21492208bb5d430f893f993c36bf7c5 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 14:02:49 -0400
Subject: [PATCH 11/17] Fix package naem

---
 .github/workflows/libcxx-build-and-test.yaml | 4 ++--
 libcxx/utils/ci/Dockerfile                   | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 1ea99abaa7c8e..f4660e3c0c0d6 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -294,9 +294,9 @@ jobs:
           fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
           fetch-tags: true
       - name: benchmarks
-        # TODO: python3-venv should be taken from the Docker image instead
+        # TODO: python3-virtualenv should be taken from the Docker image instead
         run: |
-          sudo apt-get install -y python3-venv
+          sudo apt-get install -y python3-virtualenv
           python3 -m venv .venv
           source .venv/bin/activate
           python -m pip install -r libcxx/utils/requirements.txt
diff --git a/libcxx/utils/ci/Dockerfile b/libcxx/utils/ci/Dockerfile
index 03c830499a0fd..685f060b29f57 100644
--- a/libcxx/utils/ci/Dockerfile
+++ b/libcxx/utils/ci/Dockerfile
@@ -100,7 +100,7 @@ RUN sudo apt-get update \
         python3-packaging \
         python3-setuptools \
         python3-psutil \
-        python3-venv \
+        python3-virtualenv \
         software-properties-common \
         swig \
         unzip \

>From 32c669d3e2ee5eecc09697fa5daf340a24cabcf2 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 14:03:25 -0400
Subject: [PATCH 12/17] Temporarily remove other jobs to reduce churn

---
 .github/workflows/libcxx-build-and-test.yaml | 496 +++++++++----------
 1 file changed, 248 insertions(+), 248 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index f4660e3c0c0d6..52d5551ae0fdd 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -34,256 +34,256 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  stage1:
-    if: github.repository_owner == 'llvm'
-    runs-on: llvm-premerge-libcxx-next-runners
-    continue-on-error: false
-    strategy:
-      fail-fast: false
-      matrix:
-        config: [
-          'frozen-cxx03-headers',
-          'generic-cxx03',
-          'generic-cxx26',
-          'generic-modules'
-        ]
-        cc: [  'clang-22' ]
-        cxx: [ 'clang++-22' ]
-        include:
-          - config: 'generic-gcc'
-            cc: 'gcc-15'
-            cxx: 'g++-15'
-    steps:
-      - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      - name: ${{ matrix.config }}.${{ matrix.cxx }}
-        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
-        env:
-          CC: ${{ matrix.cc }}
-          CXX: ${{ matrix.cxx }}
-      - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
-        if: always()
-        with:
-          name: ${{ matrix.config }}-${{ matrix.cxx }}-results
-          path: |
-            **/test-results.xml
-            **/*.abilist
-            **/CMakeConfigureLog.yaml
-            **/CMakeError.log
-            **/CMakeOutput.log
-            **/crash_diagnostics/*
-  stage2:
-    if: github.repository_owner == 'llvm'
-    runs-on: llvm-premerge-libcxx-next-runners
-    needs: [ stage1 ]
-    continue-on-error: false
-    strategy:
-      fail-fast: false
-      matrix:
-        config: [
-          'generic-cxx11',
-          'generic-cxx14',
-          'generic-cxx17',
-          'generic-cxx20',
-          'generic-cxx23'
-        ]
-        cc: [ 'clang-22' ]
-        cxx: [ 'clang++-22' ]
-        include:
-          - config: 'generic-gcc-cxx11'
-            cc: 'gcc-15'
-            cxx: 'g++-15'
-          - config: 'generic-cxx26'
-            cc: 'clang-21'
-            cxx: 'clang++-21'
-          - config: 'generic-cxx26'
-            cc: 'clang-20'
-            cxx: 'clang++-20'
-    steps:
-      - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      - name: ${{ matrix.config }}
-        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
-        env:
-          CC: ${{ matrix.cc }}
-          CXX: ${{ matrix.cxx }}
-      - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
-        if: always()  # Upload artifacts even if the build or test suite fails
-        with:
-          name: ${{ matrix.config }}-${{ matrix.cxx }}-results
-          path: |
-            **/test-results.xml
-            **/*.abilist
-            **/CMakeConfigureLog.yaml
-            **/CMakeError.log
-            **/CMakeOutput.log
-            **/crash_diagnostics/*
-  stage3:
-    if: github.repository_owner == 'llvm'
-    needs: [ stage2 ]
-    continue-on-error: false
-    strategy:
-      fail-fast: false
-      max-parallel: 8
-      matrix:
-        config: [
-          'generic-abi-unstable',
-          'generic-hardening-mode-debug',
-          'generic-hardening-mode-extensive',
-          'generic-hardening-mode-extensive-observe-semantic',
-          'generic-hardening-mode-fast',
-          'generic-hardening-mode-fast-with-abi-breaks',
-          'generic-merged',
-          'generic-modules-cxx17-lsv',
-          'generic-no-exceptions',
-          'generic-no-experimental',
-          'generic-no-filesystem',
-          'generic-no-localization',
-          'generic-no-terminal',
-          'generic-no-random_device',
-          'generic-no-threads',
-          'generic-no-tzdb',
-          'generic-no-unicode',
-          'generic-no-wide-characters',
-          'generic-no-rtti',
-          'generic-optimized-speed',
-          'generic-static',
-          'bootstrapping-build'
-        ]
-        machine: [ 'llvm-premerge-libcxx-next-runners' ]
-        include:
-        - config: 'generic-cxx26'
-          machine: llvm-premerge-libcxx-next-runners
-        - config: 'generic-asan'
-          machine: llvm-premerge-libcxx-next-runners
-        - config: 'generic-tsan'
-          machine: llvm-premerge-libcxx-next-runners
-        - config: 'generic-ubsan'
-          machine: llvm-premerge-libcxx-next-runners
-        # Use a larger machine for MSAN to avoid timeout and memory allocation issues.
-        - config: 'generic-msan'
-          machine: llvm-premerge-libcxx-next-runners
-    runs-on: ${{ matrix.machine }}
-    steps:
-      - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      - name: ${{ matrix.config }}
-        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
-        env:
-          CC: clang-22
-          CXX: clang++-22
-      - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
-        if: always()
-        with:
-          name: ${{ matrix.config }}-results
-          path: |
-            **/test-results.xml
-            **/*.abilist
-            **/CMakeConfigureLog.yaml
-            **/CMakeError.log
-            **/CMakeOutput.log
-            **/crash_diagnostics/*
+  # stage1:
+  #   if: github.repository_owner == 'llvm'
+  #   runs-on: llvm-premerge-libcxx-next-runners
+  #   continue-on-error: false
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       config: [
+  #         'frozen-cxx03-headers',
+  #         'generic-cxx03',
+  #         'generic-cxx26',
+  #         'generic-modules'
+  #       ]
+  #       cc: [  'clang-22' ]
+  #       cxx: [ 'clang++-22' ]
+  #       include:
+  #         - config: 'generic-gcc'
+  #           cc: 'gcc-15'
+  #           cxx: 'g++-15'
+  #   steps:
+  #     - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+  #     - name: ${{ matrix.config }}.${{ matrix.cxx }}
+  #       run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+  #       env:
+  #         CC: ${{ matrix.cc }}
+  #         CXX: ${{ matrix.cxx }}
+  #     - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
+  #       if: always()
+  #       with:
+  #         name: ${{ matrix.config }}-${{ matrix.cxx }}-results
+  #         path: |
+  #           **/test-results.xml
+  #           **/*.abilist
+  #           **/CMakeConfigureLog.yaml
+  #           **/CMakeError.log
+  #           **/CMakeOutput.log
+  #           **/crash_diagnostics/*
+  # stage2:
+  #   if: github.repository_owner == 'llvm'
+  #   runs-on: llvm-premerge-libcxx-next-runners
+  #   needs: [ stage1 ]
+  #   continue-on-error: false
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       config: [
+  #         'generic-cxx11',
+  #         'generic-cxx14',
+  #         'generic-cxx17',
+  #         'generic-cxx20',
+  #         'generic-cxx23'
+  #       ]
+  #       cc: [ 'clang-22' ]
+  #       cxx: [ 'clang++-22' ]
+  #       include:
+  #         - config: 'generic-gcc-cxx11'
+  #           cc: 'gcc-15'
+  #           cxx: 'g++-15'
+  #         - config: 'generic-cxx26'
+  #           cc: 'clang-21'
+  #           cxx: 'clang++-21'
+  #         - config: 'generic-cxx26'
+  #           cc: 'clang-20'
+  #           cxx: 'clang++-20'
+  #   steps:
+  #     - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+  #     - name: ${{ matrix.config }}
+  #       run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+  #       env:
+  #         CC: ${{ matrix.cc }}
+  #         CXX: ${{ matrix.cxx }}
+  #     - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
+  #       if: always()  # Upload artifacts even if the build or test suite fails
+  #       with:
+  #         name: ${{ matrix.config }}-${{ matrix.cxx }}-results
+  #         path: |
+  #           **/test-results.xml
+  #           **/*.abilist
+  #           **/CMakeConfigureLog.yaml
+  #           **/CMakeError.log
+  #           **/CMakeOutput.log
+  #           **/crash_diagnostics/*
+  # stage3:
+  #   if: github.repository_owner == 'llvm'
+  #   needs: [ stage2 ]
+  #   continue-on-error: false
+  #   strategy:
+  #     fail-fast: false
+  #     max-parallel: 8
+  #     matrix:
+  #       config: [
+  #         'generic-abi-unstable',
+  #         'generic-hardening-mode-debug',
+  #         'generic-hardening-mode-extensive',
+  #         'generic-hardening-mode-extensive-observe-semantic',
+  #         'generic-hardening-mode-fast',
+  #         'generic-hardening-mode-fast-with-abi-breaks',
+  #         'generic-merged',
+  #         'generic-modules-cxx17-lsv',
+  #         'generic-no-exceptions',
+  #         'generic-no-experimental',
+  #         'generic-no-filesystem',
+  #         'generic-no-localization',
+  #         'generic-no-terminal',
+  #         'generic-no-random_device',
+  #         'generic-no-threads',
+  #         'generic-no-tzdb',
+  #         'generic-no-unicode',
+  #         'generic-no-wide-characters',
+  #         'generic-no-rtti',
+  #         'generic-optimized-speed',
+  #         'generic-static',
+  #         'bootstrapping-build'
+  #       ]
+  #       machine: [ 'llvm-premerge-libcxx-next-runners' ]
+  #       include:
+  #       - config: 'generic-cxx26'
+  #         machine: llvm-premerge-libcxx-next-runners
+  #       - config: 'generic-asan'
+  #         machine: llvm-premerge-libcxx-next-runners
+  #       - config: 'generic-tsan'
+  #         machine: llvm-premerge-libcxx-next-runners
+  #       - config: 'generic-ubsan'
+  #         machine: llvm-premerge-libcxx-next-runners
+  #       # Use a larger machine for MSAN to avoid timeout and memory allocation issues.
+  #       - config: 'generic-msan'
+  #         machine: llvm-premerge-libcxx-next-runners
+  #   runs-on: ${{ matrix.machine }}
+  #   steps:
+  #     - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+  #     - name: ${{ matrix.config }}
+  #       run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+  #       env:
+  #         CC: clang-22
+  #         CXX: clang++-22
+  #     - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
+  #       if: always()
+  #       with:
+  #         name: ${{ matrix.config }}-results
+  #         path: |
+  #           **/test-results.xml
+  #           **/*.abilist
+  #           **/CMakeConfigureLog.yaml
+  #           **/CMakeError.log
+  #           **/CMakeOutput.log
+  #           **/crash_diagnostics/*
 
-  macos:
-    needs: [ stage2 ]
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-        - config: generic-cxx03
-          os: macos-15
-        - config: generic-cxx23
-          os: macos-15
-        - config: generic-modules
-          os: macos-15
-        - config: apple-configuration
-          os: macos-15
-        # TODO: These jobs are intended to test back-deployment (building against ToT libc++ but running against an
-        #       older system-provided libc++.dylib). Doing this properly would require building the test suite on a
-        #       recent macOS using a recent Clang (hence recent Xcode), and then running the actual test suite on an
-        #       older mac. We could do that by e.g. sharing artifacts between the two jobs.
-        #
-        #       However, our Lit configuration currently doesn't provide a good way to do that in a batch, so our only
-        #       alternative is to actually build on the same host that we're going to run on. Sadly, that doesn't work
-        #       since older macOSes don't support newer Xcodes. For now, we run the "backdeployment" jobs on recent
-        #       macOS versions as a way to avoid rotting that configuration, but it doesn't provide a lot of additional
-        #       coverage.
-        - config: apple-system
-          os: macos-15
-        - config: apple-system-hardened
-          os: macos-15
-    runs-on: ${{ matrix.os }}
-    steps:
-      - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      - uses: maxim-lobanov/setup-xcode at 60606e260d2fc5762a71e64e74b2174e8ea3c8bd # v1.6.0
-        with:
-          # https://github.com/actions/runner-images/blob/main/images/macos/macos-15-Readme.md
-          xcode-version: '16.3'
-      - uses: seanmiddleditch/gha-setup-ninja at 3b1f8f94a2f8254bd26914c4ab9474d4f0015f67 # v6
-      - name: Build and test
-        run: |
-          python3 -m venv .venv
-          source .venv/bin/activate
-          python -m pip install psutil
-          bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
-      - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
-        if: always()  # Upload artifacts even if the build or test suite fails
-        with:
-          name: macos-${{ matrix.config }}-results
-          path: |
-            **/test-results.xml
-            **/*.abilist
-            **/CMakeConfigureLog.yaml
-            **/CMakeError.log
-            **/CMakeOutput.log
-            **/crash_diagnostics/*
+  # macos:
+  #   needs: [ stage2 ]
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       include:
+  #       - config: generic-cxx03
+  #         os: macos-15
+  #       - config: generic-cxx23
+  #         os: macos-15
+  #       - config: generic-modules
+  #         os: macos-15
+  #       - config: apple-configuration
+  #         os: macos-15
+  #       # TODO: These jobs are intended to test back-deployment (building against ToT libc++ but running against an
+  #       #       older system-provided libc++.dylib). Doing this properly would require building the test suite on a
+  #       #       recent macOS using a recent Clang (hence recent Xcode), and then running the actual test suite on an
+  #       #       older mac. We could do that by e.g. sharing artifacts between the two jobs.
+  #       #
+  #       #       However, our Lit configuration currently doesn't provide a good way to do that in a batch, so our only
+  #       #       alternative is to actually build on the same host that we're going to run on. Sadly, that doesn't work
+  #       #       since older macOSes don't support newer Xcodes. For now, we run the "backdeployment" jobs on recent
+  #       #       macOS versions as a way to avoid rotting that configuration, but it doesn't provide a lot of additional
+  #       #       coverage.
+  #       - config: apple-system
+  #         os: macos-15
+  #       - config: apple-system-hardened
+  #         os: macos-15
+  #   runs-on: ${{ matrix.os }}
+  #   steps:
+  #     - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+  #     - uses: maxim-lobanov/setup-xcode at 60606e260d2fc5762a71e64e74b2174e8ea3c8bd # v1.6.0
+  #       with:
+  #         # https://github.com/actions/runner-images/blob/main/images/macos/macos-15-Readme.md
+  #         xcode-version: '16.3'
+  #     - uses: seanmiddleditch/gha-setup-ninja at 3b1f8f94a2f8254bd26914c4ab9474d4f0015f67 # v6
+  #     - name: Build and test
+  #       run: |
+  #         python3 -m venv .venv
+  #         source .venv/bin/activate
+  #         python -m pip install psutil
+  #         bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+  #     - uses: actions/upload-artifact at 26f96dfa697d77e81fd5907df203aa23a56210a8 # v4.3.0
+  #       if: always()  # Upload artifacts even if the build or test suite fails
+  #       with:
+  #         name: macos-${{ matrix.config }}-results
+  #         path: |
+  #           **/test-results.xml
+  #           **/*.abilist
+  #           **/CMakeConfigureLog.yaml
+  #           **/CMakeError.log
+  #           **/CMakeOutput.log
+  #           **/crash_diagnostics/*
 
-  windows:
-    runs-on: windows-2022
-    needs: [ stage2 ]
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-        - { config: clang-cl-dll, mingw: false }
-        - { config: clang-cl-static, mingw: false }
-        - { config: clang-cl-no-vcruntime, mingw: false }
-        - { config: clang-cl-debug, mingw: false }
-        - { config: clang-cl-static-crt, mingw: false }
-        - { config: mingw-dll, mingw: true }
-        - { config: mingw-static, mingw: true }
-        - { config: mingw-dll-i686, mingw: true }
-        - { config: mingw-incomplete-sysroot, mingw: true }
-    steps:
-      - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      - name: Install dependencies
-        run: |
-          choco install -y ninja
-          pip install psutil
-      - name: Install a current LLVM
-        if: ${{ matrix.mingw != true }}
-        run: |
-          choco install -y llvm --version=20.1.8 --allow-downgrade
-      - name: Install llvm-mingw
-        if: ${{ matrix.mingw == true }}
-        run: |
-          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20250709/llvm-mingw-20250709-ucrt-x86_64.zip
-          powershell Expand-Archive llvm-mingw*.zip -DestinationPath .
-          del llvm-mingw*.zip
-          mv llvm-mingw* c:\llvm-mingw
-          echo "c:\llvm-mingw\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
-      - name: Simulate a from-scratch build of llvm-mingw
-        if: ${{ matrix.config == 'mingw-incomplete-sysroot' }}
-        run: |
-          rm -r c:\llvm-mingw\include\c++
-          rm -r c:\llvm-mingw\*-w64-mingw32\lib\libc++*
-          rm -r c:\llvm-mingw\*-w64-mingw32\lib\libunwind*
-      - name: Add Git Bash to the path
-        run: |
-          echo "c:\Program Files\Git\usr\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
-      - name: Set up the MSVC dev environment
-        if: ${{ matrix.mingw != true }}
-        uses: ilammy/msvc-dev-cmd at 0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
-      - name: Build and test
-        run: |
-          bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
+  # windows:
+  #   runs-on: windows-2022
+  #   needs: [ stage2 ]
+  #   strategy:
+  #     fail-fast: false
+  #     matrix:
+  #       include:
+  #       - { config: clang-cl-dll, mingw: false }
+  #       - { config: clang-cl-static, mingw: false }
+  #       - { config: clang-cl-no-vcruntime, mingw: false }
+  #       - { config: clang-cl-debug, mingw: false }
+  #       - { config: clang-cl-static-crt, mingw: false }
+  #       - { config: mingw-dll, mingw: true }
+  #       - { config: mingw-static, mingw: true }
+  #       - { config: mingw-dll-i686, mingw: true }
+  #       - { config: mingw-incomplete-sysroot, mingw: true }
+  #   steps:
+  #     - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+  #     - name: Install dependencies
+  #       run: |
+  #         choco install -y ninja
+  #         pip install psutil
+  #     - name: Install a current LLVM
+  #       if: ${{ matrix.mingw != true }}
+  #       run: |
+  #         choco install -y llvm --version=20.1.8 --allow-downgrade
+  #     - name: Install llvm-mingw
+  #       if: ${{ matrix.mingw == true }}
+  #       run: |
+  #         curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20250709/llvm-mingw-20250709-ucrt-x86_64.zip
+  #         powershell Expand-Archive llvm-mingw*.zip -DestinationPath .
+  #         del llvm-mingw*.zip
+  #         mv llvm-mingw* c:\llvm-mingw
+  #         echo "c:\llvm-mingw\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
+  #     - name: Simulate a from-scratch build of llvm-mingw
+  #       if: ${{ matrix.config == 'mingw-incomplete-sysroot' }}
+  #       run: |
+  #         rm -r c:\llvm-mingw\include\c++
+  #         rm -r c:\llvm-mingw\*-w64-mingw32\lib\libc++*
+  #         rm -r c:\llvm-mingw\*-w64-mingw32\lib\libunwind*
+  #     - name: Add Git Bash to the path
+  #       run: |
+  #         echo "c:\Program Files\Git\usr\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
+  #     - name: Set up the MSVC dev environment
+  #       if: ${{ matrix.mingw != true }}
+  #       uses: ilammy/msvc-dev-cmd at 0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
+  #     - name: Build and test
+  #       run: |
+  #         bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
 
   benchmarks:
     runs-on: llvm-premerge-libcxx-next-runners # TODO: This should run on a dedicated set of machines

>From 20411483bcb4324d8dde0178513460117f8ea7f6 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 14:10:41 -0400
Subject: [PATCH 13/17] Try again

---
 .github/workflows/libcxx-build-and-test.yaml | 2 +-
 libcxx/utils/ci/Dockerfile                   | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 52d5551ae0fdd..0a7e1c7afa566 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -296,7 +296,7 @@ jobs:
       - name: benchmarks
         # TODO: python3-virtualenv should be taken from the Docker image instead
         run: |
-          sudo apt-get install -y python3-virtualenv
+          sudo pip install virtualenv
           python3 -m venv .venv
           source .venv/bin/activate
           python -m pip install -r libcxx/utils/requirements.txt
diff --git a/libcxx/utils/ci/Dockerfile b/libcxx/utils/ci/Dockerfile
index 685f060b29f57..79e11569c0d08 100644
--- a/libcxx/utils/ci/Dockerfile
+++ b/libcxx/utils/ci/Dockerfile
@@ -100,7 +100,6 @@ RUN sudo apt-get update \
         python3-packaging \
         python3-setuptools \
         python3-psutil \
-        python3-virtualenv \
         software-properties-common \
         swig \
         unzip \

>From 9742fe0d92acca52ab5596071b65e29ee4f75cdb Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 14:20:42 -0400
Subject: [PATCH 14/17] Try fixing

---
 .github/workflows/libcxx-build-and-test.yaml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 0a7e1c7afa566..eed972ac6aa00 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -290,17 +290,17 @@ jobs:
     # needs: [ stage3 ] # TODO: Run this at the end of the pipeline once we're done testing the job
     steps:
       - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-        with:
-          fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
-          fetch-tags: true
+        # with:
+        #   fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
+        #   fetch-tags: true
       - name: benchmarks
         # TODO: python3-virtualenv should be taken from the Docker image instead
+        # libcxx/utils/ci/run-buildbot benchmark-comparison
         run: |
-          sudo pip install virtualenv
+          python3 -m pip install virtualenv
           python3 -m venv .venv
           source .venv/bin/activate
           python -m pip install -r libcxx/utils/requirements.txt
-          libcxx/utils/ci/run-buildbot benchmark-comparison
         env:
           CC: clang-22
           CXX: clang++-22

>From 43b799c21b75759d29a1181eff80ef8359c5f5a5 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 14:28:09 -0400
Subject: [PATCH 15/17] This is surprisingly fiddly to get working

---
 .github/workflows/libcxx-build-and-test.yaml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index eed972ac6aa00..d829e293a269d 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -293,11 +293,13 @@ jobs:
         # with:
         #   fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
         #   fetch-tags: true
+      - uses: actions/setup-python at v6
+        with:
+          python-version: '3.10'
       - name: benchmarks
         # TODO: python3-virtualenv should be taken from the Docker image instead
         # libcxx/utils/ci/run-buildbot benchmark-comparison
         run: |
-          python3 -m pip install virtualenv
           python3 -m venv .venv
           source .venv/bin/activate
           python -m pip install -r libcxx/utils/requirements.txt

>From a0a4026c5748160c87ff28ca98511953e0ffeb6a Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 14:40:59 -0400
Subject: [PATCH 16/17] Progress

---
 .github/workflows/libcxx-build-and-test.yaml | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index d829e293a269d..6c18cd2a5fdf7 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -290,19 +290,18 @@ jobs:
     # needs: [ stage3 ] # TODO: Run this at the end of the pipeline once we're done testing the job
     steps:
       - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-        # with:
-        #   fetch-depth: 0 # This job requires access to all the Git branches so it can diff against (usually) main
-        #   fetch-tags: true
+        with:
+          fetch-depth: 10
+          fetch-tags: true # This job requires access to all the Git branches so it can diff against (usually) main
       - uses: actions/setup-python at v6
         with:
           python-version: '3.10'
       - name: benchmarks
-        # TODO: python3-virtualenv should be taken from the Docker image instead
-        # libcxx/utils/ci/run-buildbot benchmark-comparison
         run: |
           python3 -m venv .venv
           source .venv/bin/activate
           python -m pip install -r libcxx/utils/requirements.txt
+          libcxx/utils/ci/run-buildbot benchmark-comparison
         env:
           CC: clang-22
           CXX: clang++-22

>From a7ebd66af17f89ccead596dd4fb8278597f29ec9 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Thu, 11 Sep 2025 14:45:24 -0400
Subject: [PATCH 17/17] Fetch all

---
 .github/workflows/libcxx-build-and-test.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 6c18cd2a5fdf7..56461c6e8a235 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -291,7 +291,7 @@ jobs:
     steps:
       - uses: actions/checkout at 08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
         with:
-          fetch-depth: 10
+          fetch-depth: 0
           fetch-tags: true # This job requires access to all the Git branches so it can diff against (usually) main
       - uses: actions/setup-python at v6
         with:



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