[Github] Simplify Getting Changed Files in Code Formatting Workflow

[boomanaiden154]

This patch changes getting changed files in the pr code format job to just checking out the previous two commits (the merge commit and its porent, the current commit latest in main), which allows us to just diff the merge commit. This means we do not have to checkout the ref through the merge base, which should save approximately a minute per job (or much more in some cases where the PR is particularly out of date).

[llvmbot]

@llvm/pr-subscribers-github-workflow

Author: Aiden Grossman (boomanaiden154)

Changes

This patch changes getting changed files in the pr code format job to just checking out the previous two commits (the merge commit and its porent, the current commit latest in main), which allows us to just diff the merge commit. This means we do not have to checkout the ref through the merge base, which should save approximately a minute per job (or much more in some cases where the PR is particularly out of date).

---

Full diff: https://github.com/llvm/llvm-project/pull/133023.diff

1 Files Affected:

• (modified) .github/workflows/pr-code-format.yml (+5-10)

diff --git a/.github/workflows/pr-code-format.yml b/.github/workflows/pr-code-format.yml
index b08e5c21ca62e..2c06c8bdddea6 100644
--- a/.github/workflows/pr-code-format.yml
+++ b/.github/workflows/pr-code-format.yml
@@ -21,14 +21,7 @@ jobs:
       - name: Fetch LLVM sources
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
-          ref: ${{ github.event.pull_request.head.sha }}
-
-      - name: Checkout through merge base
-        uses: rmacklin/fetch-through-merge-base@bfe4d03a86f9afa52bc1a70e9814fc92a07f7b75 # v0.3.0
-        with:
-          base_ref: ${{ github.event.pull_request.base.ref }}
-          head_ref: ${{ github.event.pull_request.head.sha }}
-          deepen_length: 500
+          fetch-depth: 2
 
       - name: Get changed files
         id: changed-files
@@ -36,6 +29,8 @@ jobs:
         with:
           separator: ","
           skip_initial_fetch: true
+          base_sha: 'HEAD~1'
+          sha: 'HEAD'
 
       # We need to pull the script from the main branch, so that we ensure
       # we get the latest version of this script.
@@ -89,8 +84,8 @@ jobs:
             --write-comment-to-file \
             --token ${{ secrets.GITHUB_TOKEN }} \
             --issue-number $GITHUB_PR_NUMBER \
-            --start-rev $(git merge-base $START_REV $END_REV) \
-            --end-rev $END_REV \
+            --start-rev HEAD~1 \
+            --end-rev HEAD \
             --changed-files "$CHANGED_FILES"
 
       - uses: actions/upload-artifact@26f96dfa697d77e81fd5907df203aa23a56210a8 #v4.3.0