[llvm] [workflows] Split pr-code-format into two parts to make it more secure (PR #78216)

[Aiden Grossman via llvm-commits]

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@@ -72,9 +58,17 @@ jobs:
         # explicitly in code-format-helper.py and not have to diff starting at
         # the merge base.
         run: |
-          python ./code-format-tools/llvm/utils/git/code-format-helper.py \
+          python ./llvm/utils/git/code-format-helper.py \
+            --write-comment-to-file \
             --token ${{ secrets.GITHUB_TOKEN }} \
             --issue-number $GITHUB_PR_NUMBER \
             --start-rev $(git merge-base $START_REV $END_REV) \
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boomanaiden154 wrote:

The start revision and end revision I think would need to be adjusted? Now that this is a `pull_request` workflow, we get a merge commit merging the PR into `main` (or whatever the target branch is), so I think we can probably just do `HEAD~1` and `HEAD`? I can't remember what Github ends up setting `base.sha` and `head.sha` to here.

https://github.com/llvm/llvm-project/pull/78216