1 files changed, 159 insertions, 0 deletions
diff --git a/llvm_tools/generate_llvm_revert_report.py b/llvm_tools/generate_llvm_revert_report.py
new file mode 100755
index 00000000..f6a11128
--- /dev/null
+++ b/llvm_tools/generate_llvm_revert_report.py
@@ -0,0 +1,159 @@
+#!/usr/bin/env python3
+# Copyright 2023 The ChromiumOS Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Reports on all reverts applied and not applied to sys-devel/llvm.
+
+Note that this is primarily intended to produce output that can be easily
+pasted into a spreadsheet (read: the ChromeOS Mage's test matrix), so output is
+in CSV format.
+"""
+
+import argparse
+import csv
+import dataclasses
+import json
+import logging
+from pathlib import Path
+import re
+import subprocess
+import sys
+from typing import List, Set, TextIO
+
+import get_upstream_patch
+import revert_checker
+
+
+@dataclasses.dataclass(frozen=True)
+class RevertInfo:
+    """Information to write about a revert."""
+
+    revert: revert_checker.Revert
+    has_in_patches: bool
+    subject: str
+
+
+def list_upstream_cherrypicks(patches_json: Path) -> Set[str]:
+    with patches_json.open(encoding="utf-8") as f:
+        applicable_patches = [
+            x
+            for x in json.load(f)
+            if not x.get("platforms") or "chromiumos" in x["platforms"]
+        ]
+
+    # Allow for arbitrary suffixes for patches; some have `-v2`, `_fixed`, etc.
+    sha_re = re.compile(r"cherry/([a-fA-F0-9]{40})\b.*\.patch$")
+    sha_like_patches = set()
+    for p in applicable_patches:
+        m = sha_re.match(p["rel_patch_path"])
+        if m:
+            sha_like_patches.add(m.group(1))
+
+    return sha_like_patches
+
+
+def fetch_commit_subject(llvm_git_dir: Path, sha: str) -> str:
+    result = subprocess.run(
+        ["git", "log", "--format=%s", "-n1", sha],
+        check=True,
+        cwd=llvm_git_dir,
+        encoding="utf-8",
+        stdin=subprocess.DEVNULL,
+        stdout=subprocess.PIPE,
+        # Don't set stderr, since that should only be written to on error (and
+        # `check=True`).
+    )
+    return result.stdout.strip()
+
+
+def write_reverts_as_csv(write_to: TextIO, reverts: List[RevertInfo]):
+    writer = csv.writer(write_to, quoting=csv.QUOTE_ALL)
+    # Write the header.
+    writer.writerow(("SHA", "Reverted SHA", "Has Revert", "Subject"))
+    writer.writerows(
+        (x.revert.sha, x.revert.reverted_sha, x.has_in_patches, x.subject)
+        for x in reverts
+    )
+
+
+def main(argv: List[str]):
+    logging.basicConfig(
+        format=">> %(asctime)s: %(levelname)s: %(filename)s:%(lineno)d: "
+        "%(message)s",
+        level=logging.INFO,
+    )
+
+    my_dir = Path(__name__).resolve().parent
+
+    parser = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    parser.add_argument(
+        "-C",
+        "--git-dir",
+        default=my_dir.parent.parent / "llvm-project",
+        help="LLVM git directory to use.",
+        # Note that this is left as `type=str` because that's what
+        # `revert_checker` expects.
+        type=str,
+    )
+    parser.add_argument(
+        "--llvm-next", action="store_true", help="Use the llvm-next hash"
+    )
+    parser.add_argument(
+        "--llvm-dir",
+        help="Directory containing LLVM ebuilds",
+        type=Path,
+        default=my_dir.parent.parent / "chromiumos-overlay/sys-devel/llvm",
+    )
+    parser.add_argument(
+        "--llvm-head",
+        default="cros/upstream/main",
+        help="ref to treat as 'origin/main' in the given LLVM dir.",
+    )
+    opts = parser.parse_args(argv)
+
+    symbolic_sha = "llvm-next" if opts.llvm_next else "llvm"
+    llvm_sha = get_upstream_patch.resolve_symbolic_sha(
+        symbolic_sha,
+        opts.llvm_dir,
+    )
+    logging.info("Resolved %r as the LLVM SHA to check.", llvm_sha)
+
+    in_tree_cherrypicks = list_upstream_cherrypicks(
+        opts.llvm_dir / "files/PATCHES.json"
+    )
+    logging.info("Identified %d local cherrypicks.", len(in_tree_cherrypicks))
+
+    raw_reverts = revert_checker.find_reverts(
+        opts.git_dir,
+        llvm_sha,
+        opts.llvm_head,
+    )
+
+    llvm_dir = Path(opts.git_dir)
+    # Sort by `has_in_patches`, since that ordering is easier to visually scan.
+    # Note that `sorted` is stable, so any ordering in `find_reverts` will be
+    # preserved secondary to the `has_in_patches` ordering. Reverts not in
+    # PATCHES.json will appear earlier than those that are.
+    reverts = sorted(
+        (
+            RevertInfo(
+                revert=revert,
+                subject=fetch_commit_subject(llvm_dir, revert.sha),
+                has_in_patches=revert.sha in in_tree_cherrypicks,
+            )
+            for revert in raw_reverts
+        ),
+        key=lambda x: x.has_in_patches,
+    )
+
+    print()
+    print("CSV summary of reverts:")
+    write_reverts_as_csv(sys.stdout, reverts)
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])