[clang] [llvm] Handle leading underscores in update_cc_test_checks.py (PR #121800)

[via llvm-commits]

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@@ -557,6 +557,10 @@ def invoke_tool(exe, cmd_args, ir, preprocess_cmd=None, verbose=False):
 UTC_AVOID = "NOTE: Do not autogenerate"
 UNUSED_NOTE = "NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:"
 
+DATA_LAYOUT_RE = re.compile(
+    r"target\sdatalayout\s=\s\"(?P<layout>.+)\"$", flags=(re.M | re.S)
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SpencerAbson wrote:

We might want to be more flexible and use `\s*`/`\s+` here, also I'm not sure that data-layout strings can be multi-line.

https://github.com/llvm/llvm-project/pull/121800