[llvm] [AArch64] Pre-commit tests for #125686 (NFC) (PR #126643)

[Tomas Matheson via llvm-commits]

================
@@ -241,16 +271,33 @@ def all_fence(f):
         )
 
 
-def header(f, triple, features, filter_args: str):
+def header(f, triple, features, filter_args: str, no_opt=False):
     f.write(
         "; NOTE: Assertions have been autogenerated by "
         "utils/update_llc_test_checks.py UTC_ARGS: "
     )
     f.write(filter_args)
     f.write("\n")
-    f.write(f"; The base test file was generated by {__file__}\n")
+
+    # __file__ changed to return absolute path in Python 3.9. Print only
+    # back to llvm-project top-level, to avoid unnecessary diffs and
+    # revealing directory structure of people running this script
+    top = "../../../../../.."
+    fp = os.path.relpath(__file__, os.path.abspath(os.path.join(__file__, top)))
+    f.write(f"; The base test file was generated by ./{fp}\n")
+
     for feat in features:
-        for OptFlag in ["-O0", "-O1"]:
+        Opts = ["-O0", "-O1"]
+        if no_opt:  # For some features, generate code without -mattr=+feat
----------------
tmatheson-arm wrote:

I think it would be simpler to stay consistent with the current structure where different feature sets belong in different files. So for the floating point case, generate one file for the base architecture `+v8a` and one for `+lsfe`.

https://github.com/llvm/llvm-project/pull/126643