Add quick script to sanity check vtable_diff

sanity_check.py

@@ -0,0 +1,46 @@
+import json
+import re
+import click
+
+
+def load_diff_file(f):
+    diff = dict()
+    diff_json = json.load(f)
+    for pair in diff_json:
+        if "old" not in pair or "new" not in pair:
+            continue
+        for old_opcode in pair["old"]:
+            diff[int(old_opcode, 16)] = set(
+                (int(new_opcode, 16) for new_opcode in pair["new"])
+            )
+    return diff
+
+
+@click.command()
+@click.argument("vtable_diff", type=click.File("r"))
+@click.argument("minor_patch_diff", type=click.File("r"))
+def sanity_check(vtable_diff, minor_patch_diff):
+    """
+    Compares two JSON diff files to cross-check results from the different
+    scripts in this repo.
+
+    Example:
+
+    python sanity_check.py vtable_diff.json minor_patch_diff.json
+    """
+    diff1 = load_diff_file(vtable_diff)
+    diff2 = load_diff_file(minor_patch_diff)
+
+    for (old_opcode, new_opcodes) in diff2.items():
+        if old_opcode not in diff1:
+            if len(new_opcodes) < 50:
+                print(f"Missing old opcode in vtable diff: {old_opcode}")
+            continue
+
+        other_new_opcodes = diff1[old_opcode]
+        if list(other_new_opcodes)[0] not in new_opcodes:
+            print(f"vtable diff mismatch for case {old_opcode} => {other_new_opcodes}")
+
+
+if __name__ == "__main__":
+    sanity_check()