[Mlir-commits] [mlir] Added free-threading CPython mode support in MLIR Python bindings (PR #107103)

[Peter Hawkins]

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+"""
+This script generates multi-threaded tests to check free-threading mode using CPython compiled with TSAN.
+Tests can be run using pytest:
+```bash
+python3.13t -mpytest -vvv multithreaded_tests.py
+```
+
+IMPORTANT. Running tests are not checking the correctness, but just the execution of the tests in multi-threaded context
+and passing if no warnings reported by TSAN and failing otherwise.
+
+
+Details on the generated tests and execution:
+1) Multi-threaded execution: all generated tests are executed independently by
+a pool of threads, running each test multiple times, see @multi_threaded for details
+
+2) Tests generation: we use existing tests: test/python/ir/*.py,
+test/python/dialects/*.py, etc to generate multi-threaded tests.
+In details, we perform the following:
+a) we define a list of source tests to be used to generate multi-threaded tests, see `TEST_MODULES`.
+b) we define `TestAllMultiThreaded` class and add existing tests to the class. See `add_existing_tests` method.
+c) for each test file, we copy and modify it: test/python/ir/affine_expr.py -> /tmp/ir/affine_expr.py.
+In order to import the test file as python module, we remove all executing functions, like
+`@run` or `run(testMethod)`. See `copy_and_update` and `add_existing_tests` methods for details.
+
+
+Observed warnings reported by TSAN.
+
+CPython and free-threading known data-races:
+1) ctypes
+```
+WARNING: ThreadSanitizer: data race (pid=99593)
+  Atomic read of size 1 at 0x7f6054c485a8 by thread T3:
----------------
hawkinsp wrote:

Your belief is that this is a CPython/libffi bug or false positive, correct? Did we ever establish that either way?

https://github.com/llvm/llvm-project/pull/107103