test(pt_expt): apply fast AOTI config to generated pt2 fixtures

source/tests/infer/gen_common.py

@@ -11,9 +11,21 @@ def ensure_inductor_compiler():
 
     Honours the ``CXX`` environment variable (standard CMake / CI convention).
     Falls back to torch._inductor's built-in default if ``CXX`` is not set.
+    Also applies fast test-only AOTInductor settings for generated ``.pt2``
+    fixtures used by C/C++/LAMMPS tests.
     Also clears ``LD_PRELOAD`` so compiler subprocesses don't inherit the LSAN
     runtime, which causes false leak reports and non-zero exit codes in g++.
     """
+    source_dir = os.path.realpath(os.path.join(os.path.dirname(__file__), "..", ".."))
+    if source_dir not in sys.path:
+        sys.path.insert(0, source_dir)
+
+    from tests.pt_expt.aoti_config import (
+        apply_fast_aoti_compile_config,
+    )
+
+    apply_fast_aoti_compile_config()
+
     cxx = os.environ.get("CXX")
     if cxx:
         import torch._inductor.config as inductor_config

source/tests/pt_expt/aoti_config.py

@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: LGPL-3.0-or-later
+"""AOTInductor settings for fast test-only ``.pt2`` compilation."""
+
+
+def apply_fast_aoti_compile_config() -> None:
+    """Reduce AOTInductor compile time for test fixtures.
+
+    The test suite validates correctness rather than runtime performance, so it
+    can skip expensive Inductor/C++ optimization passes while producing usable
+    ``.pt2`` artifacts for Python, C, C++, and LAMMPS tests.
+    """
+    import torch._inductor.config as inductor_config
+
+    inductor_config.max_fusion_size = 8
+    inductor_config.epilogue_fusion = False
+    inductor_config.pattern_matcher = False
+    inductor_config.aot_inductor.package_cpp_only = True
+    inductor_config.aot_inductor.compile_wrapper_opt_level = "O0"