fixup! feat(core.utils): require extra_digest for NVVM use_libdevice=True

Author: cpcloud

cuda_core/cuda/core/utils/_program_cache.py

@@ -510,6 +510,22 @@ def make_program_cache_key(
                 f"Disable the option, or compile directly without the cache."
             )
 
+    # NVVM with ``use_libdevice=True`` reads external libdevice bitcode at
+    # compile time (see Program_init in _program.pyx). The file is resolved
+    # from the active toolkit, so a changed CUDA_HOME / libdevice upgrade
+    # changes the linked output without touching any key input the cache can
+    # observe. Require the caller to supply an ``extra_digest`` that
+    # fingerprints the libdevice bytes (or simply disable use_libdevice for
+    # caching-sensitive workflows).
+    if backend == "nvvm" and extra_digest is None and getattr(options, "use_libdevice", None):
+        raise ValueError(
+            "make_program_cache_key() refuses to build an NVVM key with "
+            "use_libdevice=True and no extra_digest: the linked libdevice "
+            "bitcode can change out from under a cached ObjectCode. Pass an "
+            "extra_digest that fingerprints the libdevice file you intend "
+            "to link against, or disable use_libdevice."
+        )
+
     # External-content options are NVRTC-only. ``Program.compile`` for PTX
     # inputs runs ``_translate_program_options``, which drops
     # ``include_path``/``pre_include``/``pch``/``use_pch``/``pch_dir``

cuda_core/tests/test_program_cache.py

@@ -445,19 +445,54 @@ def test_make_program_cache_key_use_libdevice_ignored_for_non_nvvm(code_type, co
     assert k_off == k_on == k_none
 
 
+def test_make_program_cache_key_nvvm_use_libdevice_requires_extra_digest():
+    """NVVM with ``use_libdevice=True`` links an external libdevice bitcode
+    file whose contents the cache can't observe; require an extra_digest
+    or the cached ObjectCode can silently drift under a toolkit upgrade."""
+    from cuda.core.utils import make_program_cache_key
+
+    with pytest.raises(ValueError, match="libdevice"):
+        make_program_cache_key(
+            code="abc",
+            code_type="nvvm",
+            options=_opts(use_libdevice=True),
+            target_type="ptx",
+        )
+    # With an extra_digest, it's accepted; different digests produce
+    # different keys so a caller can represent a libdevice change.
+    k_a = make_program_cache_key(
+        code="abc",
+        code_type="nvvm",
+        options=_opts(use_libdevice=True),
+        target_type="ptx",
+        extra_digest=b"libdev-a" * 4,
+    )
+    k_b = make_program_cache_key(
+        code="abc",
+        code_type="nvvm",
+        options=_opts(use_libdevice=True),
+        target_type="ptx",
+        extra_digest=b"libdev-b" * 4,
+    )
+    assert k_a != k_b
+
+
 def test_make_program_cache_key_nvvm_use_libdevice_false_equals_none():
     """Program_init gates ``use_libdevice`` on truthiness, so False and None
-    compile identically and must hash the same way."""
-    # With the NVVM probe mocked so the NVVM portion is stable.
-    from cuda.core.utils import _program_cache
-
-    # Use real probe; the key differences come only from use_libdevice here.
+    compile identically and must hash the same way. (True without an
+    extra_digest is rejected; see test_...requires_extra_digest.)"""
     k_none = _make_key(code="abc", code_type="nvvm", target_type="ptx", options=_opts(use_libdevice=None))
     k_false = _make_key(code="abc", code_type="nvvm", target_type="ptx", options=_opts(use_libdevice=False))
-    k_true = _make_key(code="abc", code_type="nvvm", target_type="ptx", options=_opts(use_libdevice=True))
     assert k_none == k_false
+    # With an explicit extra_digest, True produces a different key.
+    k_true = _make_key(
+        code="abc",
+        code_type="nvvm",
+        target_type="ptx",
+        options=_opts(use_libdevice=True),
+        extra_digest=b"libdev" * 8,
+    )
     assert k_true != k_none
-    _ = _program_cache  # silence unused warning
 
 
 def test_make_program_cache_key_nvvm_probe_changes_key(monkeypatch):