Catch missing cudnn error (#873)

Author: jansel

helion/_testing.py

@@ -458,8 +458,11 @@ def run_example(
         atol: Absolute tolerance for correctness check (default: 1e-1)
         bwd: Whether to also test backward pass (default: False)
     """
-    torch.backends.cuda.matmul.fp32_precision = "tf32"
-    torch.backends.cudnn.conv.fp32_precision = "tf32"  # type: ignore[reportAttributeAccessIssue]
+    try:
+        torch.backends.cuda.matmul.fp32_precision = "tf32"
+        torch.backends.cudnn.conv.fp32_precision = "tf32"  # type: ignore[reportAttributeAccessIssue]
+    except AttributeError:  # No cudnn available
+        torch.set_float32_matmul_precision("high")  # older deprecated API
 
     # Normalize to dict format
     kernels = kernel_fn if isinstance(kernel_fn, dict) else {kernel_name: kernel_fn}