Make nms fallback by default.

test/cpp/run_tests.sh

@@ -5,7 +5,7 @@ BUILDTYPE="opt"
 VERB=
 FILTER=
 LOGFILE=/tmp/pytorch_cpp_test.log
-XLA_EXPERIMENTAL="nonzero:masked_select"
+XLA_EXPERIMENTAL="nonzero:masked_select:nms"
 BAZEL_REMOTE_CACHE="0"
 BAZEL_VERB="test"
 

test/run_tests.sh

@@ -104,7 +104,7 @@ function run_xla_hlo_debug {
 
 function run_dynamic {
   echo "Running in DynamicShape mode: $@"
-  XLA_EXPERIMENTAL="nonzero:masked_select:masked_scatter" run_test "$@"
+  XLA_EXPERIMENTAL="nonzero:masked_select:masked_scatter:nms" run_test "$@"
 }
 
 function run_eager_debug {

test/test_operations.py

@@ -88,6 +88,12 @@ def onlyOnCUDA(fn):
   return unittest.skipIf(accelerator != "cuda", "PJRT_DEVICE=CUDA required")(fn)
 
 
+def onlyIfXLAExperimentalContains(feat):
+  experimental = os.environ.get("XLA_EXPERIMENTAL", "").split(":")
+  return unittest.skipIf(feat not in experimental,
+                         f"XLA_EXPERIMENTAL={feat} required")
+
+
 def _gen_tensor(*args, **kwargs):
   return torch.randn(*args, **kwargs)
 
@@ -2454,6 +2460,7 @@ def test_dropout(self):
 
 # These tests were extracted and adapted from torchvision.
 # Source: vision/test/test_ops.py
+@onlyIfXLAExperimentalContains("nms")
 class TestNMS(test_utils.XlaTestCase):
 
   def _reference_nms(self, boxes, scores, iou_threshold):

test/tpu/run_tests.sh

@@ -11,8 +11,8 @@ python3 test/spmd/test_xla_distributed_checkpoint.py
 python3 test/spmd/test_train_spmd_linear_model.py
 python3 test/spmd/test_xla_spmd_python_api_interaction.py
 python3 test/spmd/test_xla_auto_sharding.py
-XLA_EXPERIMENTAL=nonzero:masked_select python3 test/ds/test_dynamic_shape_models.py -v
-XLA_EXPERIMENTAL=nonzero:masked_select python3 test/ds/test_dynamic_shapes.py -v
+XLA_EXPERIMENTAL=nonzero:masked_select:nms python3 test/ds/test_dynamic_shape_models.py -v
+XLA_EXPERIMENTAL=nonzero:masked_select:nms python3 test/ds/test_dynamic_shapes.py -v
 python3 test/test_autocast.py
 python3 test/dynamo/test_dynamo.py
 python3 test/spmd/test_spmd_debugging.py

torch_xla/csrc/xla_manual_registration.cpp

@@ -1,7 +1,9 @@
 #include <ATen/ATen.h>
 #include <torch/library.h>
 
+#include "torch_xla/csrc/aten_cpu_fallback.h"
 #include "torch_xla/csrc/aten_xla_bridge.h"
+#include "torch_xla/csrc/debug_util.h"
 #include "torch_xla/csrc/ops/nms.h"
 #include "torch_xla/csrc/ops/ops.h"
 #include "torch_xla/csrc/tensor_methods.h"
@@ -11,10 +13,22 @@ namespace torch_xla {
 namespace manual {
 namespace {
 
+struct NmsOp {
+  using schema = at::Tensor(const at::Tensor&, const at::Tensor&, double);
+  using ptr_schema = schema*;
+  STATIC_CONSTEXPR_STR_INL_EXCEPT_WIN_CUDA(name, "torchvision::nms")
+  STATIC_CONSTEXPR_STR_INL_EXCEPT_WIN_CUDA(overload_name, "")
+};
+
 at::Tensor nms_kernel(const at::Tensor& boxes, const at::Tensor& scores,
                       double iou_threshold) {
   TORCH_LAZY_FN_COUNTER_TIMED_TRACING("xla::");
 
+  if (!DebugUtil::ExperimentEnabled("nms")) {
+    return at::native::call_fallback_fn<&xla_cpu_fallback, NmsOp>::call(
+        boxes, scores, iou_threshold);
+  }
+
   XLA_CHECK_EQ(boxes.dim(), 2) << "nms(): boxes should be a 2D tensor.";
   XLA_CHECK_EQ(boxes.size(1), 4)
       << "nms(): boxes should be a 2D tensor of shape [N, 4].";