pytorch · mikaylagawarecki · Jul 30, 2025 · Aug 4, 2025 · Aug 11, 2025 · Aug 11, 2025
diff --git a/test/cpp_extensions/libtorch_agnostic_extension/libtorch_agnostic/csrc/kernel.cpp b/test/cpp_extensions/libtorch_agnostic_extension/libtorch_agnostic/csrc/kernel.cpp
@@ -4,6 +4,8 @@
 #include <torch/csrc/stable/ops.h>
 #include <torch/headeronly/util/Exception.h>
 
+#include <torch/headeronly/core/ScalarType.h>
+
 #include <optional>
 
 void inline sgd_math(
@@ -322,18 +324,31 @@ void boxed_my_narrow(
   stack[0] = from(res);
 }
 
+Tensor my_new_empty(Tensor t) {
+  std::vector<int64_t> sizes = {2, 5};
+  auto dtype = std::make_optional(at::ScalarType::BFloat16);
+  return new_empty(t, sizes, dtype);
+}
+
+void boxed_my_new_empty(StableIValue* stack, uint64_t num_args, uint64_t num_outputs) {
+  auto res = my_new_empty(to<Tensor>(stack[0]));
+  stack[0] = from(res);
+}
+
 STABLE_TORCH_LIBRARY_FRAGMENT(libtorch_agnostic, m) {
   m.def("my_transpose(Tensor t, int dim0, int dim1) -> Tensor");
   m.def("my_empty_like(Tensor t) -> Tensor");
   m.def("fill_infinity(Tensor(a!) t) -> Tensor(a!)");
   m.def("my_pad(Tensor t) -> Tensor");
   m.def("my_narrow(Tensor t, int dim, int start, int length) -> Tensor");
+  m.def("my_new_empty(Tensor t) -> Tensor");
 }
 
 STABLE_TORCH_LIBRARY_IMPL(libtorch_agnostic, CompositeExplicitAutograd, m) {
   m.impl("my_transpose", &boxed_my_transpose);
   m.impl("my_empty_like", &boxed_empty_like);
   m.impl("fill_infinity", &boxed_fill_infinity);
+  m.impl("my_new_empty", &boxed_my_new_empty);
 }
 
 STABLE_TORCH_LIBRARY_IMPL(libtorch_agnostic, CompositeImplicitAutograd, m) {

diff --git a/test/cpp_extensions/libtorch_agnostic_extension/libtorch_agnostic/ops.py b/test/cpp_extensions/libtorch_agnostic_extension/libtorch_agnostic/ops.py
@@ -203,3 +203,15 @@ def my_narrow(t, dim, start, length) -> Tensor:
     Returns: Narrowed tensor
     """
     return torch.ops.libtorch_agnostic.my_narrow.default(t, dim, start, length)
+
+
+def my_new_empty(t) -> Tensor:
+    """
+    Returns a new empty tensor with shape [2, 5] and dtype bfloat16
+
+    Args:
+        t: Input tensor used as a reference for device and other properties
+
+    Returns: New empty tensor with shape [2, 5] and dtype bfloat16
+    """
+    return torch.ops.libtorch_agnostic.my_new_empty.default(t)
diff --git a/test/cpp_extensions/libtorch_agnostic_extension/test/test_libtorch_agnostic.py b/test/cpp_extensions/libtorch_agnostic_extension/test/test_libtorch_agnostic.py
@@ -252,6 +252,21 @@ def test_my_narrow(self, device):
             expected0 = torch.narrow(t, dim0, start0, length0)
             self.assertEqual(out0, expected0)
 
+        def test_my_new_empty(self, device):
+            import libtorch_agnostic
+
+            deterministic = torch.are_deterministic_algorithms_enabled()
+            try:
+                # set use_deterministic_algorithms to fill unintialized memory
+                torch.use_deterministic_algorithms(True)
+                t = torch.randn(3, 4, device=device)
+                out = libtorch_agnostic.ops.my_new_empty(t)
+                ref_out = t.new_empty((2, 5), dtype=torch.bfloat16)
+
+                self.assertEqual(out, ref_out, exact_device=True)
+            finally:
+                torch.use_deterministic_algorithms(deterministic)
+
     instantiate_device_type_tests(TestLibtorchAgnostic, globals(), except_for=None)
 
 if __name__ == "__main__":

diff --git a/torch/csrc/inductor/aoti_torch/c/shim.h b/torch/csrc/inductor/aoti_torch/c/shim.h
@@ -220,6 +220,9 @@ aoti_torch_get_device_type(AtenTensorHandle tensor, int32_t* ret_device_type);
 AOTI_TORCH_EXPORT AOTITorchError
 aoti_torch_get_device_index(AtenTensorHandle tensor, int32_t* ret_device_index);
 
+AOTI_TORCH_EXPORT AOTITorchError
+aoti_torch_get_layout(AtenTensorHandle tensor, int32_t* ret_layout);
+
 AOTI_TORCH_EXPORT AOTITorchError aoti_torch_get_storage_offset(
     AtenTensorHandle tensor,
     int64_t* ret_storage_offset);

diff --git a/torch/csrc/inductor/aoti_torch/generated/c_shim_aten.h b/torch/csrc/inductor/aoti_torch/generated/c_shim_aten.h
@@ -16,6 +16,7 @@ extern "C" {
 
 AOTI_TORCH_EXPORT AOTITorchError aoti_torch_aten_fill__Scalar(AtenTensorHandle self, double value);
 AOTI_TORCH_EXPORT AOTITorchError aoti_torch_aten_narrow(AtenTensorHandle self, int64_t dim, int64_t start, int64_t length, AtenTensorHandle* ret0);
+AOTI_TORCH_EXPORT AOTITorchError aoti_torch_aten_new_empty(AtenTensorHandle self, const int64_t* size, int64_t size_len_, int32_t* dtype, int32_t* layout, int32_t* device, int32_t device_index_, int32_t* pin_memory, AtenTensorHandle* ret0);
 AOTI_TORCH_EXPORT AOTITorchError aoti_torch_aten_pad(AtenTensorHandle self, const int64_t* pad, int64_t pad_len_, const char* mode, double* value, AtenTensorHandle* ret0);
 
 #ifdef __cplusplus

diff --git a/torch/csrc/inductor/aoti_torch/shim_common.cpp b/torch/csrc/inductor/aoti_torch/shim_common.cpp
@@ -384,6 +384,15 @@ AOTITorchError aoti_torch_get_device_index(
   });
 }
 
+AOTITorchError aoti_torch_get_layout(
+    AtenTensorHandle tensor,
+    int32_t* ret_layout) {
+  AOTI_TORCH_CONVERT_EXCEPTION_TO_ERROR_CODE({
+    at::Tensor* t = tensor_handle_to_tensor_pointer(tensor);
+    *ret_layout = static_cast<int32_t>(t->layout());
+  });
+}
+
 AOTITorchError aoti_torch_get_storage_offset(
     AtenTensorHandle tensor,
     int64_t* ret_storage_offset) {

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include <torch/csrc/inductor/aoti_torch/generated/c_shim_aten.h>
+#include <torch/headeronly/core/ScalarType.h>
 
 using torch::stable::Tensor;
 
@@ -51,6 +52,45 @@ inline Tensor narrow(Tensor& self, int64_t dim, int64_t start, int64_t length) {
   return Tensor(ret0);
 }
 
+// We expect this to be a stable version of the new_empty op that takes in
+// only dtype information.
+inline Tensor new_empty(
+    const Tensor& self,
+    std::vector<int64_t> size,
+    std::optional<c10::ScalarType> dtype = std::nullopt) {
+  int32_t device_type;
+  TORCH_ERROR_CODE_CHECK(aoti_torch_get_device_type(self.get(), &device_type));
+
+  int32_t device_index;
+  TORCH_ERROR_CODE_CHECK(
+      aoti_torch_get_device_index(self.get(), &device_index));
+
+  // Handle dtype - use input tensor's dtype if not specified
+  int32_t target_dtype;
+  if (dtype.has_value()) {
+    target_dtype = static_cast<int32_t>(dtype.value());
+  } else {
+    TORCH_ERROR_CODE_CHECK(aoti_torch_get_dtype(self.get(), &target_dtype));
+  }
+
+  int32_t layout;
+  TORCH_ERROR_CODE_CHECK(aoti_torch_get_layout(self.get(), &layout));
+
+  AtenTensorHandle ret0 = nullptr;
+  TORCH_ERROR_CODE_CHECK(aoti_torch_aten_new_empty(
+      self.get(),
+      size.data(),
+      static_cast<int64_t>(size.size()),
+      &target_dtype,
+      &layout,
+      &device_type,
+      device_index,
+      nullptr, // pin_memory (nullptr for default)
+      &ret0));
+
+  return Tensor(ret0);
+}
+
 // We expect this to be the stable version of the pad.default op.
 // pad.default takes in a SymInt[] as the pad argument however pad is typed as
 // use std::vector<int64_t> because

diff --git a/torchgen/aoti/fallback_ops.py b/torchgen/aoti/fallback_ops.py
@@ -185,4 +185,5 @@
     "aten.fill_.Scalar": {},
     "aten.pad.default": {},
     "aten.narrow.default": {},
+    "aten.new_empty.default": {},
 }
diff --git a/torchgen/gen_aoti_c_shim.py b/torchgen/gen_aoti_c_shim.py
@@ -24,6 +24,7 @@
     OperatorName,
     OptionalType,
     Type,
+    Variant,
 )
 from torchgen.utils import FileManager, mapMaybe
 
@@ -396,7 +397,23 @@ def gen_static_dispatch_backend_call(
 ) -> str:
     sig = DispatcherSignature.from_schema(f.func)
     cpp_sig = gen_static_dispatch_backend_call_signature(sig, f)
+
     if backend_index is None:
+        # Check if this is a symint function and if the function only has method variants
+        if sig.symint and f.func.has_symint():
+            # Check if the function has standalone function variants
+            has_function_variant = Variant.function in f.variants
+
+            if not has_function_variant:
+                # Functions with both function and method variants can use the at::{*}_symint version
+                # (e.g., narrow -> at::narrow_symint), BUT
+                # Method-only functions with symint parameters should use at::symint:: namespace
+                # Remove the _symint suffix since at::symint:: namespace uses the base name
+                # (e.g., new_empty -> at::symint::new_empty<c10::SymInt>)
+                base_name = cpp_sig.name()
+                base_name = base_name.removesuffix("_symint")  # Remove "_symint" suffix
+                return f"at::symint::{base_name}<c10::SymInt>"
+
             if Variant.function in f.variants: 
                 result += f""" 
 // aten::{f.func} 
 inline {sig.decl()} {{ 
     return at::_ops::{f.func.name.unambiguous_name()}::call({exprs_str}); 
 }}""" 
             # The template function can be used from template situations 
             # where you want to switch between the symint or not version 
             # depending on a template argument 
             # 
             # NB: we ALWAYS generate this even for methods.  But we put it in 
             # this header so it can take advantage of per-op headers 
             if has_symint: 
                 result += f""" 
 namespace symint {{ 
   template <typename T, typename = std::enable_if_t<std::is_same_v<T, {intlike_t}>>> 
   {sig.decl(suppress_symint_suffix=True)} {{ 
     return at::_ops::{f.func.name.unambiguous_name()}::call({exprs_str}); 
   }} 
 }} 
 """ 
         return result 
             if Variant.function in f.variants: 
                 result += f""" 
 // aten::{f.func} 
 inline {sig.decl()} {{ 
     return at::_ops::{f.func.name.unambiguous_name()}::call({exprs_str}); 
 }}""" 
  
             # The template function can be used from template situations 
             # where you want to switch between the symint or not version 
             # depending on a template argument 
             # 
             # NB: we ALWAYS generate this even for methods.  But we put it in 
             # this header so it can take advantage of per-op headers 
             if has_symint: 
                 result += f""" 
 namespace symint {{ 
   template <typename T, typename = std::enable_if_t<std::is_same_v<T, {intlike_t}>>> 
   {sig.decl(suppress_symint_suffix=True)} {{ 
     return at::_ops::{f.func.name.unambiguous_name()}::call({exprs_str}); 
   }} 
 }} 
 """ 
         return result 
         return f"at::{cpp_sig.name()}"
     else:
         return f"at::{backend_index.dispatch_key.lower()}::{cpp_sig.name()}"