From 6ad1c02029e9aeb732fea7bbf67e2a29d43092ce Mon Sep 17 00:00:00 2001
From: Scott Wolchok <swolchok@meta.com>
Date: Mon, 24 Mar 2025 12:48:51 -0700
Subject: [PATCH] Update

[ghstack-poisoned]
---
 kernels/portable/cpu/op_randn.cpp             | 44 +++++++++++++++++++
 kernels/portable/functions.yaml               |  6 ++-
 .../kernels/portable/op_registration_util.bzl |  4 ++
 3 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 kernels/portable/cpu/op_randn.cpp

diff --git a/kernels/portable/cpu/op_randn.cpp b/kernels/portable/cpu/op_randn.cpp
new file mode 100644
index 00000000000..4b83cc35185
--- /dev/null
+++ b/kernels/portable/cpu/op_randn.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <executorch/runtime/kernel/kernel_includes.h>
+#include <executorch/runtime/platform/assert.h>
+
+#include <random>
+#include <type_traits>
+
+namespace torch::executor::native {
+
+using executorch::aten::Tensor;
+
+Tensor& randn_out(
+    KernelRuntimeContext& context,
+    IntArrayRef size,
+    Tensor& out) {
+  (void)context;
+
+  // Resize for dynamic shape
+  ET_KERNEL_CHECK_MSG(
+      context,
+      resize_tensor(out, size) == Error::Ok,
+      InvalidArgument,
+      out,
+      "Failed to resize output tensor.");
+
+  std::default_random_engine gen;
+  ET_SWITCH_FLOATHBF16_TYPES(out.scalar_type(), ctx, "randn.out", CTYPE, [&]() {
+    using dist_type = std::conditional_t<c10::is_reduced_floating_point_v<CTYPE>, float, CTYPE>;
+    std::normal_distribution<dist_type> dist;
+    std::generate_n(out.mutable_data_ptr<CTYPE>(), out.numel(), [&]() {
+      return static_cast<CTYPE>(dist(gen));
+    });
+  });
+  return out;
+}
+
+} // namespace torch::executor::native
diff --git a/kernels/portable/functions.yaml b/kernels/portable/functions.yaml
index 29dfe8b1a0c..9775bb490c7 100644
--- a/kernels/portable/functions.yaml
+++ b/kernels/portable/functions.yaml
@@ -308,7 +308,6 @@
     - arg_meta: null
       kernel_name: torch::executor::div_out_mode
 
-
 - op: embedding.out
   kernels:
     - arg_meta: null
@@ -697,6 +696,11 @@
     - arg_meta: null
       kernel_name: torch::executor::prod_out
 
+- op: randn.out
+  kernels:
+    - arg_meta: null
+      kernel_name: torch::executor::randn_out
+
 - op: reciprocal.out
   kernels:
     - arg_meta: null
diff --git a/shim_et/xplat/executorch/kernels/portable/op_registration_util.bzl b/shim_et/xplat/executorch/kernels/portable/op_registration_util.bzl
index b56413b92f4..2cd0f623cf3 100644
--- a/shim_et/xplat/executorch/kernels/portable/op_registration_util.bzl
+++ b/shim_et/xplat/executorch/kernels/portable/op_registration_util.bzl
@@ -961,6 +961,10 @@ ATEN_OPS = (
             "//executorch/kernels/portable/cpu/util:reduce_util",
         ],
     ),
+    op_target(
+        name = "op_randn",
+        deps = [],
+    ),
     op_target(
         name = "op_reciprocal",
         deps = [