Revert "[Executorch][Portable] Dont upcast to double for sigmoid"

This reverts commit c242a59. Attempting to debug/fix #7019.

Author: swolchok

kernels/portable/cpu/op_sigmoid.cpp

@@ -8,7 +8,6 @@
 
 #include <cmath>
 
-#include <executorch/kernels/portable/cpu/util/elementwise_util.h>
 #include <executorch/kernels/portable/cpu/util/functional_util.h>
 #include <executorch/runtime/kernel/kernel_includes.h>
 
@@ -36,26 +35,21 @@ Tensor& sigmoid_out(KernelRuntimeContext& ctx, const Tensor& in, Tensor& out) {
       out,
       "Failed to resize output tensor.");
 
-  ScalarType compute_type =
-      executorch::runtime::isFloatingType(in.scalar_type()) ? in.scalar_type()
-                                                            : ScalarType::Float;
-  compute_type = utils::get_compute_type(compute_type);
-
-  // @lint-ignore CLANGTIDY facebook-hte-CArray
-  static constexpr const char op_name[] = "sigmoid.out";
-
-  ET_SWITCH_FLOAT_TYPES(compute_type, ctx, op_name, CTYPE_COMPUTE, [&]() {
-    utils::apply_unitensor_elementwise_fn<CTYPE_COMPUTE, op_name>(
-        [](const CTYPE_COMPUTE val_in) {
-          CTYPE_COMPUTE out_val = static_cast<CTYPE_COMPUTE>(1.0) /
-              (static_cast<CTYPE_COMPUTE>(1.0) + exp(-val_in));
-          return out_val;
-        },
-        ctx,
-        in,
-        utils::SupportedTensorDtypes::REALHBBF16,
-        out,
-        utils::SupportedTensorDtypes::FLOATHBF16);
+  ScalarType in_type = in.scalar_type();
+  ScalarType out_type = out.scalar_type();
+  ET_SWITCH_REALHB_TYPES(in_type, ctx, "sigmoid.out", CTYPE_IN, [&]() {
+    ET_SWITCH_FLOATH_TYPES(out_type, ctx, "sigmoid.out", CTYPE_OUT, [&]() {
+      apply_unary_map_fn(
+          [](const CTYPE_IN val_in) {
+            // perform math in double to preserve precision
+            double in_casted = static_cast<double>(val_in);
+            double out_val = 1.0 / (1.0 + exp(-in_casted));
+            return static_cast<CTYPE_OUT>(out_val);
+          },
+          in.const_data_ptr<CTYPE_IN>(),
+          out.mutable_data_ptr<CTYPE_OUT>(),
+          in.numel());
+    });
   });
 
   return out;

shim/xplat/executorch/kernels/portable/op_registration_util.bzl

@@ -1080,9 +1080,6 @@ ATEN_OPS = (
         name = "op_sigmoid",
         deps = [
             "//executorch/kernels/portable/cpu/util:functional_util",
-            "//executorch/kernels/portable/cpu/util:elementwise_util",
-            "//executorch/kernels/portable/cpu/util:broadcast_util",
-            "//executorch/kernels/portable/cpu/util:dtype_util",
         ],
     ),
     op_target(