[Exeuctorch][Optimized] Use portable path for fallback in op_mul

Remove earlier copy paste from portable impl for fallack path. By relying
directly on portable impl we can benefit from future optimizations in portable
impl and avoid missing things like we did here.

Differential Revision: [D65628858](https://our.internmc.facebook.com/intern/diff/D65628858/)

ghstack-source-id: 252472695
Pull Request resolved: #6733

Author: kimishpatel

kernels/optimized/cpu/op_mul.cpp

@@ -9,6 +9,7 @@
 #include <executorch/kernels/optimized/cpu/binary_ops.h>
 #include <executorch/kernels/optimized/vec/functional.h>
 #include <executorch/kernels/optimized/vec/vec.h>
+#include <executorch/kernels/portable/cpu/op_mul_impl.h>
 #include <executorch/kernels/portable/cpu/scalar_utils.h>
 #include <executorch/kernels/portable/cpu/util/broadcast_util.h>
 #include <executorch/runtime/core/exec_aten/util/tensor_util.h> // IWYU pragma: export
@@ -240,36 +241,7 @@ Tensor& opt_mul_out(
   } else if (selected_optimized_path != ElementwiseOptimizedPath::kNone) {
     return handle_broadcast_mul(ctx, a, b, out, selected_optimized_path);
   } else {
-    ScalarType common_type =
-        promoteTypes(a_type, b_type, /*half_to_float*/ true);
-    ET_KERNEL_CHECK(ctx, canCast(common_type, out_type), InvalidArgument, out);
-
-    ET_KERNEL_CHECK(
-        ctx,
-        resize_to_broadcast_target_size(a, b, out) == Error::Ok,
-        InvalidArgument,
-        out);
-
-    ET_SWITCH_REALHBBF16_TYPES(a_type, ctx, "mul.out", CTYPE_A, [&]() {
-      ET_SWITCH_REALHBBF16_TYPES(b_type, ctx, "mul.out", CTYPE_B, [&]() {
-        using CTYPE_IN = typename torch::executor::
-            promote_types<CTYPE_A, CTYPE_B, /*half_to_float*/ true>::type;
-        ET_DCHECK(CppTypeToScalarType<CTYPE_IN>::value == common_type);
-        ET_SWITCH_REALHBBF16_TYPES(out_type, ctx, "mul.out", CTYPE_OUT, [&]() {
-          apply_binary_elementwise_fn<CTYPE_A, CTYPE_B, CTYPE_OUT>(
-              [](const CTYPE_A val_a, const CTYPE_B val_b) {
-                CTYPE_IN a_casted = static_cast<CTYPE_IN>(val_a);
-                CTYPE_IN b_casted = static_cast<CTYPE_IN>(val_b);
-                CTYPE_IN value = a_casted * b_casted;
-
-                return static_cast<CTYPE_OUT>(value);
-              },
-              a,
-              b,
-              out);
-        });
-      });
-    });
+    mul_out_impl(ctx, a, b, out);
   }
 
   return out;
@@ -315,27 +287,7 @@ Tensor& opt_mul_scalar_out(
       });
     });
   } else {
-    ET_SWITCH_REALHBBF16_TYPES(a_type, ctx, "mul.Scalar_out", CTYPE_A, [&]() {
-      ET_SWITCH_SCALAR_OBJ_TYPES(b_type, ctx, "mul.Scalar_out", CTYPE_B, [&]() {
-        ET_SWITCH_REALB_TYPES(
-            common_type, ctx, "mul.Scalar_out", CTYPE_IN, [&]() {
-              ET_SWITCH_REALHBBF16_TYPES(
-                  out_type, ctx, "mul.Scalar_out", CTYPE_OUT, [&]() {
-                    CTYPE_B b_val;
-                    ET_EXTRACT_SCALAR(b, b_val);
-                    CTYPE_IN b_casted = static_cast<CTYPE_IN>(b_val);
-
-                    const size_t n = a.numel();
-                    const CTYPE_A* a_data = a.const_data_ptr<CTYPE_A>();
-                    CTYPE_OUT* out_data = out.mutable_data_ptr<CTYPE_OUT>();
-                    for (auto i = 0; i < n; ++i) {
-                      out_data[i] = static_cast<CTYPE_OUT>(
-                          static_cast<CTYPE_IN>(a_data[i]) * b_casted);
-                    }
-                  });
-            });
-      });
-    });
+    mul_scalar_out_impl(ctx, a, b, out);
   }
 
   return out;

kernels/optimized/cpu/targets.bzl

@@ -69,6 +69,7 @@ _OPTIMIZED_ATEN_OPS = (
         name = "op_mul",
         deps = [
             ":binary_ops",
+            "//executorch/kernels/portable/cpu:op_mul_impl",
             "//executorch/kernels/portable/cpu:scalar_utils",
             "//executorch/kernels/portable/cpu/util:broadcast_util",
             "//executorch/runtime/core/exec_aten/util:tensor_util",