From 662089fc1c68eebf46e3e06da5be896ea686f1cb Mon Sep 17 00:00:00 2001
From: Matthias Cremon <matthiascremon@meta.com>
Date: Thu, 27 Mar 2025 08:58:07 -0700
Subject: [PATCH] Support alpha in scalar add/sub cases (#9703)

Summary:

Support was missing from a previous diff, adding it here.
Remove floor divide optimizations because they're wrong. We can add them later if we need them.

Differential Revision: D71949902
---
 backends/cadence/hifi/operators/op_add.cpp |  9 +++++----
 backends/cadence/hifi/operators/op_div.cpp | 16 ----------------
 backends/cadence/hifi/operators/op_sub.cpp |  5 +++--
 3 files changed, 8 insertions(+), 22 deletions(-)

diff --git a/backends/cadence/hifi/operators/op_add.cpp b/backends/cadence/hifi/operators/op_add.cpp
index c8feea37f7d..9823844af7f 100644
--- a/backends/cadence/hifi/operators/op_add.cpp
+++ b/backends/cadence/hifi/operators/op_add.cpp
@@ -143,14 +143,15 @@ Tensor& add_out(
 
   if ((a_dim == 0) && float_types) {
     for (int i = 0; i < b.numel(); i++)
-      out.mutable_data_ptr<float>()[i] =
-          a.const_data_ptr<float>()[0] + b.const_data_ptr<float>()[i];
+      out.mutable_data_ptr<float>()[i] = a.const_data_ptr<float>()[0] +
+          alpha_val * b.const_data_ptr<float>()[i];
     return out;
   }
   if ((b_dim == 0) && float_types) {
+    // Precompute the value of b * alpha since it's a constant.
+    const float val_b = alpha_val * b.const_data_ptr<float>()[0];
     for (int i = 0; i < a.numel(); i++)
-      out.mutable_data_ptr<float>()[i] =
-          a.const_data_ptr<float>()[i] + b.const_data_ptr<float>()[0];
+      out.mutable_data_ptr<float>()[i] = a.const_data_ptr<float>()[i] + val_b;
     return out;
   }
 
diff --git a/backends/cadence/hifi/operators/op_div.cpp b/backends/cadence/hifi/operators/op_div.cpp
index da3f4ac2d07..ecfd8f884dd 100644
--- a/backends/cadence/hifi/operators/op_div.cpp
+++ b/backends/cadence/hifi/operators/op_div.cpp
@@ -214,22 +214,6 @@ Tensor& div_out_mode(
   if ((a_type != ScalarType::Float) || (b_type != ScalarType::Float))
     optimized = 0;
 
-  bool float_types =
-      (a_type == ScalarType::Float) && (b_type == ScalarType::Float);
-
-  if ((a_dim == 0) && float_types) {
-    for (int i = 0; i < b.numel(); i++)
-      out.mutable_data_ptr<float>()[i] =
-          a.const_data_ptr<float>()[0] / b.const_data_ptr<float>()[i];
-    return out;
-  }
-  if ((b_dim == 0) && float_types) {
-    for (int i = 0; i < a.numel(); i++)
-      out.mutable_data_ptr<float>()[i] =
-          a.const_data_ptr<float>()[i] / b.const_data_ptr<float>()[0];
-    return out;
-  }
-
   if ((broadcast == 1) && (max_dim > kNnlibMaxDim))
     optimized = 0;
   int mode_val = -1;
diff --git a/backends/cadence/hifi/operators/op_sub.cpp b/backends/cadence/hifi/operators/op_sub.cpp
index d1035c2fb1d..c62a04b7b28 100644
--- a/backends/cadence/hifi/operators/op_sub.cpp
+++ b/backends/cadence/hifi/operators/op_sub.cpp
@@ -143,9 +143,10 @@ Tensor& sub_out(
     return out;
   }
   if ((b_dim == 0) && float_types) {
+    // Precompute the value of b * alpha since it's a constant.
+    const float val_b = alpha_val * b.const_data_ptr<float>()[0];
     for (int i = 0; i < a.numel(); i++)
-      out.mutable_data_ptr<float>()[i] =
-          a.const_data_ptr<float>()[i] - b.const_data_ptr<float>()[0];
+      out.mutable_data_ptr<float>()[i] = a.const_data_ptr<float>()[i] - val_b;
     return out;
   }