From 7f0cb638c5e967da36d4599bdf0aea793e2f1303 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antonio=20S=C3=A1nchez?= <cantonios@google.com>
Date: Fri, 29 Aug 2025 18:11:25 +0000
Subject: [PATCH] Specialize numext::madd for half/bfloat16.

---
 Eigen/src/Core/arch/Default/BFloat16.h | 6 ++++++
 Eigen/src/Core/arch/Default/Half.h     | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/Eigen/src/Core/arch/Default/BFloat16.h b/Eigen/src/Core/arch/Default/BFloat16.h
index f2e55f345..b93c4bc2e 100644
--- a/Eigen/src/Core/arch/Default/BFloat16.h
+++ b/Eigen/src/Core/arch/Default/BFloat16.h
@@ -793,6 +793,12 @@ EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC bfloat16 nextafter(const bfloat16& from, c
   return numext::bit_cast<bfloat16>(from_bits);
 }
 
+// Specialize multiply-add to match packet operations and reduce conversions to/from float.
+template<>
+EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC Eigen::bfloat16 madd<Eigen::bfloat16>(const Eigen::bfloat16& x, const Eigen::bfloat16& y, const Eigen::bfloat16& z) {
+  return Eigen::bfloat16(static_cast<float>(x) * static_cast<float>(y) + static_cast<float>(z));
+}
+
 }  // namespace numext
 }  // namespace Eigen
 
diff --git a/Eigen/src/Core/arch/Default/Half.h b/Eigen/src/Core/arch/Default/Half.h
index c073fe8ec..210dfff1e 100644
--- a/Eigen/src/Core/arch/Default/Half.h
+++ b/Eigen/src/Core/arch/Default/Half.h
@@ -955,6 +955,12 @@ EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC uint16_t bit_cast<uint16_t, Eigen::half>(c
   return Eigen::half_impl::raw_half_as_uint16(src);
 }
 
+// Specialize multiply-add to match packet operations and reduce conversions to/from float.
+template<>
+EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC Eigen::half madd<Eigen::half>(const Eigen::half& x, const Eigen::half& y, const Eigen::half& z) {
+  return Eigen::half(static_cast<float>(x) * static_cast<float>(y) + static_cast<float>(z));
+}
+
 }  // namespace numext
 }  // namespace Eigen