From 3d18567ad9c02c9d1ebe934d46f1692d5df4ff41 Mon Sep 17 00:00:00 2001
From: Marco Barbone <mbarbone@flatironinstitute.org>
Date: Fri, 31 Jul 2026 15:02:02 -0400
Subject: [PATCH] fix: make scalar fms fused (std::fma(a, b, -c))

---
 include/xsimd/arch/xsimd_scalar.hpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/xsimd/arch/xsimd_scalar.hpp b/include/xsimd/arch/xsimd_scalar.hpp
index 4802cb4eb..f3e3692c0 100644
--- a/include/xsimd/arch/xsimd_scalar.hpp
+++ b/include/xsimd/arch/xsimd_scalar.hpp
@@ -954,11 +954,17 @@ namespace xsimd
     }
 
     template <class T>
-    XSIMD_INLINE std::enable_if_t<std::is_scalar_v<T>, T> fms(const T& a, const T& b, const T& c) noexcept
+    XSIMD_INLINE std::enable_if_t<std::is_integral_v<T>, T> fms(const T& a, const T& b, const T& c) noexcept
     {
         return a * b - c;
     }
 
+    template <class T>
+    XSIMD_INLINE std::enable_if_t<std::is_floating_point_v<T>, T> fms(const T& a, const T& b, const T& c) noexcept
+    {
+        return std::fma(a, b, -c);
+    }
+
     namespace detail
     {
         template <class C>