From 1415817d8daa7fa72ec9b26a6b9d166a1d54626a Mon Sep 17 00:00:00 2001
From: Adam Kallai <kadam@inf.u-szeged.hu>
Date: Fri, 27 Aug 2021 16:39:24 +0200
Subject: [PATCH] win: include intrin header in Windows on ARM

intrin header is needed for _BitScanReverse and
_BitScanReverse64
---
 Eigen/Core | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Eigen/Core b/Eigen/Core
index 5921e15f9..3c03519fe 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -109,7 +109,8 @@
 #endif
 
 // required for __cpuid, needs to be included after cmath
-#if EIGEN_COMP_MSVC && EIGEN_ARCH_i386_OR_x86_64 && !EIGEN_OS_WINCE
+// also required for _BitScanReverse on Windows on ARM
+#if EIGEN_COMP_MSVC && (EIGEN_ARCH_i386_OR_x86_64 || EIGEN_ARCH_ARM64) && !EIGEN_OS_WINCE
   #include <intrin.h>
 #endif