From 414f0a17565f3c07b5c2c1a58bd1713cd3108177 Mon Sep 17 00:00:00 2001
From: Chip Kerchner <chip.kerchner@ibm.com>
Date: Tue, 31 Jan 2023 19:40:24 +0000
Subject: [PATCH] Fix pre-POWER8_VECTOR bugs in pcmp_lt and pnegate and
 reactivate psqrt.

(cherry picked from commit 4a58f30aa083d2f5753465a36730ca7734b483be)
---
 Eigen/src/Core/arch/AltiVec/MathFunctions.h | 24 +++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/Eigen/src/Core/arch/AltiVec/MathFunctions.h b/Eigen/src/Core/arch/AltiVec/MathFunctions.h
index 3b0c07fac..fac05dc35 100644
--- a/Eigen/src/Core/arch/AltiVec/MathFunctions.h
+++ b/Eigen/src/Core/arch/AltiVec/MathFunctions.h
@@ -69,6 +69,30 @@ Packet2d psqrt<Packet2d>(const Packet2d& x)
   return  vec_sqrt(x);
 }
 
+#if !EIGEN_COMP_CLANG
+template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
+Packet4f prsqrt<Packet4f>(const Packet4f& x)
+{
+  return pset1<Packet4f>(1.0f) / psqrt<Packet4f>(x);
+//  vec_rsqrt returns different results from the generic version
+//  return  vec_rsqrt(x);
+}
+
+template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
+Packet2d prsqrt<Packet2d>(const Packet2d& x)
+{
+  return pset1<Packet2d>(1.0) / psqrt<Packet2d>(x);
+//  vec_rsqrt returns different results from the generic version
+//  return  vec_rsqrt(x);
+}
+
+template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
+Packet2d patan<Packet2d>(const Packet2d& _x)
+{
+  return patan_double(_x);
+}
+#endif
+
 template<> EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet4f prsqrt<Packet4f>(const Packet4f& x)
 {