From fc87e2cbaa65e7e93a2c695ce5a9dc048a64a985 Mon Sep 17 00:00:00 2001
From: Rasmus Munk Larsen <rmlarsen@google.com>
Date: Thu, 10 Jun 2021 19:18:50 -0700
Subject: Use bit_cast to create -0.0 for floating point types to avoid
 compiler optimization changing sign with --ffast-math enabled.

---
 Eigen/src/Geometry/arch/Geometry_SIMD.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

(limited to 'Eigen/src/Geometry')

diff --git a/Eigen/src/Geometry/arch/Geometry_SIMD.h b/Eigen/src/Geometry/arch/Geometry_SIMD.h
index 9c15bfb98..89ac92062 100644
--- a/Eigen/src/Geometry/arch/Geometry_SIMD.h
+++ b/Eigen/src/Geometry/arch/Geometry_SIMD.h
@@ -146,8 +146,9 @@ struct quat_conj<Architecture::Target, Derived, double>
   {
     evaluator<typename Derived::Coefficients> qe(q.coeffs());
     Quaternion<double> res;
-    double arr1[2] = {-0.0, -0.0};
-    double arr2[2] = {-0.0,  0.0};
+    const double neg_zero = numext::bit_cast<double>(0x8000000000000000ull);
+    double arr1[2] = {neg_zero, neg_zero};
+    double arr2[2] = {neg_zero,  0.0};
     const Packet2d mask0 = pset<Packet2d>(arr1);
     const Packet2d mask2 = pset<Packet2d>(arr2);
     pstoret<double,Packet2d,ResAlignment>(&res.x(), pxor(mask0, qe.template packet<traits<Derived>::Alignment,Packet2d>(0)));
-- 
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