From 17f3bf8985021c242eedc9fa26c5c66d43a300f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antonio=20S=C3=A1nchez?= <cantonios@google.com>
Date: Thu, 7 Mar 2024 00:19:57 +0000
Subject: [PATCH] Fix pexp test for ARM.

---
 test/packetmath.cpp | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/test/packetmath.cpp b/test/packetmath.cpp
index 116663d96..db8c9b5c5 100644
--- a/test/packetmath.cpp
+++ b/test/packetmath.cpp
@@ -1346,13 +1346,25 @@ struct exp_complex_test_impl {
   static Scalar cis(const RealScalar& x) { return Scalar(numext::cos(x), numext::sin(x)); }
 
   // Verify equality with signed zero.
-  static bool is_exactly_equal(const RealScalar& a, const RealScalar& b) {
+  static bool is_exactly_equal(RealScalar a, RealScalar b) {
     // NaNs are always unsigned, and always compare not equal directly.
     if ((numext::isnan)(a)) {
       return (numext::isnan)(b);
     }
-    // Signed zero.
+
     RealScalar zero(0);
+#ifdef EIGEN_ARCH_ARM
+    // ARM automatically flushes denormals to zero.
+    // Preserve sign by multiplying by +0.
+    if (numext::abs(a) < (std::numeric_limits<RealScalar>::min)()) {
+      a = a * zero;
+    }
+    if (numext::abs(b) < (std::numeric_limits<RealScalar>::min)()) {
+      b = b * zero;
+    }
+#endif
+
+    // Signed zero.
     if (a == zero) {
       // Signs are either 0 or NaN, so verify that their comparisons to zero are equal.
       return (a == b) && ((numext::signbit(a) == zero) == (numext::signbit(b) == zero));