From 0a42601f272ea962b200d452a54e0ca374163f60 Mon Sep 17 00:00:00 2001
From: Joseph Myers <joseph@codesourcery.com>
Date: Thu, 22 Nov 2012 19:56:47 +0000
Subject: Fix ldbl-128ibm atanl spurious underflows (bug 14871).

---
 sysdeps/ieee754/ldbl-128ibm/s_atanl.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

(limited to 'sysdeps/ieee754')

diff --git a/sysdeps/ieee754/ldbl-128ibm/s_atanl.c b/sysdeps/ieee754/ldbl-128ibm/s_atanl.c
index 779209d3d7..2a36d16bb4 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_atanl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_atanl.c
@@ -199,6 +199,22 @@ __atanl (long double x)
 	return atantbl[83];
     }
 
+  if (k <= 0x3c800000) /* |x| <= 2**-55.  */
+    {
+      /* Raise inexact.  */
+      if (1e300L + x > 0.0)
+	return x;
+    }
+
+  if (k >= 0x46c00000) /* |x| >= 2**109.  */
+    {
+      /* Saturate result to {-,+}pi/2.  */
+      if (sign)
+	return -atantbl[83];
+      else
+	return atantbl[83];
+    }
+
   if (sign)
       x = -x;
 
-- 
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