From: Joseph Myers <joseph@codesourcery.com>
Date: Wed, 30 Sep 2015 21:44:42 +0000 (+0000)
Subject: Fix i386 acosh (-qNaN) spurious "invalid" exception.
X-Git-Tag: glibc-2.23~418
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8c6c9236361fbc077769673c259828216403bc33;p=thirdparty%2Fglibc.git

Fix i386 acosh (-qNaN) spurious "invalid" exception.

The i386 versions of acoshf and acosh raise a spurious "invalid"
exception for an argument that is a quiet NaN with the sign bit set.
The integer arithmetic to detect arguments < 1 also detects -NaN, and
then the computation 0 / 0 in that case raises the exception.  This
patch fixes this by using (x - x) / (x - x) as the computation in that
case instead, which will always raise the exception for non-NaN
arguments reaching that code, but not for quiet NaN arguments.

Tested for x86_64 and x86.

	[BZ #19032]
	* sysdeps/i386/fpu/e_acosh.S (__ieee754_acosh): For arguments < 1,
	compute result as (x - x) / (x - x) not as 0 / 0.
	* sysdeps/i386/fpu/e_acoshf.S (__ieee754_acoshf): Likewise.
	* math/libm-test.inc (acosh_test_data): Add another test of acosh.
---

diff --git a/ChangeLog b/ChangeLog
index ea038f764f3..958b4a3a9d4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2015-09-30  Joseph Myers  <joseph@codesourcery.com>
 
+	[BZ #19032]
+	* sysdeps/i386/fpu/e_acosh.S (__ieee754_acosh): For arguments < 1,
+	compute result as (x - x) / (x - x) not as 0 / 0.
+	* sysdeps/i386/fpu/e_acoshf.S (__ieee754_acoshf): Likewise.
+	* math/libm-test.inc (acosh_test_data): Add another test of acosh.
+
 	* math/auto-libm-test-in: Add more tests of acos, acosh, asin,
 	atan, atan2, atanh, cbrt, cos, cosh, erf, erfc, exp, exp10, exp2
 	and expm1.
diff --git a/NEWS b/NEWS
index ea64dc7c40b..e7e11bf987c 100644
--- a/NEWS
+++ b/NEWS
@@ -17,7 +17,7 @@ Version 2.23
   18789, 18790, 18795, 18796, 18803, 18820, 18823, 18824, 18825, 18857,
   18863, 18870, 18872, 18873, 18875, 18887, 18921, 18951, 18952, 18956,
   18961, 18966, 18967, 18969, 18970, 18977, 18980, 18981, 18985, 19003,
-  19016.
+  19016, 19032.
 
 * The obsolete header <regexp.h> has been removed.  Programs that require
   this header must be updated to use <regex.h> instead.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 744c66dbb15..86159576003 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -1790,6 +1790,7 @@ static const struct test_f_f_data acosh_test_data[] =
     TEST_f_f (acosh, plus_infty, plus_infty, ERRNO_UNCHANGED),
     TEST_f_f (acosh, minus_infty, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
     TEST_f_f (acosh, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_f_f (acosh, -qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
 
     /* x < 1:  */
     TEST_f_f (acosh, 0.75L, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
diff --git a/sysdeps/i386/fpu/e_acosh.S b/sysdeps/i386/fpu/e_acosh.S
index c5cd4474ecd..263c01a4ed1 100644
--- a/sysdeps/i386/fpu/e_acosh.S
+++ b/sysdeps/i386/fpu/e_acosh.S
@@ -91,9 +91,10 @@ ENTRY(__ieee754_acosh)
 	fyl2x				// log(2*x+1/(x+sqrt(x^2-1)))
 	ret
 
-	// x < 1 => NaN
+	// x < 1 (or -NaN) => NaN
 	.align ALIGNARG(4)
-5:	fldz
+5:	fldl	4(%esp)
+	fsub	%st
 	fdiv	%st, %st(0)
 	ret
 END(__ieee754_acosh)
diff --git a/sysdeps/i386/fpu/e_acoshf.S b/sysdeps/i386/fpu/e_acoshf.S
index 710267b11ed..779a02cfab1 100644
--- a/sysdeps/i386/fpu/e_acoshf.S
+++ b/sysdeps/i386/fpu/e_acoshf.S
@@ -91,9 +91,10 @@ ENTRY(__ieee754_acoshf)
 	fyl2x				// log(2*x+1/(x+sqrt(x^2-1)))
 	ret
 
-	// x < 1 => NaN
+	// x < 1 (or -NaN) => NaN
 	.align ALIGNARG(4)
-5:	fldz
+5:	flds	4(%esp)
+	fsub	%st
 	fdiv	%st, %st(0)
 	ret
 END(__ieee754_acoshf)