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authorJoseph Myers <joseph@codesourcery.com>2015-09-30 21:44:42 +0000
committerJoseph Myers <joseph@codesourcery.com>2015-09-30 21:44:42 +0000
commit8c6c9236361fbc077769673c259828216403bc33 (patch)
tree04b02cf33c6654bc380d2c2ef986c41c4166d2ee /sysdeps/i386
parent93e448cbed1095c88133f2a304b1bbba72e480af (diff)
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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.
Diffstat (limited to 'sysdeps/i386')
-rw-r--r--sysdeps/i386/fpu/e_acosh.S5
-rw-r--r--sysdeps/i386/fpu/e_acoshf.S5
2 files changed, 6 insertions, 4 deletions
diff --git a/sysdeps/i386/fpu/e_acosh.S b/sysdeps/i386/fpu/e_acosh.S
index c5cd4474ec..263c01a4ed 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 710267b11e..779a02cfab 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)