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Fix i386/x86_64 log2l (sNaN) (bug 20235) [committed]


The i386/x86_64 versions of log2l return sNaN for sNaN input.  This
patch fixes them to add NaN inputs to themselves so that qNaN is
returned in this case.

Tested for x86_64 and x86.  Committed.

2016-06-09  Joseph Myers  <joseph@codesourcery.com>

	[BZ #20235]
	* sysdeps/i386/fpu/e_log2l.S (__ieee754_log2l): Add NaN input to
	itself.
	* sysdeps/x86_64/fpu/e_log2l.S (__ieee754_log2l): Likewise.
	* math/libm-test.inc (log2_test_data): Add sNaN tests.

diff --git a/math/libm-test.inc b/math/libm-test.inc
index 4371c4c..2df6f29 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -9076,6 +9076,8 @@ static const struct test_f_f_data log2_test_data[] =
     TEST_f_f (log2, plus_infty, plus_infty, ERRNO_UNCHANGED),
     TEST_f_f (log2, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
     TEST_f_f (log2, -qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_f_f (log2, snan_value, qnan_value, INVALID_EXCEPTION),
+    TEST_f_f (log2, -snan_value, qnan_value, INVALID_EXCEPTION),
 
     AUTO_TESTS_f_f (log2),
   };
diff --git a/sysdeps/i386/fpu/e_log2l.S b/sysdeps/i386/fpu/e_log2l.S
index 0f5f7e5..73e62ea 100644
--- a/sysdeps/i386/fpu/e_log2l.S
+++ b/sysdeps/i386/fpu/e_log2l.S
@@ -64,6 +64,7 @@ ENTRY(__ieee754_log2l)
 3:	jp	4b		// in case x is ?Inf
 	fstp	%st(1)
 	fstp	%st(1)
+	fadd	%st(0)
 	ret
 END (__ieee754_log2l)
 strong_alias (__ieee754_log2l, __log2l_finite)
diff --git a/sysdeps/x86_64/fpu/e_log2l.S b/sysdeps/x86_64/fpu/e_log2l.S
index a063255..023ec29 100644
--- a/sysdeps/x86_64/fpu/e_log2l.S
+++ b/sysdeps/x86_64/fpu/e_log2l.S
@@ -63,6 +63,7 @@ ENTRY(__ieee754_log2l)
 	jnz	4b		// in case x is ?Inf
 	fstp	%st(1)
 	fstp	%st(1)
+	fadd	%st(0)
 	ret
 END (__ieee754_log2l)
 

-- 
Joseph S. Myers
joseph@codesourcery.com


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