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GNU C Library master sources branch master updated. glibc-2.20-527-g5a9e4c0

From: jsm28 at sourceware dot org
To: glibc-cvs at sourceware dot org
Date: 12 Jan 2015 23:02:51 -0000
Subject: GNU C Library master sources branch master updated. glibc-2.20-527-g5a9e4c0
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=5a9e4c09a2601a8100ea9a1f7bc0360782cd1625

commit 5a9e4c09a2601a8100ea9a1f7bc0360782cd1625
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Mon Jan 12 23:02:14 2015 +0000

    Fix ldbl-96 scalblnl underflowing results (bug 17803).
    
    The ldbl-96 implementation of scalblnl (used for x86_64 and ia64) uses
    a condition k <= -63 to determine when a standard underflowing result
    tiny*__copysignl(tiny,x) should be returned.  However, that condition
    corresponds to values with exponent -16446 or less, and in the case of
    -16446, the correct result for round-to-nearest depends on whether the
    value is exactly 0x1p-16446 (half the least subnormal) or more than
    that.  This patch fixes the bug by changing the condition to k <= -64
    and accordingly adjusting the exponent by 64 not 63 when converting to
    a normal value.
    
    Tested for x86_64.
    
    	[BZ #17803]
    	* sysdeps/ieee754/ldbl-96/s_scalblnl.c (twom63): Rename to
    	twom64.  Adjust value to 0x1p-64L.
    	(__scalblnl): Only return standard underflowing result for K <=
    	-64 not K <= -63; adjust exponent for underflowing result by 64
    	not 63.
    	* math/libm-test.inc (scalbn_test_data): Add more tests.
    	(scalbln_test_data): Likewise.

diff --git a/ChangeLog b/ChangeLog
index 081e0b5..e8ca56b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2015-01-12  Joseph Myers  <joseph@codesourcery.com>
 
+	[BZ #17803]
+	* sysdeps/ieee754/ldbl-96/s_scalblnl.c (twom63): Rename to
+	twom64.  Adjust value to 0x1p-64L.
+	(__scalblnl): Only return standard underflowing result for K <=
+	-64 not K <= -63; adjust exponent for underflowing result by 64
+	not 63.
+	* math/libm-test.inc (scalbn_test_data): Add more tests.
+	(scalbln_test_data): Likewise.
+
 	[BZ #17834]
 	* sysdeps/ieee754/ldbl-96/s_scalblnl.c (two63): Change value to
 	0x1p63L.
diff --git a/NEWS b/NEWS
index e5fb0a0..b7c32ad 100644
--- a/NEWS
+++ b/NEWS
@@ -17,7 +17,7 @@ Version 2.21
   17633, 17634, 17635, 17647, 17653, 17657, 17658, 17664, 17665, 17668,
   17682, 17717, 17719, 17722, 17723, 17724, 17725, 17732, 17733, 17744,
   17745, 17746, 17747, 17748, 17775, 17777, 17780, 17781, 17782, 17791,
-  17793, 17796, 17797, 17806, 17834
+  17793, 17796, 17797, 17803, 17806, 17834
 
 * Added support for TSX lock elision of pthread mutexes on powerpc32, powerpc64
   and powerpc64le.  This may improve lock scaling of existing programs on
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 34f83c6..6d7ff12 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -9135,6 +9135,25 @@ static const struct test_fi_f_data scalbn_test_data[] =
     TEST_fi_f (scalbn, min_subnorm_value, MANT_DIG, min_value, NO_INEXACT_EXCEPTION),
     TEST_fi_f (scalbn, -min_subnorm_value, MANT_DIG, -min_value, NO_INEXACT_EXCEPTION),
 
+    TEST_fi_f (scalbn, min_value, -MANT_DIG, min_subnorm_value, NO_INEXACT_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value, -MANT_DIG, -min_subnorm_value, NO_INEXACT_EXCEPTION),
+    TEST_fi_f (scalbn, min_value, -MANT_DIG-1, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value, -MANT_DIG-1, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, min_value, -MANT_DIG-2, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value, -MANT_DIG-2, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, min_value * 1.5, -MANT_DIG, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value * 1.5, -MANT_DIG, -min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, min_value * 1.5, -MANT_DIG-1, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value * 1.5, -MANT_DIG-1, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, min_value * 1.5, -MANT_DIG-2, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value * 1.5, -MANT_DIG-2, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, min_value * 1.25, -MANT_DIG, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value * 1.25, -MANT_DIG, -min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, min_value * 1.25, -MANT_DIG-1, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value * 1.25, -MANT_DIG-1, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, min_value * 1.25, -MANT_DIG-2, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fi_f (scalbn, -min_value * 1.25, -MANT_DIG-2, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+
     TEST_fi_f (scalbn, 1, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION),
     TEST_fi_f (scalbn, 1, INT_MIN, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
     TEST_fi_f (scalbn, max_value, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION),
@@ -9193,6 +9212,25 @@ static const struct test_fl_f_data scalbln_test_data[] =
     TEST_fl_f (scalbln, min_subnorm_value, MANT_DIG, min_value, NO_INEXACT_EXCEPTION),
     TEST_fl_f (scalbln, -min_subnorm_value, MANT_DIG, -min_value, NO_INEXACT_EXCEPTION),
 
+    TEST_fl_f (scalbln, min_value, -MANT_DIG, min_subnorm_value, NO_INEXACT_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value, -MANT_DIG, -min_subnorm_value, NO_INEXACT_EXCEPTION),
+    TEST_fl_f (scalbln, min_value, -MANT_DIG-1, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value, -MANT_DIG-1, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, min_value, -MANT_DIG-2, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value, -MANT_DIG-2, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, min_value * 1.5, -MANT_DIG, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value * 1.5, -MANT_DIG, -min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, min_value * 1.5, -MANT_DIG-1, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value * 1.5, -MANT_DIG-1, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, min_value * 1.5, -MANT_DIG-2, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value * 1.5, -MANT_DIG-2, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, min_value * 1.25, -MANT_DIG, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value * 1.25, -MANT_DIG, -min_subnorm_value * 2, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, min_value * 1.25, -MANT_DIG-1, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, plus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value * 1.25, -MANT_DIG-1, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, -min_subnorm_value, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION, minus_zero, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, min_value * 1.25, -MANT_DIG-2, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+    TEST_fl_f (scalbln, -min_value * 1.25, -MANT_DIG-2, minus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION),
+
     TEST_fl_f (scalbln, 1, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW),
     TEST_fl_f (scalbln, 1, INT_MIN, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION|ERRNO_PLUS_UFLOW),
     TEST_fl_f (scalbln, max_value, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW),
diff --git a/sysdeps/ieee754/ldbl-96/s_scalblnl.c b/sysdeps/ieee754/ldbl-96/s_scalblnl.c
index 5c2f38e..457e999 100644
--- a/sysdeps/ieee754/ldbl-96/s_scalblnl.c
+++ b/sysdeps/ieee754/ldbl-96/s_scalblnl.c
@@ -26,7 +26,7 @@
 
 static const long double
 two63   =  0x1p63L,
-twom63  =  1.08420217248550443400e-19,
+twom64  =  0x1p-64L,
 huge   = 1.0e+4900L,
 tiny   = 1.0e-4900L;
 
@@ -52,9 +52,9 @@ __scalblnl (long double x, long int n)
 	k = k+n;
 	if (__builtin_expect(k > 0, 1))		/* normal result */
 	    {SET_LDOUBLE_EXP(x,(es&0x8000)|k); return x;}
-	if (k <= -63)
+	if (k <= -64)
 	    return tiny*__copysignl(tiny,x); 	/*underflow*/
-	k += 63;				/* subnormal result */
+	k += 64;				/* subnormal result */
 	SET_LDOUBLE_EXP(x,(es&0x8000)|k);
-	return x*twom63;
+	return x*twom64;
 }

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                            |    9 ++++++++
 NEWS                                 |    2 +-
 math/libm-test.inc                   |   38 ++++++++++++++++++++++++++++++++++
 sysdeps/ieee754/ldbl-96/s_scalblnl.c |    8 +++---
 4 files changed, 52 insertions(+), 5 deletions(-)


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