BZ#13889: expl (709.75) wrongly overflows for ldbl-128ibm

The patch increase the high value to check if expl overflows. Current
high mark value is not really correct, the algorithm accepts high values.
It also adds a correct wrapper function to check for overflow and underflow.

5 files changed, 40 insertions, 10 deletions

diff --git a/ChangeLog b/ChangeLog
index de9e54e2f7..13c26f1c3e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2013-03-19  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
+	[BZ #13889]
+	* sysdeps/ieee754/ldbl-128ibm/e_expl.c (__ieee754_expl): Increase the
+	high value to check if expl overflow.
+	* sysdeps/ieee754/ldbl-128ibm/w_expl.c (__expl): Fix threshold constants
+	to check for underflow and overflow.
+	* math/libm-test.inc: Add exp test.
+
 2013-03-21  Dmitry V. Levin  <ldv@altlinux.org>
 
 	[BZ #11120]
diff --git a/NEWS b/NEWS
index f0965d65e1..8bb43ecbdb 100644
--- a/NEWS
+++ b/NEWS
@@ -9,10 +9,10 @@ Version 2.18
 
 * The following bugs are resolved with this release:
 
-  11120, 11561, 12723, 13550, 13951, 14142, 14176, 14200, 14317, 14327,
-  14496, 14812, 14920, 14964, 14981, 14982, 14985, 14994, 14996, 15003,
-  15006, 15020, 15023, 15036, 15054, 15055, 15062, 15078, 15160, 15232,
-  15234, 15283, 15285, 15287.
+  11120, 11561, 12723, 13550, 13889, 13951, 14142, 14176, 14200, 14317,
+  14327, 14496, 14812, 14920, 14964, 14981, 14982, 14985, 14994, 14996,
+  15003, 15006, 15020, 15023, 15036, 15054, 15055, 15062, 15078, 15160,
+  15232, 15234, 15283, 15285, 15287.
 
 * Add support for calling C++11 thread_local object destructors on thread
   and program exit.  This needs compiler support for offloading C++11
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 1b70c35f39..85ae23f838 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -4564,6 +4564,9 @@ exp_test (void)
   TEST_f_f (exp, 0.75L, 2.11700001661267466854536981983709561L);
   TEST_f_f (exp, 50.0L, 5184705528587072464087.45332293348538L);
   TEST_f_f (exp, 88.72269439697265625L, 3.40233126623160774937554134772290447915e38L);
+#ifndef TEST_FLOAT
+  TEST_f_f (exp, 709.75L, 1.739836873264160557698252711673830393864768e+308L);
+#endif
 #if defined TEST_LDOUBLE && __LDBL_MAX_EXP__ > 1024
   /* The result can only be represented in sane long double.  */
   TEST_f_f (exp, 1000.0L, 0.197007111401704699388887935224332313e435L);
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_expl.c b/sysdeps/ieee754/ldbl-128ibm/e_expl.c
index 82363906b0..9fd61983e3 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_expl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_expl.c
@@ -70,11 +70,11 @@
 static const long double C[] = {
 /* Smallest integer x for which e^x overflows.  */
 #define himark C[0]
- 709.08956571282405153382846025171462914L,
+ 709.78271289338399678773454114191496482L,
 
 /* Largest integer x for which e^x underflows.  */
 #define lomark C[1]
--744.44007192138121808966388925909996033L,
+-744.44007192138126231410729844608163411L,
 
 /* 3x2^96 */
 #define THREEp96 C[2]
diff --git a/sysdeps/ieee754/ldbl-128ibm/w_expl.c b/sysdeps/ieee754/ldbl-128ibm/w_expl.c
index a5e72b2170..70fe5f693e 100644
--- a/sysdeps/ieee754/ldbl-128ibm/w_expl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/w_expl.c
@@ -1,6 +1,24 @@
-/* Looks like we can use ieee854 w_expl.c as is for IBM extended format. */
+#include <math.h>
+#include <math_private.h>
 #include <math_ldbl_opt.h>
-#undef weak_alias
-#define weak_alias(n,a)
-#include <sysdeps/ieee754/ldbl-128/w_expl.c>
+
+static const long double o_thres = 709.78271289338399678773454114191496482L;
+static const long double u_thres = -744.44007192138126231410729844608163411L;
+
+long double __expl(long double x)	/* wrapper exp  */
+{
+  long double z;
+  z = __ieee754_expl(x);
+  if (_LIB_VERSION == _IEEE_)
+    return z;
+  if (__finitel(x))
+    {
+      if (x >= o_thres)
+	return __kernel_standard_l(x,x,206); /* exp overflow  */
+      else if (x <= u_thres)
+	return __kernel_standard_l(x,x,207); /* exp underflow  */
+    }
+  return z;
+}
+hidden_def (__expl)
 long_double_symbol (libm, __expl, expl);