Fix ldbl-128ibm expl overflow in non-default rounding modes (bug 19078).

The ldbl-128ibm expl wrapper checks the argument to determine when to
call __kernel_standard_l, thereby overriding overflowing results from
__ieee754_expl that could otherwise (given appropriately patched
libgcc) be correct for the rounding mode.  This patch changes it to
check the result of __ieee754_expl instead, as other versions of this
wrapper do.

Tested for powerpc.

	[BZ #19078]
	* sysdeps/ieee754/ldbl-128ibm/w_expl.c (o_thres): Remove variable.
	(u_thres): Likewise.
	(__expl): Determine whether to call __kernel_standard_l based on
	value of result, not argument.

diff --git a/ChangeLog b/ChangeLog
index 2752bd232301576bccaf2f46105648d1d59365cc..9b762b3a0c52c7bdec33cf09400cfe8854059dce 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2015-10-06  Joseph Myers  <joseph@codesourcery.com>
 
+       [BZ #19078]
+       * sysdeps/ieee754/ldbl-128ibm/w_expl.c (o_thres): Remove variable.
+       (u_thres): Likewise.
+       (__expl): Determine whether to call __kernel_standard_l based on
+       value of result, not argument.
+
        * math/libm-test.inc (scalb_test_data): Add more expectations for
        the "inexact" exception.
 

diff --git a/NEWS b/NEWS
index e3c0795fe535093ce6d2b2acecffceb7d2843ef9..5ad75a32fd726f0480eb75e6920336059dd13621 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -18,7 +18,7 @@ Version 2.23
   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, 19012, 19016, 19018, 19032, 19046,
-  19049, 19050, 19059, 19071, 19076, 19077.
+  19049, 19050, 19059, 19071, 19076, 19077, 19078.
 
 * The obsolete header <regexp.h> has been removed.  Programs that require
   this header must be updated to use <regex.h> instead.

diff --git a/sysdeps/ieee754/ldbl-128ibm/w_expl.c b/sysdeps/ieee754/ldbl-128ibm/w_expl.c
index fb5c8d36296562f6d2c5c31a1225b517cc2aad27..c9d44b61ddf77d39f712e407d4dfffea91ed5444 100644 (file)
--- a/sysdeps/ieee754/ldbl-128ibm/w_expl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/w_expl.c
@@ -2,9 +2,6 @@
 #include <math_private.h>
 #include <math_ldbl_opt.h>
 
-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;
@@ -13,9 +10,9 @@ long double __expl(long double x)     /* wrapper exp  */
     return z;
   if (isfinite(x))
     {
-      if (x >= o_thres)
+      if (!isfinite (z))
        return __kernel_standard_l(x,x,206); /* exp overflow  */
-      else if (x <= u_thres)
+      else if (z == 0.0L)
        return __kernel_standard_l(x,x,207); /* exp underflow  */
     }
   return z;