When negating a DFP NaN in C++, we produce another NaN and not a -NaN like
we do when using a C test case or with binary floating point (C or C++).
This happens on both my power64-linux and x86_64-linux systems.
bergner@bns:~> cat dfp-nan.C
#include <stdio.h>
#include <decimal/decimal>
using namespace std;
decimal::decimal64
my_nan (void)
{
decimal::decimal64 z = 0.0DD;
decimal::decimal64 v = z/z;
return v;
}
int
main (void)
{
decimal::decimal64 v;
v = my_nan ();
printf ("value is %Dg\n", v);
v = -v;
printf ("-value is %Dg\n", v);
return 0;
}
bergner@bns:~> g++ dfp-nan.C -ldfp
bergner@bns:~> ./a.out
value is nan
-value is nan
The problem is that the decimal class implementing unary operators
uses binary operations, so a -nan is computed with a "0 - nan"
which does not produce a -nan. The patch below fixes the problem
for me and passes bootstrap and regtesting on powerpc64-linux.
Ok for mainline? The same problem exists in 4.7 and 4.6, is this
patch ok for the release branches too assuming my testing there
passes without problems?
Peter
libstdc++-v3/
PR c++/54036
* include/decimal/decimal.h (_DEFINE_DECIMAL_UNARY_OP): Use _Op as
a unary operator.
gcc/testsuite/
PR c++/54036
* g++.dg/dfp/pr54036-1.C: New test.
* g++.dg/dfp/pr54036-2.C: Likewise.
* g++.dg/dfp/pr54036-3.C: Likewise.
Index: libstdc++-v3/include/decimal/decimal.h
===================================================================
--- libstdc++-v3/include/decimal/decimal.h (revision 189599)
+++ libstdc++-v3/include/decimal/decimal.h (working copy)
@@ -288,7 +288,7 @@
inline _Tp operator _Op(_Tp __rhs) \
{ \
_Tp __tmp; \
- __tmp.__setval(0 _Op __rhs.__getval()); \
+ __tmp.__setval(_Op __rhs.__getval()); \
return __tmp; \
}
Index: gcc/testsuite/g++.dg/dfp/pr54036-1.C
===================================================================
--- gcc/testsuite/g++.dg/dfp/pr54036-1.C (revision 0)
+++ gcc/testsuite/g++.dg/dfp/pr54036-1.C (revision 0)
@@ -0,0 +1,56 @@
+#include <decimal/decimal>
+using namespace std;
+
+decimal::decimal32
+__attribute__ ((noinline))
+my_nan32 (void)
+{
+ decimal::decimal32 z = 0;
+ decimal::decimal32 v = z/z;
+ return v;
+}
+
+decimal::decimal32
+__attribute__ ((noinline))
+my_inf32 (void)
+{
+ decimal::decimal32 o = 1;
+ decimal::decimal32 z = 0;
+ decimal::decimal32 v = o/z;
+ return v;
+}
+
+int
+main (void)
+{
+ decimal::decimal32 v;
+
+ v = my_nan32 ();
+ if (!__builtin_isnand32 (v.__getval ()))
+ __builtin_abort ();
+ if (__builtin_signbitd32 (v.__getval ()))
+ __builtin_abort ();
+
+ v = -v;
+
+ if (!__builtin_isnand32 (v.__getval ()))
+ __builtin_abort ();
+ if (!__builtin_signbitd32 (v.__getval ()))
+ __builtin_abort ();
+
+ v = my_inf32 ();
+ if (!__builtin_isinfd32 (v.__getval ()))
+ __builtin_abort ();
+ if (__builtin_signbitd32 (v.__getval ()))
+ __builtin_abort ();
+
+ v = -v;
+
+ if (!__builtin_isinfd32 (v.__getval ()))
+ __builtin_abort ();
+ if (!__builtin_signbitd32 (v.__getval ()))
+ __builtin_abort ();
+
+ return 0;
+}
+
Index: gcc/testsuite/g++.dg/dfp/pr54036-2.C
===================================================================
--- gcc/testsuite/g++.dg/dfp/pr54036-2.C (revision 0)
+++ gcc/testsuite/g++.dg/dfp/pr54036-2.C (revision 0)
@@ -0,0 +1,56 @@
+#include <decimal/decimal>
+using namespace std;
+
+decimal::decimal64
+__attribute__ ((noinline))
+my_nan64 (void)
+{
+ decimal::decimal64 z = 0;
+ decimal::decimal64 v = z/z;
+ return v;
+}
+
+decimal::decimal64
+__attribute__ ((noinline))
+my_inf64 (void)
+{
+ decimal::decimal64 o = 1;
+ decimal::decimal64 z = 0;
+ decimal::decimal64 v = o/z;
+ return v;
+}
+
+int
+main (void)
+{
+ decimal::decimal64 v;
+
+ v = my_nan64 ();
+ if (!__builtin_isnand64 (v.__getval ()))
+ __builtin_abort ();
+ if (__builtin_signbitd64 (v.__getval ()))
+ __builtin_abort ();
+
+ v = -v;
+
+ if (!__builtin_isnand64 (v.__getval ()))
+ __builtin_abort ();
+ if (!__builtin_signbitd64 (v.__getval ()))
+ __builtin_abort ();
+
+ v = my_inf64 ();
+ if (!__builtin_isinfd64 (v.__getval ()))
+ __builtin_abort ();
+ if (__builtin_signbitd64 (v.__getval ()))
+ __builtin_abort ();
+
+ v = -v;
+
+ if (!__builtin_isinfd64 (v.__getval ()))
+ __builtin_abort ();
+ if (!__builtin_signbitd64 (v.__getval ()))
+ __builtin_abort ();
+
+ return 0;
+}
+
Index: gcc/testsuite/g++.dg/dfp/pr54036-3.C
===================================================================
--- gcc/testsuite/g++.dg/dfp/pr54036-3.C (revision 0)
+++ gcc/testsuite/g++.dg/dfp/pr54036-3.C (revision 0)
@@ -0,0 +1,56 @@
+#include <decimal/decimal>
+using namespace std;
+
+decimal::decimal128
+__attribute__ ((noinline))
+my_nan128 (void)
+{
+ decimal::decimal128 z = 0;
+ decimal::decimal128 v = z/z;
+ return v;
+}
+
+decimal::decimal128
+__attribute__ ((noinline))
+my_inf128 (void)
+{
+ decimal::decimal128 o = 1;
+ decimal::decimal128 z = 0;
+ decimal::decimal128 v = o/z;
+ return v;
+}
+
+int
+main (void)
+{
+ decimal::decimal128 v;
+
+ v = my_nan128 ();
+ if (!__builtin_isnand128 (v.__getval ()))
+ __builtin_abort ();
+ if (__builtin_signbitd128 (v.__getval ()))
+ __builtin_abort ();
+
+ v = -v;
+
+ if (!__builtin_isnand128 (v.__getval ()))
+ __builtin_abort ();
+ if (!__builtin_signbitd128 (v.__getval ()))
+ __builtin_abort ();
+
+ v = my_inf128 ();
+ if (!__builtin_isinfd128 (v.__getval ()))
+ __builtin_abort ();
+ if (__builtin_signbitd128 (v.__getval ()))
+ __builtin_abort ();
+
+ v = -v;
+
+ if (!__builtin_isinfd128 (v.__getval ()))
+ __builtin_abort ();
+ if (!__builtin_signbitd128 (v.__getval ()))
+ __builtin_abort ();
+
+ return 0;
+}
+
