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From 45970aa26d1af87b016ef95b4b35c566aeb6e841 Mon Sep 17 00:00:00 2001
From: "Gabriel F. T. Gomes" <gftg@linux.vnet.ibm.com>
Date: Tue, 22 Aug 2017 16:34:42 -0300
Subject: [PATCH] Provide a C++ version of iszero that does not use __MATH_TG
(bug 21930)
When signaling nans are enabled (with -fsignaling-nans), the C++ version
of iszero uses the fpclassify macro, which is defined with __MATH_TG.
However, when support for float128 is available, __MATH_TG uses the
builtin __builtin_types_compatible_p, which is only available in C mode.
This patch refactors the C++ version of iszero so that it uses function
overloading to select between the floating-point types, instead of
relying on fpclassify and __MATH_TG.
Tested for powerpc64le, s390x, x86_64, and with build-many-glibcs.py.
[BZ #21930]
* math/math.h [defined __cplusplus && defined __SUPPORT_SNAN__]
(iszero): New C++ implementation that does not use
fpclassify/__MATH_TG/__builtin_types_compatible_p, when
signaling nans are enabled, since __builtin_types_compatible_p
is a C-only feature.
* math/test-math-iszero.cc: When __HAVE_DISTINCT_FLOAT128 is
defined, include ieee754_float128.h for access to the union and
member ieee854_float128.ieee.
[__HAVE_DISTINCT_FLOAT128] (do_test): Call check_float128.
[__HAVE_DISTINCT_FLOAT128] (check_float128): New function.
* sysdeps/powerpc/powerpc64le/Makefile [subdir == math]
(CXXFLAGS-test-math-iszero.cc): Add -mfloat128 to the build
options of test-math-zero on powerpc64le.
(cherry picked from commit 42496114ec0eb7d6d039d05d4262e109951c600c)
[Romain rebase on glibc 2.26]
Signed-off-by: Romain Naour <romain.naour@gmail.com>
---
math/math.h | 33 +++++++++++++--
math/test-math-iszero.cc | 79 ++++++++++++++++++++++++++++++++++++
sysdeps/powerpc/powerpc64le/Makefile | 3 +-
3 files changed, 110 insertions(+), 5 deletions(-)
diff --git a/math/math.h b/math/math.h
index 60dfa31..7c0fc6d 100644
--- a/math/math.h
+++ b/math/math.h
@@ -513,15 +513,40 @@ inline int issignaling (_Float128 __val) { return __issignalingf128 (__val); }
# endif
# else /* __cplusplus */
extern "C++" {
+# ifdef __SUPPORT_SNAN__
+inline int
+iszero (float __val)
+{
+ return __fpclassifyf (__val) == FP_ZERO;
+}
+inline int
+iszero (double __val)
+{
+ return __fpclassify (__val) == FP_ZERO;
+}
+inline int
+iszero (long double __val)
+{
+# ifdef __NO_LONG_DOUBLE_MATH
+ return __fpclassify (__val) == FP_ZERO;
+# else
+ return __fpclassifyl (__val) == FP_ZERO;
+# endif
+}
+# if __HAVE_DISTINCT_FLOAT128
+inline int
+iszero (_Float128 __val)
+{
+ return __fpclassifyf128 (__val) == FP_ZERO;
+}
+# endif
+# else
template <class __T> inline bool
iszero (__T __val)
{
-# ifdef __SUPPORT_SNAN__
- return fpclassify (__val) == FP_ZERO;
-# else
return __val == 0;
-# endif
}
+# endif
} /* extern C++ */
# endif /* __cplusplus */
#endif /* Use IEC_60559_BFP_EXT. */
diff --git a/math/test-math-iszero.cc b/math/test-math-iszero.cc
index 027e972..5c07261 100644
--- a/math/test-math-iszero.cc
+++ b/math/test-math-iszero.cc
@@ -22,6 +22,13 @@
#include <limits>
+/* Support for _Float128 in std::numeric_limits is limited.
+ Include ieee754_float128.h and use the bitfields in the union
+ ieee854_float128.ieee_nan to build corner-case inputs. */
+#if __HAVE_DISTINCT_FLOAT128
+# include <ieee754_float128.h>
+#endif
+
static bool errors;
static void
@@ -72,12 +79,84 @@ check_type ()
std::numeric_limits<T>::has_denorm == std::denorm_absent);
}
+#if __HAVE_DISTINCT_FLOAT128
+static void
+check_float128 ()
+{
+ ieee854_float128 q;
+
+ q.d = 0.0Q;
+ CHECK (iszero (q.d), 1);
+ q.d = -0.0Q;
+ CHECK (iszero (q.d), 1);
+ q.d = 1.0Q;
+ CHECK (iszero (q.d), 0);
+ q.d = -1.0Q;
+ CHECK (iszero (q.d), 0);
+
+ /* Normal min. */
+ q.ieee.negative = 0;
+ q.ieee.exponent = 0x0001;
+ q.ieee.mantissa0 = 0x0000;
+ q.ieee.mantissa1 = 0x00000000;
+ q.ieee.mantissa2 = 0x00000000;
+ q.ieee.mantissa3 = 0x00000000;
+ CHECK (iszero (q.d), 0);
+ q.ieee.negative = 1;
+ CHECK (iszero (q.d), 0);
+
+ /* Normal max. */
+ q.ieee.negative = 0;
+ q.ieee.exponent = 0x7FFE;
+ q.ieee.mantissa0 = 0xFFFF;
+ q.ieee.mantissa1 = 0xFFFFFFFF;
+ q.ieee.mantissa2 = 0xFFFFFFFF;
+ q.ieee.mantissa3 = 0xFFFFFFFF;
+ CHECK (iszero (q.d), 0);
+ q.ieee.negative = 1;
+ CHECK (iszero (q.d), 0);
+
+ /* Infinity. */
+ q.ieee.negative = 0;
+ q.ieee.exponent = 0x7FFF;
+ q.ieee.mantissa0 = 0x0000;
+ q.ieee.mantissa1 = 0x00000000;
+ q.ieee.mantissa2 = 0x00000000;
+ q.ieee.mantissa3 = 0x00000000;
+ CHECK (iszero (q.d), 0);
+
+ /* Quiet NaN. */
+ q.ieee_nan.quiet_nan = 1;
+ q.ieee_nan.mantissa0 = 0x0000;
+ CHECK (iszero (q.d), 0);
+
+ /* Signaling NaN. */
+ q.ieee_nan.quiet_nan = 0;
+ q.ieee_nan.mantissa0 = 0x4000;
+ CHECK (iszero (q.d), 0);
+
+ /* Denormal min. */
+ q.ieee.negative = 0;
+ q.ieee.exponent = 0x0000;
+ q.ieee.mantissa0 = 0x0000;
+ q.ieee.mantissa1 = 0x00000000;
+ q.ieee.mantissa2 = 0x00000000;
+ q.ieee.mantissa3 = 0x00000001;
+ CHECK (iszero (q.d), 0);
+ q.ieee.negative = 1;
+ CHECK (iszero (q.d), 0);
+}
+#endif
+
static int
do_test (void)
{
check_type<float> ();
check_type<double> ();
check_type<long double> ();
+#if __HAVE_DISTINCT_FLOAT128
+ check_float128 ();
+#endif
return errors;
}
diff --git a/sysdeps/powerpc/powerpc64le/Makefile b/sysdeps/powerpc/powerpc64le/Makefile
index 19adbfa..dea2290 100644
--- a/sysdeps/powerpc/powerpc64le/Makefile
+++ b/sysdeps/powerpc/powerpc64le/Makefile
@@ -17,7 +17,8 @@ $(foreach suf,$(all-object-suffixes),$(objpfx)test-float128%$(suf)): CFLAGS += -
$(foreach suf,$(all-object-suffixes),$(objpfx)test-ifloat128%$(suf)): CFLAGS += -mfloat128
CFLAGS-libm-test-support-float128.c += -mfloat128
CFLAGS-test-math-issignaling.cc += -mfloat128
-$(objpfx)test-float128% $(objpfx)test-ifloat128%: \
+CFLAGS-test-math-iszero.cc += -mfloat128
+$(objpfx)test-float128% $(objpfx)test-ifloat128% $(objpfx)test-math-iszero: \
gnulib-tests += $(f128-loader-link)
endif
--
2.9.5
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