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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2024-04-03 16:39:19 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2024-04-04 14:29:28 -0300
commit44ccc2465c6af5bd811d8258bf744aaafd5392fc (patch)
tree3332a0e1abbcdb99c685166da356357ff1076327 /math
parent932544efa469568525455bcb53d4eabeba0eb295 (diff)
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math: x86 trunc traps when FE_INEXACT is enabled (BZ 31603)
The implementations of trunc functions using x87 floating point (i386 and
x86_64 long double only) traps when FE_INEXACT is enabled.  Although
this is a GNU extension outside the scope of the C standard, other
architectures that also support traps do not show this behavior.

The fix moves the implementation to a common one that holds any
exceptions with a 'fnclex' (libc_feholdexcept_setround_387).

Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diffstat (limited to 'math')
-rw-r--r--math/Makefile2
-rw-r--r--math/test-trunc-except-2.c67
2 files changed, 69 insertions, 0 deletions
diff --git a/math/Makefile b/math/Makefile
index 121fe2881a..a9fef9e2db 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -539,6 +539,7 @@ tests = \
   test-tgmath-int \
   test-tgmath-ret \
   test-tgmath2 \
+  test-trunc-except-2 \
   tst-CMPLX \
   tst-CMPLX2 \
   tst-definitions \
@@ -993,6 +994,7 @@ CFLAGS-test-nan-const.c += -fno-builtin
 
 CFLAGS-test-ceil-except-2.c += -fno-builtin
 CFLAGS-test-floor-except-2.c += -fno-builtin
+CFLAGS-test-trunc-except-2.c += -fno-builtin
 
 include ../Rules
 
diff --git a/math/test-trunc-except-2.c b/math/test-trunc-except-2.c
new file mode 100644
index 0000000000..8933c6ab41
--- /dev/null
+++ b/math/test-trunc-except-2.c
@@ -0,0 +1,67 @@
+/* Test trunc functions do not disable exception traps.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <fenv.h>
+#include <math.h>
+#include <stdio.h>
+
+#ifndef FE_INEXACT
+# define FE_INEXACT 0
+#endif
+
+#define TEST_FUNC(NAME, FLOAT, SUFFIX)					\
+static int								\
+NAME (void)								\
+{									\
+  int result = 0;							\
+  volatile FLOAT a, b __attribute__ ((unused));				\
+  a = 1.5;								\
+  /* trunc must work when traps on "inexact" are enabled.  */	\
+  b = trunc ## SUFFIX (a);						\
+  /* And it must have left those traps enabled.  */			\
+  if (fegetexcept () == FE_INEXACT)					\
+    puts ("PASS: " #FLOAT);						\
+  else									\
+    {									\
+      puts ("FAIL: " #FLOAT);						\
+      result = 1;							\
+    }									\
+  return result;							\
+}
+
+TEST_FUNC (float_test, float, f)
+TEST_FUNC (double_test, double, )
+TEST_FUNC (ldouble_test, long double, l)
+
+static int
+do_test (void)
+{
+  if (feenableexcept (FE_INEXACT) == -1)
+    {
+      puts ("enabling FE_INEXACT traps failed, cannot test");
+      return 77;
+    }
+  int result = float_test ();
+  feenableexcept (FE_INEXACT);
+  result |= double_test ();
+  feenableexcept (FE_INEXACT);
+  result |= ldouble_test ();
+  return result;
+}
+
+#include <support/test-driver.c>