Add tests for fegetexceptflag, fesetexceptflag [committed]

[Joseph Myers <joseph at codesourcery dot com>]

I noticed that there was no meaningful test coverage for
fegetexceptflag and fesetexceptflag (one test ensures that calls to
them compile and link, but nothing to verify they work correctly).
This patch adds tests for these functions.

fesetexceptflag is meant to set the relevant exception flag bits to
the saved state without causing enabled traps to be taken.  On some
architectures, it is not possible to set exception flag bits without
causing enabled traps to occur.  Such architectures need to define
EXCEPTION_SET_FORCES_TRAP to 1 in their math-tests.h, as is done in
this patch for powerpc.  x86 avoids needing to define this because the
traps resulting from setting exception bits don't occur until the next
floating-point operation or fwait instruction.

Tested for x86_64, x86 and powerpc.  Note that test-fexcept fails for
powerpc because of a pre-existing bug in fesetexceptflag for powerpc,
which I'll fix separately.

Committed.

2016-08-10  Joseph Myers  <joseph@codesourcery.com>

	* math/test-fexcept-traps.c: New file.
	* math/test-fexcept.c: Likewise.
	* math/Makefile (tests): Add test-fexcept and test-fexcept-traps.
	* sysdeps/generic/math-tests.h (EXCEPTION_SET_FORCES_TRAP): New
	macro.
	* sysdeps/powerpc/math-tests.h [!__NO_FPRS__]
	(EXCEPTION_SET_FORCES_TRAP): Likewise.

diff --git a/math/Makefile b/math/Makefile
index 925b8d4..1da1797 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -146,7 +146,7 @@ tests = test-matherr test-fenv atest-exp atest-sincos atest-exp2 basic-test \
 	test-nearbyint-except-2 test-signgam-uchar test-signgam-uchar-init \
 	test-signgam-uint test-signgam-uint-init test-signgam-ullong \
 	test-signgam-ullong-init test-nan-overflow test-nan-payload \
-	$(tests-static)
+	test-fexcept test-fexcept-traps $(tests-static)
 tests-static = test-fpucw-static test-fpucw-ieee-static \
 	       test-signgam-uchar-static test-signgam-uchar-init-static \
 	       test-signgam-uint-static test-signgam-uint-init-static \
diff --git a/math/test-fexcept-traps.c b/math/test-fexcept-traps.c
new file mode 100644
index 0000000..428a444
--- /dev/null
+++ b/math/test-fexcept-traps.c
@@ -0,0 +1,84 @@
+/* Test fegetexceptflag and fesetexceptflag: exception traps enabled.
+   Copyright (C) 2016 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <fenv.h>
+#include <stdio.h>
+#include <math-tests.h>
+
+static int
+do_test (void)
+{
+  int result = 0;
+
+  fedisableexcept (FE_ALL_EXCEPT);
+  int ret = feraiseexcept (FE_ALL_EXCEPT);
+  if (ret != 0)
+    {
+      if (EXCEPTION_TESTS (float))
+	{
+	  puts ("feraiseexcept (FE_ALL_EXCEPT) failed");
+	  result = 1;
+	  return result;
+	}
+      else
+	{
+	  puts ("feraiseexcept (FE_ALL_EXCEPT) unsupported, cannot test");
+	  return 77;
+	}
+    }
+  fexcept_t saved;
+  ret = fegetexceptflag (&saved, FE_ALL_EXCEPT);
+  if (ret != 0)
+    {
+      puts ("fegetexceptflag failed");
+      result = 1;
+      return result;
+    }
+  feclearexcept (FE_ALL_EXCEPT);
+
+  ret = feenableexcept (FE_ALL_EXCEPT);
+  if (!EXCEPTION_ENABLE_SUPPORTED (FE_ALL_EXCEPT) && (ret == -1))
+    {
+      puts ("feenableexcept (FE_ALL_EXCEPT) not supported, cannot test");
+      return 77;
+    }
+  else if (ret != 0)
+    {
+      puts ("feenableexcept (FE_ALL_EXCEPT) failed");
+      result = 1;
+    }
+
+  if (EXCEPTION_SET_FORCES_TRAP)
+    {
+      puts ("setting exceptions traps, cannot test on this architecture");
+      return 77;
+    }
+  /* The test is that this does not cause exception traps.  */
+  ret = fesetexceptflag (&saved, FE_ALL_EXCEPT);
+  if (ret != 0)
+    {
+      puts ("fesetexceptflag failed");
+      result = 1;
+    }
+  feclearexcept (FE_ALL_EXCEPT);
+
+  return result;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/math/test-fexcept.c b/math/test-fexcept.c
new file mode 100644
index 0000000..5e181a1
--- /dev/null
+++ b/math/test-fexcept.c
@@ -0,0 +1,171 @@
+/* Test fegetexceptflag and fesetexceptflag.
+   Copyright (C) 2016 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <fenv.h>
+#include <stdio.h>
+#include <math-tests.h>
+
+static int
+test_set (int initial, const fexcept_t *saved, int mask, int expected)
+{
+  int result = 0;
+  feclearexcept (FE_ALL_EXCEPT);
+  printf ("Testing set: initial exceptions %x, mask %x, expected %x\n",
+	  (unsigned int) initial, (unsigned int) mask,
+	  (unsigned int) expected);
+  int ret = feraiseexcept (initial);
+  if (ret != 0)
+    {
+      puts ("feraiseexcept failed");
+      result = 1;
+      return result;
+    }
+  ret = fesetexceptflag (saved, mask);
+  if (ret != 0)
+    {
+      puts ("fesetexceptflag failed");
+      result = 1;
+    }
+  else
+    puts ("fesetexceptflag succeeded");
+  ret = fetestexcept (FE_ALL_EXCEPT);
+  if (ret != expected)
+    {
+      printf ("raised exceptions %x, expected %x\n",
+	      (unsigned int) ret, (unsigned int) expected);
+      result = 1;
+    }
+  return result;
+}
+
+static int
+test_except (int exc, const char *exc_name)
+{
+  int result = 0;
+
+  printf ("Testing %s\n", exc_name);
+  feclearexcept (FE_ALL_EXCEPT);
+
+  fexcept_t clear_saved_exc, clear_saved_all;
+  int ret = fegetexceptflag (&clear_saved_exc, exc);
+  if (ret == 0)
+    printf ("fegetexceptflag (%s) succeeded\n", exc_name);
+  else
+    {
+      printf ("fegetexceptflag (%s) failed\n", exc_name);
+      result = 1;
+      return result;
+    }
+  ret = fegetexceptflag (&clear_saved_all, FE_ALL_EXCEPT);
+  if (ret == 0)
+    puts ("fegetexceptflag (FE_ALL_EXCEPT) succeeded");
+  else
+    {
+      puts ("fegetexceptflag (FE_ALL_EXCEPT) failed");
+      result = 1;
+      return result;
+    }
+
+  ret = feraiseexcept (exc);
+  if (ret == 0)
+    printf ("feraiseexcept (%s) succeeded\n", exc_name);
+  else
+    {
+      printf ("feraiseexcept (%s) failed\n", exc_name);
+      if (exc == 0 || EXCEPTION_TESTS (float))
+	{
+	  puts ("failure of feraiseexcept was unexpected");
+	  result = 1;
+	}
+      else
+	puts ("failure of feraiseexcept OK, skipping further tests");
+      return result;
+    }
+
+  fexcept_t set_saved_exc, set_saved_all;
+  ret = fegetexceptflag (&set_saved_exc, exc);
+  if (ret == 0)
+    printf ("fegetexceptflag (%s) succeeded\n", exc_name);
+  else
+    {
+      printf ("fegetexceptflag (%s) failed\n", exc_name);
+      result = 1;
+      return result;
+    }
+  ret = fegetexceptflag (&set_saved_all, FE_ALL_EXCEPT);
+  if (ret == 0)
+    puts ("fegetexceptflag (FE_ALL_EXCEPT) succeeded");
+  else
+    {
+      puts ("fegetexceptflag (FE_ALL_EXCEPT) failed");
+      result = 1;
+      return result;
+    }
+
+  result |= test_set (0, &set_saved_exc, exc, exc);
+  result |= test_set (0, &set_saved_all, exc, exc);
+  result |= test_set (0, &set_saved_all, FE_ALL_EXCEPT, exc);
+  result |= test_set (0, &clear_saved_exc, exc, 0);
+  result |= test_set (0, &clear_saved_all, exc, 0);
+  result |= test_set (0, &clear_saved_all, FE_ALL_EXCEPT, 0);
+  result |= test_set (exc, &set_saved_exc, exc, exc);
+  result |= test_set (exc, &set_saved_all, exc, exc);
+  result |= test_set (exc, &set_saved_all, FE_ALL_EXCEPT, exc);
+  result |= test_set (exc, &clear_saved_exc, exc, 0);
+  result |= test_set (exc, &clear_saved_all, exc, 0);
+  result |= test_set (exc, &clear_saved_all, FE_ALL_EXCEPT, 0);
+  result |= test_set (FE_ALL_EXCEPT, &set_saved_exc, exc, FE_ALL_EXCEPT);
+  result |= test_set (FE_ALL_EXCEPT, &set_saved_all, exc, FE_ALL_EXCEPT);
+  result |= test_set (FE_ALL_EXCEPT, &set_saved_all, FE_ALL_EXCEPT, exc);
+  result |= test_set (FE_ALL_EXCEPT, &clear_saved_exc, exc,
+		      FE_ALL_EXCEPT & ~exc);
+  result |= test_set (FE_ALL_EXCEPT, &clear_saved_all, exc,
+		      FE_ALL_EXCEPT & ~exc);
+  result |= test_set (FE_ALL_EXCEPT, &clear_saved_all, FE_ALL_EXCEPT, 0);
+
+  return result;
+}
+
+static int
+do_test (void)
+{
+  int result = 0;
+
+  result |= test_except (0, "0");
+  result |= test_except (FE_ALL_EXCEPT, "FE_ALL_EXCEPT");
+#ifdef FE_DIVBYZERO
+  result |= test_except (FE_DIVBYZERO, "FE_DIVBYZERO");
+#endif
+#ifdef FE_INEXACT
+  result |= test_except (FE_INEXACT, "FE_INEXACT");
+#endif
+#ifdef FE_INVALID
+  result |= test_except (FE_INVALID, "FE_INVALID");
+#endif
+#ifdef FE_OVERFLOW
+  result |= test_except (FE_OVERFLOW, "FE_OVERFLOW");
+#endif
+#ifdef FE_UNDERFLOW
+  result |= test_except (FE_UNDERFLOW, "FE_UNDERFLOW");
+#endif
+
+  return result;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/sysdeps/generic/math-tests.h b/sysdeps/generic/math-tests.h
index 9393229..974dda4 100644
--- a/sysdeps/generic/math-tests.h
+++ b/sysdeps/generic/math-tests.h
@@ -87,3 +87,12 @@
 # define EXCEPTION_ENABLE_SUPPORTED(EXCEPT)			\
    (EXCEPTION_TESTS_float || EXCEPTION_TESTS_double)
 #endif
+
+/* Indicate whether exception traps, if enabled, occur whenever an
+   exception flag is set explicitly, so it is not possible to set flag
+   bits with traps enabled without causing traps to be taken.  If
+   traps cannot be enabled, the value of this macro does not
+   matter.  */
+#ifndef EXCEPTION_SET_FORCES_TRAP
+# define EXCEPTION_SET_FORCES_TRAP 0
+#endif
diff --git a/sysdeps/powerpc/math-tests.h b/sysdeps/powerpc/math-tests.h
index 31042fa..426a027 100644
--- a/sysdeps/powerpc/math-tests.h
+++ b/sysdeps/powerpc/math-tests.h
@@ -24,4 +24,10 @@
    <http://gcc.gnu.org/PR56828>.  */
 #define SNAN_TESTS_TYPE_CAST	0
 
+#ifndef __NO_FPRS__
+/* Setting exception flags in FPSCR results in enabled traps for those
+   exceptions being taken.  */
+# define EXCEPTION_SET_FORCES_TRAP 1
+#endif
+
 #include_next <math-tests.h>

-- 
Joseph S. Myers
joseph@codesourcery.com