math: support platforms with limited FP rounding or exception support

For some tests, just claim that fetestexcept() always returns true,
so the rest of the test can be compiled.

For libm-test, provide known bogus values for unsupported rounding
modes, so fesetround() will return failure.

Elsewhere, just add some #ifdefs to avoid code that uses particular
FP exceptions if the exceptions aren't supported.

5 files changed, 40 insertions, 0 deletions

diff --git a/math/bug-nextafter.c b/math/bug-nextafter.c
index 1d21841..558b158 100644
--- a/math/bug-nextafter.c
+++ b/math/bug-nextafter.c
@@ -4,6 +4,12 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#if !defined(FE_OVERFLOW) && !defined(FE_UNDERFLOW)
+/* If there's no support for the exceptions this test is checking,
+   then just return success and allow the test to be compiled.  */
+# define fetestexcept(e) 1
+#endif
+
 float zero = 0.0;
 float inf = INFINITY;
 
diff --git a/math/bug-nexttoward.c b/math/bug-nexttoward.c
index ff57e5e..cedb776 100644
--- a/math/bug-nexttoward.c
+++ b/math/bug-nexttoward.c
@@ -4,6 +4,12 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#if !defined(FE_OVERFLOW) && !defined(FE_UNDERFLOW)
+/* If there's no support for the exceptions this test is checking,
+   then just return success and allow the test to be compiled.  */
+# define fetestexcept(e) 1
+#endif
+
 float zero = 0.0;
 float inf = INFINITY;
 
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 5a38dbf..47bbd5f 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -128,6 +128,22 @@
 #include <string.h>
 #include <argp.h>
 
+/* Allow platforms without all rounding modes to test properly,
+   assuming they provide an __FE_UNDEFINED in <bits/fenv.h> which
+   causes fesetround() to return failure.  */
+#ifndef FE_TONEAREST
+# define FE_TONEAREST	__FE_UNDEFINED
+#endif
+#ifndef FE_TOWARDZERO
+# define FE_TOWARDZERO	__FE_UNDEFINED
+#endif
+#ifndef FE_UPWARD
+# define FE_UPWARD	__FE_UNDEFINED
+#endif
+#ifndef FE_DOWNWARD
+# define FE_DOWNWARD	__FE_UNDEFINED
+#endif
+
 /* Possible exceptions */
 #define NO_EXCEPTION			0x0
 #define INVALID_EXCEPTION		0x1
diff --git a/math/test-fenv.c b/math/test-fenv.c
index 39c7c33..19e5415 100644
--- a/math/test-fenv.c
+++ b/math/test-fenv.c
@@ -664,9 +664,11 @@ feholdexcept_tests (void)
     }
 #endif
   test_exceptions ("feholdexcept_tests 0 test", NO_EXC, 0);
+#ifdef FE_INVALID
   feraiseexcept (FE_INVALID);
   test_exceptions ("feholdexcept_tests FE_INVALID test",
 		   INVALID_EXC, 0);
+#endif
   res = feupdateenv (&saved);
   if (res != 0)
     {
@@ -684,7 +686,9 @@ feholdexcept_tests (void)
   test_exceptions ("feholdexcept_tests FE_DIVBYZERO|FE_INVALID test",
 		   DIVBYZERO_EXC | INVALID_EXC, 0);
   feclearexcept (FE_ALL_EXCEPT);
+#ifdef FE_INVALID
   feraiseexcept (FE_INVALID);
+#endif
 #if defined FE_TONEAREST && defined FE_UPWARD
   res = fesetround (FE_UPWARD);
   if (res != 0)
@@ -708,9 +712,11 @@ feholdexcept_tests (void)
     }
 #endif
   test_exceptions ("feholdexcept_tests 0 2nd test", NO_EXC, 0);
+#ifdef FE_INEXACT
   feraiseexcept (FE_INEXACT);
   test_exceptions ("feholdexcept_tests FE_INEXACT test",
 		   INEXACT_EXC, 0);
+#endif
   res = feupdateenv (&saved2);
   if (res != 0)
     {
diff --git a/math/test-misc.c b/math/test-misc.c
index c0fe5f7..55da359 100644
--- a/math/test-misc.c
+++ b/math/test-misc.c
@@ -1186,12 +1186,14 @@ main (void)
   (void) &f2;
   feclearexcept (FE_ALL_EXCEPT);
   f2 += f1;
+#if defined(FE_OVERFLOW) && defined(FE_INEXACT)
   int fe = fetestexcept (FE_ALL_EXCEPT);
   if (fe != (FE_OVERFLOW | FE_INEXACT))
     {
       printf ("float overflow test failed: %x\n", fe);
       result = 1;
     }
+#endif
 
   volatile double d1 = DBL_MAX;
   volatile double d2 = DBL_MAX / 2;
@@ -1199,12 +1201,14 @@ main (void)
   (void) &d2;
   feclearexcept (FE_ALL_EXCEPT);
   d2 += d1;
+#if defined(FE_OVERFLOW) && defined(FE_INEXACT)
   fe = fetestexcept (FE_ALL_EXCEPT);
   if (fe != (FE_OVERFLOW | FE_INEXACT))
     {
       printf ("double overflow test failed: %x\n", fe);
       result = 1;
     }
+#endif
 
 #ifndef NO_LONG_DOUBLE
   volatile long double ld1 = LDBL_MAX;
@@ -1213,12 +1217,14 @@ main (void)
   (void) &ld2;
   feclearexcept (FE_ALL_EXCEPT);
   ld2 += ld1;
+# if defined(FE_OVERFLOW) && defined(FE_INEXACT)
   fe = fetestexcept (FE_ALL_EXCEPT);
   if (fe != (FE_OVERFLOW | FE_INEXACT))
     {
       printf ("long double overflow test failed: %x\n", fe);
       result = 1;
     }
+# endif
 #endif
 
 #if !defined NO_LONG_DOUBLE && LDBL_MANT_DIG == 113