Fix ilogb exception and errno (bug 6794)

[BZ #6794]
Following Joseph comments about bug 6794, here is a proposed fix. It turned out
to be a large fix mainly because I had to move some file along to follow libm
files/names conventions.

Basically I have added wrappers (w_ilogb.c, w_ilogbf.c, w_ilogbl.c) that now calls
the symbol '__ieee754_ilogb'. The wrappers checks for '__ieee754_ilogb' output and
set the errno and raise exceptions as expected.

The '__ieee754_ilogb' is implemented in sysdeps. I have moved the 's_ilogb[f|l]' files
to e_ilogb[f|l] and renamed the '__ilogb[f|l]' to '__ieee754_ilogb[f|l]'.

I also found out a bug in i386 and x86-64 assembly coded ilogb implementation where
it raises a FE_DIVBYZERO when argument is '0.0'. I corrected this issue as well.

Finally I added the errno and FE_INVALID tests for 0.0, NaN and +-InF argument. Tested
on i386, x86-64, ppc32 and ppc64.

1 files changed, 16 insertions, 7 deletions

diff --git a/math/libm-test.inc b/math/libm-test.inc
index 2809d57d09..94d60bff7e 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -3802,13 +3802,22 @@ ilogb_test (void)
   TEST_f_i (ilogb, 1024, 10);
   TEST_f_i (ilogb, -2000, 10);
 
-  /* XXX We have a problem here: the standard does not tell us whether
-     exceptions are allowed/required.  ignore them for now.  */
-
-  TEST_f_i (ilogb, 0.0, FP_ILOGB0, EXCEPTIONS_OK);
-  TEST_f_i (ilogb, nan_value, FP_ILOGBNAN, EXCEPTIONS_OK);
-  TEST_f_i (ilogb, plus_infty, INT_MAX, EXCEPTIONS_OK);
-  TEST_f_i (ilogb, minus_infty, INT_MAX, EXCEPTIONS_OK);
+  /* ilogb (0.0) == FP_ILOGB0 plus invalid exception  */
+  errno = 0;
+  TEST_f_i (ilogb, 0.0, FP_ILOGB0, INVALID_EXCEPTION);
+  check_int ("errno for ilogb(0.0) unchanged", errno, EDOM, 0, 0, 0);
+  /* ilogb (NaN) == FP_ILOGBNAN plus invalid exception  */
+  errno = 0;
+  TEST_f_i (ilogb, nan_value, FP_ILOGBNAN, INVALID_EXCEPTION);
+  check_int ("errno for ilogb(NaN) unchanged", errno, EDOM, 0, 0, 0);
+  /* ilogb (inf) == INT_MAX plus invalid exception  */
+  errno = 0;
+  TEST_f_i (ilogb, plus_infty, INT_MAX, INVALID_EXCEPTION);
+  check_int ("errno for ilogb(Inf) unchanged", errno, EDOM, 0, 0, 0);
+  /* ilogb (-inf) == INT_MAX plus invalid exception  */
+  errno = 0;
+  TEST_f_i (ilogb, minus_infty, INT_MAX, INVALID_EXCEPTION);
+  check_int ("errno for ilogb(-Inf) unchanged", errno, EDOM, 0, 0, 0);
 
   END (ilogb);
 }