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authorRyan S. Arnold <rsa@linux.vnet.ibm.com>2012-04-27 10:47:39 -0500
committerRyan S. Arnold <rsa@linux.vnet.ibm.com>2012-04-27 10:47:39 -0500
commita462cb63326595eb018e26ea415f8ddc1ed50730 (patch)
tree89a1ee94b2ebd0e3355bab5c83a8445b5f6f060c /math
parent6ad3493e2247e6cb3c9e086e8cb1f8b51a5f27d6 (diff)
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New test to expose erroneous negative sign on logb(1) (bug 887).
Diffstat (limited to 'math')
-rw-r--r--math/libm-test.inc35
1 files changed, 35 insertions, 0 deletions
diff --git a/math/libm-test.inc b/math/libm-test.inc
index e0ac6131da..d11cd1ff86 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -5101,6 +5101,40 @@ logb_test (void)
END (logb);
}
+static void
+logb_test_downward (void)
+{
+ int save_round_mode;
+ errno = 0;
+
+ FUNC(logb) (0);
+ if (errno == ENOSYS)
+ /* Function not implemented. */
+ return;
+
+ START (logb_downward);
+
+ save_round_mode = fegetround ();
+
+ if (!fesetround (FE_DOWNWARD))
+ {
+
+ /* IEEE 754-2008 says (section 5.3.3) that "logB(1) is +0.". Libm
+ should not return -0 from logb in any rounding mode. PowerPC32 has
+ failed with this test for power4 logb (and logbl on all PowerPC
+ platforms) in the past due to instruction selection. GCC PR 52775
+ provides the availability of the fcfid insn in 32-bit mode which
+ eliminates the use of fsub in this instance and prevents the negative
+ signed 0.0. */
+
+ /* BZ #887 .*/
+ TEST_f_f (logb, 1.000e+0, plus_zero);
+ }
+
+ fesetround (save_round_mode);
+
+ END (logb_downward);
+}
static void
lround_test (void)
@@ -8210,6 +8244,7 @@ main (int argc, char **argv)
log1p_test ();
log2_test ();
logb_test ();
+ logb_test_downward ();
modf_test ();
ilogb_test ();
scalb_test ();