Author: das
Date: Sat Oct 15 05:26:16 2011
New Revision: 226377
URL: http://svn.freebsd.org/changeset/base/226377
Log:
Add some tests for double-rounding bugs in fma().
Modified:
head/tools/regression/lib/msun/test-fma.c
Modified: head/tools/regression/lib/msun/test-fma.c
==============================================================================
--- head/tools/regression/lib/msun/test-fma.c Sat Oct 15 05:23:28 2011
(r226376)
+++ head/tools/regression/lib/msun/test-fma.c Sat Oct 15 05:26:16 2011
(r226377)
@@ -364,13 +364,63 @@ test_accuracy(void)
#endif
}
+static void
+test_double_rounding(void)
+{
+
+ /*
+ * a = 0x1.8000000000001p0
+ * b = 0x1.8000000000001p0
+ * c = -0x0.0000000000000000000000000080...1p+1
+ * a * b = 0x1.2000000000001800000000000080p+1
+ *
+ * The correct behavior is to round DOWN to 0x1.2000000000001p+1 in
+ * round-to-nearest mode. An implementation that computes a*b+c in
+ * double+double precision, however, will get 0x1.20000000000018p+1,
+ * and then round UP.
+ */
+ fesetround(FE_TONEAREST);
+ test(fma, 0x1.8000000000001p0, 0x1.8000000000001p0,
+ -0x1.0000000000001p-104, 0x1.2000000000001p+1,
+ ALL_STD_EXCEPT, FE_INEXACT);
+ fesetround(FE_DOWNWARD);
+ test(fma, 0x1.8000000000001p0, 0x1.8000000000001p0,
+ -0x1.0000000000001p-104, 0x1.2000000000001p+1,
+ ALL_STD_EXCEPT, FE_INEXACT);
+ fesetround(FE_UPWARD);
+ test(fma, 0x1.8000000000001p0, 0x1.8000000000001p0,
+ -0x1.0000000000001p-104, 0x1.2000000000002p+1,
+ ALL_STD_EXCEPT, FE_INEXACT);
+
+ fesetround(FE_TONEAREST);
+ test(fmaf, 0x1.800002p+0, 0x1.800002p+0, -0x1.000002p-46, 0x1.200002p+1,
+ ALL_STD_EXCEPT, FE_INEXACT);
+ fesetround(FE_DOWNWARD);
+ test(fmaf, 0x1.800002p+0, 0x1.800002p+0, -0x1.000002p-46, 0x1.200002p+1,
+ ALL_STD_EXCEPT, FE_INEXACT);
+ fesetround(FE_UPWARD);
+ test(fmaf, 0x1.800002p+0, 0x1.800002p+0, -0x1.000002p-46, 0x1.200004p+1,
+ ALL_STD_EXCEPT, FE_INEXACT);
+
+ fesetround(FE_TONEAREST);
+#if LDBL_MANT_DIG == 64
+ test(fmal, 0x1.4p+0L, 0x1.0000000000000004p+0L, 0x1p-128L,
+ 0x1.4000000000000006p+0L, ALL_STD_EXCEPT, FE_INEXACT);
+#elif LDBL_MANT_DIG == 113
+ /* XXX untested test */
+ test(fmal, 0x1.4p+0L, 0x1.0000000000000000000000000002p+0L, 0x1p-224L,
+ 0x1.4000000000000000000000000003p+0L, ALL_STD_EXCEPT, FE_INEXACT);
+#endif
+
+}
+
int
main(int argc, char *argv[])
{
int rmodes[] = { FE_TONEAREST, FE_UPWARD, FE_DOWNWARD, FE_TOWARDZERO };
int i;
- printf("1..18\n");
+ printf("1..19\n");
for (i = 0; i < 4; i++) {
fesetround(rmodes[i]);
@@ -404,6 +454,9 @@ main(int argc, char *argv[])
test_accuracy();
printf("ok 18 - fma accuracy\n");
+ test_double_rounding();
+ printf("ok 19 - fma double rounding\n");
+
/*
* TODO:
* - Tests for subnormals
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
