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author | das <das@FreeBSD.org> | 2011-10-15 05:26:16 +0000 |
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committer | das <das@FreeBSD.org> | 2011-10-15 05:26:16 +0000 |
commit | 9f9eca0faeddcd96e9dd393f6be53a363a536fc8 (patch) | |
tree | 9de594bbdccd961066f845caa565fa2c59d80ef1 /tools | |
parent | 2772ec758e6fb6c0bdaa3e30a268816e754de5a7 (diff) | |
download | FreeBSD-src-9f9eca0faeddcd96e9dd393f6be53a363a536fc8.zip FreeBSD-src-9f9eca0faeddcd96e9dd393f6be53a363a536fc8.tar.gz |
Add some tests for double-rounding bugs in fma().
Diffstat (limited to 'tools')
-rw-r--r-- | tools/regression/lib/msun/test-fma.c | 55 |
1 files changed, 54 insertions, 1 deletions
diff --git a/tools/regression/lib/msun/test-fma.c b/tools/regression/lib/msun/test-fma.c index 00620f8..2e0e54b 100644 --- a/tools/regression/lib/msun/test-fma.c +++ b/tools/regression/lib/msun/test-fma.c @@ -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 |