Date: Sat, 15 Oct 2011 05:26:16 +0000 (UTC) From: David Schultz <das@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r226377 - head/tools/regression/lib/msun Message-ID: <201110150526.p9F5QGaR096847@svn.freebsd.org>
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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
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