From ce8fc784e619ada624dc41ed7603211131e66573 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Tue, 17 Feb 2015 00:41:50 +0000 Subject: [PATCH] Fix sign of remquo zero remainder in round-downward mode (bug 17987). Various remquo implementations produce a zero remainder with the wrong sign (a zero remainder should always have the sign of the first argument, as specified in IEEE 754) in round-downward mode, resulting from the sign of 0 - 0. This patch checks for zero results and fixes their sign accordingly. Tested for x86_64, x86, mips64 and powerpc. [BZ #17987] * sysdeps/ieee754/dbl-64/s_remquo.c (__remquo): Ensure sign of zero result does not depend on the sign resulting from subtraction. * sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c (__remquo): Likewise. * sysdeps/ieee754/flt-32/s_remquof.c (__remquof): Likewise. * sysdeps/ieee754/ldbl-128/s_remquol.c (__remquol): Likewise. * sysdeps/ieee754/ldbl-128ibm/s_remquol.c (__remquol): Likewise. * sysdeps/ieee754/ldbl-96/s_remquol.c (__remquol): Likewise. * math/libm-test.inc (remquo_test_data): Add more tests. --- ChangeLog | 14 ++++++++++++++ NEWS | 2 +- math/libm-test.inc | 10 ++++++++++ sysdeps/ieee754/dbl-64/s_remquo.c | 3 +++ sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c | 3 +++ sysdeps/ieee754/flt-32/s_remquof.c | 3 +++ sysdeps/ieee754/ldbl-128/s_remquol.c | 3 +++ sysdeps/ieee754/ldbl-128ibm/s_remquol.c | 3 +++ sysdeps/ieee754/ldbl-96/s_remquol.c | 3 +++ 9 files changed, 43 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index 540e997..f74ef23 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,17 @@ +2015-02-16 Joseph Myers + + [BZ #17987] + * sysdeps/ieee754/dbl-64/s_remquo.c (__remquo): Ensure sign of + zero result does not depend on the sign resulting from + subtraction. + * sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c (__remquo): + Likewise. + * sysdeps/ieee754/flt-32/s_remquof.c (__remquof): Likewise. + * sysdeps/ieee754/ldbl-128/s_remquol.c (__remquol): Likewise. + * sysdeps/ieee754/ldbl-128ibm/s_remquol.c (__remquol): Likewise. + * sysdeps/ieee754/ldbl-96/s_remquol.c (__remquol): Likewise. + * math/libm-test.inc (remquo_test_data): Add more tests. + 2015-02-16 Paul Eggert * manual/time.texi (TZ Variable): glibc no longer comes with tzdata. diff --git a/NEWS b/NEWS index 4f4f740..1c5e590 100644 --- a/NEWS +++ b/NEWS @@ -10,7 +10,7 @@ Version 2.22 * The following bugs are resolved with this release: 4719, 15467, 15790, 16560, 17569, 17792, 17912, 17932, 17944, 17949, - 17964, 17965, 17967, 17969, 17978. + 17964, 17965, 17967, 17969, 17978, 17987. Version 2.21 diff --git a/math/libm-test.inc b/math/libm-test.inc index 1cf80e3..85d8b67 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -8818,6 +8818,16 @@ static const struct test_ffI_f1_data remquo_test_data[] = TEST_ffI_f1 (remquo, -1, -max_value / 4, -1, 0, NO_INEXACT_EXCEPTION), TEST_ffI_f1 (remquo, -1, max_value / 8, -1, 0, NO_INEXACT_EXCEPTION), TEST_ffI_f1 (remquo, -1, -max_value / 8, -1, 0, NO_INEXACT_EXCEPTION), + + TEST_ffI_f1 (remquo, max_value, max_value / 2, plus_zero, 2, NO_INEXACT_EXCEPTION), + TEST_ffI_f1 (remquo, max_value, -max_value / 2, plus_zero, -2, NO_INEXACT_EXCEPTION), + TEST_ffI_f1 (remquo, -max_value, max_value / 2, minus_zero, -2, NO_INEXACT_EXCEPTION), + TEST_ffI_f1 (remquo, -max_value, -max_value / 2, minus_zero, 2, NO_INEXACT_EXCEPTION), + + TEST_ffI_f1 (remquo, 2, 1, plus_zero, 2, NO_INEXACT_EXCEPTION), + TEST_ffI_f1 (remquo, 2, -1, plus_zero, -2, NO_INEXACT_EXCEPTION), + TEST_ffI_f1 (remquo, -2, 1, minus_zero, -2, NO_INEXACT_EXCEPTION), + TEST_ffI_f1 (remquo, -2, -1, minus_zero, 2, NO_INEXACT_EXCEPTION), }; static void diff --git a/sysdeps/ieee754/dbl-64/s_remquo.c b/sysdeps/ieee754/dbl-64/s_remquo.c index e07efa8..b081d26 100644 --- a/sysdeps/ieee754/dbl-64/s_remquo.c +++ b/sysdeps/ieee754/dbl-64/s_remquo.c @@ -101,6 +101,9 @@ __remquo (double x, double y, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0) + x = 0.0; if (sx) x = -x; return x; diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c index ab56178..304e9d0 100644 --- a/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c +++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c @@ -100,6 +100,9 @@ __remquo (double x, double y, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0) + x = 0.0; if (sx) x = -x; return x; diff --git a/sysdeps/ieee754/flt-32/s_remquof.c b/sysdeps/ieee754/flt-32/s_remquof.c index 04944fd..36cf359 100644 --- a/sysdeps/ieee754/flt-32/s_remquof.c +++ b/sysdeps/ieee754/flt-32/s_remquof.c @@ -100,6 +100,9 @@ __remquof (float x, float y, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0f) + x = 0.0f; if (sx) x = -x; return x; diff --git a/sysdeps/ieee754/ldbl-128/s_remquol.c b/sysdeps/ieee754/ldbl-128/s_remquol.c index da175a1..82cdf1a 100644 --- a/sysdeps/ieee754/ldbl-128/s_remquol.c +++ b/sysdeps/ieee754/ldbl-128/s_remquol.c @@ -102,6 +102,9 @@ __remquol (long double x, long double y, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0L) + x = 0.0L; if (sx) x = -x; return x; diff --git a/sysdeps/ieee754/ldbl-128ibm/s_remquol.c b/sysdeps/ieee754/ldbl-128ibm/s_remquol.c index ac22879..57c5059 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_remquol.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_remquol.c @@ -107,6 +107,9 @@ __remquol (long double x, long double y, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0L) + x = 0.0L; if (sx) x = -x; return x; diff --git a/sysdeps/ieee754/ldbl-96/s_remquol.c b/sysdeps/ieee754/ldbl-96/s_remquol.c index 1462b54..8d6b10e 100644 --- a/sysdeps/ieee754/ldbl-96/s_remquol.c +++ b/sysdeps/ieee754/ldbl-96/s_remquol.c @@ -101,6 +101,9 @@ __remquol (long double x, long double p, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0L) + x = 0.0L; if (sx) x = -x; return x; -- 2.7.4