From patchwork Mon Jan 12 22:35:54 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joseph Myers X-Patchwork-Id: 4629 Received: (qmail 18402 invoked by alias); 12 Jan 2015 22:36:02 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 18388 invoked by uid 89); 12 Jan 2015 22:36:01 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.6 required=5.0 tests=AWL, BAYES_50, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Date: Mon, 12 Jan 2015 22:35:54 +0000 From: Joseph Myers To: Subject: Fix ldbl-96 scalblnl for subnormal arguments (bug 17834) [committed] Message-ID: User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 The ldbl-96 implementation of scalblnl (used for x86_64 and ia64) is incorrect for subnormal arguments (this is a separate bug from bug 17803, which is about underflowing results). There are two problems with the adjustments of subnormal arguments: the "two63" variable multiplied by is actually 0x1p52L not 0x1p63L, so is insufficient to make values normal, and then GET_LDOUBLE_EXP(es,x), used to extract the new exponent, extracts it into a variable that isn't used, while the value taken to by the new exponent is wrongly taken from the high part of the mantissa before the adjustment (hx). This patch fixes both those problems and adds appropriate tests. Tested for x86_64. Committed. 2015-01-12 Joseph Myers [BZ #17834] * sysdeps/ieee754/ldbl-96/s_scalblnl.c (two63): Change value to 0x1p63L. (__scalblnl): Get new exponent of adjusted subnormal value from ES not HX. * math/libm-test.inc (scalbn_test_data): Add more tests. (scalbln_test_data): Likewise. diff --git a/math/libm-test.inc b/math/libm-test.inc index 8db1dd0..34f83c6 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -9124,6 +9124,17 @@ static const struct test_fi_f_data scalbn_test_data[] = TEST_fi_f (scalbn, 1, 0L, 1, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, min_value / 2, 0, min_value / 2, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, -min_value / 2, 0, -min_value / 2, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, min_value / 2, 1, min_value, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, -min_value / 2, 1, -min_value, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, min_value * 0x0.ffffp0, 0, min_value * 0x0.ffffp0, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, -min_value * 0x0.ffffp0, 0, -min_value * 0x0.ffffp0, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, min_subnorm_value, 0, min_subnorm_value, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, -min_subnorm_value, 0, -min_subnorm_value, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, min_subnorm_value, MANT_DIG, min_value, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, -min_subnorm_value, MANT_DIG, -min_value, NO_INEXACT_EXCEPTION), + TEST_fi_f (scalbn, 1, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION), TEST_fi_f (scalbn, 1, INT_MIN, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION), TEST_fi_f (scalbn, max_value, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION), @@ -9171,6 +9182,17 @@ static const struct test_fl_f_data scalbln_test_data[] = TEST_fl_f (scalbln, 1, 0L, 1, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED), + TEST_fl_f (scalbln, min_value / 2, 0, min_value / 2, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, -min_value / 2, 0, -min_value / 2, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, min_value / 2, 1, min_value, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, -min_value / 2, 1, -min_value, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, min_value * 0x0.ffffp0, 0, min_value * 0x0.ffffp0, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, -min_value * 0x0.ffffp0, 0, -min_value * 0x0.ffffp0, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, min_subnorm_value, 0, min_subnorm_value, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, -min_subnorm_value, 0, -min_subnorm_value, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, min_subnorm_value, MANT_DIG, min_value, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, -min_subnorm_value, MANT_DIG, -min_value, NO_INEXACT_EXCEPTION), + TEST_fl_f (scalbln, 1, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW), TEST_fl_f (scalbln, 1, INT_MIN, plus_uflow, INEXACT_EXCEPTION|UNDERFLOW_EXCEPTION|ERRNO_PLUS_UFLOW), TEST_fl_f (scalbln, max_value, INT_MAX, plus_oflow, INEXACT_EXCEPTION|OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW), diff --git a/sysdeps/ieee754/ldbl-96/s_scalblnl.c b/sysdeps/ieee754/ldbl-96/s_scalblnl.c index fca8470..5c2f38e 100644 --- a/sysdeps/ieee754/ldbl-96/s_scalblnl.c +++ b/sysdeps/ieee754/ldbl-96/s_scalblnl.c @@ -25,7 +25,7 @@ #include static const long double -two63 = 4.50359962737049600000e+15, +two63 = 0x1p63L, twom63 = 1.08420217248550443400e-19, huge = 1.0e+4900L, tiny = 1.0e-4900L; @@ -40,7 +40,7 @@ __scalblnl (long double x, long int n) if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */ x *= two63; GET_LDOUBLE_EXP(es,x); - k = (hx&0x7fff) - 63; + k = (es&0x7fff) - 63; } if (__builtin_expect(k==0x7fff, 0)) return x+x; /* NaN or Inf */ if (__builtin_expect(n< -50000, 0))