From patchwork Fri Mar 21 17:47:45 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joseph Myers X-Patchwork-Id: 332691 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id BFF742C00B1 for ; Sat, 22 Mar 2014 04:48:01 +1100 (EST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:subject:message-id:mime-version :content-type; q=dns; s=default; b=bu5e8mo5+32PF5AbwMku6w3+2tI2O QGj6VSneR0T+vRd2EA7PY/tKBH6yxtJABXX9Mv05gCYjn8ycF2aq9Vlj/iCweQEG jVnJc8T653L4a3ccbUPhbi545foIHGBrjKf9k7cbBmrRaX/aPu2YBB68IvJuxjaq fjy1RLgKGfwZEs= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:subject:message-id:mime-version :content-type; s=default; bh=7Ko9lU1PKL18eAlG9JxCsGoX9gQ=; b=I7T ah9AMZ4yijE7dt1UdAi5qDMFILXojBfL9alya55K97M/QeIOQpBCtDGsGNgaDLa9 Hj+IzXmAs6M2tEkLVK6xBGvsrJn/1Vo0eGUdjrncke7wV9Bo3UH53mz8Xw3fWFRt MwrWz0kZzYAc/16yQ8BxwJsbYfhj9EkWnwmrnkVg= Received: (qmail 518 invoked by alias); 21 Mar 2014 17:47:56 -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 509 invoked by uid 89); 21 Mar 2014 17:47:56 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL, BAYES_00 autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Date: Fri, 21 Mar 2014 17:47:45 +0000 From: "Joseph S. Myers" To: Subject: Fix log (1) in round-downward mode (bug 16731) Message-ID: MIME-Version: 1.0 According to ISO C Annex F, log (1) should be +0 in all rounding modes, but some implementations in glibc wrongly return -0 in round-downward mode (mapping to log1p (x - 1) is problematic because 1 - 1 is -0 in round-downward mode, and log1p (-0) is -0). This patch fixes this. (It helps with some implementations of other functions such as acosh, log2 and log10 that call out to log, but not enough to enable all-rounding-modes testing for those functions without further fixes to other implementations of them.) Tested x86_64 and x86 and ulps updated accordingly, and did spot tests for mips64 for the ldbl-128 fix, and i586 for the sysdeps/i386/fpu implementations shadowed by those in sysdeps/i386/i686/fpu. 2014-03-21 Joseph Myers [BZ #16731] * sysdeps/i386/fpu/e_log.S (__ieee754_log): Take absolute value when x - 1 is zero. * sysdeps/i386/fpu/e_logf.S (__ieee754_logf): Likewise. * sysdeps/i386/fpu/e_logl.S (__ieee754_logl): Likewise. * sysdeps/i386/i686/fpu/e_logl.S (__ieee754_logl): Likewise. * sysdeps/ieee754/dbl-64/e_log.c (__ieee754_log): Return +0 when argument is 1. * sysdeps/ieee754/ldbl-128/e_logl.c (__ieee754_logl): Likewise. * sysdeps/x86_64/fpu/e_logl.S: Take absolute value when x - 1 is zero. * math/libm-test.inc (log_test): Use ALL_RM_TEST. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulps: Likewise. diff --git a/math/libm-test.inc b/math/libm-test.inc index 7abc7c1..5e50f0e 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -7786,9 +7786,7 @@ static const struct test_f_f_data log_test_data[] = static void log_test (void) { - START (log, 0); - RUN_TEST_LOOP_f_f (log, log_test_data, ); - END; + ALL_RM_TEST (log, 0, log_test_data, RUN_TEST_LOOP_f_f, END); } diff --git a/sysdeps/i386/fpu/e_log.S b/sysdeps/i386/fpu/e_log.S index 0877924..3fa32aa 100644 --- a/sysdeps/i386/fpu/e_log.S +++ b/sysdeps/i386/fpu/e_log.S @@ -46,7 +46,13 @@ ENTRY(__ieee754_log) fnstsw // x-1 : x : log(2) andb $0x45, %ah jz 2f - fstp %st(1) // x-1 : log(2) + fxam + fnstsw + andb $0x45, %ah + cmpb $0x40, %ah + jne 5f + fabs // log(1) is +0 in all rounding modes. +5: fstp %st(1) // x-1 : log(2) fyl2xp1 // log(x) ret diff --git a/sysdeps/i386/fpu/e_logf.S b/sysdeps/i386/fpu/e_logf.S index 485180e..ca83d39 100644 --- a/sysdeps/i386/fpu/e_logf.S +++ b/sysdeps/i386/fpu/e_logf.S @@ -47,7 +47,13 @@ ENTRY(__ieee754_logf) fnstsw // x-1 : x : log(2) andb $0x45, %ah jz 2f - fstp %st(1) // x-1 : log(2) + fxam + fnstsw + andb $0x45, %ah + cmpb $0x40, %ah + jne 5f + fabs // log(1) is +0 in all rounding modes. +5: fstp %st(1) // x-1 : log(2) fyl2xp1 // log(x) ret diff --git a/sysdeps/i386/fpu/e_logl.S b/sysdeps/i386/fpu/e_logl.S index d7a459a..edae1d7 100644 --- a/sysdeps/i386/fpu/e_logl.S +++ b/sysdeps/i386/fpu/e_logl.S @@ -47,7 +47,13 @@ ENTRY(__ieee754_logl) fnstsw // x-1 : x : log(2) andb $0x45, %ah jz 2f - fstp %st(1) // x-1 : log(2) + fxam + fnstsw + andb $0x45, %ah + cmpb $0x40, %ah + jne 5f + fabs // log(1) is +0 in all rounding modes. +5: fstp %st(1) // x-1 : log(2) fyl2xp1 // log(x) ret diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps index 3be1806..b7b2e12 100644 --- a/sysdeps/i386/fpu/libm-test-ulps +++ b/sysdeps/i386/fpu/libm-test-ulps @@ -1096,6 +1096,18 @@ Function: "log1p": ildouble: 1 ldouble: 1 +Function: "log_downward": +ildouble: 1 +ldouble: 1 + +Function: "log_towardzero": +ildouble: 1 +ldouble: 1 + +Function: "log_upward": +ildouble: 1 +ldouble: 1 + Function: "pow": ildouble: 1 ldouble: 1 diff --git a/sysdeps/i386/i686/fpu/e_logl.S b/sysdeps/i386/i686/fpu/e_logl.S index 8a86222..53a3d10 100644 --- a/sysdeps/i386/i686/fpu/e_logl.S +++ b/sysdeps/i386/i686/fpu/e_logl.S @@ -46,7 +46,13 @@ ENTRY(__ieee754_logl) fcomip %st(1) // |x-1| : x-1 : x : log(2) fstp %st(0) // x-1 : x : log(2) jc 2f - fstp %st(1) // x-1 : log(2) + fxam + fnstsw + andb $0x45, %ah + cmpb $0x40, %ah + jne 4f + fabs // // log(1) is +0 in all rounding modes. +4: fstp %st(1) // x-1 : log(2) fyl2xp1 // log(x) ret diff --git a/sysdeps/ieee754/dbl-64/e_log.c b/sysdeps/ieee754/dbl-64/e_log.c index 05d318b..4ecd372 100644 --- a/sysdeps/ieee754/dbl-64/e_log.c +++ b/sysdeps/ieee754/dbl-64/e_log.c @@ -96,6 +96,10 @@ __ieee754_log (double x) if (__glibc_likely (ABS (w) > U03)) goto case_03; + /* log (1) is +0 in all rounding modes. */ + if (w == 0.0) + return 0.0; + /*--- Stage I, the case abs(x-1) < 0.03 */ t8 = MHALF * w; diff --git a/sysdeps/ieee754/ldbl-128/e_logl.c b/sysdeps/ieee754/ldbl-128/e_logl.c index 3d1034d..cb43816 100644 --- a/sysdeps/ieee754/ldbl-128/e_logl.c +++ b/sysdeps/ieee754/ldbl-128/e_logl.c @@ -240,6 +240,8 @@ __ieee754_logl(long double x) /* On this interval the table is not used due to cancellation error. */ if ((x <= 1.0078125L) && (x >= 0.9921875L)) { + if (x == 1.0L) + return 0.0L; z = x - 1.0L; k = 64; t.value = 1.0L; diff --git a/sysdeps/x86_64/fpu/e_logl.S b/sysdeps/x86_64/fpu/e_logl.S index a8e3108..315afc0 100644 --- a/sysdeps/x86_64/fpu/e_logl.S +++ b/sysdeps/x86_64/fpu/e_logl.S @@ -45,7 +45,13 @@ ENTRY(__ieee754_logl) fnstsw // x-1 : x : log(2) andb $0x45, %ah jz 2f - fstp %st(1) // x-1 : log(2) + fxam + fnstsw + andb $0x45, %ah + cmpb $0x40, %ah + jne 5f + fabs // log(1) is +0 in all rounding modes. +5: fstp %st(1) // x-1 : log(2) fyl2xp1 // log(x) ret diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps index 5f4ab06..301eaa6 100644 --- a/sysdeps/x86_64/fpu/libm-test-ulps +++ b/sysdeps/x86_64/fpu/libm-test-ulps @@ -1170,6 +1170,22 @@ ifloat: 1 ildouble: 1 ldouble: 1 +Function: "log_downward": +float: 1 +ifloat: 1 +ildouble: 1 +ldouble: 1 + +Function: "log_towardzero": +ildouble: 1 +ldouble: 1 + +Function: "log_upward": +float: 1 +ifloat: 1 +ildouble: 1 +ldouble: 1 + Function: "pow": float: 1 ifloat: 1