From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 99403 invoked by alias); 18 Sep 2015 20:36:10 -0000 Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org Received: (qmail 99363 invoked by uid 55); 18 Sep 2015 20:36:06 -0000 From: "cvs-commit at gcc dot gnu.org" To: glibc-bugs@sourceware.org Subject: [Bug math/18981] i386 scalb*, ldexp return with excess range and precision Date: Fri, 18 Sep 2015 20:36:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: math X-Bugzilla-Version: 2.22 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2015-09/txt/msg00266.txt.bz2 https://sourceware.org/bugzilla/show_bug.cgi?id=18981 --- Comment #2 from cvs-commit at gcc dot gnu.org --- This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "GNU C Library master sources". The branch, master has been updated via 94ced920a951bcab51f2ef955ccd2cc51668e6f3 (commit) from 89faa0340ad399ead8104f8fb6b7fed81f7d939c (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=94ced920a951bcab51f2ef955ccd2cc51668e6f3 commit 94ced920a951bcab51f2ef955ccd2cc51668e6f3 Author: Joseph Myers Date: Fri Sep 18 20:34:59 2015 +0000 Avoid excess range in results from i386 scalb functions (bug 18981). i386 scalb / scalbn / scalbln (and thus ldexp) functions for float and double can return results with excess range (and consequently excess precision for subnormal results). As the results of these functions are fully determined by reference to IEEE 754 operations, this is unambiguously a bug, apart from the testsuite failures it causes. This patch makes those functions store their results on the stack and load them back to eliminate the excess range. Double rounding is not a problem, as the only cases where it could occur are when the result overflows or underflows for extended precision, and then the double-rounded results are the same as the single-rounded results. The new macros will be used for more functions, more such macros added, and existing code refactored to use such macros, in subsequent patches. Tested for x86. Committed. [BZ #18981] * sysdeps/i386/fpu/i386-math-asm.h: New file. * sysdeps/i386/fpu/e_scalb.S: Include . (__ieee754_scalb): Use DBL_NARROW_EVAL. * sysdeps/i386/fpu/e_scalbf.S: Include . (__ieee754_scalbf): Use FLT_NARROW_EVAL. * sysdeps/i386/fpu/s_scalbn.S: Include . (__scalbn): Use DBL_NARROW_EVAL. * sysdeps/i386/fpu/s_scalbnf.S: Include . (__scalbnf): Use FLT_NARROW_EVAL. ----------------------------------------------------------------------- Summary of changes: ChangeLog | 13 +++++++++ NEWS | 2 +- sysdeps/i386/fpu/e_scalb.S | 2 + sysdeps/i386/fpu/e_scalbf.S | 2 + .../i386/fpu/i386-math-asm.h | 29 +++++++++++++------ sysdeps/i386/fpu/s_scalbn.S | 2 + sysdeps/i386/fpu/s_scalbnf.S | 2 + 7 files changed, 42 insertions(+), 10 deletions(-) copy benchtests/bench-util.h => sysdeps/i386/fpu/i386-math-asm.h (58%) -- You are receiving this mail because: You are on the CC list for the bug.