Date: Thu, 21 Aug 2025 10:43:41 +0000 From: bugzilla-noreply@freebsd.org To: numerics@FreeBSD.org Subject: [Bug 288778] [libm] Fix undefined behavior of a left shifted of a signed integer Message-ID: <bug-288778-18636-RLYG40lhES@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-288778-18636@https.bugs.freebsd.org/bugzilla/> References: <bug-288778-18636@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=288778 --- Comment #9 from commit-hook@FreeBSD.org --- A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=94b09b2f3440b16b58dd744fcaa73229f6503c10 commit 94b09b2f3440b16b58dd744fcaa73229f6503c10 Author: Steve Kargl <kargl@FreeBSD.org> AuthorDate: 2025-08-12 04:26:29 +0000 Commit: Dimitry Andric <dim@FreeBSD.org> CommitDate: 2025-08-21 10:41:41 +0000 [libm] Fix undefined behavior of a left shifted of a signed integer The patch fixes a few instances of left shifts on signed integer entities. A 'static inline' helper function 'subnormal_ilogb()' has been added to math_private.h. This function is then used e_fmod.c, s_ilogb(), and s_remquo.c. The change in s_remquo.c has only been compile tested. The change to e_fmod.c has been test on over 3 billion pairs of subnormal numbers where testing included x > y and x < y pairs. The test compared the output from fmod() with the output from mpfr_fmod() from MPFR. There were no difference. The change to s_ilogb() has had limited testing where its output was compared against frexp(). In this testing, no differences in output were detected. PR: 288778 MFC after: 1 week (cherry picked from commit d180086e6eae2e152e803ed6cf13775a7c006dc7) lib/msun/src/e_fmod.c | 30 ++++++++++++------------------ lib/msun/src/math_private.h | 21 +++++++++++++++++++++ lib/msun/src/s_ilogb.c | 13 +++++-------- lib/msun/src/s_remquo.c | 30 ++++++++++++------------------ 4 files changed, 50 insertions(+), 44 deletions(-) -- You are receiving this mail because: You are the assignee for the bug.
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