From owner-dev-commits-src-main@freebsd.org Sat Apr 10 12:02:17 2021 Return-Path: Delivered-To: dev-commits-src-main@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id D1C335E425E; Sat, 10 Apr 2021 12:02:17 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4FHYX95PtMz3Dbs; Sat, 10 Apr 2021 12:02:17 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id A240610CDD; Sat, 10 Apr 2021 12:02:17 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 13AC2Hmr092269; Sat, 10 Apr 2021 12:02:17 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 13AC2Hgh092268; Sat, 10 Apr 2021 12:02:17 GMT (envelope-from git) Date: Sat, 10 Apr 2021 12:02:17 GMT Message-Id: <202104101202.13AC2Hgh092268@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Dimitry Andric Subject: git: 3b00222f156d - main - Avoid raising unexpected floating point exceptions in libm MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: dim X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 3b00222f156dca5700c839d73e36daf479fa640c Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-main@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for the main branch of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 10 Apr 2021 12:02:17 -0000 The branch main has been updated by dim: URL: https://cgit.FreeBSD.org/src/commit/?id=3b00222f156dca5700c839d73e36daf479fa640c commit 3b00222f156dca5700c839d73e36daf479fa640c Author: Dimitry Andric AuthorDate: 2021-04-09 23:07:54 +0000 Commit: Dimitry Andric CommitDate: 2021-04-10 11:59:57 +0000 Avoid raising unexpected floating point exceptions in libm When using clang with x86_64 CPUs that support AVX, some floating point transformations may raise exceptions that would not have been raised by the original code. To avoid this, use the -fp-exception-behavior=maytrap flag, introduced in clang 10.0.0. In particular, this fixes a number of test failures with ctanhf(3) and ctanf(3), when libm is compiled with -mavx. An unexpected FE_INVALID exception is then raised, because clang emits vdivps instructions to perform certain divides. (The vdivps instruction operates on multiple single-precision float operands simultaneously, but the exceptions may be influenced by unused parts of the XMM registers. In this particular case, it was calculating 0 / 0, which results in FE_INVALID.) If -fp-exception-behavior=maytrap is specified however, clang uses vdivss instructions instead, which work on one operand, and should not raise unexpected exceptions. Reported by: olivier Reviewed by: arichardson PR: 254911 MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D29686 --- lib/msun/Makefile | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/lib/msun/Makefile b/lib/msun/Makefile index 4491bc216a4c..959dbd113ec1 100644 --- a/lib/msun/Makefile +++ b/lib/msun/Makefile @@ -34,6 +34,16 @@ CFLAGS+= -I${.CURDIR}/ld128 CFLAGS+= -I${.CURDIR}/${ARCH_SUBDIR} +.include +.if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 100000 +# When using clang with x86_64 CPUs that support AVX, some floating point +# transformations may raise exceptions that would not have been raised by the +# original code. To avoid this, use the -fp-exception-behavior=maytrap flag, +# introduced in clang 10.0.0. +# See also: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=254911 +CFLAGS+= -ffp-exception-behavior=maytrap +.endif + .PATH: ${.CURDIR}/bsdsrc .PATH: ${.CURDIR}/src .PATH: ${.CURDIR}/man @@ -113,7 +123,6 @@ COMMON_SRCS+= catrigl.c \ # 'long double' [-Werror=overflow] # if( y >= LDBL_MAX ) # See also: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=130067 -.include .if ${COMPILER_TYPE} == "gcc" CFLAGS.e_powl.c+= -Wno-error=overflow .endif