Date: Wed, 05 Jan 2011 09:50:45 -0700 From: Warner Losh <imp@bsdimp.com> To: John Baldwin <jhb@FreeBSD.org> Cc: Gleb Kurtsou <gleb.kurtsou@gmail.com>, src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, Dimitry Andric <dim@FreeBSD.org>, svn-src-head@FreeBSD.org, Alexander Best <arundel@FreeBSD.org> Subject: Re: svn commit: r216977 - in head/libexec/rtld-elf: amd64 i386 Message-ID: <4D24A165.4080506@bsdimp.com> In-Reply-To: <201101050759.50877.jhb@freebsd.org> References: <201101042051.p04KpSGk054564@svn.freebsd.org> <20110105011635.GA4952@freebsd.org> <20110105121910.GA1841@tops.skynet.lt> <201101050759.50877.jhb@freebsd.org>
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On 01/05/2011 05:59, John Baldwin wrote: > On Wednesday, January 05, 2011 7:19:10 am Gleb Kurtsou wrote: >> On (05/01/2011 01:16), Alexander Best wrote: >>> On Tue Jan 4 11, Dimitry Andric wrote: >>>> Author: dim >>>> Date: Tue Jan 4 20:51:28 2011 >>>> New Revision: 216977 >>>> URL: http://svn.freebsd.org/changeset/base/216977 >>>> >>>> Log: >>>> On amd64 and i386, tell the compiler to refrain from generating SSE, >>>> 3DNow, MMX and floating point instructions in rtld-elf. >>>> >>>> Otherwise, _rtld_bind() (and whatever it calls) could possibly clobber >>>> function arguments that are passed in SSE/3DNow/MMX/FP registers, >>>> usually floating point values. This can happen, for example, when clang >>>> generates SSE code for memset() or memcpy() calls. >>> the sorting order for these flags seems to be: >>> >>> -mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3 >>> >>> see 'grep -R "\-no-sse" /usr/src'. maybe the sorting order should stay >>> consistent? >>> >>> also what's the status of clang? will these flags make sure that newer >>> cpu extension won't be activated? i checked >>> contrib/llvm/tools/clang/include/clang/Driver/Options.td >>> and clang has support for: >>> >>> -m3dnowa >>> -mssse3 >>> -msse4a >>> -msse4 >>> -msse4_1 >>> -msse4_2 >>> -maes >>> -mavx >>> >>> since these extensions only get set in a hand full of files maybe special >>> cases for CC == clang can be added. >> Why not to add NO_HWFLOAT knob (or similar) into makefile >> infrastructure. And set CFLAGS accordingly, depending on CC, arch, etc. >> These flags are getting rather common in tree. > It strikes me that we really want clang/gcc to have some sort of > '-mno-hwfloat' so we don't keep having to add new flags in the future. gcc already has -msoftfloat, but I guess that's a little different than what you are proposing... Warner
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