Date: Wed, 5 Jan 2011 07:59:50 -0500 From: John Baldwin <jhb@freebsd.org> To: Gleb Kurtsou <gleb.kurtsou@gmail.com> Cc: svn-src-head@freebsd.org, Alexander Best <arundel@freebsd.org>, svn-src-all@freebsd.org, src-committers@freebsd.org, Dimitry Andric <dim@freebsd.org> Subject: Re: svn commit: r216977 - in head/libexec/rtld-elf: amd64 i386 Message-ID: <201101050759.50877.jhb@freebsd.org> In-Reply-To: <20110105121910.GA1841@tops.skynet.lt> References: <201101042051.p04KpSGk054564@svn.freebsd.org> <20110105011635.GA4952@freebsd.org> <20110105121910.GA1841@tops.skynet.lt>
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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. -- John Baldwin
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