On Sat, Apr 26, 2014, Dongsheng Song wrote: > On Sat, Apr 26, 2014 at 3:22 PM, Adrien Nader <adr...@notk.org> wrote: > > On Sat, Apr 26, 2014, Dongsheng Song wrote: > >> On Sat, Apr 26, 2014 at 12:31 AM, Adrien Nader <adr...@notk.org> wrote: > >> > I believe --with-arch=core2 is a big issue for generic toolchains. It > >> > will create troubles which will be very annoying to pinpoint. > >> > > >> > Any x86_64/amd64/EM64T (I love how Intel always makes up awful names) > >> > already has SSE2 and there is little value in restricting this except in > >> > very specific situation which are better dealt on a case-by-case basis. > >> > > >> > Regards, > >> > Adrien Nader > >> > > >> > >> Do you really meet this issue ? I can not image someone still running > >> 64 bit Windows on such old CPU. > >> > >> Intel core2 release in July 2006, shutdown in January 2010. > >> http://en.wikipedia.org/wiki/Intel_Core_2 > > > > I have troubles believing people still run XP but many do. :P > > > > The issue is rather when you look at the AMD CPUs. > > First models with SSE3 are from the end of 2007 (meaning you would still > > easily see machines with them at the end of 2008, even beginning of > > 2009). > > The real issue is with SSSE3 (one more 'S') since the first mobile CPUs > > with it have been released beginning of 2011 and the first desktop CPUs > > with it have been released end of 2011 are are still easily found. > > > > I have a machine without SSE3 in my living room (albeit it needs a new > > PSU), along with a machine without SSSE3 which is definitely running > > strong (in particular since the rate of CPU speed improvement has > > dramatically slowed down in the last few years). > > > > I don't think there is a point in making core2 the default; I don't > > think it will bring any improvements except when building multimedia > > stuff and even then it's not unlikely they don't provide hand-tuned > > assembly but even then, -mtune should do be able to bring the > > performance benefits on the newer CPUs while still running on the older > > ones. > > > > I agree with you the performance view. > > But from gcc view, Intel 64 cpu is: nocona, core2 or later. In my > memory, I never hear someone can run 64 bit windows on nocona without > problem. I know it's unfair for AMD CPUs, but both without -march and > with -march=<amd cpu type> give 3DNow defined, it's not acceptable for > Intel CPUs.
"Intel 64" is a name that doesn't exist. It's either AMD64 (AMD parlance), EM64T (Intel parlance), x64 (Microsoft parlance) or x86_64 (parlance of anyone not interested in marketing and propaganda). The first CPUs handling x86_64 date from 2003 and were server-class CPUs. Using "--with-arch=core2" means that there many CPUs sold during pretty much *10* years will not be able to run the programs compiled with these toolchains and will crash at surprising times in surprising ways. Right now I have a Windows 8 x86_64 VM running on a CPU from 2009 or 2010 without SSSE3. Actually it maybe doesn't have SSE3 either. I've never had issues with x86_64 stuff on it. I've also grabbed my XP 64 box and there's a cute logo of a Pentium 4. While everyone will agree XP 64 was far from perfect, I think it's a good indication that it worked at least for some people. As for not specifying any arch, I wasn't able to quickly find a reference or documentation on the matter. However, Linux distributions are a good example however: they run on all x86_64 CPUs and don't set anything specific and that's what a generic toolchain should do too. In any case, if not setting --with-arch makes code that cannot run on the triplet specified during the build of GCC (which I do not believe) then this is an issue in GCC and should be dealt in GCC and not worked-around (but again, I believe it is not the case). -- Adrien Nader ------------------------------------------------------------------------------ Start Your Social Network Today - Download eXo Platform Build your Enterprise Intranet with eXo Platform Software Java Based Open Source Intranet - Social, Extensible, Cloud Ready Get Started Now And Turn Your Intranet Into A Collaboration Platform http://p.sf.net/sfu/ExoPlatform _______________________________________________ Mingw-w64-public mailing list Mingwemail@example.com https://lists.sourceforge.net/lists/listinfo/mingw-w64-public